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Some Physical Properties of Two-Dimensional Metals, Graphene and Nanocomposites Prepared by Embedding them in an Insulating Matrix
Full text linkThe present dissertation deals with the synthesis, characterizations and measurement of some physical properties of two-dimensional metals, graphene and nanocomposites prepared by embedding them in an insulating matrix. For the growth of two dimensional metals, the nanochannels of a clay mineral, Na-4 mica was used as template. For graphene based nanocomposites and functionalized graphene, chemical methods were used. The materials were characterized by different techniques, e.g. X-ray diffraction, transmission electron microscopy, atomic force microscopy. Mainly, electrical transport, dielectric and magnetic
properties of the prepared materials were studied by using Kiethley electrometer, Agilent
LCR meter and Superconducting Quantum Interference Device (SQUID) respectively, over
various temperature ranges. The experimental data were analyzed to understand the physics
behind the observed phenomena. In some cases, possible applications of the materials, as
revealed from the performed measurements were discussed.The research was carried out under the supervision of Prof. Dipankar Chakraborty of MLS under SPS [School of Physical Sciences]The research was conducted under UGC and DST research gran
STUDY OF ORGANIZED MEDIA USING FEMTOSECOND SPECTROSCOPY AND CONFOCAL MICROSCOPY
Full text linkSelf-organized nanostructures play a crucial role in a wide range of natural
phenomena ranging from molecular recognition (e.g. enzyme-substrate, antigenantibody interaction), to a more general case of unusual chemistry in confined environments. Due to the confinement and local interaction, the biological activity and dynamics in these assemblies are significantly different from those in ordinary solutions. In recent years, ultrafast time resolved spectroscopy revealed substantial
amount of new information on these systems.The experimented results has
stimulated a large body theoretical studies and in particular, large scale computer simulations.
The main motivation of this thesis is to understand the role of confinement on
the spectroscopy and dynamics with both temporal and spatial resolution. In the
present thesis, we studied different organized media using femtosecond upconversion, time resolved confocal microscopy and fluorescence correlation
spectroscopy (FCS). In bulk, all chemical informations are averaged over an exceedingly large number of molecules of the order of the Avogadro number. Recent single molecule studies have demonstrated variation of properties of individual molecular systems in an ensemble. This has completely revolutionized our understanding of chemistry.The research was carried out under the supervision of Prof. Kankan Bhattacharyya of the Physical Chemistry division under SCS [School of Chemical Sciences]The research was conducted under CSIR fellowship and DST research gran
Study of magnetic interaction in transition metal complexes
Full text linkRecent times, the major goal of studying polynuclear coordination complexes is
to elucidate their interesting properties, which could have prospective
applications to develop modern technology. Designing of polynuclear transition
metal complexes with Schiff base or small molecular organic ligands and
studying their magnetic interactions including macroscopic magnetic properties
such as magnetic hysteresis, photomagnetism, nanomagnetism, spin crossover and so on, to explore the possibility of new technological applications are the major concerning subject of this thesis. Along with magnetic measurements, various structural and spectroscopic characterizations such as X-ray crystallography, electrical measurements (impedance spectroscopy), UV-Vis absorption, EPR, FTIR, Mossbauer study etc were used to investigate their
structures as well as several molecular properties associated with their magnetic
behaviour. We have also used theoretical calculations based on density
functional theory in order to understand their magneto-structural correlations.The research was conducted under the supervision of Prof. Shyamal Kr. Saha of the Materials Science division under SMS [School of Materials Sciences]The research was carried out under CSIR fellowship and research gran
Functionalization of Nanoparticles and their Application as Cellular and Subcellular Imaging Probe
No full textThe work in this thesis entitled “Functionalization of Nanoparticles and their Application es Cellular and Subcellular Imaging Probe” was initiated by the author in April 2012 in Centre for advanced Materials, Indian Association for the Cultivation of Science, Kolkata ender the supervision of Dr. Nikhil Ranjan Jana.
Optical imaging plays an important role in bioimaging, clinical diagnostics and sensing spplications. Fluorescent nanoparticles offer promises in this area due to their strong ehotoluminescence and low photobleaching property in comparison to the existing organic yes. These unique properties exist in nanoparticles like carbon dots, quantum dots and semiconductor nanoparticles, silicon nanoparticles, gold cluster and thus they serve as seperior imaging probes for various bio-diagnostics. In parallel to the synthesis of this «ssomaterials the functionalization is also very important. For the bioimaging application, igh colloidal stability and retained optical stability is always desired and therefore different seating strategy has been introduced. In addition selective detection of cancer cell over seemal cell is still very challenging issue. Generally functionalization with different peptides, ssemolecules is used for the specific detection of the diseased cells or tissues. Nanoparticle sesed subcellular imaging probe is also very important for the same reasons. Nanoparticle «<& tunable surface functionality can offer endosomal escape and the specific ligand Seectionalization can target the desired subcellular organelle. Subcellular localization of the samoparticles is sometimes restricted due to the endosomal trapping which is main obstacle the the gene delivery, drug delivery or bioimaging. Therefore some endosomal escape route ees to be designed for successful subcellular targeting. Proper functionalization of emmeperticles may offer the endosomal escape that include hyper branched poly L lysine, eely ethylene imine (PEI). Endocytosis mechanism also plays important role in subcellular ‘eslization of the particles. Clathrin mediated endocytosis, which is well known for almost <) “ed of nanoparticles, leads the particle to the endosomes or lysosomes of the cells sereas caveolae or lipid raft mediated endocytosis bypass the endosomal pathway and takes ‘the particle to the Golgi apparatus or endoplasmic reticulum. But the endocytosis mechanism aeeys depend on the particle surface functionalization by which it interacts with the cell sub-membranes and that needs to characterized. Nanoparticle can be used as powerful drug ery carrier in particular antioxidant delivery to the cells is very important similar to drug delivery.The research was carried out under the supervision of Prof. N R Jana under SMS [School of Materials Science]The research was carried out under IACS fellowshi
Synthesis and Functionalization of Carbon-Based Nanomaterials for Biomedical and Environmental
No full textThe work presented in this thesis entitled “Synthesis and Functionalization of Carbon-Based Nanomaterials for Biomedical and Environmental Application” was initiated by the author in July, 2010 in Centre for Advanced Materials, Indian Association for the Cultivation of Science, Kolkata, under the supervision of Dr. Nikhil Ranjan Jana.
Numerous types of nanomaterials have been exploited gradually for the rapid development of nanotechnology in different applications such as biological science, photocatalysis, catalysis, solar cell, fuel cell, nanoelectronics, optical detection ete. Convensional tunable emissive semiconductor quantum dots (QD) and gold nanoparticles are widely used in ongoing research. But these QD are composed of toxic metals such as cadmium (Cd) and non-metals like selenium (Se), tellurium (Te) etc. Consequently, human sivilization and environment being gradually affected by applying such QD. Gold nanoparticle-based probes afford dark field imaging which has limited applications for cellular imaging because of the high scattering background from the cell. Besides fluorescent nanomaterials based on doped semiconductor nanocrystals, fluorescent gold clusters and fluororescent silicon nanoparticles are under development and have yet to exhibit performances size with enhanced tunable emission from blue to red via carbonisation approach from different types of carbohydrates. The as prepared FCN are hydrophilic and hydrophobic in =seere and their fluorescence quantum yield varies from 6-30 %. These particles also exhibit sxe-dependent, tunable visible emission. These FCN have been transformed into similar «eed various functionalized nanoprobes by linking with folic acid, long chain amine and TAT peptide. Long chain amine and TAT peptide functionalization increase the cellular eptske and efficiency, whereas folate functionalization offers specific detection and imaging of cancer cells. The small size of these nanoprobes affords easier subcellular targeting. Chapter 5 describes interdigited bilayer type coating strategy which provides both eellieadal stability and functionalization option for graphene. Colloidal graphene oxide have Seen first converted into interdigited bilayer coated graphene oxide and next they have been transformed into colloidal graphene by hydrazine reduction. These coated graphenes can be Secber transformed into colloidal functional graphene using covalent conjugation chemistry. Functional graphene has been synthesized for optical detection of enzyme where a flourescent dye is covalently linked through a peptide so that the dye fluorescence is quenched by graphene but switches on once enzymes cleave the peptide bond. The qemeediested bilayer coating reported here is unique as it provides an optimum coating Geckness (< 3 nm), offering optically responsive graphene fluorophore substrate with high colloidal stability.
Chapter 6 describes a simple and large scale synthesis method for graphene-silver nanoparticle based composite for sunlight induced mineralisation of colourless endocrine disruptors (phenol, bisphenol A and atrazine). It is found that photocatalytic efficiency of the composite under visible light is significantly higher as compared to graphene or silver nanoparticle. It is proposed that presence of graphene not only provides a large surface area support for the Ag nanoparticle and organic molecule, but also stabilises charge separation via electrons transfer, thereby enhancing photocatalytic efficiency through oxidative degradation of organic pollutants.
Chapter 7 describes the summary of all the chapters and scope of my work has been
described.
Attention has been given to incorporate all the current references related to this contemporary area of research. Any unintended omission is deeply regretted.The research was carried out under the supervision of Prof. N R Jana under SMS [School of Materials Sciences]The research was conducted under CSIR research gran
A Time-of-Flight Mass Spectrometric Study of Multiphoton Dissociation and Ionization of Selected Atmospherically Important Compounds
Full text linkThe thesis is concerned with the dissociation and ionization dynamics of selected atmospherically significant volatile organic compounds. The primary objective is to investigate the various photochemical events that take place within these molecules upon multiphoton excitation in the ultraviolet region of the electromagnetic spectrum. The major process that takes place upon multiphoton excitation of molecules is ionization of the followed by its dissociation in to different fragments.
However, many isomerization and rearrangement process can occur when the
molecules are excited to the intermediate excited states and can be probed using
multiphoton ionization. The new products formed due to isomerization or
rearrangement further absorb photons in the ultraviolet region can undergo
fragmentation and ionization.Thesis
Submitted for the Degree of
Doctor of Philosophy (Science)
in
Chemistry (Physical)
by
Arup Kumar Ghosh
Department of Chemistry
University of Calcutta
2014The research was conducted under CSIR project in the Physical Chemistry division of IACS under the supervision of Prof. Tapas Chakrabort
C-N BOND FORMING REACTIVITY IN ANILINE AND THEIR CO-ORDINATION CHEMISTRY
Full text linkThe research has been originated from an attempt to explore direct and selective transformation of c-h bonds that are mediated either by metal coordination or by protonation of anilido substrate oxidative dimerization and polymerization reactionsThe research guide was Prof. Sreebrata Goswami of Inorganic Chemistry division under SCS [School of Chemical Science]Research was conducted under CSIR fellowship in IAC
Studies on Coordination Complexes Metal Organic Framework (MOFs) and Network using Salicylic Acid Derivatives and Pyrazole based Ligand
No full textThe whole work is divided in three parts. The 1st part deals with synthesis if series of metal organic framework from bis-pyrazole ligands and various aromatic carboxylic acids and their potential application. the 2nd part contains synthesis and investigation of energy parametres of supramolecular framework resulting from the combination between a bispyrazole ligand and inorganic anions. The 3rd part and the final part contains synthesis of diverse metal organic framework and metal complexes based on chloro-salicyclic acid.Research was carried out under the supervision of Dr. Raju Mondal of the Inorganic Chemistry division under SCS [School of Chemical Sciences]Research was conducted under DST grant and CSIR fellowshi
Functional Soft Nano-hybrids: Synthesis and Biological Applications
Full text linkNature implements the route of self-assembly in several
fundamental processes. Researchers around the globe are always fascinated
by the subtle and intricate mysteries of Nature. They try to mimic natural
ways by building supramolecular self-assembly of molecules, which bear
resemblance to those occurring in Nature. In this regard, amphiphilic
molecules comprised of polar hydrophilic head and hydrophobic tail self
assembles in water to form different supramolecular structures. These
structures are widely diverse and are utilized to understand structurefunction
relation of biological processes. On the other hand, the birth of
nanotechnology has revolutionized almost every domain of research,
especially from material science to biomedicinal arena. However, the
potential of any nanomaterial is extremely constricted without the use of
supramolecular chemistry. From the very synthesis and stabilization of any
nanomaterial the invisible bonds play the central role. Hence the
fundamental process of self assembly is the key towards utilizing
nanomaterials in almost any direction of research. In this respect, carbon
nanomaterials and metal nanoparticles have gained major attention owing
to their amazing optical and electronic properties. Recently, it has also
gained huge impetus in biomedicinal arena. The present thesis gives an
overview on the development of novel self-assembled aggregates with a
particular focus on gelation and some of their task specific applications.
Also, it deals with amalgamation of supramolecular self-assembled
systems with nanomaterials like carbon nanotube, graphene, silver
nanoparticles (AgNPs) and thereby developing soft nanocomposites having
superior physicochemical and biochemical properties.Research was conducted under the supervision of Prof. P K Das of Biological Chemistry division under SBS [School of Biological Sciences]Research was carried out under CSIR fellowshi
TUNABLE FERRITIN BIOELECTRONICS AT THE NANOSCALE
Full text linkFerritin, the iron storage protein, which is found in human body, holds great potential for applications in molecular bioelectronics and in vivo bio-nanotechnology, since the iron core of holoferritin is semiconducting in nature. Ferritin can exhibit clear electron transfer properties, is stable within a wide range of pH and temperature, and can retain structural integrity when immobilized onto a solid surface. Inspite of appearing as a suitable candidate for broad-spectrum technological applications, some of the practical aspects, e.g., how its electronic properties can be varied/tuned, need to be better addressed. In this direction, we have successfully tested that temperature, pressure and the nature of the metal core (e.g., copper, cobalt, iron and manganese) can exert clear control on the solid-state electron transport properties of the ferritin molecules. We explored a correlation between the mechanical properties of the ferritins with their electromechanical response as the concluding part of the thesis work.
For this thesis, we have adopted a multi-technique approach and have applied scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), atomic force microscopy (AFM), atomic force spectroscopy (AFS), current-sensing atomic force spectroscopy (CSAFS), synthetic preparative methods, scanning electron microscopy (SEM), uv-visible spectrophotometry (UV-VIS), transmission electron microscopy (TEM) (with EDX) and inductively coupled plasma (ICP). The present thesis includes an introduction and four results chapters.Research was conducted under the supervision of Prof. Rupa Mukhopadhyay of the Biological Chemistry division under SBS [School of Biological Sciences]Research was carried out under DST fellowshi