Syntheses and Optoelectronic Properties of Planar Compounds 3,7‐diaryl‐1,5,2,4,6,8‐dithiotetrazocine

Abstract

Planar molecules 3,7‐diaryl‐1,5,2,4,6,8‐dithiotetrazocines would be potential acceptor materials of organic solar cell because of their containing SN units. One‐pot synthetic procedures of 3,7‐diaryl‐1,5,2,4,6,8‐dithiotetrazocine compounds are developed to improve their yields up to 2.1–5.9 times as much as those in literatures. The geometries of title compounds were optimized by the density functional theory calculations. Their optoelectronic properties were studied by ultraviolet and cyclic voltammetry spectra and fluorescence quenching experiments. The highest occupied and lowest unoccupied molecular orbital energy level values show that these compounds are suitable to be employed as acceptor materials for developing bulk heterojunction organic solar cells with high open circuit voltages. Emission fluorescence of poly(3‐hexylthiophene) at excited state in dichloromethane was quenched by addition of title compound. Therefore, these compounds used as acceptor materials could exhibit good mobility.

Effect of bromine substituent on optical properties of aryl compounds

“…Compound 8b was synthesized according to the literature . The pure compound 8b was given as a yellow powder (yield: 85.1%).…”

“…In compounds 5b , 6b , 7b , 8b , and 9b , conjugation between a benzene or thiophene ring and a connected aryl ring is enhanced by the introduction of bromine substituents into benzene or thiophene rings. As a result, planarity of bromine‐substituted aryl compound is better than its reference compound because of p‐π conjugation . The π electron would delocalize well in the whole aryl compound.…”

“…Compounds 9a and 9b were synthesized by oxidation reactions of 4a and 4b with PbO 2 , respectively. Compounds 6a , 7a , 7b , 8a , and 8b were synthesized according to the literature . Compound 6b was obtained by a bromination reaction of 6a with N ‐bromosuccinimide in anhydrous tetrahydrofuran (THF).…”

“…The crude compound was purified by chromatography to get a yellow crystal, pure compound 8a (yield: 29.3%). The 1 H NMR spectrum is in accordance with that in the literature . 1 H NMR (CDCl 3 ): δ = 7.92 (d, J = 4.0 Hz, 2H), 7.48 (d, J = 5.0 Hz, 2H), 7.18 (dd, J a = 4.0 Hz, J b = 5.0 Hz, 2H).…”

“…Therefore, a weak electron‐withdrawing or electron‐pushing substituent would be desired to enhance the optical properties of π‐conjugated organic compounds. Benzene, carbazole, acenaphthenequinone, and 1,5,2,4,6,8‐dithiotetrazocine derivatives had been employed as optical materials . Therefore, these aryl compounds with different π electrons were used to study the effect of bromine substituent on the optical properties of aryl compounds.…”