Synthesis of π (Pai)-conjugated Materials for Organic Electronics and Sensors

Pati, Palas Baran (2014) Synthesis of π (Pai)-conjugated Materials for Organic Electronics and Sensors. PhD thesis, Indian Institute of Science Education and Research Kolkata.

PDF (PhD Thesis of Palas Baran Pati) Palas-Baran-Pati-Phd-Thesis.pdf - Submitted Version Restricted to Repository staff only Download (7MB)

Abstract

This thesis deals with synthesis and characterization of new organic donor-acceptor (D-A) type π-conjugated materials comprising triphenylamine derivatives and group-16 aromatic heterocycle, mainly, furan, thiophene, selenophene and their applications in organic electronics and sensing for environmentally hazardous cyanide anion. Bromination of 2,5-bis(2- thienyl)pyrrole with NBS in AcOH/THF prefers β-position of pyrrole over -position of thiophene that was explored by experimental and DFT study. For first time unusual solid-state polymerization (SSP) of β,β'-dibrominated 2,5-bis(2-thienyl)pyrrole was observed through β-C of pyrrole to afford bromine doped conjugated polymer. A part of the thesis deals with synthesis of furan, thiophene, selenophene and EDOT capped small donor-acceptor-donor (D-A-D) type small molecules where benzooxadiazole (BDO), benzothiadiazole (BDT) and benzoselenadiazole (BDS) used as acceptor moieties. The electropolymerization, spectroelectrochemistry and electrochromic properties of BDO based polymers were studied. All these D-A-D type small molecules showed planar structure with the peculiar crystal packing with the various short-range non-bonding interactions as studied from their single crystal X-ray analysis. As planarity and crystal packing are crucial factors for FET device performance, FET devices of these D-A-D small molecules showed high hole mobility. A series of new D-A type organic dyes comprising triphenylamine as active donor unit and cyanoacrylic acid as acceptor and thiophene, selenophene, EDOT as spacer were synthesized and their photophysical properties were studied. Two new dyes were synthesized comprising triphenylamine and salicylaldehide and explored them as cyanide sensors. Cyanovinylic functionalized terthiophene molecule was explored as reaction based ratiometric cyanide sensor.

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