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Recent Submissions
Formulation and characterization of room temperature ferroelectric and antiferroelectric liquid crystal mixtures
(University of North Bengal, 2018) Debnath, Asim; Mandal, Pradip Kumar
Now-a-days displays have become a field of tremendous importance as they
provide the best means for interface between man and machine. Large numbers
of displays are presently available in the market, but among all these displays
about 90% are controlled by the liquid crystal display (LCD) technology. Most
of the LCD devices starting from simplest wrist watches or calculators to
complex laptops or flat TV sets mainly use the nematic liquid crystal phase for
their operation. Although a tremendous improvement in the quality of display as
well as reduction of manufacturing cost has taken place over the years, there are
many issues which the LC industry is trying hard to address. Ferroelectric liquid
crystals (FLC) are of current interest in the LCD industry since among various
other advantages FLC based displays have micro-second order switching
compared to milli-second order switching in nematic based displays. To meet
the market demand much effort has been made to optimize the physical
parameters of FLCs, such as temperature range, spontaneous polarization (PS),
helical pitch (p), switching time (τ), tilt angle (θ) and rotational viscosity (γφ).
Multicomponent mixtures are, usually formulated to optimize all the required
properties for practical applications since no single FLC compound can satisfy
the above requirements. Keeping all these in mind we have prepared room
temperature ferroelectric and antiferroelectric liquid crystal mixtures to the best
of our knowledge first time by any Indian group, which have properties suitable
for FLC based display devices and at par with mixtures used in the industry.
Suitability of the formulated mixtures for display applications were
characterized by optical polarizing microscopy, differential scanning
calorimetry, synchrotron X-ray diffraction, dielectric spectroscopy and electrooptic
methods.
First of all, six binary mixtures (M1-M6) were formulated by using a
biphenylyl benzoate ester with oligomethylene spacer based non-flourinated
chiral compound (DP1) as dopant and a three ring pyrimidine compound (H5)
as host. Of these, M4 exhibit the wide range (100o) and lowest temperature
(24oC) ferroelectric phase at 10wt% concentration of DP1. In addition to I-N*-
A*-C* phase sequence all the mixtures found to exhibit weakly temperature
dependent optical tilt (~22.5o) and fast response time (~200μs), can be useful
for high speed SSFLCD applications where contrast and brightness will be less
temperature dependent. Temperature range and response time are also found to
improve when the binary mixture M4 is used as chiral dopant in a multicomponent
host mixture (HM) to formulate another mixture (M7).
Next, six multi-component mixtures (M8-M13) were prepared by doping a nonmesogenic
chiral terphenyl compound (DP2) with chiral centers at opposite
ends in the multi-component host mixture (HM). This HM was prepared
mixing four phenyl pyrimidine compounds. Although DP2 is non-mesogenic
but only 2wt% of it induces SmC* phase in the HM at or close to room
temperature and with increased concentration it produces SmC* phase below
ambient down to at least 12°C with physical properties useful for SSFLCD
based applications.
An oligomethylene spacer based partially fluorinated chiral liquid crystal (DP3)
which has smaller spacer length than DP3 and which has only SmC* phase
when doped in the HM, resulting mixture (M14) was found to exhibit very
broad temperature range SmC* phase (~93o) from below ambient down to at
least 12°C and almost temperature independent high optical tilt, low driving
voltage and switching speed around 100μs suitable for display applications.
To study the effect of SmC*A- SmC*- SmA* phase sequence and molecular
structure, four partially fluorinated chiral compounds DP4, DP5, DP6, DP7,
which differ only in the number and position of fluorine atoms in the benzoate
ring of the molecular rigid core, were doped in the multi-component host
mixture (HM). Number and location of fluorine atoms in the dopant structure
shows significant effect on the phase sequences as well as on the different
physical properties of the mixtures (M15-M18) critically important for display
applications. Mixture M15 and M18 showed extended antiferroelectric phase
while M16 and M17 exhibited only ferroelectric phase.
A wide range room temperature electroclinic mixture, M19 was obtained when
only 10wt% of DP6 was mixed in the HM. The mixture exhibits large field
induced optical tilt (~23.5o) with less than 0.1% shrinkage of layers suitable for
developing fast electroclinic devices free from defects due to buckling of layers.
Most of the results have been published in the peer reviewed journals viz;
Journal of Applied Physics, Journal of Molecular Liquids, RSC Advances,
Liquid Crystals.
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 Nath
Thermo-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:
Preparation, characterization of bimetalic nanoparticles soakedon poly-ionic resins and their ctalalytic applications
(University of North Bengal, 2014) Sengupta, Debasish; Basu, Basudeb
The 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.
Spatial variations in the levels of development in Sikkim
(University of North Bengal, 2013) Jana, Amar Kanti; Sahu, Rangadhar
Reality of the concept of motion: east-west dialogue
(University of North Bengal, 2013) Chattopadhyay, Sudipta; Chakrabarti, Bhaswati. B.