Electropolymerization of chiral chromium–salen complexes: new materials for heterogeneous asymmetric catalysis

Direct insights into metal-induced conductivity enhancement in conducting metallopolymers

“…It was reported previously that a Schiff-base ligand monomer with monothiophene substitutents, N,N'-ethylenebis(2thienyl)salcylidenimine, (L I , ESI) was not electropolymerizable and it was explained as being due to the high redox potential of the organic backbone. [15][16][17] However, our studies in this work revealed that the growth of poly-L I is a concentration dependent process. When varying the concentration of the ligand monomer L I , it is possible to obtain the corresponding polymer by electropolymerization grown onto various electrodes ( Figure S2, ESI) at low concentrations (ca.…”

Incorporation of Thieno[3,2‐b]thiophene Moieties as Novel Electropolymerizable Groups in a Conducting Metallopolymer and Study of the Effect on Photostability

“…Interestingly, a solution of ligand TTL1 also resulted in polymer growth when treated with the same conditions. It was reported previously that Schiff‐base ligand monomers with thiophene as the electropolymerizable substituents did not form polymer films via electropolymerization due to the high redox potential of the organic group . The ligand TTL1 with thieno[3,2‐ b ]thiophene as electropolymerizable groups, however, exhibited polymer growth with oxidative cycling (Figure B).…”

“…It was reported previously that Schiff-base ligand monomers with thiophene as the electropolymerizable substituents did not form polymer fi lms via electropolymerization due to the high redox potential of the organic group. [22][23][24] The ligand TTL1 with thieno[3,2-b ]thiophene as electropolymerizable groups, however, exhibited polymer growth with oxidative cycling (Figure 2 B). The observed electropolymerization could possibly be due to the lower oxidation potential of the thieno[3,2-b ]thiophene fused ring compared to that of the monothiophene moiety used previously.…”

Chiral Salen Complexes for Asymmetric Heterogeneous Catalysis: Recent Examples for Recycling and Cooperativity

“…We have described another method in which salicylaldehydes have been flanked with thiophene groups to form functionalized salen derivatives, suitable for oxidative polymerization after introduction of a metallic salt. [36] Electrochemical polymerization occurred on a platinum grid at a constant current in an undivided electrochemical cell, leading for instance to the recovery of Cr-salen polymers as insoluble powder from the electrode surface. These electrogenerated polymers were tested as heterogeneous catalysts in an original multi reaction procedure in which the same catalyst batch was engaged in a complete new transformation at each recycling.…”