Impact of Isomeric Dicarboxylate Ligands on the Formation of One-Dimensional Coordination Polymers and Metallocycles: A Novel cis→trans Isomerization

oleh: Kuan-Ting Chen, Ji-Hong Hu, Xiang-Kai Yang, Jhy-Der Chen

Format: Article
Diterbitkan: MDPI AG 2020-06-01

Deskripsi

A series of Co(II), Ni(II) and Cu(II) coordination polymers and dinuclear metallocycles containing 4-aminopyridine (4-ampy) and benzenedicarboxylate ligands, {[M(4-ampy)<sub>2</sub>(1,4-BDC)]·H<sub>2</sub>O·CH<sub>3</sub>CH<sub>2</sub>OH}<sub>n</sub> (M = Ni, <b>1a</b>; Co, <b>1b</b>, 1,4-H<sub>2</sub>BDC = benzene-1,4-dicarboxylic acid), {[Ni<sub>2</sub>(4-ampy)<sub>4</sub>(1,3-BDC)<sub>2</sub>]·H<sub>2</sub>O·CH<sub>3</sub>CH<sub>2</sub>OH}<sub>n</sub> (1,3-H<sub>2</sub>BDC = benzene-1,3-dicarboxylic acid), <b>2</b>, [M<sub>2</sub>(4-ampy)<sub>4</sub>(1,2-BDC)<sub>2</sub>] (M = Ni, <b>3a</b>; Co, <b>3b</b>, 1,2-H<sub>2</sub>BDC = benzene-1,2-dicarboxylic acid), [Co(4-ampy)<sub>2</sub>(1,3-BDC)]<sub>n,</sub> <b>4</b>, {[Cu(4-ampy)<sub>2</sub>(1,4-BDC)] CH<sub>3</sub>CH<sub>2</sub>OH}<sub>n</sub>, <b>5a</b>, and {[Cu(4-ampy)<sub>2</sub>(1,4-BDC)]·H<sub>2</sub>O}<sub>n</sub>, <b>5b</b>·H<sub>2</sub>O, are reported, which were hydrothermally prepared and structurally characterized by using single crystal X-ray diffraction. Complexes <b>1a</b> and <b>1b</b> are isomorphous 1D zigzag chains, while <b>2</b> displays a concave–convex chain and <b>3a</b> and <b>3b</b> are dinuclear metallocycles that differ in the boding modes of the 1,2-BDC<sup>2−</sup> ligands, forming a 3D and a 2D supramolecular structures with the <b>pcu</b> and <b>sql</b> topologies, respectively. Complex <b>4</b> exhibit a 1D helical chain and complexes <b>5a</b> and <b>5b</b>·H<sub>2</sub>O are 1D linear and zigzag chains, in which the Cu<sub>2</sub>-1,4-BDC<sup>2−</sup> units adopt the <i>cis</i> and <i>trans</i> configurations, respectively. A novel irreversible structural transformation due to <i>cis</i>→<i>trans</i> isomerization of the Cu<sub>2</sub>-1,4-BDC<sup>2−</sup> units was observed in <b>5b</b>⋅H<sub>2</sub>O and <b>5a</b> upon water adsorption of the desolvated product of <b>5b</b>·H<sub>2</sub>O.