Water-induced structural transformation of zinc supramolecular complex based on a terpyridine carboxylate ligand: Crystal structure and fluorescence sensing

For the past few years, the transformation of single crystal to single crystal in the field of metal-organic su-pramolecular complexes has aroused researchers' extensive interest. The structural transformation of metal -organic supramolecular complexes using chemical stimuli provides alternative approaches to realize fasci-nating optical properties. Herein, a new 3D Zinc based supramolecular complex ZnTCA-1 (hereafter denoted SC1) was synthesized by solvothermal method with terpyridine carboxylic acid (TCA) as a ligand. By soaking SC1 in deionized water for 3 days, SC1 exhibited unique structural transformation properties, transforming from a 3D framework to a discontinuous 0D supramolecular complex ZnTCA-2 (hereafter denoted SC2). SC2 exhibits excellent water stability and acid-base stability (pH = 4-8), which inspired us to utilize SC2 for fluorescence detection, and found that SC2 exhibits a highly selective and sensitive (LOD = 3.97 mu M) response to Cr2O72-based on fluorescence quenching, and the corresponding quenching coefficient (Ksv) is calculated to be 2.995 mM-1.