Related Experiment Video
Updated: Jul 24, 2025

Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds
Published on: October 18, 2018
Impact of the bromination of carbazole-based D-π-A organic dyes on their optical and electrochemical properties and
Zhangli Hu1, Jiamin Kuang1, Wenmo Fu1
1College of Chemistry Materials, Hengyang Normal University Hengyang 421008 China laixhua163@163.com.
Abstract:
Brominated dyes, 2C-n (n = 1-5), 3C-4 and 4C-4, were prepared through bromination of three carbazole-based D-π-A dyes, 2C, 3C and 4C with N-bromosuccinimide (NBS). The detailed structures of the brominated dyes were confirmed by 1H NMR spectroscopy and mass spectrometry (MS). The introduction of the Br atom on the 1,8-positon of carbazole moieties led to blueshifted UV-vis and photoluminescence (PL) spectra, increased initial oxidation potentials and enlarged dihedral angles, indicating bromination enhanced non-planarity of the dye molecules. In the hydrogen production experiments, with the increase of the Br content in brominated dyes, the photocatalytic activity increased continuously (except 2C-1). The dye-sensitized Pt/TiO2, 2C-4@T, 3C-4@T and 4C-4@T, exhibited high hydrogen production efficiencies of 655.4, 877.9 and 905.6 μmol h-1 g-1, respectively, which were 4-6-fold higher than those of 2C@T, 3C@T and 4C@T. The enhanced performance of photocatalytic hydrogen evolution was attributed to decreased dye aggregation resulting from the highly non-planar molecular structures of the brominated dyes.
More Related Videos
Related Concept Videos
Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Formation of Halohydrin from Alkenes

