Recursos de colección

ETD at Indian Institute of Science (3.494 recursos)

Repository of Theses and Dissertations of Indian Institute of Science, Bangalore, India. The repository has been developed to capture, disseminate and preserve research theses of Indian Institute of Science.

Solid State and Structural Chemistry Unit (sscu)

Mostrando recursos 1 - 20 de 88

  1. Study of Charge Separation in Quantum Dots and Their Assemblies

    Rekha, M
    This thesis reports a passive method for Fermi level regulation in quantum dot assemblies through ground state transfer between QDs. Here, ZnTe/CdS, and PbSe/CdSe core/shell QDs were used as valence band electron donors, while Cu containing CdS or ZnSe acts as electron acceptor QDs. Prior to study of ground state charge transfer process, this report discusses the synthesis of ZnTe/CdS, and PbSe/CdSe core shell QDs, which are later used to study charge transfer. Since ZnTe QDs are unstable and prone to oxidation, a CdS coated ZnTe QDs were used. Growing a CdS shell on ZnTe core is difficult because high...

  2. NMR based Studies and Applications of Molecular Interactions : From Small Moleculecules to Bio-nanoconjugates

    Pal, Indrani
    The work described in this thesis involves the study of weak interactions by NMR spectroscopy and using them to develop novel applications. The two different applications chosen are i) using molecular interactions for chiral discrimination and ii) understanding the nature of the interaction between peptide and nanoparticles to develop potent antibacterial agents. The thesis, which is divided into five chapters starts with a general introduction of NMR spectroscopy for the study of molecular interactions in conjunction with other techniques. The remaining four chapters focus on four different areas/projects that I have worked on. Chapter 1: Introduction This chapter reviews different...

  3. Maleimide Based Materials for Organic Light-Emitting Diodes (OLEDs)

    Sharma, Nidhi
    Maleimide based highly luminescent material Cbz-MI with donor acceptor donor (D-A-D) backbone has been synthesized and characterized. An organic light emitting diode fabricated using this material as emitting layer exhibited EQE of 2.5% in the yellow region of visible spectrum. Due to the small energy gap of materials emitting in this region of spectrum, EQE of OLED is usually limited by various non-radiative decays and high EQE of OLED using this material proves that most of the nonradiative decay pathways have been avoided by the careful design of molecule and device structure. Although Cbz-MI did not show TADF properties, but if tailored with...

  4. Study on Self-Assembly of Fullerenes and Biopolymers

    Mohanta, Vaishakhi
    The understanding of self-assembly processes is important for fabrication of well-defined structures with new functionalities for applications in the area of biomedical sciences, material sciences and electronics. In this thesis, two types of self-assembly processes are described: (1) self-assembly of fullerene derivatives in water and (2) self-assembly on surfaces using layer-by-layer (LbL) approach. The various interactions and parameters involved in the self-assembly are detailed in the introductory chapter 1. The various internal parameters like molecular geometry, intramolecular and intermolecular forces that guides the self-assembly process of amphiphiles in water are discussed. The experimental procedures used in the present thesis for...

  5. Photophysical Properties of Manganese Doped Semiconductor Nanocrystals

    Hazarika, Abhijit
    Electronic and optical properties of semiconducting nanocrystals, that can be engineered and manipulated by various ways like varying size, shape, composition, structure, has been a subject of intense research for more than last two decades. The size dependency of these properties in semiconductor nanocrystals is direct manifestation of the quantum confinement effect. Study of electronic and optical properties in smaller dimensions provides a platform to understand the evolution of fundamental bulk properties in the semiconductors, often leading to realization and exploration of entirely new and novel properties. Not only of fundamental interests, the semiconductor nanocrystals are also shown to have...

  6. Probing Mechanical Properties Of Molecular Crystals with Nanoindentation : Applications to Crystal Engineering

    Mishra, Manish Kumar
    Crystal engineering is widely applied in the design of new solids with desired physical and chemical properties based on an understanding of intermolecular interactions in terms of crystal packing. The understanding of such structure-property correlations increased my interest in the modulation of macroscopic properties of solid compounds. Establishing connections between structure and macroscopic properties is a classical aspect of materials science and engineering. With the advent of the nanoindentation technique, it is now possible to make such a link between micro-level structures with mechanical properties of molecular solids - in other words, between chemistry and engineering. Nanoindentation is a quantitative...

  7. Study of Diverse Chemical Problems by NMR and the Design of Novel Two Dimensional Techniques

    Mishra, Sandeep Kumar
    The research work reported in this thesis is focused on the chiral analysis, quantification of enantiomeric composition, assignment of absolute configuration of molecules with chosen functional groups. The weak intra-molecular hydrogen bonding interactions are detected by exploiting several multinuclear and multi-dimensional techniques. Pulse sequences have been designed to manipulate the spin dynamics to derive specific information from the complex NMR spectra encountered in diverse situations. Broadly, the thesis can be classified in to three sections. The section I containing two chapters reports the introduction of new chiral auxiliaries and protocols developed for enantiomeric discrimination, measurement of enantiomeric contents, assignment of...

  8. Theoretical Investigation of OPTO-Electronic Processes in Organic Conjugated Systems Within Interacting Models : Exact Diagonalization and DMRG Studies

    Prodhan, Suryoday
    The present thesis deals with a theoretical study of electronic structures in -conjugated molecular materials with focus on their application in organic elec-tronics. We also discuss a modified and efficient symmetrized DMRG algorithm for studying excited states in these systems. In recent times, organic conjugated systems have emerged as potential candidates in a wide range of fascinating fields by virtue of their tunable electronic properties, easy processability and low cost. Tunability in the electronic and optical properties primarily are centered on the or-dering and nature of the low-lying excited states. Probing these important excited states also demands development of efficient...

  9. Study of Diverse Chemical Problems by NMR and the Design of Novel Two Dimensional Techniques

    Mishra, Sandeep Kumar
    The research work reported in this thesis is focused on the chiral analysis, quantification of enantiomeric composition, assignment of absolute configuration of molecules with chosen functional groups. The weak intra-molecular hydrogen bonding interactions are detected by exploiting several multinuclear and multi-dimensional techniques. Pulse sequences have been designed to manipulate the spin dynamics to derive specific information from the complex NMR spectra encountered in diverse situations. Broadly, the thesis can be classified in to three sections. The section I containing two chapters reports the introduction of new chiral auxiliaries and protocols developed for enantiomeric discrimination, measurement of enantiomeric contents, assignment of...

  10. Fluoranthene-Based Materials for Non-Doped Blue Organic Light-Emitting Diodes

    Shiv Kumar, *
    The organic light-emitting diode (OLED) technology is emerging to be the future technology of choice for thin, flexible and efficient display and lighting panels and is a potential competitor for the existing flat panel display technologies, like liquid crystal display (LCD) and plasma display panel (PDP). OLEDs display is already making their way from both lab and industry research to display market and the pace of development of laboratory OLED design into a commercial product is very impressive. The OLED display offers several advantages over other display technologies, such as low power consumption, easy fabrication, high brightness & resolution, light...

  11. Syntheses Structural Transformations, Magnetism, Ferroelectricity and Proton Conduction of Metal Organic Frameworks (MOF) Compounds

    Bhattacharya, Saurav
    The past few decades have witnessed an almost exponential increase in interest in the field of metal organic frameworks (MOFs), which can be evidenced from the large number of scientific articles being published routinely in this area. The MOFs are crystalline hybrid materials built via the judicial use of inorganic metal ions and organic linkers, thereby bridging the gap between purely inorganic and organic materials. The structural versatility and the potential tunability of the MOFs imparts unique physicochemical and thermomechanical properties, which have rendered them immensely useful in the branches of chemistry, material science, physics, biology, nanotechnology, medicine as well as environmental engineering. The MOFs have...

  12. Design, Development and Applications R & D on Substrate-Integrated Lead-Carbon Hybrid Ultracapacitors

    Banerjee, Anjan
    Electrochemical capacitors or supercapacitors or ultracapacitors are potential energy storage devices that could help bringing major advances in future energy storage applications. Unlike batteries that store energy in chemical reactants capable of generating charge, electrochemical capacitors store energy directly through charge separation. Most electrochemical capacitors rely on carbon-based structures utilizing electrical double-layer capacitance effect. By contrast, a pseudocapacitor relies on charge stored due to fast faradaic charge-transfer processes with surface atoms. A combination of faradaic and non-faradaic components would generate hybrid electrochemical capacitors or hybrid ultracapacitors that attain high capacitance for pulse power and sustained energy. This thesis comprises studies...

  13. Internal Structure and Self-Assembly of Low Dimensional Materials

    Mukherjee, Sumanta
    The properties of bulk 3D materials of metals or semiconductors are manifested with various length scales(e.g., Bohr excitonic radius, magnetic correlation length, mean free path etc.) and are important in controlling their properties. When the size of the material is smaller than these characteristics length scales, the confinement effects operate reflecting changes in their physical behavior. Materials with such confinement effects can be designated as low dimensional materials. There are exceedingly large numbers of low dimensional materials and the last half a century has probably seen the maximum evolution of such materials in terms of synthesis, characterization, understanding and modification...

  14. Building Upon Supramolecular Synthons : Some Aspects of Crystal Engineering

    Mukherjee, Arijit
    Crystal engineering offers a rational way of analyzing crystal structures and designing new structures with properties. The supramolecular synthon concept was introduced in 1995 and has shown versatility and utility in the design of molecular solids. Chapter 1 gives a general introduction about the development of the concept of supramolecular synthons over the years which has seen a transition from synthesis to structures and dynamics. This thesis focuses on the later phase of the development of the concept of supramolecular synthons. Chapter 2 introduces the idea of structural landscape and describes a structural landscape of a conformationally flexible molecule, orcinol,...

  15. Dynamics of Water under Confinement and Studies of Structural Transformation in Complex Systems

    Biswas, Rajib
    The thesis involves computer simulation and theoretical studies of dynamics of water under confinement and structural transformation in different complex systems. Based on the systems and phenomena of interest, the work has been classified in to three major parts: I. Dynamics of water under confinement II. Dynamics of water in presence of amphiphilic solutes III. Structural transformation in complex systems The three parts have further been divided into nine chapters. Brief chapter wise outline of the thesis is discussed below. Part I deals with the dynamics of water in confined systems. In Chapter I.1, we provide a brief introduction of water dynamics...

  16. Rational Design of Diketopyrrolopyrrole-Based Conjugated Polymers for Ambipolar Charge Transport

    Kanimozhi, K Catherine
    The present thesis is focused on the rational design of Diketopyrrolopyrrole based π- conjugated polymers for organic electronics. The thesis is organized into six different chapters and a brief description of the individual chapters is provided below. Chapter 1 briefly describes the physics governing the electronic processes occurring in organic photovoltaics (OPVs) and organic field-effect transistors (OFETs) followed by design rules for the synthesis of conjugated polymers for organic electronics. Diketopyrrolopyrrole (DPP) based π-conjugated materials and their development in OPVs and OFETs have been highlighted. Chapter 2 discusses the synthesis and characterization of a series of small molecules of DPP derivatives...

  17. Phase Behaviour in Crystalline Solids : Exploring the Structure Guiding Factors Via Polymorphism, Phase Transitions and Charge Density Studies

    Thomas, Sajesh P
    The thesis entitled "Phase Behaviour in Crystalline Solids: Exploring the Structure Guiding Factors via Polymorphism, Phase Transitions and Charge Density Studies" consists of five chapters divided into two parts. A basic introductory section describes the topics relevant to the work and the methods and techniques utilized. Part A contains two chapters that discuss the structural aspects related to polymorphism, solvatomorphism, conformational preferences and phase transitions exhibited by active pharmaceutical ingredients (APIs). It also discusses the structure-property correlations in API crystal forms and the possible utility of second harmonic generation (SHG) for their bulk characterization. Part B has three chapters that...

  18. Study of Enantiomeric Discrimination and Enzyme Kinetics using NMR Spectroscopy

    Reddy, U Venkateswara
    Obtaining enantio pure drug molecules is a long standing challenge in asymmetric synthesis implying that the identification of enantiomers and the determination of enantiomeric purity from a racemic mixture are of profound importance. In achieving this target NMR spectroscopy has proven to be an excellent analytical tool. It is well known that normal achiral NMR solvents do not distinguish the spectra of enantiomers. On the other hand, the conversion of substrates to diastereomers using one of the enantiopure chiral auxiliaries, such as, chiral solvating agent, chiral derivatizing agent and chiral lanthanide shift reagent, circumvents this problem. The imposition of diasteomeric...

  19. Organic Fluorine in Crystal Engineering : Consequences on Molecular and Supramolecular Organization

    Dikundwar, Amol G
    The thesis entitled “Organic fluorine in crystal engineering: Consequences on molecular and supramolecular organization” consists of six chapters. The main theme of the thesis is to address the role of substituted fluorine atoms in altering the geometrical and electronic features in organic molecules and its subsequent consequences on crystal packing. The thesis is divided into three parts. Part I deals with compounds that are liquids under ambient conditions, crystal structures of which have been determined by the technique of in situ cryocrystallography. Part II demonstrates the utilization of in situ cryocrystallography to study kinetically trapped metastable crystalline phases that provide...

  20. Synthesis, Structure and Catalytic Properties of Pd2+, Pt2+ and Pt4+ Ion Substituted TiO2

    Mukri, Bhaskar Devu
    After introducing fundamentals of catalysis with noble metal surfaces especially Pt metal for CO oxidation and subsequent developments on nano-crystalline Pt metals supported on oxide supports, an idea of Pt ion in reducible oxide supports acting as adsorption sites is proposed in chapter 1. Idea of red-ox cycling of an ion in an oxide matrix is presented taking Cu ion in YBa2Cu3O7 as an example. Noble metal ions in reducible oxides such as CeO2 or TiO2 acting as adsorption sites and hence a red-ox catalyst was arrived at from chemical considerations. Among several reducible oxide supports, TiO2 was chosen from...

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