Synthesis, structure and properties of one novel 2D Mn-heterocyclic carboxylic acid complex [Mn(TPA)Cl(H2O)]n

A novel 2D layer complex [Mn(TPA)Cl(H2O)]n (1) has been synthesized by two methods through the reaction of MnCl2 and TPC or TPA under hydrothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, infrared spectrometry (IR), powder X-ray diffraction (XRD) and thermogravimetric analysis (TGA), where heterocyclic carboxylic acid ligand TPA = 2-(5-(pyridin-2-yl)-2H-tetrazol-2-yl)acetic acid, TPC = 2-(5-(pyridin-2-yl)-2H-tetrazol-2-yl)acetonitrile. The distorted octahedral Mn(II) centers are bridged by carboxylic O atoms resulting in the formation of a 1D chain. Then the 1D chains are connected with each other through TPA ligands into a 2D (3,3)-connected topology framework. The H-bonding interactions extend the complex into a three-dimensional network, and such weak interactions further stabilized the complex. Furthermore, solid-state fluorescence spectrum of complex 1 exhibits intense broad emissions at 396 nm at room temperature, which is red-shifted by 21 nm relative to that of free ligand TPA.

► Complex 1 has been synthesized by performing two different methods.
► The conjugation effect promotes the luminescence intensity and red-shift effect.
► Formation of (3,3)-connected topology framework.