Effect of bromine substituent on optical properties of aryl compounds

Abstract

Substituents significantly affect optical properties of organic compounds. In this study, a series of organic compounds were synthesized. Ultraviolet‐visible and cyclic voltammetry spectra were determined. The relationships between the number of π electron in an aryl ring and the redshift (and molecular orbital energy levels) were studied. To investigate mechanisms of the bromine substituent effects, theoretical calculations were carried out. Ultraviolet‐visible spectra of bromine‐containing compounds exhibit obvious redshifts (0.04‐0.17 eV) of the maximal absorption wavelengths and enhanced absorbance (11%‐57%) compared with corresponding reference compounds. The lowest unoccupied and highest occupied molecular orbital energy levels of compounds containing bromine substituents are 0.05 to 0.60 and 0.02 to 0.40 eV lower than that of corresponding reference compounds. On the whole, the redshifts and the reduced molecular orbital energy levels caused by bromine substituent decrease with the increase in the number of π electron in an aryl ring. The effects would be attributed to strong p‐π conjugation between p electron in the bromine substituent and π electrons in aryl rings. Therefore, this paper suggests a useful way for tuning optical absorption and molecular orbital energy levels of aryl compounds.

Synthesis of a new W-type of functional polymer for improving intermolecular charge transfer processes at donor/acceptor interfaces

“…The 1 H NMR spectrum of the compound 1 is in accordance with that in the literature. 26 1 H NMR (, ppm; DMSO-d 6 ): 12.85 (s, 1H, NH), 10.32 (s, 1H, NH), 8.42…”

“…1 H NMR spectrum of the compound 2 is in accordance with that in the literature. 26 1 H NMR (, ppm; DMSO Synthesis of compound 3. Compound 3 was prepared by a method in literature.…”

“…Compound 3 was prepared by a method in literature. 26 Pure compound 3 was acquired as colorless oil (yield: 76.7%). 1 H NMR spectrum of the compound 3 is in accordance with that in the literature.…”

“…Acenaphthoquinone bis(4-bromophenylhydrazone) ( 1 ) was synthesized by a Schiff base reaction of acenaphthoquinone with 4-bromophenylhydrazine. 26 A key intermediate 1,2-bis(4-bromophenylazo)acenaphthylene ( 2 ) was synthesized by oxidation reactions of compound 1 with PbO 2 . 26 9-(2-Ethylhexyl)carbazole ( 3 ) was prepared by an alkylation reaction between carbazole and 2-ethylhexyl bromide.…”

“…26 A key intermediate 1,2-bis(4-bromophenylazo)acenaphthylene ( 2 ) was synthesized by oxidation reactions of compound 1 with PbO 2 . 26 9-(2-Ethylhexyl)carbazole ( 3 ) was prepared by an alkylation reaction between carbazole and 2-ethylhexyl bromide. 25 3,6-Dibromo-9-(2-ethylhexyl)carbazole ( 4 ) was prepared by a bromination reaction of compound 3 with N -bromosuccinimide.…”