Crystal Structure Solid-State Cross Polarization Magic Angle Spinning 13C NMR Correlation in Luminescent d10 Metal-Organic Frameworks Constructed with the 1,2-Bis(1,2,4-triazol-4-yl)ethane Ligand

Hydrothermal reactions of 1,2-bis(1,2,4-triazol-4-yl)ethane (btre) with copper(II), zinc(II), and cadmium(II) salts have yielded the dinuclear complexes [Zn2Cl42-btre)2] (1) and [Zn2Br42-btre)2] (2), the one-dimensional coordination polymer 1[Zn(NCS)22-btre)] (3), the two-dimensional networks 2[Cu22-Cl)24-btre)] (4), 2[Cu22-Br)24-btre)] (5), and 2{[Cd63-OH)23-SO4)44-btre)3(H2O)6](SO4)·∼6H2O} (6), and the three-dimensional frameworks 3{[Cu(μ4-btre)]ClO4·∼0.25H2O} (7), 3{[Zn(μ4-btre)(μ2-btre)](ClO4)2} (8), 3{[Cd(μ4-btre)(μ2-btre)](ClO4)2} (9), and 3[Cu22-CN)24-btre)] (10, 2-fold 3D interpenetrated framework). The copper-containing products 4, 5, 7, and 10 contain the metal in the +1 oxidation state, from a simultaneous redox and self-assembly reaction of the Cu(II) starting materials. The cyanide-containing framework 10 has captured the CN ions from the oxidative btre decomposition. The perchlorate frameworks 7, 8, or 9 react in an aqueous NH4+PF6 solution with formation of the related PF6-containing frameworks. The differences in the metal-btre bridging mode (μ2N1:N1′, μ2N1:N2 or μ4N1:N2:N1′:N2′) and the btre ligand symmetry can be correlated with different signal patterns in the 13C cross polarization magic angle spinning (CPMAS) NMR spectra. Compounds 2, 4, 5 and 7 to 10 exhibit fluorescence at 403−481 nm upon excitation at 270−373 nm which is not seen in the free btre ligand.