Crystal structures and solid-state CPMAS 13C NMR correlations in luminescent zinc(II) and cadmium(II) mixed-ligand coordination polymers constructed from 1,2-bis(1,2,4-triazol-4-yl)ethane and benzenedicarboxylate?

Dalton Transactions Pub Date: 2009-01-16 DOI: 10.1039/B812670D

Abstract

The hydrothermal reaction of M(NO3)2·4H2O (M = Zn and Cd) with benzene-1,4-dicarboxylic acid (H2bdc) or benzene-1,3-dicarboxylic acid (H2ip) and 1,2-bis(1,2,4-triazol-4-yl)ethane (btre) produced the mixed-ligand coordination polymers (MOFs) 3∞{[Zn2(μ2-bdc)2(μ4-btre)]} (1), 3∞{[Cd2(μ4-bdc)(μ4-btre)2](NO3)2·H2O} (2) and 2∞{[Zn2(μ3-ip)2(μ2-btre)(H2O)2]·2H2O} (3). The compounds, characterized by single-crystal X-ray diffraction, X-ray powder diffraction, solid-state cross-polarization (CP) magic-angle-spinning (MAS) 13C NMR and thermoanalysis, feature 3D metal–organic frameworks for 1 and 2 and 2D double layers which are connected through hydrogen bonds from the aqua ligands for 3. The CPMAS 13C NMR spectra picture the symmetry-independent (unique) C atoms and the bdc/ip-to-btre ligand ratio in agreement with the crystal structures. The zinc and cadmium coordination polymers 1–3 show a strong bluish fluorescence upon excitation with UV light (the free btre ligand is non-luminescent).

Graphical abstract: Crystal structures and solid-state CPMAS 13C NMR correlations in luminescent zinc(II) and cadmium(II) mixed-ligand coordination polymers constructed from 1,2-bis(1,2,4-triazol-4-yl)ethane and benzenedicarboxylate
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