Synthesis, Crystal Structures And Properties Of Novel Supra Molecular Complexes Based On The Ligands Containing Nitrogen Atoms

The first examples of fourteen metal coordination compounds based onbenzimidazole or1,10-Phenanthroline-5,6-dione (as listed in the table below) weresuccessfully synthesized under hydrothermal/solvothermal conditions. Theirstructures were determined by single-crystal X-ray diffraction analyses and furthercharacterized by elemental analyses, IR, TG-DSC and PXRD. Photoluminescenceproperties and thermo-stability were also investigated.Fourteen metal coordination polymers were designed and synthesized:[Cd(bim)4(1,5-nds)]n1[Ag(bim)2]1/2(1,5-nds)2[Cu2(bim)6(1,5-nds)2]3[Ni2(bim)4(H2O)8]2(1,5-nds) H2O4[Ni2(bim)5(H2O)7]2(1,5-nds) H2O5[Co(pdon)(2,6-H2pydc)(H2O)] H2O6[Zn(pdon)(2,6-H2pydc)(H2O)] H2O7[Cd(pdon)(2,6-H2pydc)(H2O)2]·H2O8[Ag(pdon)(2,6-H2pydc)]9[Mn2(pdon)4(1,5-nds)(H2O)2]·1,5-nds·H2O10[Co(pdon)(1,5-nds)(H2O)4]·3H2O11[Cu(pdon)(1,5-nds)(H2O)2]·2H2O12[Pb2(pdon)(dafo)(H2O)5]·2(1,5-nds)·2H2O13[Ag(pdon)2]1/21,5-nds14These complexes can be divided into three groups: M-bim-(1,5-nds),M-pdon-(2,6-H2pydc), and M-pdon-(1,5-nds) according to the ligands used.M-pdon-(2,6-H2pydc): There are five complexes in this group, namely,1-5.1is aone-dimensional structure polymer which further assemble to a layer with inlaid ringand displays a3D structure finally by supramolecular interactions. The asymmetricunits of2are connected into parallel ladders through hydrogen bonds, the chainsinterconnected each other to form a layer and the layers are arranged into3Dsupramolecular structure through π-π interactions. Every two asymmetric units of3combine with each other to be a dimer to form a3D supramolecular stratifiedstructure in which the layers are actually parallel to each other.4and5are isomersthat were born in different environments with the same starting material, they bothdisplay3D supramolecular structures except for the difference that there’s a1Ddiamond-shaped hole in4.M-pdon-(2,6-H2pydc): There are four complexes in this group, namely,6-9,which were set up by the coordination of both pdon and2,6-H2pydc to metal ions inthe form of chelating.4and5display similar3D stratified structures, but mostnoteworthy is that there’s1D channel exists between layers where free watermolecules stay. Both8and9were built from chain to layer to construct the final structures, but the difference is that the final structure of8is double-layer structureconstructed by hydrogen bonds while9displays a3D stratified structure throughπ-π interactions.M-pdon-(1,5-nds): There are five complexes in this group, namely,10-14. Inthese complexes, the1,5-nds, which dose not always participate in the coordination,play an important role in building framework by generating hydrogen bonds. Theasymmetric unit of10combines another to obtain a dimer. The dimers combine witheach other through hydrogen bonds to be stair-step chains which connect each other tobe a2D structure and get a3D supramolecular structure finally.11also displays a3D stratified supramolecular structure which experienced helix chains and layers.12is different from the others and displays a2D planar structure which experiencedchains. Both13and14present3D structures that experienced chains and layers, butthe differenceis the supramolecular interactions which helped the layers construct thefinal3D supramolecular structures.The powder XRD patterns of1-14were carried out at room temperature to checkthe phase purity. The experimental results are in good agreement with the simulatedpatterns, indicating the good phase purity of the compounds.Coordination bonds and abundant intermolecular interactions including hydrogenbonds and π-π interactions lead to collapsing of organic frameworks at highertemperature. Especially,2,10,11and12do not collapse until the temperature rise upto about300°C and even more.The photoluminescence properties of1-14and the free ligands have been measured inthe solid state at room temperature and all of them show excellent photoluminescenceproperties and are promising for potential application in the field of luminescencematerials.