Metal-Directed Supramolecular Architectures:  From Mononuclear to 3D Frameworks Based on In Situ Tetrazole Ligand Synthesis

Abstract

This work focuses on the investigation of the influence of metal ions and supramolecular interactions on the self-assembly of in situ generated tetrazolate coordination architectures. A series of new metal−organic complexes, [Zn(pzta) 2 (H 2 O) 2 ] ( 1 ), [Cu(pzta) 2 ](H 2 O) 3 ( 2 ), [Cd(pzta) 2 ] n ( 3 ), [Ag(pzta)] n ( 4 ), and [Cd 2 (pzta)(OH)(SO 4 )] n ( 5 ) [pzta = pyrazinyl tetrazolate], have been achieved by the in situ hydrothermal reactions of pyrazinecarbonitrile, sodium azide, and different metal ions. Complexes 1 and 2 have similar mononuclear structures bearing distinct intermolecular hydrogen-bond interactions to form two different 3D supramolecular networks based on 4 4 -subnets. Complex 3 features a 1D crossed-shape chain structure. Complex 4 is a coordination polymer comprised of mildly undulated 2D layers with a (4.8 2 ) topological network. Complex 5 is a 3D diamondoid framework constructed by pentanuclear cadmium cluster nodes and pzta linkers. The configurations of complexes 1 − 5 span from mononuclear ( 1, 2 ), to one-dimensional ( 3 ) and two-dimensional ( 4 ), to three-dimensional ( 5 ), which indicates that metal ions play an essential role in the framework formation of the in situ generated tetrazolate architectures. Furthermore, complexes 1, 3, and 5 exhibit strong blue photoluminescence in similar energy regions.