Department of Chemistry
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Item Application of atom transfer radical polymerization for the preparation of multifunctional materialsChatterjee, Dhruba PrasadThe present thesis entitled “APPLICATION OF ATOM TRANSFER RADICAL POLYMERIZATION FOR THE PREPARATION OF MULTIFUNCTIONAL MATERIALS” deals with the controlled synthesis and application of different multifunction amphiphilic block and graft copolymers. The work is carried out at the department of chemistry, Presidency University, Kolkata 700073, India, under the supervision of Dr. Dhruba Prosad Chatterjee. The thesis comprises of five chapters. Chapter 1 deals with a brief introduction of classification and architectures of polymers and different techniques of polymerization. It also emphasizes the advantage of ‘living’ radical polymerization. This chapter provides an elaborate discussion of commercially attractive different LRP techniques with low metal mediated complex concentration. Chapter 2 deals with the synthesis of ‘living’ poly(2- dimethylaminoethyl methacrylate) by bulk atom transfer radical polymerization using CuCl/ N,N,N/ ,N/ ,N// -pentamethyldiethylenetriamine catalyst at ambient temperature which occurs through soluble ATRP catalyst entrapped within reverse micelles where an adventitious role of water molecules during polymerization is noted. Synthesized PDMAEMA molecules work efficiently as macroinitiators for the synthesis of different stimuli responsive, multifunctional di- or triblock copolymers through sequential polymerization. Chapter 3 deals with the stabilization of CdS quantum dots by the diblock copolymer PDMAEMA-bpoly[di(ethyleneglycol)methyl ether methacrylate] in aqueous medium which show stimuli dependent reversible switch between micelle ‘core-confined’ and ‘corona-embedded’ morphologies. Chapter 4 deals with the synthesis of different Poly(vinylidene fluoride) grafted amphiphilic random ter/bi- copolymers containing reactive Poly(furfuryl methacrylate) or thermo responsive PDEGMEM etc. as constituents by ATRP in homogeneous solution followed by the post polymerization modification with maleimide by the Diels-Alder reaction to introduce imidodicarbonyl moieties. Membrane fabrication is subsequently done by breath figure or immersion-precipitation techniques. The fabricated membrane offers the capability of exerting affinity-interaction with melamine or nucleobases in the protein immobilization. Chapter 5 deals with the future objective where synthesis of PVDF based graft copolymers having hydrophobic/hydrophilic stimuli responsive polymer systems effective in metal-ion affinity membrane chromatography along with the preparation v of block copolymers based on (2-hydroxyethyl) methacrylate chains which has an immense utility in the industrial and biomedical field has been proposed.Item Design and Synthesis of some Fluorescent Probes studies with Biomacromolecular SystemsMajhi, AnjoyFluorescent probes are powerful tools for biosensing and bioimaging because of their high sensitivity, specificity, high fluorescence intensity, excellent solubility, biocompatibility and simple preparation. Hence, development of fluorescent probes specifically for biological settings and clinical setting has attracted intense interest. They can provide direct visualization and dynamic information concerning the localization and quantity of biomolecules of interest. Till to date, different kind of fluorescent probes is commercially available and can be used in biological investigations. ‘Click reaction’ is one of our main strategy for the synthesis of fluorescent probes. Click reaction is Cu(I)-catalyzed cycloaddition of alkyne and azide (CuAAC) reaction and by the CuAAC reaction, 1,2,3-triazole moiety-containing compounds can be synthesized conveniently. This triazole moiety have enormous application including pharmaceuticals, and are available as drugs today. Bovine serum albumin (BSA) and human serum albumin (HSA) are the most abundant plasma proteins which play a key role in many biological systems. The molecular weight of these two serum albumins (SA) are almost similar (66 KDa and 66.5 KDa are the molecular weight of BSA and HSA respectively) and also shows 80% structure similarity with each other. Protein ligand binding study is very important in drug design and developing system. Information is obtained from this study, whether it can act as a drug or not at very preliminary stage of research. Photophysical studies of protein ligand interaction using different spectroscopic technique enhance our knowledge towards the way of binding. Our research work mainly categorized into two parts namely, the synthesis of some novel compounds using standard methods such as click reaction, and thereafter investigation of the interaction of the synthesized compounds with serum albumins (e.g. BSA/HSA) by different spectroscopic technique and also the biological activities of the compounds. Hence, an attempt is taken for the binding study of the newly synthesized compounds with biomolecules to assemble the information about the role of a novel compounds for development of biomedicines in the drug design or drug delivery process at very preliminary stage of the modern researchItem Photoluminescence study of the synthesized nanomaterials in presence of macromolecules and heavy metal ionsHalder, ArnabThis work illustrates synthesis, structure, band modulation and optical tuning of many kinds of carbon-based nanomaterials. Among the different types of natural and synthesised carbonbased materials, graphene and graphene oxide based nanomaterials, which include graphene oxide, functionalized graphene oxide, graphene oxide quantum dots, graphene quantum dots have wide range of multidimensional applicability in various field of science and technologies. Non emitting behaviour of graphene and very low photoluminescence quantum yield of graphene oxide restrict their utilities in optoelectronics and optical tracking in biology. As a new approach, incorporation of lanthanide metal ion, cerium, in to graphene oxide based nanoparticles becomes successful to increase a 100-fold amplification of photoluminescence intensity is obtained. The origin of this enhancement of GO-Ce nanoparticles is investigated by examining the interactions between cerium ions and GO nanoparticles as well as the structural modification of the GO nanoparticles in presence of cerium. A mechanism that includes energy pumping of cerium by photoexcited GO nanoparticles and photoinduced reduction of non-emissive Ce (IV) to luminous Ce (III) is supported by experimental data. To understand the interactions based on the local environment of the cerium ions, we have explored the effect of aromatic nitro compounds and fluoride ions on the photoluminescence of cerium incorporated GO nanoparticles. Experimental observation on the basis of fluorescence quenching reveals the role of accessibility and local polarity of the excited cerium (III) ions. By incorporating surface functional groups, photoluminescence from graphene oxide (GO), and hydroxyl enriched graphene oxide quantum dots (OH-GO QDs) in the UV-visible range, we have examined the interaction between the graphene oxide layers. The contribution of the visible PL band is noticeably increased along with the decrease in the PL band in the UV region as the concentration of OH-GO QDs in the aqueous medium increases. Hydrogen bonding interaction between the hydroxyl functional groups on the surface of OH-GO QDs favours to form the aggregates exhibiting the PL band in the visible spectrum. In order to investigate the modification of photoluminescence bands caused by the interaction between GO and PANI in GO-PANI nanocomposites at three different pH levels the effect of temperature on the PL of GO-PANI has been examined. Experimental findings indicate the role of temperature on the charge transfer interaction between GO and PANI is prominent at pH 6. We have synthesised graphitic carbon nitride (g-C3N4) and studied its photoluminescence properties at three distinct pH. The intensity of the defect-induced luminescence band is found to be significantly influenced by protonation-deprotonation on the nitrogen atoms in graphitic carbon nitride through experimental observation. Finally, we have studied the effect of a co-polymer, Pluronic F-127 (PF-127) on the PL bands of GO. Anchorbuoy type adsorption of PF-127 on the GO sheets significantly modulates the intensity and peak positions of the photoluminescence bands of graphene oxide (GO), in both acidic and alkaline media.Item Synthesis and Characterization of Metal Organic Framework Based on 3d and 4f MetalsBiswas, BiplabThis thesis covers the broader section of the chemistry and the material sciences of our daily needs. The main objective of our work was to design different 3d and 3d-4f hetero bimetallic Metal Organic Framework (MOF) using different clickable Schiff base ligand having N,N,O donor sites. We have further used co-ligand such as azide, thiocyanate, 4-tert-butyl-benzoic acid to increase the nuclearity of the metal complex. Careful design of these complexes has allowed us to isolate these complexes with versatile structural motif and application in the field of data storage, luminescence and sensing. We have explored the sensing study for the detection of the hazardous analytes such as sulfide (S2-) and Ag+ , Cu2+, Fe3+ by Metal Organic Framework. We have also studied the anti-cancer activity towards the breast cancer cells Zn azido and Zn perchloato complex where we have found that a 0.5 mM dose of the Zn-azido and Zn-perchlorato complex could kill the 81% and 72% of the breast cancer cells respectively. However Zn-azido complex affects the normal cell as well although Zn-perchlorato complex does not affect the normal cells. Hence Znperchlorato complex has potential biological activity and may be used for the therapeutic purposes. We have also synthesised 3d-4f metal complexes which could be used as fluorescence biomarker and could be used as data storage. This thesis covers a broader sector of material science in corroboration of biological studies in few cases.Item Synthesis, Characterisation of Mixed Metal Oxide Based Inorganic Materials and It’s Application Towards the Removal of Fluoride and Heavy Metals From Contaminated WaterPalani, SasikumarAmong all water contaminants, fluoride and copper contamination in groundwater as a result of natural and anthropogenic activities has been identified as one of the biggest issues worldwide, posing a serious threat to human health. Mixed metal oxides-based adsorbents, particularly Zr(IV), La(III), Ce(IV), and others, have sparked a lot of attention in recent years due to their high selectivity and affinity for fluoride and copper. Therefore a binary [Cr(III)- Zr(IV)] (CZ) or a ternary mixed metal oxide [Ce(IV)-Zr(IV)-La(III)] (CZL) inorganic adsorbent material and efficiently apply for F - and Cu(II) adsorption from aqueous phases. Further surface modification CZ was performed with chitosan and -cyclodextrin (CB@CZ) for further application to remove Cu(II). The adsorbent CZ's effectiveness was also exploited for practical applications, such as expanding the study's potential applicability for removing F - ions from laboratory and real field contaminated water. The entire work is split into different chapters. The first chapter offers a review of the literature as well as a background analysis of the project. The presence of harmful pollutants such as fluoride and other heavy metal ions in drinking water, as well as their allowed limits, has been extensively discussed. A comparison analysis based on the adsorption capabilities of adsorbents towards various adsorbates, particularly F - and Cu(II), has also been discussed. The description of employed chemicals, solution preparations, materials, adsorbent synthesis, instrumental details (FESEM, TEM, p-XRD, FT-IR, etc.), batch study experimental details, and mathematical model equations that were used to analyze the experimentally obtained data are all included in Chapter 2. The characterization of the binary mixed metal oxide based adsorbent [Cr(III)-Zr(IV)] (CZ) used to remove F - from artificially and naturally contaminated water is covered in Chapter 3. For further use in the removal of heavy metals, particularly Cu(II), surface modification of CZ using chitosan and -cyclodextrin (CB@CZ) is described in Chapter 4. The characterization of the ternary mixed metal oxide [Ce(IV)- Zr(IV)-La(III)] (CZL) and its applications to the removal of F - and Cu(II) from wastewater are both covered in Chapter 5. In Chapter 6, the findings are compiled in a table along with a broad conclusion on the work's future potential.Item Transport properties of artificial micro-swimmers and related non equilibrium phenomenonaGhosh, Pulak KumarThe present thesis entitled “Transport properties of artificial micro-swimmers and related non equilibrium phenomenona” deals with an important class of artificial micro-swimmers (self-propelled Janus particles) which are capable of autonomous propulsion by extracting energy out of fluctuations. Based on the numerical analytical modeling we address the following issues- 1)dynamics of fast moving particles in the presence of the slower moving one 2) effect of flow field on the diffusion of self-propelled particles 3) diffusion mechanism when transient effects are important, and 4) diffusion in various types of confined structures. The work is carried out at the Department of Chemistry,Presidency University, Kolkata 700073 India, under the supervision of Dr. Pulakkumar Ghosh The present thesis addressed the above mentioned issues based on the simulation of dynamics of Janus particles. The thesis is organized as follows. In Chapter 1, we present the introduction of self-propelled Janus particles and briefly describe significance of our works in the context of previous works in this field as well as applications in nanotechnology and medical sciences. Chapter 2, presents transport properties of Janus particles in a binary mixture of two kinds of swimmers in the under-damped limit. Based on the numerical simulation we show the presence of strong Janus particles considerably improves velocity distribution of weak particles. In the Chapter 3, we show that even in the absence of inertia, motility can transfer from weak to strong particles in the binary mixture. This has been confirmed by studying how effusion of weak particles changes by the presence of passive particles. Chapter 4, presents diffusion of selfpropelled Janus particles in the counter rotating convection rolls. We focus on the large Péclet numbers, i.e., for self-propulsion speeds below a certain depinning threshold and weak rototranslational fluctuations. In this limit the particle undergoes asymptotic normal diffusion with diffusion constant proportional to the square root of its diffusion constant in the absence of flow. We model Chirality effects in the propulsion mechanism assuming a tunable applied torque which induce particle jumping between adjacent convection rolls. The jumping mechanism among adjacent convection rolls can be identified by an excess diffusion peak. In the Chapter 5, we explore interplay between inertial relaxations to the time correlated selfpropelled motion in confined structures. This issue is potentially important as most of the novel nano-technological applications of Janus particles involve diffusion through different types of confined structures v where inertial impact as well as self-propulsion. We address this issue and show that inertial impact is important in the experimentally accessible situations for both selfpropelled and passive particles. In Chapter 6, we present a summary of our works and possible futureItem Tunable Luminescence of Graphene Based Nanomaterials: Role of Surfactants and MacromoleculesHalder, ArnabThe present thesis entitled “Tunable Luminescence of Graphene Based Nanomaterials: Role of Surfactants and Macromolecules” addresses the synthesis of graphene based nano materials like graphene oxide (GO), chemically modified graphene oxide (CM-GO), graphene oxide polyaniline (GO-PANI) nanocomposite with tunable photoluminescence nature (PL). The role surfactants like sodium dodecyl sulphate (SDS), cetyl trimethyl ammonium bromide (CTAB) has been also described to modulate the PL of GO. This thesis comprises of eight chapters. Chapter 1 deals with the general introduction and brief description of the summary of the research work. The motivation, objectives and plan of the present investigation are also stated in this chapter. Chapter 2 deals with the properties and structure of graphene, the different method of synthesis of graphene existing in literature and the literature review on the photoluminescence properties of GO and GO based nanomaterials till 2020. Chapter 3 describes the method of synthesis with the characterization of GO, CM-GO and GO-PANI nano-composite. Chapter 4 discusses the effect of pH on the PL properties of GO-PANI nano-composite. The interaction between polyanilne and GO changes with the change in pH, which strongly affects the PL properties of the GO-PANI nanocomposite. Chapter 5 includes the study of PL of GO in the aqueous medium in the presence of different concentration of surfactants (SDS and CTAB).The mode interaction between GO and surfactant strongly depends on the pH of the medium which modulates the band gap of GO are described in this chapter. Chapter 6 includes the study of PL of GO-PANI in the aqueous medium in the presence of an anionic surfactant (SDS) at both acidic and alkaline medium. The interaction between GO-PANI and SDS is different in different pH, which modulates the PL of the GO-PANI nano-composite material. Chapter 7 describes the PL properties of both GO and CM-GO in aqueous medium with proper explanation of the origin of the luminescence. The modulation of luminescence both GO and CM-GO by changing concentration also described in this chapter. The conclusion of the research work along with the future prospects obtained from this thesis are presented in Chapter 8.