A Mixed-Ligand Coordination Polymer from the in Situ, Cu(I)-Mediated Isomerization of Bis(4-pyridyl)ethylene

Abstract

Reaction of [Cu(PPh(3))(2)(MeCN)(2)]PF(6) and trans-1,2-bis(4-pyridyl)ethylene (bpe) results in the trans-cis isomerization of the bpe and subsequent formation of a mixed-isomer linear coordination polymer over the course of several days or weeks depending on solvent. The one unique copper atom in the structure is coordinated to two bridging cis-bpe ligands, one bridging trans-bpe ligand, and one terminal triphenylphoshine ligand to create [Cu(trans-bpe)(0.5)(cis-bpe)(PPh(3))](+)( infinity ) zigzag chains. The reaction requires both visible light and Cu(I), and the crystallization of this particular coordination polymer is insensitive to the ratio of trans:cis isomers in solution, occurring both from trans-rich and cis-rich solutions.

Structural relationship of two coordination polymers of Cu(i) with the ligand ethanediyl bis(isonicotinate)Electronic supplementary information (ESI) available: Selected crystal data, views of 2, and colour pictures of Fig. 3c and d. See http://www.rsc.org/suppdata/ce/b3/b309410c/

“…The same trend for distances is also found in other molecular and polymer compounds where Cu(I) has a tetrahedral environment and at least one pyridine or a similar nitrogen donor ligand bonded to the cation. 12, [21][22][23][24][25][26][27][28] The most analogous compound to 3 is a Cu(I) coordination polymer obtained with the same ligand L, but with bromide as counter ion and additional water in the structure. 29 It features an overall similar structure as 3, but with longer Cu-X and Cu-Cu contacts, as expected from the larger bromine anion.…”

Sunlight‐Induced In Situ Isomerization of Both Ligands in a Mixed‐Ligand Coordination Polymer: From Photosalient to Photoinert Crystals

“…Till date, a number of N=N based coordination compounds (monomeric and polymeric) are reported which demonstrate photoisomerization along with mechanical effects such as bending and curling etc [18–20] . However, cis‐trans photoisomerization in olefinic C=C based coordination polymers (CPs) is rare and remains highly unexplored [21] . This transformation in CPs in presence of visible light is further scarce.…”

Emerging Trends in Coordination Polymers and Metal-Organic Frameworks: Perspectives, Synthesis, Properties and Applications

“…Flexible ligands produce more variety in the structure because they can bend, rotate around bonds and orient themselves again. There are examples of coordination polymers with two configuration of the same ligand within one structure [13] and two separate structures with different ligand orientation. Example of a flexible ligand is shown in Figures 6a and b.…”