Structure And Properties Of Aza-ring Assembly, Poly-complexes

In this paper, we have synthesized seven novel coordination polymers at room temperature, which contain ligands l,l'-(l,3-propylene)bis-lH-benzotriazole (pbbt) and l,r-(l,5-pentamethylene)bis-lH-benzimidazole (pbbm), and characterized their structures by single crystal X-ray diffraction as well as thermoanalysis and The third-order NLO properties.Polymer {[Ag2(pbbt)3](NO3)2-0.5H2O}n 1 shows a 2-D layered network with less common hexagonal units in which six Ag atoms occupy the six corners of each hexagonal unit with six pbbt ligands acting as six sides. The six Ag atoms are nearly coplanar. The third-order nonlinear optical property is investigated by Z-scan technique. The results show that it possesses very strong the third NLO properties and self-defocusing behavior. The absorptive coefficient a2 is 3.2 x 10-8 m W-1, which is the largest than those of the reported coordination polymers, and the refractive index n2 value is calculated to be -2.78 x 10-17 m W-1. The rvalue is calculated to be 2.23 x 10-28 esu.Polymer {[Ni(pbbt)2(NCS)2] H2O}n 2 possesses a 2-D double helix chain structure. The Ni(II) center is in a slightly compresses octahedron environment, in which four nitrogen atoms from four pbbt ligands occupy the equatorial positions and the other two nitrogen atoms from two NCS" groups occupy the axial positions. Two strands of pbbt ligands wrap each other, and held together by Ni(II) ions forming a double-stranded helical chain along the a-axis direction. There are weak - interactions between adjacent chains along b-axis and c-axis directions. It adopts weak NLO absorptive effect and strong NLO refractive behavior with n2 value of 3.02 x 10-18 m2 W-1, and shows self-focusing behavior. The rvalue is calculated to be 1.68 x 10-29 esu.Polymer {[Co(pbbt)2(NCS)2]-H2O}n 3 has the same helical chain as polymer 2. The Co atom is five-coordinate. The Co(II) centers are linked by pbbt ligands leading to the double helix chain. Along b-axis and c-axis directions, weak interactions between adjacent chains also exist between two Py. It exhibits very strong the third NLO properties and self-defocusing behavior with a2 value of 1.4 x 10-9 m W-1 and n2value of 8.23 x 10-18 m2 W-1. The rvalue is calculated to be 4.58 x 10-29 esu.Polymer [Zn(pbbt)(NCS)2]n 4 exhibits one-dimensional zigzag chain structure. The central Zn ion is located in a slightly distorted tetrahedron environment. Each Zn(II) ion is coordinated by two nitrogen atoms from trans-pbbt ligands and two nitrogen atoms from isothiocyanate (NCS~) groups. These zigzag chains are arranged as ...ABAB... layered structure. In the same layer, two chains are connected by the weak interactions between Zn ions and S atoms, and interactions between benzene rings, which are parallel to each other. Moreover, between adjacent layers, there are also two kinds of interactions including the weak C-H-S2 hydrogen bond and the -stacking interaction between benzene rings, which are arranged in face-to-face fashion. Its third-order nonlinear optical (NLO) properties were determined with a 7-ns pulsed laser at 532 nm. The result shows that it exhibits weakerNLO absorption and strong refractive properties. The rvalue is 3.02 x 10-18 m W in a 4.35 x 10-4 mol dm-3 DMF solution. The x(3) value is calculated to be 1.08x 10"n esu.Polymer {[Co(NO3)(pbbm)2]NO3 1/2H2O}n 5 is a one-dimensional cup-like helical chains. The Co(II) center is in a square pyramidal geometry with four nitrogen atoms from four pbbm groups and one oxygen atom from one NO3- anion. The system is electrically cationic. Disorder occurs in the coordinated NO3- anion. Every cobalt atom binds with four pbbm ligands forming a cup-like unit. Every cup-like unit binds with two cobalt atoms to form a novel one-dimensional helical polymeric chain. ItsTG curve exhibits three continuous weight loss stages in the ranges of 72-221C, 221-267C and 267-810C, corresponding to the concomitant release of the crystallized water molecule decompositions of the nitrate anions and pbbm. A brown amorphous residue of CoO was remained...