Systematic Investigation of Porous Inorganic-Organic Hybrid Compounds with Photo-Switchable Properties

Four new compounds [Co2(NDC)2(AzBIPY)] (1), [Cu2(NDC)2(AzBIPY)] (2), [Zn2(BPDC)2(AzBIPY)] (3) and [Zn2(CCA)2(AzBIPY)] (4) (with H2NDC: 2, 6-naphthalenedicarboxylic acid, AzBIPY: 3-azo-phenyl-4, 4'-bipyridine, H2BPDC: 4, 4'-biphenyl-dicarboxylic acid and H2CCA: 4-carboxy-cinnamic acid) were synthesized and characterized. All compounds have paddle-wheel units and photo switchable linker molecules in common. In all four compounds the azo group of the AzBIPY linker molecule protrudes into the pores. For compound 1 and 2 isomerization can be accomplished upon irradiation with UV light (lambda = 365 nm) to switch the thermodynamically stable trans-isomer into the cis-isomer. Back switching can be achieved thermally or by irradiation with visible light (lambda = 455 nm).