8071 research outputs found
Sort by
Designing Functional Coordination Polymers - A Crystal Engineering Approach
Full text linkChapter 1 briefly describes the basic introduction on coordination polymer (CP),
coordination polymeric gel or metallogel, discrete coordination compound (metal-organic polyhedron), their applications in diverse fields and the role of crystal engineering and supramolecular chemistry in designing such materials. Chapter 2 gives an overview of coordination polymers and metallogels derived from a bis-pyridyl-bis-urea ligand and CuII metal salts. The coordination polymer obtained from Cu(SO4)2, capable of separating anion (sulphate) via in situ competitive crystallization technique. An attempt has been made to design metallogelator based on crystal
engineering approach.
Chapter 3 deals with metal-organic polyhedron (MOP) synthesized from a C3-symmetric trimesic acid and Cu(NO3)2. Such nano sized MOP molecules have been seen under transmission electron microscopy (TEM). Interestingly, this CuII based MOP shows
catalytic property towards oxidation of benzyl alcohol to benzaldehyde.
Chapter 4 consists of CPs derived from pyridyl-carboxylate ligands equipped with
amide functionality and different transition metals. The environmentally toxic CuII metalcation has been separated in the form of the corresponding CuII coordination polymer following in situ crystallization technique. Chapter 5 deals with metallogels derived from silver coordination polymers of C3-
symmetric tris(pyridylamide) tripodal ligands. Upon exposure to visible light, these silver metallogels produce silver nanoparticles (AgNPs), which are characterized by different physicochemical techniques. These NPs effectively catalyze the reduction of 4-nitrophenolate to 4-aminophenolate without the use of any exogenous reducing agent.
Chapter 6 consists of bioactive CPs derived from a series of nonsteroidal antiinflammatory drugs (NSAIDs) and a biogenic MnII metal salt. A nontoxic bis-pyridyl molecule has been used as a co-ligand. Two of such CPs display intriguing
photoluminescence. These CPs have been applied in cell imaging performed on a murine macrophage cell line RAW 264.7.
A conscious effort was made to incorporate most of the significant literature
considering the limitation imposed by the space constraint and relevance to the
current focus of topic.Research was carried out under the supervision of Prof. P. Dastidar of the Organic Chemistry division under SCS [School of Chemical Sciences]Research was conducted under DST, CSIR & DBT gran
Chemistry of selected d-block elements with some bi- and multi- dentate N- donor ligands
Full text linkThe main objective of this thesis is to develop some newer aspects of the chemistry of
some transition (Fe, Ni, Pd, Ru and Cu) and non-transition metals (Zn, Cd and Hg) by
means of studying their new mono- and poly-nuclear complexes of some bi- and polydentate
ligands. The ligands will have N donor sites. Some hetero donor atoms are
incorporated in the ligand frameworks for the sake of comparison. The new complexes
will be characterised by magnetic susceptibility studies, mass spectrometry, EPR, NMR,
ATR, Resonance Raman, UV-Vis spectra, Emission spectra, Mössbauer spectra and other
spectroscopic methods. Wherever possible, structure will be determined by X-ray
crystallography. Electrochemical techniques like cyclic voltammetry and coulometry will
be used for uncommon oxidation states of metals. Various quantum mechanical theories
like AM1, MP2, DFT and AIM etc. will be applied to examine structure reactivity
correlations. This thesis begins with a brief introduction (chapter I) to the coordination chemistry of some transition and non-transition metals relevant to the present study. Chapter II deals with the chemistry of transition metal complexes with bidentate N-donor ligands like 1,10-phenanthroline and 5,6-dihydro-5,6-epoxy-1,10-phenanthroline.
Uncommon Cu(II)-S8 bond, six coordinate Cu(I) in solution, crystallisation of an MLCT state in iron complexes, epoxide ring opening in a zinc complexes without any catalyst in a diastereoselective mannar, substituents’ effect on10Dq have been determined for nickel complexes and heteroleotic metal complexes also have been discussed in chapter II. A tridentate ligand L (dihydrazone of 2,6-diacetyl pyridine) and its metal complexes are discussed in Chapter III. Increasing denticity of L and corresponding metal complexes are also discussed. Chapter IV describes the chemistry of two tetradentate ligands derived from the condensation of benzil and 2-hydrazinopyridine, benzil dihydrazone and 2- (methylthio)benzaldehyde. Cu(II)-P bond formation, Ni-Ni and Pd-Pd bonding have been discussed. NICS and side dependent aromaticity of phosphole, a new aromaticity index, aromaticity of metallacycles and a Möbius chelate constitute Chapter V. Chapter VI
introduces a new structural index for the 5-coordinate Cu(II) complexes.Research was carried out under the supervision of Prof. Dipankar Dutta of Inorganic Chemistry division under SCS [School of Chemical Sciences]Research was carried out under CSIR & DST gran
Ion Dynamics and Relaxation in some Composite Polymer Electrolytes
Full text linkThis thesis is devoted to study the relaxation dynamics in some composite polymer
electrolytes. The organization of the thesis is as follows
Chapter 1 of this thesis describes the literature review in the field of polymer electrolytes and
their composites. A brief introduction to polymer electrolytes and their composites is
presented and their exotic features are discussed. The thermodynamics behind the dissolution
of the salts in polymers, phase diagram and ionic species of polymer electrolyte have been
outlined briefly. Several theoretical models and concepts used to explain and understand the
ion dynamics are pointed out. It also includes different models of ac and dc conduction in ion
conducting polymer electrolytes and their composites. Finally, it presents precise objectives
of the present work.
In chapter 2, a brief description of the preparation technique and various experimental
methods used to characterize the polymer electrolytes and their composites are presented. In
the initial part of the chapter techniques for the structural characterization such as x-ray
diffraction (XRD), differential scanning calorimetry (DSC), transmission electron
microscopy (TEM), field emission scanning electron microscopy (FESEM) and Raman
spectroscopy are discussed. In the later part, electrical characterization techniques used to
study the ion dynamics are presented.
In chapter 3, firstly PEO-LiClO4 solid polymer electrolytes embedded with plasticizer
propylene carbonate have been studied extensively. The structural investigations have been
carried out using XRD, DSC and Raman spectroscopy. The dynamics of Li+ ions in these
electrolytes has been investigated using ac impedance spectroscopy. The conductivity and
dielectric relaxation in these electrolytes have been studied, using the existing theories of the
conductivity, modulus and dielectric formalism. To get further insights into the ion dynamics,
the complex dielectric permittivity data has been studied using Havriliak–Negami function.
Secondly, a comparative study of polymer electrolytes using different kind of plasticizers has
been presented. It has been shown that dielectric constant of plasticizer affects the ionic
conductivity and relaxation mechanism in polymer electrolytes.
In chapter 4, the effect of Al2O3 nanoparticle on the structure and relaxation mechanism of
PEO-LiTFSI nanocomposite electrolytes has been investigated. XRD, DSC and TEM
techniques have been used to explore the structural properties. The temperature dependence
x Synopsis
of the dc conductivity of the Al2O3 doped nanocomposite electrolytes has been explained by
the VTF relation. The relaxation dynamics have been studied in the framework of power law
and electric modulus formalisms and are correlated to the results of structural studies.
In chapter 5, the effect of 1propyle-3-methyleimidazoliuum bis(trifluromethylesulfonyl)imide
(PMIMTFSI) ionic liquid on the structure, ion transport and relaxation of the blend polymer
electrolytes based on PEO and PVDF-HFP and LITFSI salt has been investigated. The effect
of PMIMTFSI ionic liquid on crystallinity and structure of blend electrolyte has been studied
using XRD, DSC, TGA, FESEM, Raman Spectroscopy technique. The VTF equation has ben
used to adequately explain the temperature dependence of the dc conductivity. To understand
the ion dynamics and relaxation mechanism the ac conductivity and electric modulus spectra
have been analysed using the existing theoretical models. The electrical results have been
correlated with the structural changes occurring due to incorporation of ionic liquid.
Chapter 6 deals with a study of the effect of salt concentration on PEO and PVDF-HFP based
blend polymer electrolytes. The structural investigations have been carried out using XRD,
DSC and FESEM. The dynamics of Li+ ions in these electrolytes has been investigated using
ac impedance spectroscopy. The conductivity and dielectric relaxation in these electrolytes
have been studied, using the existing theories of the conductivity and modulus formalisms.
In chapter 7, the effect of plasticizers such as Ethylene Carbonate, Propylene carbonate and
Dimethyl carbonate effect on PEO and PVDF-HFP based blend polymer electrolytes has
been investigated. The structural investigations have been carried out using XRD, DSC and
TGA. The dynamics of Li+ ions in these electrolytes has been investigated using ac
impedance spectroscopy. The conductivity and dielectric relaxation in these electrolytes have
been studied, using the existing theories of the conductivity and modulus formalisms.
In Chapter 8, the summary of the thesis is presented. The possible future research in
continuation of this work is also highlighted.Research was carried out under the supervision of Prof. Aswini Ghosh of Solid State Physics division under SPS [School of Physical Sciences]Research grant was from Department of Science and Technology (DST), Government of India (nanoscience initiative program
Development of Nanoparticle Based Probes for Cellular Targeting, Imaging and Therapy
No full textThe research was carried out under the supervision of Prof. N R Jana under SMS [School of Materials Sciences]The research was conducted under CSIR & DST research grant and fellowship
Study of Nonlinear Dynamics of Some Chemical Reactions and Reaction-Diffusion Systems
Full text linkThe account depicted in the preceding section makes it clear that the
phenomena associated with nonlinear chemical dynamics are essentially
manifestations of the nonlinearity of the chemical system under farfrom-
equilibrium condition. Chemical systems are naturally diverse and
under far-from-equilibrium condition the possible permutations of their
disposition become manifold. Since, it is a formidable task to cover
all forms of nonlinearity the present thesis focuses primarily on chemical
systems where autocatalysis functions as the common thread of nonlinearity.
The central theme of the first four chapters of this dissertation is the
presence of at least one autocatalytic step in the concerned chemical
reaction in view of the fact that it renders the system nonlinear. Three very
distinct yet interesting phenomena associated with nonlinear chemical
systems are covered in the first three chapters while the last in this
group provides a recipe for simplification of nonlinear chemical reactions.
Spatially extended chemical reactions form the other half of the thesis
where reaction-diffusion models have been considered to study spatiotemporal
organization. The following pages provide a succinct summary
of the investigations that are covered in this thesis.
1.3.1 Oscillatory chemical reaction induced dynamical hysteresis in a
polymer gel
Hysteresis is a distinct phenomenon usually associated with ferromagnetic
and ferroelectric substances[39, 40, 41, 42, 43, 44, 45]. This fact is
attributed to the assertion that the output of the system depends not
only on the present input but also on its past values. However, it should
be kept in mind that such a phenomenon is not confined to magnetic
substances and is observed in stochastic systems[46, 47, 48, 49], selforganizing
avalanches[50], and other contexts[39]. In the same spirit
mechanical systems such as polymer gels have been found to exhibit
static hysteresis in volume-temperature curves[51, 52]. Here it is noteworthy
to acknowledgeThe research was conducted under the supervision of Prof. D. S Ray, Physical Chemistry division, SCS [School of Chemical Sciences
Gold Electrode Functionalized with Amide SAM: Electron Transfer Properties and Fabrication of Bio-inspired Electrodes
No full textAmide bonds provide primary linkage between amino acids which are basic
functional groups in biology. They support complex structures of protein backbones,
form scaffolds that transport ions and they mediate electron transfer as well.
The entire thesis work had two major objectives. First objective was to study the electron transfer properties through self assembled monolayers (SAMs) containing alkyl and amide linkages. This has been achieved by performing conventional cyclic
voltametry and chronoamperometry on alkyl and amide functionalized SAMs terminated
with a redox active group like ferrocene (Fc) and hemin. These SAM modified surfaces have been characterized using attenuated total reflection mode FTIR (ATR-FTIR)
spectroscopy, X-ray photoelectron spectroscopy (XPS) and surface enhanced Raman spectroscopy (SERS). The goal was to understand how the presence of amide linkages in the electron transfer pathway alters its rate. These rates have been compared with those obtained using straight chain alkane thiols where no amide linkage exists.
Individual residues are mutated on SAMs to understand their role in tuning the
electron transfer rate. Specifically we are interested in understanding how cysteine and tryptophan residues tune the rate of electron transfer. For this reason alkylthiol SAMs are functionalized with terminal thiol and imidazole groups, which provide coordination sites of transition metal catalysts. In particular heme based catalysts are used which bind to these terminal thiol and imidazole to create bioinspired electrodes (modified electrodes with biological structure or activity can be used for electrochemical investigations). Thiol and imidazole bound bioinspired electrodes can be used for mimicking the active sites of cytochrome P450 and myoglobin, respectively. The electron transfer rate constant as well as the reorganization energies has been determined for these catalysts bound modified surfaces using conventional “Laviron” procedure. Second objective was to study the nature of S-H bond of alkylthiols at the interfaces, forming SAMs on metal (Au/Ag) surfaces. Initially the normal Raman spectra of alkylthiols and deuterated alkylthiols were collected to determine any shift in C-S stretching mode (nCS) and C-S-H bending mode (bCSH) after deuteration. This observation was extended to the detection of SH/SD on surfaces. H/D sensitive SER spectra of a series of thiols forming SAMs on Ag and Au surfaces and NPs have been recorded. The presence of characteristic H/D shifts or the lack of any shift was then used to elucidate the protonation state of thiols in a series of SAMs.Research was carried out under the supervision of Dr. Avishek Dey of the Inorganic Chemistry division of SCS [School of Chemical Sciences
Theoretical Exploration Of The Chemistry Of Isoelectronic B-N Analogs Of Alkane And Alkene
Full text linkThis thesis entitled, "Theoretical Exploration Of The Chemistry Of Isoelectronic B-N Analogs Of Alkane And Alkene" is mainly based on the exploration of the mechanistic pathways of reactions related to main group chemistry, which is an important topic of research both academically and commercially. Though the chemistry of carbon has led to the development of the vast field of organic chemistry, the knowledge domain of its periodic table neighbor boron is rather limited. Intriguingly, a B―N moiety is isoelectronic to a C―C moiety. In recent times, the chemistry of B―N based compounds have generated a lot interests. The inherent polarity in B―N compounds, which can significantly modify both electronic and optical properties in comparison to the corresponding isoelectronic C―C analogs, has caught significant attention for many decades. This thesis combines two relevant topics in research of B―N compounds. Through computational aid we have tried to shed light on the underlying mechanistic intricacies associated with: i) the fast oligomerization of aminoborane, the isoelectronic analog of ethylene, ii) trapping of the in situ generated elusive aminoborane species by external reagent cyclohexene, iii) hydrogenation of inert dinitrogen (N2) employing amine-borane as hydrogen carrier, and iv) hydrogenation across the B=N bond. It is believed that the results could give quick explanations to the chemistry lying beneath these intriguing problems which are also practically relevant. The organization of the thesis is as follows.Research was carried out under the supervision of Prof. Ankan Paul, RCAMOS under SCS [School of Chemical Sciences]Research was conducted under financial assistance of DST gran
Magnetic and Transport Properties of Perovskite-type Transition Metal Oxides
Full text linkTransition metal oxides (TMOs) belong to an interesting and challenging field of
research in condensed matter physics and materials science. This class of oxide retains a
wide range of alluring properties and reveals novel and exotic phenomena like metalinsulator
transition, ferromagnetism, exchange bias, and magnetization reversal. The
competition and coexistence of different types of ground states gives rise to complex
electronic and magnetic phases. This thesis entitled “Magnetic and Transport
Properties of Perovskite-type Transition Metal Oxides” mainly focuses on
investigations of structural, magnetic and transport properties of some perovskite-type TMOs such as BaTiO3, LaCoO3, SrRuO3, YbCrO3, and GdCrO3. Lattice distortion,
disorder and chemical composition are the key parameters to modify basic interactions and to induce new magnetic and electronic properties in such TMOs. Reduction of coherence length scale, by non-magnetic/magnetic impurity substitution, also significantly influences the long-range magnetic order in these TMOs.Research was conducted under the supervision of Prof. S K De of Materials Science division under SPS [School of Chemical Sciences]Research was carried out under CSIR & DST gran
Design of Graphene based Nanostructures and their Photophysical Properties
Full text linkGraphene is a promising material for optoelectronics purposes because of its
extraordinary properties such as near zero band gap, high electrical conductivity, ultra high mobility, and high transparency. Considering the extraordinary physical properties, significant
attention has been paid on designing graphene based hybrid materials for their potential
applications in photocatalysis and photovoltaics. The fundamental photophysical understanding
of hybrid materials of graphene with inorganic or organic semiconducting nanomaterials is still
in the embryonic stage, further investigations in this field are necessary for depth understanding
of the phenomenon for designing the efficient solar light harvesting systems. The various
functional groups like carboxylic, hydroxyl, epoxy etc are present in graphene oxide surface
which are eventually being used to attached covalently or noncovalently with organic or
inorganic semiconducting nanomaterials. Here, we have synthesized various inorganic and
organic semiconducting nanomaterials and then attached with graphene oxide or reduced
graphene oxide for designing of hybrid materials. Ultrafast spectroscopic methods have been
used to understand the decay dynamics, charge transfer dynamics of these hybrid materials to
find out their potential applications in photocatalysis and photovoltaics purposes.Research was conducted under the supervision of Prof. Amitava Patra of the Materials Science division under SPS [School of Physical Sciences]Research was carried out under CSIR fellowshi
THEORETICAL AND COMPUTATIONAL STUDIES OF HYDROGEN STORAGE MATERIALS
Full text linkThe thesis sheds light into electronic structure, complex reaction mechanism, kinetics, and thermochemistry of molecules involved in chemical hydrogen storage as well as in the modeling of various modified organic linkers to design improved metal organic frameworks (MOFs) using high-level theoretical methods. A general introduction about the ‘hydrogen storage' is given in the first chapter to provide a preliminary idea about the hydrogen storage materials. The second chapter briefly describes the computational chemistry and provides a review of theoretical methods. The remaining chapters of the thesis are based on the research papers published in reputed international journals. The original papers have been properly formatted to match the style of the thesis.Research was conducted under the supervision of Prof. A K Das of the Spectroscopy division under the SPS [School of Physical Sciences]Research was carried out under CSIR research grant & fellowshi