Modulation of Properties in [1]Benzothieno[3,2-<i>b</i>][1]benzothiophene Derivatives through Sulfur Oxidation

Abstract

This study explores the impact of sulfur oxidation on the structural, optical, and electronic properties of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) derivatives, specifically focusing on 2,7-dibromo BTBT (2,7-diBr-BTBT) and its oxidized forms, 5,5-dioxide (2,7-diBr-BTBTDO) and 5,5,10,10–tetraoxide (2,7-diBr-BTBTTO). The bromination of BTBT followed by sequential oxidation with m-chloroperoxybenzoic acid yielded the target compounds in good yields. They were characterized using a wide array of analytical techniques including different spectroscopic methods, X-ray analysis, thermal analysis, and quantum chemical calculations. The results revealed that sulfur oxidation significantly alters the crystal packing, thermal stability, and optoelectronic properties of BTBT derivatives. Notably, the oxidized forms exhibited increased thermal stability and enhanced emission properties, with quantum yields exceeding 99%. These findings provide valuable insights for designing advanced organic semiconductors and fluorescent materials with tunable properties, based on the BTBT core.

Keywords

• benzothienobenzothiophene
• sulfones
• organic electronics
• DFT calculations
• reorganization energy
• fluorescence