Conformational Isomerism of 1,2-Bis(imidazol-1′-yl)ethane Affected by the Orientation of Functional Carboxylate Groups in Cadmium and Cobalt Helical Coordination Polymers

Abstract

Four helical coordination polymers, [Cd(anti-bime)(1,3-pda)] n (1), [Cd(gauche-bime)(1,4-pda)] n (2), [Co(anti-bime)(1,2-pda)] n (3), and [Co(gauche-bime)(1,4-pda)] n (4), have been solvothermally prepared by the assembly of mixed flexible ligands, bime and 1,3-H2pda, 1,4-H2pda, 1,2-H2pda with Cd(NO3)2·4H2O and Co(NO3)2·6H2O, respectively (bime = 1,2-bis(imidazol-1′-yl)ethane, 1,3-H2pda = 1,3-phenylenediacetic acid, 1,4-H2pda = 1,4-phenylenediacetic acid, 1,2-H2pda = 1,2-phenylenediacetic acid). Single-crystal X-ray diffraction analyses reveal that all of the complexes possess helical structures owing to the use of mixed flexible ligands; the conformations of flexible bime are entirely different, anti-bime occurs in 1 and 3, while gauche-bime occurs in 2 and 4. The fluorescent properties of 1 and 2 suggest that the intense broad photoluminescence emission at 387 nm for 1 and 389 nm for 2, 3, and 4 exhibit similar weak antiferromagnetic coupling between the Co2+ centers.

Synthesis of cobalt cluster-based supramolecular triple-stranded helicates

“…There have been some synthetic examples of cobalt-based helical complexes. [11][12][13][14] In addition, transition metal-based triple-stranded helical compounds without cluster structures have been reported previously. [8,[15][16][17][18][19] Mainly oxygen-and nitrogen-donor ligands have been used to construct triple-stranded helicates, with the ligands coordinating to a single metal atom at the "hinge" sites.…”

A new two-dimensional CdII coordination polymer based on 1,3-bis(2-methyl-1H-imidazol-1-yl)benzene and 1,3-phenylenediacetic acid: synthesis, crystal structure and physical properties

“…However, to the best of our knowledge, compounds containing 1,3-bis(2methyl-1H-imidazol-1-yl)benzene (1,3-BMIB) as a bent imidazole ligand have been rarely reported (Li & Tao, 2014). On the other hand, 1,3-phenylenediacetic acid (H 2 PDA), as a multidentate carboxylate ligand, has been proven to be a good bridging ligand for the construction of novel coordination polymers because of its versatile bridging modes via the two carboxyl groups (Yang et al, 2011;Li et al, 2010). Based on the above considerations, we explored the self-assembly of the cadmium(II) ion, H 2 PDA and 1,3-BMIB under hydrothermal conditions and obtained a novel two-dimensional (2D) coordination polymer, namely, {[Cd(PDA)(1,3-BMIB)]Á2H 2 O} n , (I), the synthesis, crystal structure and physical properties of which are reported herein.…”

A zinc(II) metal organic framework based on flexible o-phenylenediacetate and rigid 4,4′-azobis(pyridine) ligands: Synthesis, crystal structure and hydrogen gas adsorption property

“…On the other hand, complexes formed by flexible carboxylate ligands are relatively rare [18]. In fact, flexible carboxylate ligands are excellent candidates for the formation of MOFs [14,[18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Studies reveal that flexible ligands play an important role to form frameworks with unique structures and useful properties.…”