title: Anion-tunable control of thermal Z→E isomerisation in basic azobenzene receptors.
abstract: Herein, we report that thermal Z→E isomerisation of simple azobenzene urea derivatives is selectively and predictably controlled by anion binding. The rate of this process depends strictly on the anion concentration and its binding affinity to the Z-isomer of the azobenzene host, i.e. increased rate constants are observed for higher anion concentration as well as for more strongly bound guests. The origin of this phenomenon is attributed to the electron density transfer from the anion to the host π-system, resulting in increased repulsion between the lone electron pairs in the N=N bond.
authors.affiliation: Institute of Organic Chemistry, Polish Academy of Science, Kasprzaka 44/52, Warsaw 01-224, Poland. janusz.jurczak@icho.edu.pl.
authors.forename: Kajetan
authors.initials: K
authors.lastname: Dąbrowa
authors.forename: Patryk
authors.initials: P
authors.lastname: Niedbała
authors.forename: Janusz
authors.initials: J
authors.lastname: Jurczak
mesh_terms: D000838:Anions / Q000737:chemistry; D001391:Azo Compounds / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D011789:Quantum Theory; D013237:Stereoisomerism; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry
chemical_list: D000838:Anions; D001391:Azo Compounds; D014508:Urea; C009850:azobenzene