A photoluminescent 8-fold [4 + 4] interpenetrating diamond network formed through strong hydrogen bonds

A new complex with a hydrogen-bonded diamond network, [Zn(2,2′-bipy)2(HBBDC)2] (1) has been synthesized by the assembly of H2BBDC, Zn(II) and 2,2′-bipy (H2BBDC = bibenzyl-4,4′-dicarboxylic acid and 2,2′-bipy = 2,2′-bipyridine). The coordination of two 2,2′-bipy ligands and two carboxylate groups around Zn(II) interplays with the hydrogen-bonding involving the deprotonated and protonated carboxylate, making the mononuclear molecule an unusual supramolecular tetrahedral building unit for the diamond network. The long bridging ligand leads to 8-fold interpenetration of the net in the abnormal [4 + 4] mode. Compound 1 shows a strong fluorescent emission at 400 nm in solid state at room temperature.