Stable bifunctional Zn^II-based sensor toward acetylacetone and l-histidine via a fluorescence red shift and turn-on effect

A new coordination polymer, [Zn(bbip)(NH2-BDC)](n) (JXUST-15; bbip = 2,6-bis(benzimidazol-1-yl)pyridine and NH2-H2BDC = 2-aminoterephthalic acid), was synthesized by a mixed-ligand strategy. Structure analysis shows that JXUST-15 has a two-dimensional (2D) layer structure with an sql topology. Fluorescence measurements demonstrate that JXUST-15 could simultaneously and selectively sense organic molecules including acetylacetone (acac) and l-histidine (l-His) via a fluorescence red shift and enhancement with detection limits of 27.3 mu M and 3.53 mu M, respectively. The possible mechanisms of JXUST-15 for sensing acac and l-His were ascribed to the occurrence of electron transfer and the formation of strong exciplexes between JXUST-15 and analytes. Moreover, JXUST-15 displays relatively good thermal, solvent and acid-base stabilities, as well as reusability. Importantly, JXUST-15 provides a platform for fluorescence sensing of both acac and l-His via a fluorescence enhancement and shift for the first time.