Department of Chemistry
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Item Open Access Investigation in solution properties of bio-active solutes and mineral salts prevailing in some aqueous and non-aqueous solvent system(University of North Bengal, 2012) Roy, Pran Kumar; Roy, Mahendra NathThermo-physical and bulk properties of solutions are very useful to obtain information on the intermolecular interactions and geometrical effects in the systems. Moreover, knowledge of the thermodynamic properties is essential for the proper design of industrial processes. Accurate knowledge of thermodynamic properties of solution mixtures has great relevance in theoretical and applied areas of research. The branch of physical chemistry that studies the change in properties that arise when one substance dissolves in another substance is termed as solution chemistry. It investigates the solubility of substances and how it is affected by the chemical nature of both the solute and the solvent. The mixing of different solute or solvent with another solvent/solvent mixtures gives rise to solutions that generally do not behave ideally. This deviation from ideality is expressed in terms of many thermodynamic parameters, by excess properties in case of liquid-liquid mixtures and apparent molar properties in case of solid-liquid mixtures. These thermodynamic properties of solvent mixtures corresponds to the difference between the actual property and the property if the system behves ideally and thus are useful in the study of molecular interactions and arraangements. In particular, they reflect the interaction that take place between solute-solute, solute-solvent and solvent-solvent species.However, the exact structure of the solvent molecule is not known with certainity. The addition of an ion or solute modifies the solvent structure to an extent whereas the solute molecules are also modified. The extent of ion-salvation is dependent upon the interactions taking place between solute-solute, solute-solvent, solvent-solvent species. The assesment of ion-pairing in these systems is important because of its effect on the ionic mobility and hence on the ionic conductivity of the ions in solution. These phenomenon thus paves the path for research in solution chemistry to elucidate the nature of interaction through experimental studies involving densitometry, viscometry, interferrometry, refractometry and other suitable methods and to interpret the experimental data collected. Caffeine, nicotinamide, resorsinol, glycine, catechol, oxalic acid, tetrabutyl ammonium iodide, tetra pentyl ammonium iodide, tetra hexyl ammonium iodide, tetra heptyl ammonium iodide, N-Cetyl-N,N,N-trimethyl ammonium bromide, DGlucose, D-Mannitol, D-Sucrose, thorium nitrate, sodium molibdate, phosphomolibdic acid, lithim nitrate, potassium nitrate, sodium nitrate, silver sulphate which are considered as solutes, have been chosen in this research work. Nitrobenzene, carbon tetrachloride, 2-Methoxy ethanol, along with water also considered as solvents. These solutes and solvents have wide application in chemical fields and various industries like pharmaceuticals, cosmetics, battery technology, agricultural products etc. In this research work more emphasis have been given to Bio active compounds ("plant bioactives" or "bioactive compounds") they are mainly inherent non-nutrient constituents of food plants and edible mushrooms with anticipated health promoting and toxic effects when ingested. Bioactive compounds derived from plant foods, are of growing interest to the scientific community and food industry because of their putative health-promoting properties. Increasing evidences report beneficial effects of bioactive compounds, particularly against cancers, cardiovascular diseases and diabetes. They may also serve as adjusting factors in human body due to their physiological activity. Most bioactive compounds of natural origin are secondary metabolites, i.e., species-specific chemical agents. Information about food sources, concentrations and intakes of bioactive compounds, as well knowledge of their absorption, metabolism and biological effects, is needed in order to evaluate their potential health benefits. Pharmacological activity is usually taken to describe beneficial effects of bioactive compounds. There is sufficient evidence to recommend consuming food sources rich in bioactive compounds. From a practical perspective, this translates to recommending a diet rich in a variety of fruits, vegetables, whole grains, legumes, oils, and nuts. In the body under physiological conditions, many vital functions are regulated by pulsed or transient release of bioactive substances at a specific time and site. Thus, to mimic the function of living systems, it is important to develop new drug delivery devices to achieve pulsed delivery of a certain amount of a bioactive compound at predetermined time intervals. The ability to deliver bioactive compounds and/ or therapeutic agents to a patient in a palatine or staggered release profile has been a major goal in drug delivery research over the last two decades. Rice bran has been recognized as an excellence source of bioactive compounds, but only a small amount is consumed by humans. The limitation of using rice bran in a food industry is its rough texture and low concentration of bioactive compounds, when incorporated into food products. Various methods have been developed to enhance the level of bioactive components in food materials, including thermal, alkali, acid and chemical treatments. Many bioactive compounds have been discovered. These compounds vary widely in chemical structure and function and are grouped accordingly. Phenolic compounds, including their subcategory, flavonoids, are present in all plants and have been studied extensively in cereals, legumes, nuts, olive oil, vegetables, fruits, tea, and red wine. Many phenolic compounds have antioxidant properties, and some studies have demonstrated favorable effects on thrombosis and tumorogenesis and promotion. One of many phenolics in olives and olive oil is a potent antioxidant. Resveratrol, found in nuts and red wine, has antioxidant, antithrombotic, and anti-inflammatory properties, and inhibits carcinogenesis. Lycopene, a potent antioxidant carotenoid in tomatoes and other fruits, is thought to protect against prostate and other cancers, and inhibits tumor cell growth in animals. Catechol is used mainly as a precursor to pesticides, flavors and fragrances. It is also consumed in the production of pesticides, the remainder being used as a precursor to fine chemicals such as perfumes and pharmaceuticals. Mannitol is used clinically to reduce acutely raised intracranial pressure until more definitive treatment can be applied, e.g., after head trauma. It is also used to treat patients with oliguric renal failure.Glucose circulates in the blood, providing energy to organs, glands, muscles, indeed to every cell Glucose is used in oxidation. More complex sugars have to be changed to glucose first before they can be broken down to release energy in respiration Glucose is a ubiquitous fuel in biology. Caffeine is an alkaloid of methylxanthine family, its main pharmacological properties are a stimulant action on the central nervous system .it also acts as a natural pesticide since it paralyses and kills some of the insects. Organosulfur compounds in garlic and onions, isothiocyanates in cruciferous vegetables, and monoterpenes in citrus fruits, cherries, and herbs have anticarcinogenic actions in experimental models, as well as cardioprotective effects. Sodium Molybdate is used in industry for corrosion inhibition, as it is a nonoxidizing anodic inhibitor. The addition of sodium molybdate significantly reduces the nitrite requirement of fluids inhibited with nitrite-amine, and improves the corrosion protection of carboxylate salt fluids. Phosphomolybdic acid is widely used to stain connective tissues by dyes. It has been found polyvalent phosphomolybdic acid appears to form a bridge between the basic group of the substrate and the basic group of the dye. Oxalic acid and oxalates are useful as reducing agents for photography, bleaching, and rust removal. They are widely used as a purifying agent in pharmaceutical industry, precipitating agent in rare-earth metal processing, bleaching agent in textile and wood industry, rust-remover for metal treatment, grinding agent, waste water treatment. It is used as acid rinse in laundries and removing scale from automobile radiators. Nicotinamide is commonly known as vitamin B. It plays a very important role to maintain the normal function of the digestive systems and cholesterol levels in the human body. The combination of nicotinic acid and nicotinamide is clinically referred to as niacin. Glycine serves as a buffering agent in antacids, analgesics, antiperspirants, cosmetics, and toiletries. Glycine is an intermediate in the synthesis of a variety of chemical products. In summary numerous bioactive compounds appear to have beneficial health effects. I Much scientific research needs to be conducted before we can begin to make science-based dietary recommendations. On the other hand minerals are naturally-occurring elements needed by the body and its vital activities. Each mineral, with its own specific task, even in the small and often minute quantities necessary, is indispensable for important life functions; they are needed for the formation of hormones, enzymes and other body substances. They're generally found in foods in the form of chemical compounds called salts and in water in the form of ion.soluble. Animals need more than salt for proper health and nutrition. Animals need trace mineral supplements. They are needed in very small amounts, or traces, in the diet, and hence their name, "trace minerals. Mineral salts do not usually contain the element carbon and are therefore inorganic (organic compounds always contain carbon).Plant roots absorb individual mineral ions from soil water. Some of the ions travel by diffusion into the root; others are absorbed by active transport. The minerals required in the greatest amounts are those containing the element nitrogen, for example nitrate ions ( or 'nitrates'), which are a key component of inorganic fertilizer. A plant uses nitrates in the production of proteins such as enzymes, so they are important for plant growth. They are often in short supply in the soil, which is why inorganic fertilizers are required. Plants also require magnesium in order to make chlorophyll, the green chemical that absorbs the ei:iergy of sunlight for photosynthesis. Sodium nitrate is used as an ingredient in fertilizers, pyrotechnics, as an ingredient in smoke bombs, as a food preservative, and as a solid rocket propellant, as well as in glass and pottery enamels. Potassium nitrate is a strong oxidizer which burns and explodes with organics. It is used in the manufacture of gunpowder. It is also used in explosives, fireworks, matches, and fertilizers, and as a preservative in foods especially meats. It is sometimes used in medicine as a diuretic. Lithium nitrate is used as an electrolyte for high temperature batteries. It is also used for long life batteries as required, for example, by artificial pacemakers. The solid is used as a phosphor for neutron detection.Quaternary ammonium compounds compounds are used as, Surface-active agents , Solvents , Intermediates, Active Ingredient for Conditioners, Antistatic Agent, Detergent Sanitisers, Softner for textiles and paper products, Phase Transfer Catalyst, Antimicrobials, Disinfection Agents And Sanitizers, Slimicidal Agents, Algaecide, Emulsifying Agents, Pigment Dispersers. The study of these solvents and solutes, in general, are of interest because of their wide use in many industries with interests ranging from pharmaceutical to cosmetic products. Summary of the Works Done CHAPTERI This chapter contains the object and applications of the research work, the solvents and solutes used and methods of investigations. This also involves the summary of the works done associated with the thesis. CHAPTER-II This chapter contains the general introduction of the thesis and forms the background of the present work. A brief review of notable works in the field of ionsolvent interaction has been given. The discussion includes solute-solvent, solutesolute and solvent-solvent interactions of mixed solvent systems and of electrolytes in pure, aqueous, non-aqueous solvent systems at various temperatures in terms of various derived parameters of conductance, density, viscosity, ultrasonic speed, and refractive index. Critical evaluations of different methods on the relative merits and demerits on the basis of various assumptions employed from time to time of obtaining the single ion values and their implications have been made. The molecular interactions are interpreted based on various equations. l., CHAPTER-III This chapter contains the experimental section which mainly involves the structure, source, purification and application of the solvents and solutes used and the details of the experimental methods employed for measurement of the thermodynamic, transport, acoustic and optical properties. CHAPTER-IV This chapter quantifies the Precise measurements on electrical conductances of tetraalkylammonium iodides, R4NI (R = butyl to heptyl) in different mass% (20- 80) of carbon tetrachloride + nitrobenzene at 298.15 K have been performed. Limiting molar conductances ( A0 ), association constants (KA) and co-sphere diameter ( R) for ion-pair formation in the mixed solvent mixtures have been evaluated using the Lee-Wheaton conductivity equation. However, the deviation of the conductometric curves ( A versus ✓c ) from linearity for the electrolytes in 80 mass% of carbon tetrachloride + nitrobenzene indicated triple ion formation and therefore corresponding conductance data have been analyzed by the Fuoss- Kraus theory of triple ions. Limiting ionic molar conductances (A~) have been calculated by the reference electrolyte method along with a numerical evaluation of ion-pair and triple-ion formation constants ( KP ~ KA and Kr); the results have been discussed in terms of solvent properties, configurational theory and molecular scale model. CHAPTER-V In this chapter, Partial molar volumes ( (l) and viscosity B-coefficients for nicotinamide in (0.00, 0.05, 0.10, 0.15, and 0.20) mol.dm-3 aqueous resorcinol solutions have been determined from solution density and viscosity measurements at (298.15, 308.15, and 318.15) Kasa function of the concentration of nicotinamide (NA). Here the relation ¢i = a0 + a1T + a2T2 , has been used to describe the temperature dependence of the partial molar volume ( ¢i) .These results and the results obtained in pure water were used to calculate the standard volumes of transfer ( t1¢i) and viscosity B-coefficients of transfer for nicotinamide from water to aqueous resorcinol solutions to study various interactions in the ternary solutions. The partial molar volume ( ¢S) and experimental slopes obtained from the Masson equation have been interpreted in terms of solute-solvent and solutesolute interactions, respectively. The viscosity data have been analyzed using the Jones-Dole equation, and the derived parameters Band A have also been interpreted in terms of solute-solvent and solute-solute interactions, respectively in the ternary solutions. The structure making or breaking ability of nicotinamide has been discussed in terms of the sign of (c>2¢i I 8T 2 ) p. The activation parameters of viscous flow for the ternary solutions studied were also calculated and explained by the application of transition state theory. CHAPTER-VI Proteins are complex molecules and their behavior in solutions is governed by a combination of many specific interactions. One approach that reduces the degree of complexity and requires less complex measurement techniques is to study the interactions in systems containing smaller biomolecules, such as amino acids and peptides. Some studies have revealed that the presence of an electrolyte drastically affects the behaviors of amino acids in solutions and this fact can be used for their separation and purification. Therefore, in this chapter an attempt has been made to unravel the various interactions prevailing in a amino acid, Glycine in aqueous silver sulphate solutions by volumetric, viscometric study at 298.15, 308.15, 318.15 K. CHAPTER-VII In this chapter Apparent molar volume ( r/Jv) and viscosity B-coefficients were measured for phosphomolybdic acid in aqueous solution of catechol from solution density [p) and viscosity [TJ) at 298.15, 308.15 and 318.lSK at various solute concentrations. The experimental density data were evaluated by Masson equation and the derived data were interpreted in terms of ion-solvent and ion-ion interactions. The viscosity data have been analyzed using Jones -Dole equation and the derived parameters, B and A, have been interpreted in terms of ion-solvent and ion-ion interactions respectively. The structure-making or breaking capacity of the solute under investigation has been discussed in terms of sign of(f/¢i I 8T 2 ) p. The activation parameters of viscous flow were determined and discussed by application of transition state theory. CHAPTER-VIII This chapter presents a study of densities, viscosities and sound speeds have been determined for sodium molybdate in various mole-fractions of aqueous oxalic acid solutions. From the experimental data, apparent molar volume ( ¢v) and viscosity B-coefficients were calculated at 303.15, 313.15 and 323.lSK using Masson equation and Jones - Dole equation respectively. Adiabatic compressibility of different solutions has been determined from measurement of ultrasonic speeds of sound at 303.lSK. Partial molar volumes ( r/Ji) and viscosity B-coefficients (LlB) of transfer from water to aqueous oxalic acid mixtures have been calculated and discussed. The structure-making or breaking capacity of the solute under investigation has been discussed in terms of sign of ( 8 2 r/Ji I 8 T 2 ),, • The activation parameters of viscous flow were determined and discussed by application of transition state theory. CHAPTER-IX This chapter presents a study of Apparent molar volumes ( ¢i) and viscosity B-coefficients for mineral salts in aqueous binary mixture of 2-methoxy ethanol have been estimated from solution density and viscosity measurements at 298.15 K and at various electrolyte concentrations as a function of the concentration of mineral salts. Experimental density data were analyzed using the Masson equation and the derived parameters interpreted in terms of ion-solvent and ion-ion interactions. The viscosity data have been analyzed using the Jones-Dole equation, and the derived parameters B and A have also been interpreted in terms of solutesolvent and solute-solute interactions. CHAPTER-X In this chapter, Apparent molar volumes ( ¢v) and viscosity B-coefficients for some carbohydrates (D-Glucose, D-Mannitol and D-Sucrose) in 0.05%, 0.10%, 0.15%, aqueous cetrimmonium bromide (N-Cetyl-N,N,N-trimethyl ammonium bromide) (C19H42BrN) solutions have been determined from solution density (p) and viscosity (11) measurements at 298.15, 308.15, and 318.15 Kasa function of the concentration of carbohydrates. The standard partial molar volume ( ¢,~) and experimental slopes ( s:) obtained from the Masson equation have been interpreted in terms of solute-solvent and solute-solute interactions, respectively. The viscosity data were analyzed using the Jones-Dole equation, and the derived parameters A and B have also been interpreted in terms of solute-solvent and solute-solute interactions, respectively in the mixed solutions. The relation, ¢i = a0 + a1T + a2T2 , has been used to describe the temperature dependence of the standard partial molar volume ( ¢i ). The structure making or breaking ability of carbohydrates has been discussed in terms of sign of (8 2¢i / 8T 2 ) as well as dB/dT- The activation p J parameters of viscous flow were also determined and were discussed by the application of transition state theory. CHAPTER-XI This chapter contains Apparent molar volumes ( ¢v) and viscosity Bcoefficients for the alkaloid- caffeine in (0.00, 0.03, 0.05 and 0.07) mol · dm-3 aqueous thorium nitrate, Th(N03)4 solutions have been determined from solution density and viscosity measurements at temperatures in the range (298.15 to 318.15) K as function of concentration of caffeine. In the investigated temperature range, the relation:Item Open Access Preparation, characterization of bimetalic nanoparticles soakedon poly-ionic resins and their ctalalytic applications(University of North Bengal, 2014) Sengupta, Debasish; Basu, BasudebThe fields of catalysis and nanoscience have been inextricably linked to each other for quite some time. Several inorganic or organic materials like mesoporous silica, zeolites, charcoal, graphene oxides as well as organic polymers have been used either to promote surfacemediated reactions or to immobilize metal nanoparticles for catalytic performance. Both mono- and bi-metallic nanoparticles (NPs) embedded with heterogeneous supports exhibit improved catalytic activity and find applications in several industrial processes. Development of more active, versatile and recyclable catalysts has remained the contemporary challenges in this field of chemistry and catalysis. The present thesis entitled “PREPARATION, CHARACTERIZATION OF BIMETALLIC NANOPARTICLES SOAKED ON POLYIONIC RESINS AND THEIR CATALYTIC APPLICATIONS” has made some efforts to demonstrate new heterogeneous surface-promoted reactions as well as to develop mono- and bi-metallic nanocomposites mainly based on poly-ionic resins and graphene-based carbonaceous materials. These two different heterogeneous supports, either free or embedded with metals, have been utilized in diverse C−C, C−S and S−S bond-forming reactions. The thesis is divided into eight chapters. Chapter I summarizes a brief review on heterogeneous catalysis, nanocomposites and their catalytic applications. Chapter II describes the use poly-ionic resin hydroxide (Amberlyst® A-26(OH)), as an efficient heterogeneous base for the preparation of organic disulfides from alkyl and acyl methyl thiocyanates. Further extension of this protocol has been tested using two different organyl thiocyanates to prepare unsymmetrical disulfides. The present protocol shows the advantage of using the heterogeneous base Amberlyst A-26(OH) over some existing homogeneous bases (NaOH, NH3, K2CO3). The recyclability was also checked. Chapter III delineates a simple procedure for the preparation of poly-ionic amberlite resins embedded with CuO NPs (referred to as CuO@ARF). The as synthesized heterogeneous catalyst CuO@ARF was characterized and successfully applied in C−S cross–coupling reaction under ligand–free and 'on–water' conditions. Low loading of the catalyst, recyclability without leaching and chemoselectivity between aromatic halides are notable features. Further application of the chemoselectivity has been demonstrated in the synthesis of bioactive heterocyclic scaffold phenothiazine. Chapter IV deals with the bi-metallic nanocomposite material. Cationic and macroporous amberlite resins with formate (HCOO¯) as the counter anion (ARF) have been used to prepare a new class of heterogeneous Pd/Cu bimetallic composite nanoparticles (NPs) (Pd/Cu–ARF). The physicochemical characteristics of Pd/Cu−ARF revealed fairly uniform distributions of composite NPs of average size~4.9 nm. The nanocomposite material (Pd/Cu ARF) exhibited high catalytic activity in the Sonogashira cross‒coupling reaction between aryl iodide and terminal alkynes. Heterogeneity of the catalytic activity was evidenced from different tests (hot-filtration and catalyst-poisoning) and the recycling ability of the catalyst was examined for five consecutive runs without any significant loss of activity. Chapter V describes further use of the Pd/Cu bimetallic composite nanoparticles (Pd/Cu ARF) in other cross‒coupling reactions like Suzuki–Miyaura and Mizoroki–Heck reactions. The bi-metallic nanocomposite material was much effective as compared to monometallic Pd–ARF catalyst, as prepared in this laboratory previously. The catalyst was also recyclable for seven consecutive runs with excellent conversions. Chapter VI depicts successful application of graphene oxide (GO) as the metal-free carbocatalysts for (i) sequential dehydration–hydrothiolation reaction from a mixture of secondary aryl alcohols and thiols in toluene and (ii) chemoselective thioacetalization of aldehyde under mild, solvent-free and aerobic conditions. Chapter VII demonstrates the catalytic activity of Ni(0) nanoparticles supported with reduced graphene oxide (Ni/RGO) in Kumada‒Corriu cross‒coupling reaction. A detail study of the catalysis was performed by varying the haloarenes and Grignard reagents. Interestingly, this catalyst was found to be equally active for the oxidative addition to the sp2 C−F bond. The recyclability of the catalyst was examined for six consecutive runs without significant loss of activity. Finally the recovered Ni/RGO was characterized by X-ray diffraction (XRD) and Raman spectroscopy and found to be unaltered. Chapter VIII describes the use of Ni/RGO nanocomposite in C−S cross‒coupling reaction. The catalyst was found to be recyclable for six consecutive runs, as examined.Item Open Access Polydentate ligands and transition metal complexes : photophysics and catalysis(University of North Bengal, 2013) Pariyar, Anand; Bandyopadhyay, P; Biswas, AA brief overview of polydentate ligands and their metal complexes, with special emphasis on their photophysical and catalytic behaviour, has been made. In this background, the objective, scope, and application of the present investigation have been described in Chapter I. A series of novel polydentate macrocyclic corrole ligands has been synthesized and described in chapter II. The photophysical properties of the newly synthesized family of substituted nitrophenyl free base A2B-corroles have been studied. The metal ion sensing abilities of the free base ligands are explored. The A2B corroles emerge as efficient polydentate fluorophore system for selective Hg(II) ion detection in solution. Among all the corroles, the free base 10-(tridecyloxyphenyl)- 5,15-bis(nitrophenyl)corrole substituted with a long chain has been found to exhibit the highest Hg(II) sensing ability. High guest count (up to three mercuric ions per corrole) with a high association constant is observed. The experimental evidences show that the emission intensity quenches with the addition of Hg(II) ion, initially via metal coordination and subsequently through exciplex formation. This is the first report of exciplex formation of corroles with mercury ions. The results obtained will help to improve the design of sensors for the direct determination of Hg(II) ions present in ultra low concentration. The synthesis and characterization of new iron complex of 5,10,15 tris- (difluorophenyl)corrole have been described in chapter III. The catalytic properties of newly synthesized 5,10,15-tris(difluorophenyl)iron(IV)chloride complex [(tdfc)FeIVCl] with benign tert-butylhydroperoxide as the terminal oxidant has been evaluated. The [(tdfc)FeIVCl] /t-BuOOH system has been found to efficiently catalyze the oxidation of alkanes, alkenes, alkylbenzene and alcohols at room temperature. The homolytic cleavage of the O-O bond of tert-butylhydroperoxide by the catalyst is observed and the oxygenates have been shown to be derived from organoperoxides. The results clearly indicates that the main role of the iron(IV) corrole complex is the activation of alkyl hydroperoxide rather than oxygen atom transfer (OAT). Selective hydroxylation of unactivated C-H bonds of alkanes has also been realized using catalyst [(tdfc)FeIVCl] with m-chloroperbenzoic acid as the terminal oxidant. Chapter IV describes iron-corrole complex 5,10,15-tris(pentafluorophenyl) iron(IV) chloride [(tpfc)FeIVCl] catalyzed epoxidation of olefins in ionic liquid [BMIM]PF6 medium at room temperature with different terminal oxidants. For the first time, metallocorrole catalyzed epoxidation of a series of conjugated and nonconjugated olefins has been undertaken in ionic liquid ([BMIM]PF6) medium at room temperature using different terminal oxidants such as t-BuOOH, PhIO and aqueous NaOCl. The product selectivity achieved in ionic liquid medium shows remarkable improvement over those obtained in molecular solvents. The highest product yield is achieved by a biphasic system involving ionic liquid with aqueous NaOCl as the terminal oxidant. The biphasic system provides easy recovery and recycling of the catalysts without any modification of structure. The studies of homoleptic copper dipyrromethene complex has been discussed in Chapter V. The bidentate dipyrromethene complex of Cu(II) has been synthesized. The X-ray crystal structure of [Cu(II)(dpm)2] has been determined. The neutral bis(5- (4-nitrophenyl)dipyrromethene)Cu(II) complex [Cu(II)(dpm)2] is found to undergo ligand centred oxidation process to give [Cu(II)(dpm)2 •+], which has been substantiated by combined experimental and theoretical investigation. The metal bound ligand centred oxidation at high potential is of irreversible nature. The DFT calculation reveals increase in spin density over ligand moiety in the one electron oxidized [Cu(II)(dpm)2] complex, suggesting radical character of the ligand. Complex [Cu(II)(dpm)2] is found to catalyze C-H activation of alkanes and alkenes with tertbutylhydroperoxide at room temperature. The oxidation under ambient condition with benign terminal oxidant clearly indicates the involvement of the ligand based oxidation of [Cu(II)(dpm)2] in catalyzing C-H activation at room temperature. Chapter VI presents the ligand co-opertative effect in metal complex catalyzed oxidation elaborating the role of redox-neutral or redox-innocent cyclam ligand (1,4,8,11-tetraazacyclotetradecane) in C-H bond activation. The chapter describes efficient and selective hydroxylation of cycloalkanes (R-H→R-OH) catalyzed by high spin non-heme iron(III) cyclam complex [FeIII(cyclam)(OTf)2]OTf with hydrogen peroxide under mild condition. Remarkable increase in conversion and selectivity has been achieved by the addition of acid suggesting acid promoted O-O bond heterolysis. The efficient functional model of monoxygenase group of enzyme based on a highspin iron(III) complex of cyclam [FeIII(cyclam)(OTf)2]OTf provides the first example wherein a non-heme iron complex catalyzes alkane hydroxylation with 100% selectivity. The intercalation of cis-[Fe(III)(cyclam)Cl2]Cl (cyclam = 1,4,8,11- tetraazacyclo- tetradecane) complex on smectite montmorillonite K-10 is described in chapter VII. The intercalated solid is fully characterized using powder EDXRF, XRD, TGA, IR and UV-Visible analysis. Complex cis-[Fe(III)(cyclam)Cl2]Cl intercalated into Montmorillonite K-10 emerges as an efficient catalyst for selective hydroxylation (R-H→R-OH) of alkanes using environmentally benign H2O2 at room temperature. Cyclohexane and adamantane are selectively oxidized to their corresponding alcohols with remarkably high turnover number (198 and 265 respectively). Relative reaction without the clay matrix proves that a cooperative effect between the constituents of the intercalated catalyst is responsible for the enhanced selectivityItem Open Access Study on thermodynamic and transport properties of some solution systems with reference to manifestation of solvation effect(University of North Bengal, 2013) Dewan, Rajani; Roy, Mahendra NathIn ‘Solution Chemistry’ broadly three types of approaches have been made to estimate the extent of solvation. The approaches involves the studies of viscosity, conductance, etc., of electrolytic solutions and the derivation of various factors associated with ionic solvation, the second is the thermodynamic approach by measuring the free energies, enthalpies and entropies of solvation of ions from which factors associated with solvation can be elucidated, and the third is spectroscopic measurements where the spectral solvent shifts or the chemical shifts determine their qualitative and quantitative nature. Studies of thermodynamic properties of electrolytes, along with transport and acoustic studies, give very valuable information about ion-ion and ionsolvent interactions in solutions. The influence of these interactions is sufficiently large to cause dramatic changes in chemical reactions involving ions. The changes in ionic solvation have important applications in diverse areas as organic and inorganic synthesis, studies of reaction mechanisms, non-aqueous battery technology and extraction. Using mixed solvents in these studies enable the variation of properties such as dielectric constant or viscosity, and therefore the ion-ion and ion-solvent interactions could be better studied. Consequently, a number of conductometric and related studies of different electrolytes in non-aqueous solvents, especially mixed organic solvents, have been made for their optimal use in high-energy batteries and for understanding organic reaction mechanisms. Thus, extensive studies on electrical conductance in mixed organic solvents have been performed to examine the nature and magnitude of ion-ion and ion-solvent interactions. CHOICE OF SOLVENTS AND SOLUTES Solvents such as Nitromethane, 1,3-Dioxolane, Nitrobenzene, Methanol, Ethylene glycol, n-Hexanol, o-Toluidine, Aniline, Acetonitrile, N,NDimethylformamide, N,N-Dimethylacetamide and Dimethylsulphoxide have been used in the research work because these solvents are industrially very important and by mixing these solvents we could obtain a wide variation of viscosities and dielectric constants giving us an optimum environment for the study. The electrolytes used in the research work are Sodium Tetraphenylborate, Tetrabutylammonium Tetraphenylborate, Lithium Hexafluoroarsenate, Tetraalkylammonium Iodides, 1-Ethyl-3-methylimidazolium Bromide and Tetrabutylammonium Hexafluorophosphate. These electrolytes are used as reference and supporting electrolytes and are used as non-aqueous electrolytes in electrochemical applications. METHODS OF INVESTIGATION Different experimental techniques are employed to get a better insight into the phenomena of solvation and different interactions prevailing in solution. The techniques used to study various interactions in solution are: Densitometry, Viscometric, Conductometry, Ultrasonic Interferometry and Refractometry. PHYSICO-CHEMICAL PARAMETERS AND THEIR SIGNIFICANCE Limiting molar conductance (Λ0) gives an idea about the ion-solvent interaction in the solution. Association constant (KA) obtained from the conductance study gives an idea about the solvation of the ions. Partial molar volume ( 0 V φ ) and Viscosity B-coefficient obtained from the density and viscosity values respectively indicates the extent of ion-solvent interaction in a solution. From experimental speed of sound values, limiting apparent molar adiabatic compressibility ( K φ ° ) and the experimental slope ( * k S ) can be estimated. These parameters also give an idea about the ion-solvent and ion-ion interaction in the solution. SUMMARY OF WORKS DONE CHAPTER I This chapter contains the objective and applications of the research work. CHAPTER II This chapter contains the general introduction of the thesis and forms the background of the present work. A brief review of notable works in the field of ion-solvent interaction has been given. CHAPTER III This chapter contains the experimental section which mainly involves the structure, source, purification and application of the solvents and solutes used in the research work and the details of the instruments used for the study. CHAPTER IV In this chapter precise measurements on electrical conductance of sodium tetraphenylborate and tetrabutylammonium tetraphenylborate in different mass fraction (0.00–1.00) of nitromethane in nitrobenzene at 298.15K have been represented. Limiting molar conductances (Λ0), association constants (KA) and co-sphere diameter (R) for ion-pair formation in the mixed solvent systems were evaluated using the Fuoss conductance-concentration equation. FT-IR measurements for the solvents and solutions have been undertaken. CHAPTER V This chapter includes the study of electrolytic conductivities (Λ ), densities (ρ ), viscosities (η ), refractive indices (nD) and speed of sound (u) of tetrabutylammonium hexafluorophosphate in nitromethane, 1,3-dioxolane and nitrobenzene at 298.15 K. The limiting molar conductivities ( o Λ ), association constants (KA), and the distance of closest approach of the ion (R) have been evaluated using the Fuoss conductance equation. Triple ion formation in 1,3- dioxolane has been analyzed by Fuoss-Kraus theory of triple-ions. The limiting apparent molar volumes( 0 V φ ), experimental slopes( V * S ) derived from the Masson equation, and viscosity A and B coefficients using the Jones-Dole equation have been interpreted in terms of ion-ion and ion-solvent interactions, respectively. Molar refraction ( M R ) have been calculated using the Lorentz- Lorenz equation. The adiabatic compressibility ( S β ) have been evaluated using the u values. The limiting apparent molar adiabatic compressibility ( 0 K φ ) have been calculated and discussed. CHAPTER VI This chapter includes the study of electrolytic conductivities of tetraalkylammonium iodides, R4NI (R= butyl to heptyl) in (0.00, 0.25, 0.50 and 0.75) mass fraction of o-toluidine in n-hexanol at 298.15 K. Limiting molar conductances (Λ0), association constants (KA) and the co-sphere diameter R for ion-pair formation in 0.00 and 0.25 mass fraction of solvent mixture have been evaluated using the Fuoss-Equation. Triple-ion formation in 0.50 and 0.75 mass fraction of o-toluidine in n-hexanol has been analyzed by the Fuoss-Kraus theory of triple ions. CHAPTER VII Conductometric studies of 1-ethyl-3-methylimidazolium bromide in acetonitrile, methanol, N,N-dimethylformamide, N,N-dimethylacetamide and dimethylsulphoxide were undertaken at 298.15K. FT-IR measurements were supplemented to explain the ion-dipole interaction in the solution. The extent of interaction is expressed in terms of the association constant (KA) and shows the ion-dipole interaction to be a function of viscosity. CHAPTER VIII In this chapter, conductivities of some tetraalkylammonium iodides were measured at 298.15 K aniline. The observed molar conductivities were analyzed by Fuoss-Kraus theory of triple-ions. A linear relationship between the triple-ion formation constants [log (KT / KP)] and the salt concentrations at the minimum conductivity (log Cmin) have been given for all salts in aniline. The formation of triple-ions has been explained on the basis of coulombic interactions and covalent bonding forces operative between the ions. CHAPTER IX In this chapter, the electrolytic conductivities, densities and viscosities of lithium hexafluoroarsenate have been studied in different mass fraction of ethylene glycol in methanol at 298.15 K. The limiting molar conductivities (Λ0), association constants (KA) and the distance of closest approach of the ion (R) have been evaluated using the Fuoss conductance equation. The limiting apparent molar volumes (φV o), experimental slopes (SV *) derived from the Masson equation and viscosity A and B-coefficients using the Jones-Dole equation have been interpreted in terms of ion-ion and ion-solvent interactions respectively. CHAPTER X This chapter contains the concluding remarks of the works related to the thesis.Item Open Access Physico-chemical investigations on the ion-solvent interactions of some Tetraalkylammonium and common ions in non-aqueous and mixed binary aqueous solvent systems(University of North Bengal, 1992) Das, Bijan; Hazra, D.K.Item Open Access Exploration of the chelation property of few newly designed (N,O)-type schiff base ligands with d-block metals and bio-oxidase activities of their synthetic coordination compounds(University of North Bengal, 2023) Mahato, Shreya; Biswas, BhaskarThis dissertation comprises a total of seven chapters. Chapter I consists of a concise introduction to the design, foundation, and applications of the coordination compounds based on synthetic and commercially available ligands and the applicability of the present work in the recent trends of scientific development. Chapter II represents the synthesis, X-ray structural analysis, supramolecular architectures, and oxidative coupling of 2-aminophenol of a copper(II) complex, [Cu(L1)](H2O) (1) containing a previously reported Schiff base, H2L1 = 2,2'-((1,2- phenylenebis(azanylylidene))bis(methanylylidene))diphenol. The analysis of the crystal structure indicates that the Cu(II) centre adopts a square planar coordination geometry within the R3̅ space group. Furthermore, the aqua molecule located nearby actively participates in significant intermolecular hydrogen bonding, resulting in the formation of a water-mediated dimeric unit of the Cu(II) complex. The Hirshfeld surface analysis suggests that C−H…O and O−H…O types of hydrogen bonding, as well as π⋯π interactions play a crucial role. The catalytic properties of complex 1 were assessed for the oxidative dimerization of 2-aminophenol (2-AP) in methanol, revealing high catalytic efficiency with a kcat/KM value of 2.14×105. Additionally, studies utilizing mass spectrometry confirmed that the catalytic process involves the formation of an enzymesubstrate adduct in the solution phase. Chapter III represents the synthesis, X-ray structural analysis, Hirshfeld surface analysis, oxidative dimerization of 2-aminophenol and antibacterial activity of a newly designed copper(II)-Schiff base complex, [Cu(L2)2] (2), [Schiff base (HL2) = 2-(2- methoxybenzylideneamino)phenol]. X-ray analysis of complex 2 reveals that the Cu(II) complex forms crystals in a cubic crystal system with the Ia3̅ d space group. In its crystalline phase, the Cu(II) centre adopts a unique tetragonal bipyramidal geometry. Complex 2 has been tested for its phenaxozinone synthase activity in acetonitrile, mimicking biological systems, and demonstrated significant catalytic activity with a high turnover number of 536.4 h−1. Electrochemical analysis of complex 2 showed the appearance of two additional peaks at −0.15 and 0.46 V in the presence of 2-AP. This suggests the formation of AP−/AP•− and AP•−/IQ redox couples in the solution. The presence of the iminobenzosemiquinone radical at g = 2.057 was confirmed in the reaction mixture through electron paramagnetic resonance, indicating its role as the driving force for the oxidative dimerization of 2-AP. The ESI-mass spectrum exhibited a peak at m/z 624.81 for complex 2 in the presence of 2-AP, confirming that the catalytic oxidation proceeds through the formation of an enzyme-substrate adduct. Furthermore, complex 2 showed potential antibacterial properties against pathogenic bacterial species such as Staphylococcus aureus, Enterococcus, and Klebsiella pneumonia. Scanning electron microscope studies provided evidence that the antibacterial activity is attributed to the destruction of the bacterial cell membrane. Chapter IV represents the synthesis, crystal structure, supramolecular architecture, 4- methylcatechol oxidation, and bactericidal activity of an interesting zinc(II)-Schiff base complex, [Zn(L2)2Cl2] (3), [Schiff base (HL2) = 2-(2- methoxybenzylideneamino)phenol]. The analysis of the crystal structure of complex 3 indicates that the zinc centre is present in a distorted tetrahedral arrangement. The Schiff base molecule adopts three donor centres, but it becomes protonated and exists as a zwitterionic form, acting as a monodentate coordinator towards zinc. Complex 3 has been studied for its ability to catalyse the biomimetic oxidation of 4-methylcatechol (4-MC) in methanol, and it demonstrates high efficacy with a good turnover number of 1.45 × 103 h−1. Various techniques such as electrochemical studies and electron paramagnetic resonance analysis have been employed to investigate the behaviour of complex 3 in the presence of 4-MC. The results confirm that the catalytic reaction proceeds through enzyme-substrate binding, and the generation of radicals during the catalytic process drives the oxidation of 4-MC. Additionally, an antibacterial study has been conducted against several clinical pathogens including Bacillus sp, Enterococcus, and E. coli. To assess the antimicrobial properties of complex 3, scanning electron microscope and EDX analysis were performed on the pathogens treated with a low dosage of the complex. The results reveal the destruction of the bacterial cell membrane in the selected zone of inhibition area, with a zinc occurrence of 1.44%. This finding holds significant promise for the development of future antibacterial agents. Chapter V represents the synthesis and crystal structure of a palladium(II) complex [(κ4- {1,2-C6H4(N=CH−C6H4O)2}Pd] (4) supported by a dianionic salen ligand [1,2- C6H4(N=CH−C6H4O)2]2− (H2L1) was synthesized and used as a molecular pre-catalyst in the hydroboration of aldehydes and ketones. Complex 4 was evaluated as an effective catalyst in the hydroboration of aldehydes and ketones using pinacolborane (HBpin). This process yielded boronate esters in exceptional yields at room temperature without the need for solvents. Furthermore, complex 4 demonstrated its competence as a catalyst in the reductive amination of aldehydes with HBpin and primary amines. This reaction occurred under mild and solvent-free conditions, resulting in a high yield (up to 97%) of secondary amines. Both methodologies exhibited remarkable conversion rates, excellent selectivity, and a wide range of applicability, accommodating electron-withdrawing, electron-donating, and heterocyclic substituents. A computational investigation utilizing density functional theory (DFT) elucidated the reaction mechanism behind the complex 4-catalyzed hydroboration of carbonyl compounds in the presence of HBpin. Additionally, the protocols unveiled the dual functionality of HBpin in facilitating the hydroboration reaction. Chapter VI represents the design and preparation of metal complex salts of the novel hybrid d-f block type, [Cu(bpy)2]2[Ce(NO3)6]2 (5), [Cu(phen)2(NO3)]2[Ce(NO3)6](HNO3) (6), [Zn(bpy)2(NO3)][ClO4] (7), and [Zn(phen)2(NO3)]2 [Ce(NO3)6] (8); [bpy = 2,2'- bipyridine; phen = 1,10-phenanthroline]. X-ray analysis of the structures of 5 and 6 reveals that the copper(II) centres in the cationic complex units have highly distorted tetrahedral and rare bicapped square pyramidal coordination geometries, respectively. Similarly, 7 and 8 exhibits rare bicapped square pyramidal geometry for their zinc(II) ions, while 5, 6, and 8 contain cerium(IV) ions arranged in a dodecahedral geometry. Studying the supramolecular interactions, it is observed that intermolecular O⋯H and O⋯π short contacts contribute to binding the complex units in 5. In contrast, complex salt 6 demonstrates predominantly π⋯π interactions, along with O⋯H and O⋯π short contacts, which facilitate binding among the complex units. To investigate the chargetransport phenomenon, we utilized complex salts (5-8) to construct Schottky devices. The carrier mobilities (μ) for salts 5-8 were determined as 1.76 × 10−6, 9.02 × 10−6, 1.86× 10−8, and 4.31 × 10−8 m2 V−1 s−1, respectively, with corresponding transit times (τ) of 439, 85, 4.17 × 103, and 1.79 × 103 ns. These results indicate that complex salt 6 exhibits the highest transport properties among all the complex salts. Analysing the charge-transport properties from a crystal engineering perspective, the superior performance of 6 can be attributed to its predominant π⋯π interactions. Overall, the synthesis of these novel complex salts, along with their physicochemical properties and charge-transport applications, holds significant promise for the development of new crystalline materials with intelligent functionalities. Chapter VII outlines an overview of the progress made thus far and identifies prospective avenues for future research.Item Open Access Functional site mimics of few oxidase enzymes by newly developed coordination compounds with (N, N) and (N, O) donor ligands(University of North Bengal, 2023) Pal, Chanchal Kumar; Biswas, BhaskarDesign and synthesis of transition metal complexes with polydentate ligands and commercially available ligands is a significant field of research in Chemistry. Coordination compounds in coupling between transition metals and various ligands have drawn a great deal of interest to Chemist and Biologists for their remarkable structural features, biomimicking activities, catalytic activities, optoelectronic applications, magnetic materials, semiconductors, functional composites and different biological activities. Noteworthy, metal complexes that are the synthetic analogs of various metalloenzymes create significant progress in bioinspired chemistry with fascinating mechanistic perception of the catalytic cycles. Chapter I: This introductory chapter describes the design, synthesis and application of transition metal complexes based on Schiff base and commercially available ligands. It also states the catalytic and biological activities of metal complexes and the objectives of the present work. Chapter II: This chapter consists of the synthesis, catecholase, and phosphatase activity of an oxido-and acetate-bridged tetranuclear iron (III) cluster [Fe4 III(μ-O)2(μ- OAc)6(phen)2(H2O)2] (NO3)2(H2O)3 (1), [OAc = acetate; phen = 1,10-phenanthroline. Xray structural analysis of the compound reveals that all the Fe(III) centres in 1 adopt an octahedral coordination geometry and the tetra-iron(III) core exists in an unusual asymmetric conformation. The bond valence sum (BVS) calculation recommends the existence of all iron ions in the +3 oxidation level in the crystalline state. The tetra-iron(III) cluster elegantly catalyzes the oxidation of 3,5-di-tert-butylcatechol (DTBC) viz. Catecholase-like activity with a good turnover number, kcat 9.28102 h-1 in acetonitrile medium. Spectrophotometric titration exhibits two distinct isobestic points, which unanimously proves the rarely observed enzyme-substrate binding phenomenon in solution. Electrochemical analysis recommends the production of Fe(II)-semiquinone species in the catalytic oxidation of DTBC. Furthermore, the same iron(III) cluster displays phosphoester cleavage activity towards disodium salt of p-nitrophenylphosphate (PNPP) in an aqueousmethanol medium with a rate of 7.2010-4 m-1. ESI-MS measurements of tetra-iron(III) complex in the presence of PNPP recommend the formation of organophosphorous intermediate in solution and solvent aqua molecules probably make a nucleophilic attack to phosphorous centre favouring the generation of organophosphorous intermediate.Item Open Access Physicochemical studies of diverse interactions of some selected significant molecules prevalent in supramolecular and solution chemistry(University of North Bengal, 2023) Ghosh, Biswajit; Roy, Mahendra Nath; Dakua , Vikas KumarAs per the title of the thesis, I would like to show my deep insight into the field of Supramolecular Host-Guest Inclusion Complexation and the Amino Acid-Ionic Liquid interaction in aqueous medium. Supramolecular assembly has gained enormous significance these days in drug release due to their excellent bioavailability and remarkable ability to alter various properties of the drug such as its solubility, stability within the body, pharmacokinetics and pharmacodynamics. They also exhibit nontoxic properties, better encapsulation and controlled release. The spectroscopic contribution confirms the inclusion complexation of various bioactive molecules and their different photophysical properties in aqueous media. The inclusion phenomena can be satisfactorily expressed by UV-visible, 1H-NMR, FTIR, mass spectrometry and fluorescence emission spectroscopic studies. Surface tension, Powder XRD and SEM analysis provides a qualitative idea towards the formation of supramolecular assembly. The thermal stability of such assembly can be explained by TGA and DSC study. Theoretical molecular modelling studies of the supramolecular system confirm the data obtained from the experimental studies. The study of physicochemical properties of solutions provide significant knowledge on various thermodynamic properties of electrolytes and non-electrolytes, the effects of the variation in ionic constructions, mobility of ions along with their common ions. The genesis of diverse interactions between amino acids-ionic liquid in aqueous phase is usually exposed by measurement of the apparent molar volume ( v ), limiting apparent molar volume ( 0 v ), molar refraction ( M R ), limiting molar refraction ( 0 M R ), molar conductance (Ʌ), viscosity B coefficients obtained from different physicochemical methodologies. In this study, encapsulation of various biologically active molecules such as, Mephenesin, Riboflavin, 6-Propyl-2-thiouracil, have been investigated. These bioactive molecules have potential applications in living systems. Pharmacological activity is often considered to describe beneficial effects of bioactive molecules. Extensive studies on Nile blue and its derivatives have suggested that it could be potentially useful as fluorescent probes in this regard, because of their unique optical properties, excellent thermo and photostability, and low toxicity. In host–guest chemistry, the application of macrocyclic hosts in molecular recognition, controlled release of a drug and sensing field has received considerable interest. Incorporation of guest molecules in aqueous environment within the cavity of host molecules, e. g., α-cyclodextrin, β-Cyclodextrin or water soluble calixarene, provides the new insight into the molecular recognition (e. g. inclusion or complexation) through non-covalent interactions. Supramolecular host-guest chemistry gives a broad idea about the formation of inclusion complex between the host and the guest molecules. Hydrophobic cavities of host are capable of binding different guest molecules. In recent years, the whole supramolecular assemble has been vastly studied in many fields such as drug-delivery and analytical chemistry. Among the various host molecules, cyclodextrins and its derivative along with water soluble calixarene seems to be the most promising to form inclusion complexes, especially with various guest molecules with suitable dimension. Therefore, the primary objective of this thesis is to find out the influence of supramolecular recognition and solution chemistry that are inevitably significant because of their wide range of applications in many fields ranging from pharmaceutical to biomedical sciences. SUMMARY OF THE WORKS CHAPTER I This chapter contains the detail object of the research work, their scope and applications in the contemporary science. It also includes the reason of choosing the bioactive molecules, cyclodextrins, calix[4]arenes, ionic liquid, and the solvent systems. This chapter has a short list of all the methods of investigations used in the research work. CHAPTER II This chapter includes the review of the earlier works in this field of research done by various scientist and researchers across the world. This chapter also provides a detail theory of investigations, where the interacting forces among the molecules have been described. Here, the background theory of all the investigating methods, i.e., the theory of 1H-NMR, FTIR spectroscopy, UV-visible spectroscopy, Fluorescence spectroscopy, Mass Spectrometry, Differential Scanning Calorimetry, Thermogravimetric analysis, Scanning Electron microscopy, Powder XRD, Molecular docking study, Antimicrobial study, Cytotoxicity study, DNA and BSA binding study, Surface Tension, Conductivity, Density, Viscosity, Refractive Index have been discussed thoroughly and the significance of their use in the research work described in this thesis have been shown. CHAPTER III This chapter contains the experimental section. It covers the name, structure, physical properties, and applications of the biologically active molecules, cyclodextrins, calix[4]arenes, ionic liquid and solvents used in the research work. It also includes the details about the experimental methods, the descriptions and use of the instruments involved in the research work. CHAPTER IV This chapter comprises the experimental study emerged on the encapsulation of polyether compounds such as Mephenesin (MEP) into the nano hydrophobic cage of β-cyclodextrin as host molecule. The commonly known co-precipitation method was followed to prepare inclusion complex (IC) by molar ratio 1:1. Different spectrometric techniques e.g. transform infrared spectroscopy (FTIR), DSC, TGA, DTA, and scanning electron microscope (SEM) indicated molecular interactions between β-CD and MEP. UV-visible titration predicts the binding constant for βCD and MEP in solution state around 2.1×103M-1. The formation of the inclusion complex has been predicted by slight shifts in the FTIR as well as 1H NMR spectrum. Job plot and ESI-MS spectra showed that 1:1 inclusion complex has been formed. Molecular docking study unveils the inclusion mechanism which is well supported with the experimental data. In addition, UV-visible spectroscopic study predicts the binding interaction between Mephenesin with amino acid residues of BSA and DNA. *Published in the Journal of Molecular Liquids, 344, (2021) 117977 CHAPTER V This chapter consists of the formation of inclusion complex (IC) of an antithyroid drug 6-propyl-2- thiouracil (PTU) with α-cyclodextrin (α-CD) and to analyse its aqueous solubility, photostability, binding with Calf thymus DNA (CT-DNA), antibacterial and cytotoxic activities. The PTU-α-CD complex was synthesized by following the co precipitation method with a molar ratio of 1:1. The formed complex was characterized by employing several spectroscopic techniques such as 1H NMR, FTIR, DSC, TGA, powder XRD and SEM indicated the successful encapsulation of drug PTU into the nano cage of α-CD. The enhancement of thermal stability of PTU after complexation was shown by TGA and DSC analysis. Job’s plot confirmed the 1:1 molar ratio of guest (PTU) and host (α -CD) during the formation of IC and the molecular association constant as predicted between PTU and α-CD using UV-vis titration method was found to be 3297.57±0.15 M-1. The most desired orientation of the PTU molecule within the nonpolar binding pocket of α -CD cavity was speculated by molecular modelling study. The PTU- α -CD complex showed better in vitro antimicrobial activity results as compared to pure drug PTU. The aqueous solubility and photostability of PTU were greatly improved owing to the formation of the PTU- α -CD complex as shown using UV-vis spectroscopy. The PTU- α -CD complex (IC50 = 2.12 𝜇M) also displayed noteworthy in vitro cytotoxic activity than pure PTU (IC50 = 6.44 𝜇M) towards human kidney cancer cell line (ACHN) whereas (IC50 = 3.63 𝜇M) and (IC50 =2.09) 𝜇M) for PTU- α -CD and drug respectively in a normal kidney cell line (HEK-293). This research also predicts the release of PTU in presence of CT-DNA without any chemical alteration. Finally, these outcomes disclose that the complexation of PTU with α -CD could enhance the stability of PTU and display various applications associated with it. *Published in the Journal of Molecular Liquids, 380, (2023)121708 CHAPTER VI This chapter incorporates the construction of a supramolecular encapsulated complex between Nile blue (NB) and p-sulfonatothiacalix[4]arene (TSC4X). The developed inclusion complex (NB-TSC4X) was established by fluorescence spectroscopy, TGA, FTIR, 1HNMR, and DFT studies. Benesi- Hildebrand calculation showed a linear plot that indicated a 1:1 stoichiometric ratio having fairly high stability constant of 2720 M−1 in the solution phase. DFT analysis helps us to find out the optimized structure of the inclusion complex. Finally, the binding interaction of inclusion complex with bovine serum albumin (BSA) was evaluated. In brief, this work uncloses a new strategy to enhance the performance of fluorescent dye. *Communicated CHAPTER VII This chapter includes the solute–solvent interaction between ionic liquids (ILs) and amino acids (AA) in aqueous media plays a significant role for the optimization of a number of important biotechnological processes. L-Valine and L-Proline (two solute molecules) interact with an ionic liquid (Benzyltributylammonium chloride) in aqueous medium. Based on the different parameters such as apparent molar volume, viscosity B-coefficient, molar refraction, molar conductance, surface tension at different temperatures and different concentrations from density, viscosity, refractive index, conductance, surface tension measurements have been used to explain the molecular level interactions which was supported by NMR and UV-vis studies. Using Masson equation, the experimental slopes and the limiting apparent molar volumes are obtained which explain the solute-solute and solute-solvent interactions. Hepler’s technique and dB/dT values have been used to examine the structure-making and structure-breaking nature of the solutes in the solvents. Viscosity parameters, A and B obtained from Jones-Doles equation explained the solute-solute and solute-solvent interactions in the solution. Lorentz-Lorenz equation has used to calculate the molar refraction. The specific conductance and surface tension also explained the interaction properties. Further the findings have been supported by NMR study of the solutions and also considerable amount of theoretical analysis has been done which was in good agreement with the experimental result. The behavior of many other bio-molecules can be explained by considering amino acids as model and the mechanism has been extended to elucidate the behavior of other (biological) systems. In our findings we were emphasized on the nature of solute–solvent interactions and the presence of structural effect on the solvent in solution to analyze the molecular-level interactions prevalent in the systems. *Published in Fluid Phase Equilibria, 557, (2022) 113415 CHAPTER VIII This chapter includes the synthesis of a new encapsulated complex denoted as RIBO-TSC4X, that was derived from an important vitamin Riboflavin (RIBO) & psulfonatothiacalix[ 4]arene(TSC4X). The synthesized complex RIBOTSC4X was then characterized by utilizing several spectroscopic techniques such as 1HNMR, FT-IR, PXRD, SEM, and TGA. Job’s plot has been employed to show the encapsulation of RIBO (guest) with TSC4X (host) having a 1:1 molar ratio. The molecular association constant of the complex entity (RIBO-TSC4X) was found to be 3116.29±0.17 M-1, suggesting the formation of a stable complex. The augment in aqueous solubility of the RIBO-TSC4X complex compared to pure RIBO was investigated by UV-vis spectroscopy & it was viewed that the newly synthesized complex has almost 30 times enhanced solubility over pure RIBO. The enhancement of thermal stability upto 4400 C for the RIBO-TSC4X complex was examined by TG analysis. This research also forecasts RIBO’s release behaviour in the presence of CT-DNA, and at the same time, BSA binding study was also carried out. The Synthesized RIBO-TSC4X complex exhibited comparatively better free radical scavenging activity, thereby minimizing oxidative injury of the cell as evident from a series of antioxidant and anti-lipid peroxidation assay. Furthermore, the RIBO-TSC4X complex showed peroxidase-like biomimetic activity, which is very useful for several enzyme catalyst reactions. *Published in ACS Omega, 8,7, (2023) 6778-6790 CHAPTER IX This chapter includes the concluding remarks about the research works done in this thesis.Item Open Access Synthesis, insecticidal activity, toxicity, anticholinesterase activity and other biological properties of some saligenin cyclic phosphorus compounds(University of North Bengal, 1982) Roy, Prabir; Das, B. K.Item Open Access Virtual screening, molecular docking studies admet properties dencity functional theory and 2D-QSar modeling to design potential inhibitors(University of North Bengal, 2023) Sarkar, Subhajit; Das, Rajesh KumarConventional drug design processes use trial and error methods for screening natural and synthetic compounds. It costs millions of dollars and very long time approximately 10-15 years. To meet these severe challenges nowadays pharmaceutical companies rely very much on computer-aided design techniques to discover potential drugs. Throughout the research work, various natural inhibitors that regulate a variety of physiochemical processes in bacteria and human beings have been studied. Derivatives of them have been designed and developed in such a way that they may be used as potent drugs producing no or minimal side effects and overcome the antibiotic resistance property. We hope, in silico drug design processes followed in different studies would save precious time and millions of dollars, leading to novel alternate therapeutics. CHAPTER I Microorganism including bacterium communicates among themselves through a unique mechanism called quorum sensing. The different QS pathways of Gram-negative and Gram-positive bacteria have been discussed elaborately in this chapter. Bacteria develop antibiotic resistance through various mechanisms among them biofilm formation is regulated by quorum sensing. Quorum sensing inhibitors (QSIs) interrupt the expression of virulence factors production and inhibit biofilm formation without killing bacteria or inhibiting bacterial growth. The QSIs are of two types natural and synthetic. It includes a details study of different types of QSIs and inhibition mechanisms. Hamamelitannin (HAM) a phytochemical has the capability to inhibit Staphylococcus aureus agr QS system. Our approach is to modify HAM by incorporating an active functional group for better efficacy. We have followed the same in silico process in another study where the target protein was chosen as heat shock protein 90 rather known as HSP90 and found in all species ranging from bacteria to humans. Over expression of this client protein may lead to several refractory diseases including cancer, inflammation, neurodegeneration, and viral infection. It discussed the various roles and functions of HSP90 in the human body. Besides, we have performed quantitative structure activity relationship (QSAR) analysis in two different cases. Phophodiesterase-4 (PDE4) and lysine-specific demethylase 1 (LSD1) are two key proteins that regulate various physiochemical processes in humans. Over expression of PDE4 may lead to severe diseases including chronic obstructive pulmonary disorder (COPD), and cardiovascular disease whereas unregulated LSD1 may result in tumorigenesis, neurodegenerative disorders, viral infection, diabetes, fibrosis, and various types of cancers including prostate, gastric, breast, lung, and leukemia. Separate studies of QSAR on these two proteins help us to identify best-fitted designed molecules as potent inhibitors of the target proteins. Detailed information on both PDE4 and LSD1 is described here. CHAPTER II The major in silico techniques that are widely popular among researchers are molecular docking, density functional theory (DFT) calculation, molecular docking, molecular dynamics (MD) simulations, and absorption, distribution, metabolism, excretion, toxicity (ADMET) prediction. Collective use of all of the mentioned computer aided techniques is necessary to predict potential QS inhibitors. It includes methodologies of all of the above mentioned techniques in detail. CHAPTER III A set of 26 derivative compounds have been designed by incorporation of different active functional groups at various positions of hamamelitannin (HAM) shown here. All structures were optimized using Gaussian software. Gaussian outputs were used to perform molecular docking with the help of Autodock Vina software. Docking results of HAM with three target proteins of PDB ID 4AE5, 4G4K, and 2FNP exhibited the binding energy value of -6.7, -6.5 and -6.6 kcal/mol respectively. Out of 26 derivatives of HAM, 14 compounds have shown higher binding affinity than that of HAM. The above in silico studies concluded that 14 ligands could be developed as effective inhibitors of S. aureus biofilm formation and considered for in vitro and in vivo analysis. CHAPTER IV It includes the natural product oroidin (ODN) considered a potent inhibitor of heat shock protein 90 (Hsp90) and its derivatives had been designed by substituting various functional groups in the various position of five membered rings. A library of thirty nine derivatives was designed by introducing various functional groups such that amide, amine, phosphate, hydroxyl, fluorine, methoxy, and carboxylic acid in the active pharmacophore of oroidin. All the analyses expressed that seven analogues possessed better chemical activity and docking capabilities than that of the source molecule ODN. These seven computationally designed derivatives may be used as novel beneficial agents in various cancer therapies including breast, ovarian, colon, pancreas, liver carcinoma, and leukemia treatments, and could be considered to develop as effective anticancer drug candidates in the future. CHAPTER V Keeping in mind the importance of PDE4 inhibitors it includes a study where a quantitative structure-activity relationship (QSAR) modeling method was performed to develop a standard model on a dataset of sixty-six significant PDE4A inhibitors encompassing common scaffolds in pyrazolo-oxazine, and imidazo-pyridazine compounds. According to QSARINS software, the model comprises three descriptors namely MoRSEM11, MoRSEP26and MoRSEC11 were found to be the best ones. The three descriptor model which was employed to predict pIC50 values as the studied response exhibited good R2 (0.8185), and F (73.658) values. Internal validation parameters Q2loo= 0.7845, Q2LMO= 0.7771and external validation parameters Q2F1= 0.8277, Q2F2= 0.8246, Q2F3= 0.8626, confirmed the stability and robustness of the developed model. On the basis of this model equation, pIC50 values of thirty-nine designed compounds were calculated. The potent lead molecules, predicted from the QSAR model, were further investigated by performing in silico approaches such as molecular docking, molecular dynamics simulation, bioavailability assessments, and toxicity prediction. The study revealed that the eight compounds possessed potent PDE4A inhibitory activity and might be considered as future drugs subject to the viability of in situ and in vivo proceedings. CHAPTER VI In this chapter quantitative structure activity relationship (QSAR) model was built from a dataset of 44 compounds as LSD1 inhibitors. The best 10 compounds have fully satisfied all the criteria of drug-like properties and these designed lead molecules would have more potency to treat LSD1 target after going through in vivo and in vitro analysis. CHAPTER VII 3D-QSAR analysis and application of ANN validation in CADD to design potential inhibitors of many critical diseases in future.