Supramolecular Framework Based on Pyridiniodiketone Ligand via Non-classic Hydrogen Bonding

A novel ligand L, 4-(1-hydroxy-3-oxo-3-phenylpropenyl)-1-methylpyridinium was synthesized and identified by NMR spectra and X-ray single crystal structure analysis from L center dot A CH3SO4 (1L). Through self-assembling reactions, two new Cu-II/La-III-organic complexes, [CuL2(SCN)][SCN] center dot A H2O (2Cu) and [LaL2(SO4)Cl-2] center dot A (toluene) (3La), have been synthesized and characterized by X-ray crystallography. Structural analysis of 1L revealed that L and HSO4 (-) coexist in a unit cell. For 2Cu, Cu(II) ion show a five-coordinated structure with a highly compressed square pyramid configuration; For 3La, each La(III) ion has an eight-coordinated structure with a distorted capped pentagonal bipyramidal geometry. It should be mentioned that supramolecular framework was formed via a number of hydrogen bonding interactions. Here, intramolecular C-H center dot center dot center dot O hydrogen bonding interactions stabilized and restricted the distortion between different rings. On the contrary, intermolecular hydrogen bond, e.g. C-H center dot center dot center dot O dual hydrogen bond interactions (1L), O5-involving triple C-H center dot center dot center dot O/O-H center dot center dot center dot O(N) hydrogen bond (2Cu) and triple C-H center dot center dot center dot Cl hydrogen bonding(3La), greatly affect geometric distortion between rings from ligand. Finally, we believe that the cooperative effect plays more important roles in supramolecular self-assembly.