Construction Of Supramolecular Networks Based On Coordination And Hydrogen Bonds

The coordination polymers, showing such properties as electronic, magnetic, optical, absorbent and catalytic, which are formed by linking ligand and metal ion through coordination bonds, are an important field in supramolecular chemistry. Coordination polymers exhibit some distinct characteristics: by properly chosing nodes (metal ions) and ligands, one can reasonably design and synthesize coordination supramolecules of special structures and fuctionalities. In addition, the non-bonding interactions such as hydrogen bonds,π?πstacking, metal-metal bonding, metal-nonmetal weak etc. will have an important influence on the structure, the function, the stability, the toplonogy of the result supramolecules.In present studies, two novel double betaine ligands, namely sodium 2-(pyridinium-1-yl)butanedioate (L1) and N,N''-bisacetate-N,N,N',N",N"-pentamethyl diehylenetriamine (L2), have been synthesized and allowed to interact with various metal salts to investigate their coordination behavior and the ability of constructing coordination supramolecules. The single crystals of 10 coordination compounds with these two ligands were obtained, and their molecular and crystal structures have been determined by X–ray single crystal structure analysis. The compounds include {[Zn(H2O)2(L1)2]·4H2O}n (1),{[Cd(H2O)2(L1)2]·4H2O}n (2),{[Ca(H2O)2(L1)2]·6( H2O)}n (3),{[Co(H2O)4(L1)2]·2H2O}n (4),{[Ni(H2O)4(L1)2]·2H2O}n (5),[Cu(H2O)2 (L1)2] (6),[Ag2(O2CCF3)L1]n (7),[(Ag2L2 ClO4)·ClO4·H2O]n (8),{[(Ag3(L2)2 ]·3PF6}n (9),{[Cu2(L2)2]·3ClO4·OH·OHCH2CH2OCH3 }n (10).The results indicate that (1) silver(I) carboxylates have various coordination modes as shown in 7-9. To our knowledge theμ3 bridging coordination mode of hydroxyl(OH? ) to Cu(II) centre in complex 10 has not been reported by literature. (2) In the isomorphous complexes 4, 5, the metal atom is coordinated in an MO4 coordination sphere, with four aqua molecules lying on the equatorial plane; (3) The adjacent pair of metal ions of 1, 2, 3 coordination polymer are bridged by a pair of racemeric L1 molecules to form a zig-zag chain. Both carboxylate groups of the ligand act in a monodentate mode, one using its syn-lone pair and the other using its anti-lone pair. (4) The Cu(II) atom of 7 is coordinated by a pair of trans-aqua ligands and two monodentate carboxylate groups from different racemeric betaine molecules in a nearly perfect square geometry.