Structural and electronic properties of 4H-cyclopenta[2,1-b,3;4-b′]dithiophene S-oxide (BTO) derivatives with an S, S=O, O, SiH2, or BH2 bridge: semi-empirical and DFT study

Abstract

In this paper, we theoretically studied the geometries, stabilities, and the electronic and thermodynamic properties of 4H-cyclopenta[2,1-b,3;4-b']dithiopene S-oxide derivatives (BTO-X, with X = BH(2), SiH(2), S, S=O, or O) using semi-empirical methods, ab initio methods, and density functional theory. The geometries and thermodynamic parameters calculated by PM3 were in good agreement with those calculated with B3LYP/6-31 G*. The band gap calculated using B3LYP/6-31 G* ranged from 3.94 eV (BTO-O) to 3.16 eV (BTO-B). The absorption λ(max) calculated using B3LYP/6-31 G* was shifted to longer wavelengths when X = BH(2), SiH(2), or S=O (due to their electron-withdrawing effects) and to shorter wavelengths for BTO-S and BTO-O as compared to the λ(max) for the thiophene S-oxide (2TO) dimer. The changes in ΔH°, ΔS°, and ΔG° calculated using both semi-empirical and DFT methods were quite similar.

DFT study on some polythiophenes containing benzo[d]thiazole and benzo[d]oxazole: structure and band gap

“…However, only a few studies on the electronic structures of polymers using the DFT method have been done to control the band gap for determining the alternation between conductors and insulators in solar cells, diodes, or transistors. A popular pathway to synthesize new polythiophene derivatives is substitution in polythiophenes, for example, replacement of S atom with Se or Te atoms [ 43 ] or replacement of H atoms with CH 3 , NH 2 , NO 2 , or Cl [ 44 ]. The DFT method has been applied for the assessment of structural and electronic characteristics of 4 H -cyclopenta[2,1- b ,3;4- b′ ] dithiophene S-oxide derivatives including X (X: O, S, S = O, BH 2 , SiH 2 ) as a bridge [ 45 ].…”