A series of metal–organic frameworks (MOFs) with improved moisture stability based on a phosphonate monoester, featuring 1D chains, 2D layers and 3D networks, have been obtained in the presence of auxiliary N-donor ligands.

A metastable three-dimensional cadmium(II) coordination polymer with (2-carboxyethyl)(phenyl)phosphinate (L 2− ) and 4,4′-bipyridine (bipy) as ligands, namely, [Cd(L)-(bipy)(H 2 O) 2 ] (1), can be converted to two new two-dimensional/ three-dimensional varieties under hydrothermal treatments at different temperatures, that is, [Cd(L)(bipy)] (2) and [Cd(L)-(bipy) 0.5 ]•0.5H 2 O ( 3). Their syntheses, crystal structures, structural transformations, and luminescent properties are presented. In addition, 1 shows a second harmonic generation response that is ∼0.3 times that of KDP (KH 2 PO 4 ).

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The hydrothermal reaction of PbCl(2) with the achiral 2-carboxyethyl(phenyl)phosphinate ligand (H(2)L) afforded a novel lead(II) phosphinate that contains two enantiomers as a racemic mixture, namely, [Pb(HL)(2)] (Λ- and Δ-1). Each enantiomer features a two-fold symmetrical chiral chain, in which the adjacent Pb(2+) ions are doubly bridged by pairs of HL(-) ligands. The uni-oriented stacking of such 1D chains by edge-to-face π···π interactions results in its crystallization in the chiral C2 space group. Complex 1 shows a second harmonic generation response that is ∼2 times that of KDP (KH(2)PO(4)).