The syntheses, structures, and properties of metal-organic frameworks based on mixed multi-N donor and carboxylate ligands

Abstract

Four new metal-organic frameworks [Zn3(HL)2(btc)2(H2O)2]·H2O (1), [Mn(H2L)(btc)(H2O)] (2), [Zn2(L)(HL)(SIP)(H2O)]·4H2O (3) and [Cd(H2L)(SIP)(H2O)]·3H2O (4) were obtained by reactions of the different metal(II) salts with mixed ligands including 1,2,3-benzenetricarboxylic acid (H3btc), sodium 5-sulfoisophthalate (NaH2SIP) and 1-(4-(1H-imidazole-5-yl)phenyl)-1H-1,2,4-triazole (HL), respectively. All compounds were characterized by single-crystal X-ray diffraction, FT-IR spectroscopy, and elemental analysis. The study shows that the natures of organic ligands as well as metal ions play key roles in modulating the resulting frameworks of 1–4. The complex 1 is a (3, 4, 4)-connected three-dimensional (3D) net with the point (Schläfli) symbol of (42·63·8)4(64·8·10), while 2 is a two-dimensional (2D) layer structure referred as fes net with a Point (Schläfli) symbol of (4·82). Complex 3 has 2-nodal (3, 3, 4)-connected rare tfc net with a Point (Schlafli) symbol of (83)2(85·10), while 4 is a supramolecular polymer constructed from infinite one-dimensional (1D) chains by the interaction of rich hydrogen bonds and π - π stacking. The luminescent properties have been investigated for the compounds 1, 3, and 4 containing metal d10 Zn(II) and Cd(II) atoms.