A novel dibenzimidazole-based fluorescent probe with high sensitivity and selectivity for copper ions

A novel fluorescence probe TPA-BMZ for Cu2+, based on intramolecular charge transfer, was designed and synthesized. Probe was composed of triphenylamine as the fluorophore and benzimidazole derivative as the receptor. AFM measurement exhibits that TPA-BMZ possess an amorphous state without any crystallization, which benefits to its long-term stability due to application. Meanwhile, its optical character was studied and the results shown that TPA-BMZ could be used to recognize cupric ions in consequence of intramolecular charge transfer (ICT) and it even could be used to detect the presence of cupric ions in seawater. The Job's plot curve demonstrated the molar ratio of probe to copper is 1:1. Moreover, from the fluorescence titration spectrum of copper ions to probe, the limit of detection of probe is obtained (0.094 mu M) and the complex constant is 6.57 x 10(-8) M-1 which shows a high sensibility towards copper ions. In addition, probe was also used to detect copper ions in tap water, river water and seawater which demonstrated a potential application in seawater. More importantly, the response time of the probe to copper ions is within 1 s.