Donor-Acceptor Heteroacenes: Synthesis, Characterization and Structure-Property Relationship

Ghosh, Sirina (2019) Donor-Acceptor Heteroacenes: Synthesis, Characterization and Structure-Property Relationship. PhD thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

This thesis deals with the design and synthesis of a new series of donor-acceptor-donor (D-A-D) fused systems. In one part benzothiadiazole (BDT), benzoselenadiazole (BDSe) and benzotriazole (BTAz) were used as the acceptor unit fused with thienopyrrole and selenophenopyrrole donor. Another part describes indolocarbazole based fused systems with BDT, BDSe, BTAz and benzooxadiazole (BDO) acceptors. The electrochemical polymerization of five newly synthesized D-A-D fused systems was also performed. In order to understand the conducting nature of the polymers spectroelectrochemical study was also done on the polymer films. Bromination of triazole-fused indolocarbazole afforded the only meta-dibrominated product with respect to the nitrogen of fused pyrrole rings on treatment with both N-bromosuccinimide (NBS) and elemental bromine which is in contrast with bromination reaction of thiadiazole-fused indolocarbazole, where reagents-based regioselectivity was observed. Moreover, we have designed and synthesized a new series of D-A-D based small molecules. One series showed drastic color changes upon varying the heteroatom on acceptor unit. Whereas the other series explores benzodiazaborole as an acceptor unit in the D-A-D based systems. We obtained the crystal structures for almost all the fused D-A-D systems, which can help to understand their packing and geometry in a better way.

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