Two New Nonlinear Optical and Ferroelectric Zn(II) Compounds Based on Nicotinic Acid and Tetrazole Derivative Ligands

Two new zinc compounds, [Zn2(mtz)­(nic)2(OH)]n·0.5nH2O (1) and [Zn­(phtz)­(nic)]2n (2) (Hmtz = 5-methyltetrazole,
Hphtz
= 5-phenyltetrazole, Hnic = nicotinic acid), have been synthesized
by a dual-ligand approach under solvothermal conditions. The compounds
were characterized by single-crystal X-ray diffraction, elemental
analysis, and infrared spectroscopy, respectively. The X-ray diffraction
analysis reveals that both compounds exhibit a noncentrosymmetric
polar packing arrangement. Compound 1 is a 3D framework
constructed from the zigzag chain subunits of [Zn­(nic)]+ with a 4-connected “irl” topology.
Compound 2 possesses a 2D 4-connected ‘“sql” topology constructed from the linear chain subunit
of [Zn­(nic)]+, which are linked together with phtz– ligands. Impressively, both of the two compounds display
second-harmonic generation response and ferroelectric behaviors. Furthermore,
the photoluminescence of the compounds was also investigated.