Two acentric (6, 3) topological 2-D frameworks with imidazole-containing tripodal ligand and their ferroelectric properties.

Hydrothermal reaction of three-connecting ligands 1,3,5-tris(1-imidazolyl) benzene (tib) and MnSO4 or CoSO4·7H2O provides two new metal-organic frameworks, {[Mn(tib)2(H2O)4]SO4}n (1) and {[Co(tib)2(H2O)4]SO4}n (2). Single-crystal X-ray diffraction studies reveal that complexes 1 and 2 belong to the polar point group 3m, and have the same two-dimensional honeycomb networks with (6, 3) topology. The ferroelectric behavior investigation indicates that both compounds are typical ferroelectrics with an electric hysteresis loop showing a remnant polarization (P(r)) of ca. 0.586 µC cm(-2) and a coercive field (E(c)) of 2000 V cm(-1) for 1 and P(r) of ca. 0.208 µC cm(-2) and a coercive field (E(c)) of 2600 V cm(-1) for 2.

In situ synthesis and ferroelectric, SHG response, and luminescent properties of a novel 3D acentric zinc coordination polymer.

The 3D acentric metal-organic framework (MOF) of [Zn(Mitz)Cl](n) [1; Mitz = 3-tetrazolyl-6-methyl-5-(4-pyridyl)-2-pyridone] was obtained from in situ [2 + 3] cycloaddition reactions of milrinone [=3-cyano-6-methyl-5-(4-pyridyl)-2-pyridone] with sodium azide in the presence of ZnCl(2) as the Lewis acid. The compound is a typical ferroelectric material with an electric hysteresis loop showing a remnant polarization (P(r)) of ca. 0.21 µC/cm(2) and a coercive field (E(c)) of 2600 V/cm. Powdered samples of 1 display strong second-harmonic-generation responses of ∼2 times larger than that of KH(2)PO(4). Photoluminescent study show that complex 1 and the milrinone ligand exhibit maximal emission peaks at around 409 and 401 nm, respectively, in the solid state at room temperature.