Two Zn(II)-organic frameworks based on “V”-shaped terpyridine ligand and dicarboxylic ligands: Fascinating architectures and efficient luminescent aqueous-phase dual-responsive detection

Abstract

A “V”-shaped terpyridine ligand 3,3’:5′,3″-terpyridine (L) was firstly applied to construct metal-organic frameworks. Two Zn-MOFs, [Zn2(L) (BDC)2(H2O)]n (1) and {[Zn(L) (ISO)]·H2O}n (2) (H2BDC ​= ​terephthalic acid, H2ISO ​= ​isophthalic acid) had been successfully synthesized by L and auxiliary dicarboxylic ligands. Structurally, 1 features an unprecedented (3,3,8)-connected framework constructed from tridentate L units, mononuclear Zn units, binuclear [Zn2(CO)2] units and BDC2− bridges. While 2 shows a rare (3,5)-connected architecture assembled from tridentate L units, mononuclear Zn units and ISO2− bridges. The different structures and topological diversities between 1 and 2 can be attributed to different twist angles between pyridine rings in L and distinct bridging angles from auxiliary ligands. Moreover, luminescent sensing experiments exhibit that 1 can act as a promising dual-responsive sensor for detecting TNP and Fe3+ in aqueous phase with high efficiency. The luminescence test paper was successfully developed to detect TNP for the practical applications. In addition, the emission quenching mechanisms of 1 towards TNP and Fe3+ were elucidated.