Supramolecular construction of optoelectronic π- conjugated peptide and peptide- inorganic hybrid materials

Abstract

This dissertation investigates supramolecular construction of functional π-conjugated peptide and peptide-inorganic hybrids and their fascinating properties. Chapter 1 describes the current status regarding the assembly of π-conjugated peptides and small organic molecules used in electrochemical construction of functional organic-inorganic nanoscale hybrid materials. Chapter 2 summarizes synthetic methodology and characterization techniques used in the thesis. Chapter 3 describes the synthesis and self-assembly study of a dipeptide diphenylalanine (Phe-Phe) functionalized benzo[ghi]perylene monoimide (BPI). The solvent dependent photophysical behavior of newly synthesized compound 2 (BPI-FF-OMe) has been described in detail. Compound 2 exhibits positive solvatochromic emission as a function of solvent polarity with higher lifetimes and quantum yields. Compound 2 self-assembles into nanospheres in methanol and toluene solvents. Chapter 4 makes an attempt to describe an electrochromic hydrogel based on a self-assembled quinquethiophene functionalized peptide. In this study, hydrogel exhibits electrochromism due to the presence of a redox active quinquethiophene (5T) moiety in compound 4. Chapter 5 describes the fabrication of peptide/Cd-doped ZnO nanohybrid for the development of a white light emitting system. White-light luminescence of peptide/Cd-doped ZnO is attributed to cadmium doping in the zinc oxide crystal and the presence of a dipeptide-functionalized BPI fluorophore in the lamellar nanohybrid. Chapter 6 attempts to describe electrochemical construction of hybrid nanostructures utilizing small peptides as an organic component with ZnO. I-V characteristics of these hybrids under dark and light illuminations indicate that the conductivity of these nanostructure materials increases owing to the presence of photon-absorbing active self-assembled peptides. Chapter 7 describes electrochemical deposition of peptide/metal hydroxide hybrids for the purpose of developing electrochemically active materials. Peptide/Co(OH)2 nanostructured hybrid films exhibit capacitive electrochemical performance in energy storage applications. Porous nanostructure of compound 9/Co(OH)2 hybrid shows high capacitance of 3070 Fg-1 through electron transfer mechanism in the potential range -0.2 to 0.6 V at a discharge current of 5 mA. Porous and soft nanostructure facilitates electrochemical accessibilities of electrolyte OH- ions to Co(OH)2 thin film and fast diffusion rate within the redox phase. Chapter 8 summarizes the salient features of the work and its future prospects.