Development of a borondipyrromethene-based Zn2+ fluorescent probe: solvent effects on modulation sensing ability

A borondipyrromethene-based Zn2+ fluorescent probe BODPAQ was designed and synthesized. The chelators in BODPAQ, 2,2'-dipicolylamine (DPA) and 8-aminoquinoline (AQ), coordinate to Zn2+ in a synergic manner. As a result, BODPAQ displays high Zn2+ selectivity with a dramatic enhanced emission accompanied by a notable hypsochromic shift due to the binary inhibition effect of PET and ICT mechanisms, enabling the detection of Zn2+ by both ratiometric and normal turn-on fluorescence methods in acetonitrile. Interestingly, the sensitivity of BODPAQ towards Zn2+ changes upon varying the compositions of buffer solutions. In 3-morpholinopropanesulfonic acid (MOPS) buffer aqueous solution (50% CH3CN), BODPAQ displays the highest sensitivity for Zn2+, while in citrate-phosphate buffer, BODPAQ shows no response to Zn2+.