A novel mixed ligand Zn-coordination polymer: Synthesis, crystal structure, thermogravimetric analysis and photoluminescent properties

Abstract

A novel mixed ligand based coordination network of Zn, having formula [Zn8(Or)8(dpp)4(H2O)8]n (1), have been engineered and synthesized at room temperature by self-assembly of potassium orotate (OrK) and 1,3 di(4-pyridyl)propane (dpp) with metal salt, Zn(OAc)2·2H2O Single crystal X-ray structural analysis reveals that coordination sphere around Zn(II) ions, in Or-Zn-dpp moiety, having different atomic arrangement with distorted square pyramidal geometry. The syn-anti μ2η1:η1 bridging carboxylate and pyridyl moieties extended the Or-Zn-dpp skeleton into 2D coordination network showing square grid sheet. The emission spectrum of Zn-complex was recorded with 290 nm excitation wavelength which reflects that 1 has strong luminescence with peak maximum of 380 nm (3.2627 eV) and is a result of the n–π* and π–π* transitions of H3Or and dpp ligand. Thermogravimetric analysis shows that when the coordinated water molecule completely comes out from the complex around 320 °C, the dehydrated forms steadily starts to degrade, and the complete decomposition is observed above 350 °C.