Acyclic water tetramer and discrete (H2O)28 cluster with a novel topknot-shaped (H2O)24 cluster coexist in the voids of a Ag(I) polymeric solid

Two kinds of discrete water clusters, acyclic water tetramer and larger (H2O)28 cluster with a novel topknot-shaped (H2O)24 core formed from lattice water molecules, are captured in the voids of a Ag(I) polymeric solid [Ag4(bpda)2(bpp)4·18H2O]n (1) (where bpp = 1,3-bis(4-pyridyl)propane and H2bpda = 1,1′-biphenyl-2,2′-dicarboxylate acid). The centrosymmetric (H2O)24 cluster is basically an assembly of two (H2O)12 subunits and each subunit (H2O)12 has the shape of cage-like water monodecamer hydrogen bonded to one water monomer. The lattice of a crystal host provides two different sizes of hydrophilic environments for stabilizing these clusters. Moreover, the thermogravimetric curve and photoluminescence spectra of 1 were discussed. 1 exhibits strong photoluminescence maximized at 495 nm upon 390 nm excitation at ambient temperature, of which the CIE chromaticity ordinate (x = 0.23, y = 0.42) is close to that of the green component.