Formation of different polymeric water clusters via organic anionic templates: More carboxylate groups used, more water molecules gathered

Two sandwich-like frameworks with Ag(I) and mixed ligands, [Ag3(bpp)3(ctc)·16H2O]n (1) and [Ag3(bpe)3(btc)·12H2O]n (2) (where bpp = 1,3-bis(4-pyridyl)propane, H3ctc = 1,3,5-cyclohexanetricarboxylic acid, bpe = 1,2-bis(4-pyridyl)ethane, and H3btc = 1,2,4-benzenetricarboxylic acid), have been synthesized and structurally characterized. Fully deprotonated tricarboxylate ctc3 − in 1 or btc3 − in 2, serves as anionic template driving more water molecules to aggregate into different morphologies of polymeric clusters. In 1, the hydrogen-bonding association of sixteen lattice water molecules leads to the formation of 2D layered water, which is composed of three kinds of units including planar (H2O)4, ladder-like (H2O)8 and windmill-shaped (H2O)20 cluster. One novel 1D double-comb-like water aggregate constructed from alternating (H2O)22 cluster and water dimmer exists in 2. The present observations suggest that anionic templates with more carboxylate groups have high tendency of being hydrated and make polymeric clusters possible.