Does oligomerization in fused thiophene affect reactivity and aromaticity?

• Published in: Journal of chemical sciences (Bangalore, India) India), 2016-02, Vol.128 (2), p.311-324
• Main Authors: PURKAYASTHA, SIDDHARTHA KR, BHATTACHARYYA, PRADIP KR
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Chemistry/Food Science
• ISSN: 0974-3626; 0973-7103
• DOI: 10.1007/s12039-015-1021-9

Reactivity and aromaticity of a few fused thiophene oligomers and their conformers are discussed in the light of density functional theory (DFT) and conceptual density functional theory. Reactivity parameters, such as hardness ( η ) and electrophilicity ( ω ), chemical potential ( μ ) and energy of the HOMO (highest occupied molecular orbital) have been studied. Oligomerization raises the E HOMO of the species, which in turn increases the reactivity of the oligomers. The absorption spectra of the species are analysed using TDDFT (time dependent density functional theory). The absorption peaks show red shift with increasing size of the oligomers. Aromaticity of the species is gauged by nucleus independent chemical shift (NICS). The out-of-plane component, (NICS zz ) values advocate higher aromatic character at longer distance whereas, NICS supports the reverse. Graphical Abstract Reactivity and aromatic character of thiophene is influenced by oligomerization.