A novel dibenzimidazole-based fluorescent organic molecule as a turn-off fluorescent probe for Cr³⁺ ion with high sensitivity and quick response

Due to the toxicity and ubiquity of chromium contamination, fluorometric detection of chromium ions (Cr3+) has attracted much attention. Here, a new fluorescent probe 4PBI-Cz based on novel dibenzimidazole group was designed and synthesized to identify chromium ions. The photophysical and electrochemical properties of 4PBI-Cz were characterized in detail. In view of the strong complexation property, the fluorescence of 4PBI-Cz exhibit gradually turn-off phenomenon with the addition of chromium ions. In particular, the response time of the probe with chromium ions was less than 1 s, faster than most of the reported fluorescence probes. Moreover, the detection limit for chromium ions is only 3.5 nM, which can be attributed to the high sensibility of dibenzimidazole to the ions. This research indicates that the new proposed dibenzimidazole group is an exciting recognition receptor for designing quick response and ultrasensitive fluorescent probes for the determination of Cr3+. (C) 2020 Elsevier B.V. All rights reserved.