PhD Theses (Chemistry)

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Harnessing the Nitrile Functionality to Heterocycles via Thermal and Photochemical Strategies
(2024) Dhara, Hirendra Nath
The Ph.D. thesis, “Harnessing the Nitrile Functionality to Heterocycles via Thermal and Photochemical Strategies,” focuses on the synthesis of biologically relevant heterocycles and is divided into five chapters, including an introduction.
Reactivity of Co(III)-peroxo Complexes with NO and Co(II)-nitrosyl with H2O2: Putative Formation of Co-peroxynitrite
(2024) Samanta, Bapan
This thesis broadly covers our endeavor to understand both the reactivity of peroxo complexes of Co(III) with NO in non heme ligand frameworks, L1, L2, L3 and nitrosyl complex of Co(II) with reduced oxygen species, H2O2 in heme ligand framework, TTMPP2- respectively. These complexes were synthesized by varying bidentate, symmetric tetradentate, asymmetric tetradentate and square planar ligand framework. The change of reactivity pattern with ligand denticity has been studied. The reactivity of Co(III)-peroxo complexes with NO was discussed in chapters 2-4, following an attempt to mimic the mechanism of the nitric oxide dioxygenase (NOD) enzyme. In every case, formation of putative peroxynitrite intermediate was observed. Efforts were made to identify and characterized the associated intermediates that form during the course of the reaction. For instance, in chapter 2, putative formation of Co(II)-peroxynitrite intermediate was observed using a bidentate ligand framework and finally it isomerizes to the corresponding nitrate complex. In chapter 3 and 4, formation of Co(II)-peroxynitrite intermediates were observed using symmetric and asymmetric tetradentate ligand frameworks, respectively. In case of chapter 3 and chapter 4, different decomposition products were obtained i.e corresponding nitrate and nitrite complexes respectively.
Cobalt(II) and Manganese(II) Nitrosyl Complexes as Potential HNO/NOˉ Donor
(2024) Saha, Shankhadeep
This dissertation addresses our attempt to understand the potential of Co(II) and Mn(II) nitrosyl complexes as nitroxyl (HNO/NOˉ) donors. A series of nitrosyl complexes were synthesized by varying the ligand framework (from electron deficient to electron rich) with a central metal ion (e.g. Co2+ and Mn2+). The ability of these metal-nitrosyl complexes to act as HNO/NOˉ donors under different reaction conditions was discussed in chapters 2 to 5. The potential of cobalt-nitrosyl complexes as nitroxyl donors was extensively discussed in chapters 2 to 4, whereas chapter 5 addresses the manganese-nitrosyl complex, which led to some significant observations. For instance, in chapter 2, the nitroxyl releasing ability of a {Co(NO)}8 complex in presence of anionic sixth ligands like BF4ˉ and DTCˉ was observed, which is the first example of such kind of reaction. Chapter 3 describes our in detailed findings of the reaction between a {Co(NO)}8 complex and DTCˉ anion, which also leads to the NOˉ donation. In chapter 4, a neutral imidazole ligand mediated NOˉ release from a highly electron rich {Co(NO)}8 complex was studied. All of these sixth ligand mediated nitroxyl release from cobalt-nitrosyl complexes are found to be concomitant in nature. The kinetic inertness of low-spin d6 cobalt-centre of {Co(NO)}8 complexes makes the release of HNO very difficult. Our recent findings on the methodology for HNO/NOˉ release from {Co(NO)}8 complexes will contribute significantly to the existing knowledge of nitroxyl donation from cobalt-nitrosyl complexes.
Annulation and Directing Group Strategies as Tools for the Construction of Heterocycles
(2024) Das, Bubul
The contents of the thesis have been divided into four chapters with initial one as introductory and the rest of the chapters are based on experimental results obtained during the research period. The introductory chapter of the thesis is a summary of alkyl isocyanoacetate’s reactivity and its usefulness in diverse (3 + n) annulation/cycloaddition reactions. Along with this, a brief description of the directing group (DG) strategy for the functionalization of C−H bond has also been added. A brief account of the formation of important heterocyclic scaffolds following annulation/cycloaddition and DG-assisted C−H activation has been included.
Design and development of synthetic anion transporters: Towards therapeutic prospects
(2024) Das, Sribash
The thesis, titled "Design and development of synthetic anion transporters: Towards therapeutic prospects," provides a brief description of several kinds of novel anionophores that exhibit significant promise for therapeutic applications. This thesis includes insights on the recognition, transportation across cell membranes, and potential therapeutic applications. The thesis is divided into four chapters based on experimental findings obtained during the research periods
Applications of Reconstructed Nanofluidic Membrane of Layered Materials in Ionic Thermoelectricity and Moisture-Electricity-Generation
(2024) Gogoi, Raktim
This PhD thesis focuses on the development of innovative ionic thermoelectric (i-TE) materials and moisture-electric generators from the reconstruction of layered materials. The first study explores clay-based i-TE materials, where exfoliated and surface-functionalized lamellar clay nanosheets are fabricated. These materials exhibit improved thermoelectric properties, high-temperature stability (up to 300°C), and water-assisted healing capabilities. The devices can convert waste heat and sunlight into electricity, with enhancements made by integrating photothermal materials like carbon nanotubes and hydrogel coatings for improved performance in low-humidity environments. The second study investigates V₂O₅-based i-TE materials, where the Seebeck coefficient is significantly enhanced by intercalating poly(4-styrenesulfonic acid) (PSS) into the lamellar structure. These materials maintain thermal stability, even at high temperatures, and demonstrate strong thermoelectric behavior.
Catalytic Asymmetric Synthesis of Cyclic Acetals and Dearomatization Reactions of Indoles & Naphthols
(2024) Shikari, Amit
The contents of the present thesis entitled as “Catalytic Asymmetric Synthesis of Cyclic Acetals and Dearomatization Reactions of Indoles & Naphthols” have been divided into five chapters based on the results achieved from the experimental works performed during the entire course of the Ph.D. research programme.
Synthesis, Photo-Physical Properties and Applications of Novel Metal Nanoclusters
(2024) Sarkar, Priyanka
The contents embodied in this thesis is divided into seven chapters. Chapter 1 is an introductory chapter which gives a concise and lucid introduction to the field and reports the major scientific contributions relevant to metal Nanoclusters. The introductory chapter represents an overview of the synthesis procedures, photo-physical properties, factors affecting its photo-physical properties and applications of these metal nanoclusters to diverse fields. Chapter 2 provides a detailed description of the material and methods used throughout the thesis. Chapter 3 describes synthesis of a biocompatible DTT (Dithiothreitol)-reduced LYS(Lysozyme) capped silver nanoclusters(AgNCs) and its application for selective and sensitive detection of Cu2+ and VB12. Detailed detection mechanism was studied. These AgNCs were also able to detect Cu2+ and VB12 inside live cells as well. Chapter 4 describes synthesis of a DTT reduced BSA(Bovine Serum Albumin) capped dual-emissive AgNCs and its application for selective and sensitive ratiometric detection of Cu2+ and IO4-. Detailed detection mechanism was studied. Chapter 5 describes a top-down synthetic approach to synthesize time-controlled two differently emissive copper nanoclusters (green and blue CuNCs) from a non-luminescent copper nanoparticles(CuNPs). Later, blue emissive CuNCs were utilized for detection of Fe3+ and GSH(Glutathione) via fluorescence turn-off-on mechanism. Detailed detection mechanism was studied. Chapter 6 reports two different strategies to produce AIDF (Aggregation induced delayed fluorescence)-based luminescent materials at room temperature from GSH-capped CuNCs by (1) simply modifying the solvent environment and (2) introducing of gadolinium (Gd3+) ions. Detailed analysis were investigated to reveal the generation mechanism of these AIDF properties. Further, Gd3+ induced AIDF of GSH-CuNCs were utilized to selectively detect Cr+6 ions. Chapter 7 provides a concise summary with future prospects.
Crystalline Molecular and Nanoparticle Assemblies with Optoelectronic Application Potential
(2024) Bhakat, Arin
The current thesis describes the production and prospective use of molecular crystals and crystallization-induced nanomaterial assembly. The current thesis reveals that the surface of molecular crystals can serve as an appropriate SERS platform. The surface functionality of molecular crystals can participate in non-covalent interactions with the deposited analyte molecules, allowing for efficient photoinduced charge transfer. The current thesis also shows that inorganic molecular crystals can exhibit metallic characteristics and cause surface plasmon. These molecular crystals may be exploited as a possible SERS substrate due to their excellent spectrum stability, simplicity of synthesis, outstanding environmental stability, biocompatibility, target molecule selectivity, and molecular cooperativity. The thesis also depicts the tuning of NC characteristics as a dopant inside molecular crystals, which sheds light on the methods for inducing tuneable phosphorescence features on simple metal NCs via ordered packing structures inside molecular crystals by altering the surrounding environment and electronic confinements. Furthermore, we used the intermolecular interaction-based surface complexation approach that causes molecular crystal formation to self-assemble nanomaterials into the crystalline superstructure.
Utility of Sterically Strained Brønsted Salts as Organocatalysts for C-C, C-O, O-Si Bond Formations and Metal-Free Si-H Activation
(2024) Addanki, Rupa Bai
The contents of this thesis have been divided into five chapters based on the results of experimental and computation works performed during the complete course of the research period. The introductory chapter of the thesis presents an overview of the reactivity of sterically strained bulky bases like 2,4,6-tri-tert-butyl pyridine and their utility in various organic reactions. The second chapter shows the synthesis of Phenylallyl Ferrier-C-glycosides utilizing the sterically strained interactions of triflate anion with water molecule in activating allylsilanes by generating silyl cation. Third Chapter showcased the synthetically interesting SN2-type glycosylation of perbenzylated glycosyl trichloroacetimidates using tetrafluoroborate salt of sterically strained tri-tert-butylpyridine. Along with the spectroscopical evidence, theoretical calculations were performed in support of the proposed SN2 type glycosylation. The fourth chapter presents a metal free procedure for the activation of Si-H by using sterically strained TTBP-BArF salt. The thus generated silyl cation was trapped using alcohol. This method is proven efficient for various chemical transformations including synthesis of 1-deoxy glycals, reduction of indoles, ketones and alkyne. Plausible mechanisms were proposed based on several control experiments performed and literature support. The final chapter is a short study on the influence of rigid protecting groups like acetonide, electronic effects of different protecting groups of mannosyl donor aiming for beta mannosides. Apart from chapter I, the rest of the chapters comprise few subsections, including an introduction, detailed literature reports, the origin of the work, present work, experimental section, references, spectral data of selected compounds (1H, 13C, 19F and 29Si NMR) and XRD data. In addition to these, chapter III includes computations at the DFT level.
Design and Syntheses of Liquid Crystalline Perylene Derivatives as Materials for Organic Electronics
(2023) Behera, Paresh Kumar
This thesis, titled 'Design and Synthesis of Liquid Crystalline Perylene Derivatives as Materials for Organic Electronics,' comprises five comprehensive chapters, each contributing to the understanding and exploration of novel liquid crystalline organic materials for various applications. Chapter 1 serves as an introduction to liquid crystals and presents a thorough review of perylene-based discotic liquid crystals. It underscores the significance of perylene's unique properties, such as its strong π-π interactions and self-organizing capabilities, laying the foundation for our subsequent investigations. Additionally, it highlights the advantages of bay-annulated perylene derivatives in comparison to bay-substituted ones, setting the stage for research work discussed in the subsequent chapters. Chapter 2 focuses on the synthesis and characterization of electron-deficient perylene derivatives, and their hetero-atom bay-annulated analogues bearing tri-n-decylphenyl moiety. These compounds exhibit room-temperature columnar liquid crystalline behavior and possess exceptional optical properties, making them promising candidates for organic electronics. Notably, they demonstrate significant potential in the realm of solution-processed host-guest OLEDs as deep red/NIR emitters. Chapter 3 delves into the exploration of PBI and its bay-annulated analogs bearing tri-n-decyloxyphenyl moieties. These compounds exhibit remarkable room temperature columnar phases and high molar extinction coefficients, offering promising prospects for applications in organic solar cells and as non-fullerene acceptors. Their unique ambipolar conductivity behavior sets them apart from typical n-type semiconductors. Chapter 4 introduces a swallowtail modification to lower the clearing point of perylene bisimide and its heteroatom annulated derivatives. These compounds exhibit stable liquid crystalline behavior up to room temperature with low melting points, strong fluorescence, and ambipolar conductivity. Their potential in organic electronics is further highlighted. Chapter 5 addresses the challenge of solubility in the less explored class of perylene bis benzimidazole derivatives (PBs) with expanded aromatic cores. These compounds exhibit wide absorption spectra, elevated LUMO and HOMO levels, reduced band gap, enhanced solution processability, stabilized columnar hexagonal phase up to room-temperature and ambipolar behavior, making them ideal candidates for organic solar cells and unique organic semiconductors.
Design and Development of Optical and Electrical Transducers based on π-Conjugated Polymers
(2023) Zehra, Nehal
The research works presented in this thesis focuses on design, synthesis, and development CP-based optical and electrical sensors for detection of various biological and environmental important analytes with the major aim of overcoming the problem and challenges associated with existing sensing systems. Various novel CPs are rationally designed and successfully implemented as rapid, highly sensitive, and portable systems for on-field monitoring of toxic gases, food additives, disease biomarkers, and pathogens. The content of this present thesis entitled “Design and Development of Optical and Electrical Transducers based on π-Conjugated Polymers” is divided into five chapters. Chapter 1 gives a brief introduction about the respective research area where the scope and significance of the subsequent chapters are discussed. Chapter 2 describes the synthesis of cationic conjugated polyelectrolyte PFBT-MI which is applied for ratiometric detection and wash-free imaging of bacteria, and explored its antibacterial applications. Chapter 3 discusses the synthesis of an amine-functionalized conjugated polymer PFPDA and its application in the detection of lethal nerve agent vapor by developing a low-cost electrical sensor. Chapter 3 also highlights the development of an electronic model for rapid onsite detection of nerve agent mimic vapor by bright visual alerts from a light-emitting diode (LED) and a loud alarm signal. Chapter 4 discusses the synthesis of anionic conjugated polyelectrolyte PFPS for rapid and point-of-care testing of the neurotransmitter serotonin in physiological conditions using a smartphone-based system. Chapter 5 describes the synthesis of AIEE active conjugated polyelectrolyte PFTT-D and its application in the detection of multicolor artificial food dyes in solution.
Investigation of Bioinspired Oxidation Mechanism by Non-Heme High-Valent Metal Intermediates
(2023) Bagha, Umesh Kumar
High-valent non-heme metal intermediates have been invoked as key reactive species in various oxidative transformations. In this thesis, the reactivity studies towards aldehyde deformylation, S-oxidation, C-H activation and oxidative dehalogenation reactions with manganese(III)-peroxo, iron(IV)-oxo and iron(IV)-imido intermediates supported by penta-dentate ligand systems have been evaluated. These reactivity studies provide remarkable insights into the mechanistic pathways of these intermediates.The reactivities of two isomeric side-on manganese(III)-peroxo complexes with bispidine ligands have been investigated towards aldehyde deformylation reaction and was found that the reaction proceeds via an electrophilic hydrogen atom abstraction instead of the commonly proposed nucleophilic pathway. Comparative reactivity studies have been performed between iron(IV)-oxo and iron(IV)-imido complexes toward S-oxidation and C-H activation reactions. In both reactions, iron(IV)-imido complexes were found to be sluggish as compared to their oxo analogue. Finally, the reactivity of iron(IV)-oxo complexes has been evaluated with a series of mono-, di- and tri-halophenols and has established a new mechanism for their oxidative dehalogenation.
Development of ROS-responsive Turn-on Fluorogenic Prodrugs for the Delivery of Anti-inflammatory and Anti-cancer Drugs along with Hydrogen Sulfide
(2023) Sufian, Abu
My PhD thesis titled “Development of ROS-responsive Turn-on Fluorogenic Prodrugs for the Delivery of Anti-inflammatory and Anti-cancer Drugs along with Hydrogen Sulfide” comprises of five chapters. In chapter 1, the mechanism of reactive oxygen species (ROS) production and detoxification in biological systems have been highlighted. In addition, the development of ROS-responsive fluorogenic probes, non-fluorogenic anti-inflammatory and anti-cancer prodrugs, and fluorogenic anti-cancer prodrugs have been reviewed elaborately. Moreover, the biological function, detection techniques, and enzymatic production of H2S have been discussed briefly. Several synthetic donors of H2S such as hydrolysis-based, biothiol-triggered, ROS-responsive, and so on have been reviewed briefly.
Auxiliary-Assisted C-H Functionalization: Exploring the Realm of C-C and C-Heteroatom Bond Formation
(2024) Talukdar, Kangkan
The thesis is segmented into four chapters. The initial chapter delineates a Rh-Catalyzed Tandem C-C/C-N bond formation of quinoxalines with alkynes leading to heterocyclic ammonium salts. The second chapter explores the Pd-Catalyzed sp3 C-H alkoxycarbonylation of 8-methylquinolines using Mo(CO)6 as a CO surrogate. The third chapter showcases the Rh-catalyzed alkenylation of aryl 2-pyridyl ethers with vinyl acetate via sp2 C-H activation. Lastly, the fourth chapter delves into on Ru-catalyzed site selective acetoxylation of aryl 2-pyridyl ethers exploiting vinyl acetate as acetoxylating agent
Synthesis, Characterization and Applications of Aqua-Stable Metal-Organic Frameworks and their Composites for the Environmental Remediation and Bio-Molecule Sensing
(2024) Ghosh, Subhrajyoti
This thesis investigates the development of aqua-stable Metal-Organic Frameworks (MOFs) designed for potential applications in environmental remediation and bio-molecule detection. It delves deeply into the intricate structures of various functionalized Zr(IV) metal ion-containing MOFs. The functionality of these MOFs was deliberately integrated into their linkers, enabling their practical application in fluorescence-based detection and quantification of bioactive compounds and organo-toxins. Furthermore, the research explores synthetic methodologies aimed at producing hydrophobic MOFs specifically tailored for the selective and efficient adsorption of oil spills from oil-water mixtures. The findings presented in this thesis are critical for advancing sustainable environmental practices and for improving the accurate diagnosis of diseases associated with the uncontrolled release of specific biomolecules.
Expeditious Reactivity of Sulfoximines and o-Alkynylanilines Towards the Construction of C-C and C-Heteroatom Bonds
(2024) Chakraborty, Nikita
The contents embodied in this thesis is divided into five chapters including one introductory chapter based on experimental results obtained during the research period. The introductory chapter represents an overview of the utility of sulfoximines and o-alkynylanilines towards the construction of C-C and C-heteroatom bonds. This includes a brief discussion about all the possible reactive sites present in sulfoximines and their possibility of forming different functionalized molecular complexities. Similarly, the reactivity of o-alkynylanilines for the formation of diverse heterocyclic scaffolds has been discussed.
Effects of Addictives on Bio-inspired mineralization of CaCO3 and application of its Composites
(2022) Paul, Debojit
The thesis entitled “Effect of additives on bio-inspired mineralization of CaCO3 and application of its composites” is categorized into eight chapters based on the results obtained by experimental works performed during the research period.
Photo and Electrochemical Strategies to C-N Bond Formation
(2024) Alam, Tipu
The contents of this thesis have been divided into six chapters based on the experimental works performed and results obtained during the research period. The introductory chapter of the thesis represents a summary of ‘Photo and Electrochemical Strategies to CN Bond Formation’. For simplicity and brevity, Chapter I is divided into two parts. Chapter IA includes a photochemical CN bond formation via difunctionalization of alkenes and indoles, whereas, Chapter IB deals with electrochemical approach for the CN bond construction. The subsections of Chapter IA and IB are based on the mode of reactivity of difunctionalization and cross-coupling reactions.
Self-assemblies of Sulphonamide Derived Urea, Thiourea and Conformational Isomers of a Mercury complex
(2024) Nath, Jitendra
The thesis described various solid-state assemblies of urea and thiourea derivatives of sulfa-drugs that had sulphonamide functional group as part of the structural backbone. The hydrogen bonded assemblies of these compounds, solvates, and polymorphic solvates were structurally characterized. The role of dimeric hydrogen bonded moieties within those self-assemblies to modulate the number of solvent molecules in solvates and also providing an aid to understand polymorphs were discussed. A theoretical calculation on dimeric hydrogen bonded assemblies could establish the observed trends in the melting points in a series of positional isomeric compounds. The utilities of these thiourea or urea-based compounds to encapsulate tetrabutylammonium halides, and also in the detection of fluoride ions in solution were described in the thesis. The content had descriptions on the conformational isomers of a mercury complex involving a thiourea based compound linked to an anthracenyl unit where distinctions of the isomers in solution as well as in solid states could be possible. The conformational changes observed from experimental studies were also complemented by theoretical energy optimizations to provide insights to the structure-property relationships

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