| In coordination polymers, the metal ions are each linked by ligand bridges, and the ligands have been specificly directioned. We can arrange the ligands with given fuctions and configurations according to our pre-designed purposes, and consequently prepare the coordination polymers with given structures and characteristics. Non-bonding interactions such as hydrogen-bonding,π-πstacking interaction,metal-metal bonding,metal-nonmetal weak interactions etc. have determined the specified architectures.In present studies, five novel double betaine ligands, namely 1, 3-bis(4-carboxy-pyridinium)propane( L1 ), 2-(3-carboxypyridinium)ether( L2 ), α, α′-bis(4-carboxy-pyridinium)-1, 4-dimethylbenzene( L3 ), α, α′-bis(3-carboxypyridinium)-1, 4-dimethylbenzene(L4) and 1, 2-bis[2-(4-carboxypyridinium)ethoxyl] ethane (L5) 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 11 coordination compounds with the former four ligands, namely L1, L2, L3 and L4, were obtained, and their molecular and crystal structures have been determined by X-ray single crystal structure analysis. The compounds include: {[Cu L1 (H2O)4]·SO4-2H2O}n (1) , {[Cu L21]-2ClPO4·2H2O}n (2),{[Cu L22 (H2O)3]-2ClO4-2H2O}n (3),{[MnL22(H2O)2]-2ClO4}n(4),{[Ag L2 ]NO3·2H2O}n (5),{[Ag4 L22(CF3SO3)2 H2O]·2CF3SO3-3H2O}n (6),{[Cu L3 (H2O)3]2ClH2O}n (7),{[Cu L23(H2O)2]-2NO3}n (8) , {[Cd L23]-2ClO4-2H2O}n (9) , {[Ag4 L<sub>2.53 H2O]·4CF3SO3·3H2O}n (10),{[Ag L4]·ClO4}n(11).The results show that: (1) The ligand L1 exhibits two different configurations, that is, cis-L1 in 1 and trans-L1 in 2. The configuration of L1 plays a thumb role in determining the result structures. (2) In 1 and 2, the cations are Cu(?), but the anionsare SO42- and ClO4-, respectively;In coordination polymers 7 and 8 derived from the ligand L3, the cations are Cu( ?), but the anions are Cl-and NO3-, respectively. The nature of anions has great influence on the configuration of these coordination polymers as revealed in the structure of 1 and 2, 7 and 8. (3) L2 and 2-(4-carboxypyridinium)ether (L) are isomeric compounds, and the ligand L exhibits two different configurations, that is cis-and trans-. But 2-(3-carboxypyridinium)ether (L2) has shown one configuration (cis-) in four coordination compounds(3-6).Because the salts used are different, the ligand L2 in the four coordinationcompounds has adjusted its configuration in different coordination compounds. In 3,4and 5, the ligand acts in a bidentate coordination mode, and in 6 a tetradentatecoordination mode. (4) The ligands and are isomeric, both of them exhibittrans-configuration and are extended to linear configuration in coordinationcompounds. Ligand can adjust its configuration, such as switch the angle ofpyridines or the angle of pyridine and benzene, to different metal ions. (5) The knownexperimental evidences showed that the diamondoid coordination networks with an oddnumber-fold interpenetration are necessarily acentric, and the importance ofunsymmetrical linkage groups in the synthesis of noncentrosymmetric metal-organicframeworks has been emphasized. However, in 9 the ligand is symmetric, and thenetwork is odd number-folded, but the structure of 9 crystallied in a centrosymmetricspace group, which is contrary with the well-known conclusion.L3 L4L3L3... |
PDF Full Text Request