Novel Pb and Zn Coordination Polymers:  Synthesis, Molecular Structures, and Third-Order Nonlinear Optical Properties

Abstract

Three novel coordination polymers [Pb(bbbm)(2)(NO(3))(2)](n) (bbbm = 1,1'-(1,4-butanediyl)bis-1H-benzimidazole) 1, [Zn(bbbt)(NCS)(2)](n) (bbbt = 1,1'-(1,4-butanediyl)bis-1H-benzotriazole) 2, and [Zn(pbbt)(NCS)(2)](n) (pbbt = 1,1'-(1,3-propylene)bis-1H-benzotriazole) 3 were synthesized and structurally characterized. Polymer 1 exhibits a two-dimensional rhombohedral grid network structure, the dimensions of the grid are 14.274 x 14.274 A, and the diagonal-to-diagonal distances are 24.809 x 14.125 A. Polymer 2 possesses a concavo-convex chain structure different from those of the known one-dimensional polymers, which are linear chain, zigzag chain, helical chain, double-stranded chain, and ladder chain. Polymer 3 exhibits a one-dimensional zigzag chain structure, and these chains were packed as an.ABAB. layered structure. The third-order nonlinear optical (NLO) properties of polymers1, 2, and 3 were determined with a 7-ns pulsed laser at 532 nm. 1 shows strong third-order NLO absorptive and refractive properties, and its alpha(2) and n(2) values were calculated to be 5.8 x 10(-)(9) m W(-)(1) and 4.67 x 10(-)(18) m(2) W(-)(1) in a 3.4 x 10(-)(4) mol dm(-)(3) DMF solution, respectively. Both 2 and 3 exhibit weaker NLO absorption and strong refractive properties, and their n(2) values are 4.53 x 10(-)(18) m(2) W(-)(1) for 2 in a 5.2 x 10(-)(4) mol dm(-)(3) DMF solution and 3.02 x 10(-)(18) m(2) W(-)(1) for 3 in a 4.35 x 10(-)(4) mol dm(-)(3) DMF solution. The chi((3)) values of 1, 2, and 3 were calculated to be 1.67 x 10(-)(11), 1.62 x 10(-)(11), and 1.08 x 10(-)(11) esu, respectively, and the values are larger than those of the reported coordination polymers. We deduce that the valence shell structures of metal ions may have some influence on the strength of NLO properties, and discuss the relationships between the crystal structures of coordination polymers and the observed NLO properties.

Syntheses, Structures, and Optical Properties of β‐Ferrocenylacrylate Metal Polymers

“…Upon summarizing the limited literature relating to the third-order NLO properties of coordination polymers, we find that the coordina- tion polymers' large NLO properties may mainly be ascribed to the effect of metal ions, because the incorporation of transition metal ions into polymers can extend the π-conjugation length of the molecules, and the large π-conjugation system is favorable to increase the NLO susceptibility χ (3) values. [45,46] All the four polymers display self-focusing behavior, which is consistent with the previous conclusion [45] that the NLO properties of polymers are further controlled by the valence shell structures of the central metal ions. Nearly all the reported polymers with d 10 valence shell metal ions give self-focusing behaviors, such as theorganic-metal polymers [Zn(bbbt)(NCS) 2 ] n , [Zn(pbbt)(NCS) 2 ] n , [45] [HgI 2 (4,4Ј-azopyridine)] n , [HgI 2 (bpea)] n , [Pb(NCS) 2 (bpea)] n , [47] [Cd(en)-(NO 3 ) 2 (4,4Ј-bpy)] n , [48] [4] etc.…”

“…[45,46] All the four polymers display self-focusing behavior, which is consistent with the previous conclusion [45] that the NLO properties of polymers are further controlled by the valence shell structures of the central metal ions. Nearly all the reported polymers with d 10 valence shell metal ions give self-focusing behaviors, such as theorganic-metal polymers [Zn(bbbt)(NCS) 2 ] n , [Zn(pbbt)(NCS) 2 ] n , [45] [HgI 2 (4,4Ј-azopyridine)] n , [HgI 2 (bpea)] n , [Pb(NCS) 2 (bpea)] n , [47] [Cd(en)-(NO 3 ) 2 (4,4Ј-bpy)] n , [48] [4] etc. Other than the valence shell structures of the central metal ions, some other factors also have an effect on the intensity of the third-order optical nolinearity, such as the orbital overlap, orbital symmetry, degree of electron delocalization, linear polarizability etc.…”

Synthesis and X‐ray Crystal Structures of Cobalt and Copper Complexes of 1,3‐Bis(benzotriazolyl)propanes

“…The three isomers were separated by column chromatography on silica gel and recrystallized from absolute ethanol and their properties were in accord with those described previously. [13] However, ligand 1 has recently been described by other workers [14] who reported a 1 H NMR spectrum which we believe to be that of isomer 2. In order to resolve this discrepancy unambiguously, we carried out an X-ray crystal structure determination of the compound we identified as 2.…”

“…[14] As a consequence, copper atoms bridged by the ligand 1 are separated by only 9.157(1) Å, much less than the metal-metal separation in 3.…”

Crystal structure of catena-(acetato-O,O′)(bromo)- [μ-1,1′-(1,4-butanediyl)bis(benzimidazole)-N:N′]cadmium(II), CdBr(C2H3O2)(C18H18N2)

“…In particular, the uses of flexible ligands have attracted remarkable attention because their conformationsare expected to produce many intriguing architectures. Bis(imidazole) ligands are excellent candidates for the construction of extended architectures and supramolecular architectures [7][8][9][10]. 1,1'-(1,4-butanediyl)bis(benzimidazole) (bbim), bearing alonger methylene (-CH 2 -) 4 skeleton, is agood candidate for N-donor linkers.…”