Role of Ethynyl-Derived Weak Hydrogen-Bond Interactions in the Supramolecular Structures of 1D, 2D, and 3D Coordination Polymers Containing 5-Ethynyl-1,3-benzenedicarboxylate

The influence of weak hydrogen bonds on the crystal packing of a series of heavy and transition metal coordination polymers synthesized using the ligand 5-ethynyl-1,3-benzenedicarboxylic acid (H2ebdc) has been evaluated. Five coordination polymers were prepared and crystallographically characterized. These comprise two 1D chains, [Pb(ebdc)(DMSO)2] (1) and [Pb(ebdc)(DMF)] (2), two 2D nets, [Cu3(ebdc)(H2O)1.5(MeOH)0.5]·6H2O (3) and [Pb2(ebdc)2(DMF)4]·H2O (4), and a single 3D framework, [HNEt3][Zn3(?3-OH)(?2-H2O)(ebdc)3(MeOH)0.67(H2O)0.33]·MeOH·1.33H2O (5). The crystal structure of the free acid ligand form, H2ebdc·H2O, is also reported. Within the lead(II) coordination structures, ethynyl-derived C–H···O interactions are consistently found to provide the dominant influence over the crystal packing, as determined by solid-state structural analysis in combination with vibrational spectroscopy. The influence of weak hydrogen-bonding effects on the crystal packing of the transition metal coordination polymers that contain lattice water and methanol molecules was found to be far less prominent, which is interpreted in terms of the greater prevalence of strong hydrogen-bond donors and acceptors forming O–H···O interactions within these crystalline lattices.