Photochemistry of framework-supported M(diimine)(CO)3X complexes in three-dimensional lithium carboxylate metal–organic frameworks: monitoring the effect of framework cations

The structures and photochemical behaviour of two new metalorganic frameworks (MOFs) are reported. Reaction of Re(2,2-bipy-5,5-dicarboxylic acid)(CO)3Cl or Mn(2,2-bipy-5,5-dicarboxylic acid)(CO)3Br with LiCl or LiBr, respectively, produces single crystals of Li2(DMF)2 [(2,2-bipy-5,5-dicarboxylate)Re(CO)3Cl]n (ReLi) or Li2(DMF)2[(2,2-bipy-5,5-dicarboxylate)Mn(CO)3Br]n (MnLi). The structures formed by the two MOFs comprise one-dimensional chains of carboxylate-bridged Li(I) cations that are cross-linked by units of Re(2,2-bipy-5,5-dicarboxylate)(CO)3Cl (ReLi) or Mn(2,2-bipy-5,5- dicarboxylate)(CO)3Br (MnLi). The photophysical and photochemical behaviour of both ReLi and MnLi are probed. The rhenium-containing MOF, ReLi, exhibits luminescence and the excited state behaviour, as established by time-resolved infrared measurements, is closer in behaviour to that of unsubstituted [Re(bipy)(CO)3Cl] rather than a related MOF where the Li(I) cations are replaced by Mn(II) cations. These observations are further sup...