A novel Zn(II) coordination polymer with mixed N- and O-donor linker: Room temperature synthesis, comprehensive characterization and Hirshfeld surface analysis

Abstract

The present study describes the room temperature synthesis of a new two-dimensional (2D) coordination polymer (CP) having the formula [Zn(H-PCA)2]n (CP1), where H-PCA stands for 4-pyrazolecarboxylate. The mixture of Zn(OAc)2·2H2O and multitopic mixed N- and O-donor 4-pyrazolecarboxylic acid (H2-PCA) were self-assembled in a one-pot in methanol. The synthesis produced good yield and purity, and this method makes it simple to obtain multigram quantities of CP1 within a short period. Notably, this synthetic method selectively deprotonates the carboxylic acid group while maintaining pyrazole moiety in its protonated form. CP1 has been characterized by single-crystal X-ray diffraction, FTIR spectroscopy, elemental analysis, scanning electron microscopy, thermogravimetric analysis and powder X-ray diffraction. CP1 exhibits a 4-connected, 2-fold interpenetrated 2D network with the point symbol {44.62} – sql net topology. Due to the presence of the protonated pyrazole, these 2D layers further extended into a three-dimensional (3D) non-porous supramolecular network through strong 'intermolecular' NH···O hydrogen bonds between adjacent layers. Additionally, a 3D Hirshfeld Surface analysis accompanied by quantitative 2D-fingerprint plots was also investigated to explore the 'intermolecular' interactions.