We report herein a novel infinite two-dimensional water morphology, found in a metallo-organic host, made up of discrete cyclic water hexamers and which contains large circular holes defined by 18 molecules of water.

Octahedral 1:1 Ni(II) and square-planar 1:1 Pd(II) and Pt(II) complexes of formulae [Ni(HAcb4DM)(AcO)(H2O)2]·H2O (1), [Pd(HAcb4DM)Cl]·5H2O (2) and [Pt(HAcb4DM)Cl]·3H2O (3), where H2Acb4DM = 5-acetylbarbituric-4N-dimethylthiosemicarbazone (H2 denoting its two dissociable protons, one enolic and one thiolic), have been synthesized and characterized by elemental analysis and by 1H and 13C NMR, UV-vis, and IR spectroscopy. Crystallisation of compounds 1–3 from DMSO afforded complexes of formulae [Ni(HAcb4DM)2]·2H2O (1a), [Pd(Acb4DM)(DMSO)]·DMSO (2a) and [Pt(Acb4DM)(DMSO)]·DMSO (3a), the molecular and crystal structures of which were determined by X-ray diffractometry. The thiosemicarbazone in 1a coordinates to the metal ions in an ONS-tridentate manner in the O-enolate/S-thione form, but in complexes 2a and 3a the thiosemicarbazone binds Pd(II) or Pt(II) as an ONS-pincer ligand in the O-enolate/S-thiolate form. The 195Pt NMR spectrum of 3 shows a signal at −2950 ppm along with two new signals at −3348 and −2731 ppm, indicating the presence of solvolysis products. The catalytic activity of complex 2a has been explored in aryl–aryl Suzuki cross-coupling reactions. H2Acb4DM and complexes 2 and 3 were screened for in vitro cytotoxicity against a human tumour cell line (HeLa-229), with the clinically employed drug cisplatin as a reference.

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) (where SS ) 4,4′-dipyridyldisulfide, SCS ) bis(4-pyridylthio)methane, L 1 ) 2-methyllactate, and L 2 ) glycolate), have been synthesized by the reaction of the SS and SCS ligands with the corresponding copper(II) R-hydroxycarboxylates (2-methyllactate and glycolate). The structures of the mononuclear compounds 1 and 1w 1 , which could be considered as pseudo-polymorphs, show that the solvent molecules are not innocent partners and play a key role in the supramolecular association. Compound 2w 1 is a discrete dinuclear molecule in which the SCS ligand acts as bridge between the two copper(II) ions. In these three compounds it seems that the presence of the 2-methyllactate ligand prevents the formation of the expected coordination polymers through the twisted SS and SCS ligands. Compounds 3w 1D and 4w 1D , which both contain the glycolate ligand, are one-and two-dimensional (1D and 2D) coordination polymers, respectively. In the crystal lattices of the two compounds, two 1D water morphologies are hosted: a treelike chain for 3w 1D and a staircase T4(2) tape for 4w 1D . In both cases, the dehydration-rehydration processes are investigated.

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