Photoluminescent metal-organic framework with hex topology constructed from infinite rod-shaped secondary building units and single e,e-trans-1,4-cyclohexanedicarboxylic dianion

Hydrothermal reaction produced a three-dimensional zinc 1,4-cyclohexanedicarboxylate formulated as Zn5(μ3-OH)2(trans-chdc)4 (chdc = 1,4-cyclohexanedicarboxylic dianion) in high purity and good yield, which is constructed from infinite rod-shaped Zn–O–C secondary building units interconnected by –C6H12-cyclohexane rings of the ligands. The topology of the framework can be regarded as hex type. Though it is synthesized from 1,4-cyclohexanedicarboxylic acid with mixed conformations (trans and cis), interestingly, the ligands in the compound Zn5(μ3-OH)2(trans-chdc)4 are uniformly in e,e-trans conformation. This may be related to its synthetic conditions. Photoluminescence measurement reveals that the compound exhibits intense violet-blue fluorescent emission at room temperature. Origin of the emission can be assigned to intraligand transitions by comparison of the fluorescent emission bands for the free ligand chdcH2 and the compound Zn5(μ3-OH)2(trans-chdc)4.