Naphthalene-based linkers for metal phosphonates: synthesis, structure, and interesting conformational flexibility influence on final lanthanum hybrids

Two diphosphonic acids based on naphthalene scaffold, namely naphthalene-1,4-diphosphonic acid, C10H6(PO3H2)(2) [1, H4NDP(1,4)] and 1-(phosphono)naphthalene-4-(methylphosphonic) acid, C10H6(PO3H2)(CH2PO3H2) [2, H4NDP(1,4C)] were obtained. Their supramolecular self-assembly were studied as well as solvent effect for the second one (2a, 2b). These potential building blocks in coordination polymer chemistry were engaged with a La3+ ion in a room temperature reaction to produce new single crystalline metal phosphonates: (I) [La{C10H6(PO3H)(2)}{C10H6(PO3H)(PO3H2)}(H2O)(2)](n)center dot nH(2)O (3), a 2D coordination polymer with the (IO1)-O-1 structure and {4(2).6}(2){4(4).6(4).8(2)} topology of the layer, and (II) [La{C10H6(PO3H1.5)(CH2PO3H)}(2)(H2O)(7)]center dot 2H(2)O (4), a discrete complex. These drastic differences in hybrid material structures can be explained by ligand structures analysis including their conformational flexibility.