title: cis-trans Isomerisation of substituted aromatic imines: a comparative experimental and theoretical study.
abstract: The cis-trans isomerisation of N-benzylideneaniline (NBA) and derivatives containing a central C=N bond has been investigated experimentally and theoretically. Eight different NBA molecules in three different solvents were irradiated to enforce a photochemical trans--(hnu)-->cis isomerisation and the kinetics of the thermal backreaction cis--(Δ)-->trans were determined by NMR spectroscopy measurements in the temperature range between 193 and 288 K. Theoretical calculations using density functional theory and Eyring transition-state theory were carried out for 12 different NBA species in the gas phase and three different solvents to compute thermal isomerisation rates of the thermal back reaction. While the computed absolute rates are too large, they reveal and explain experimental trends. Time-dependent density functional theory provides optical spectra for vertical transitions and excitation energy differences between trans and cis forms. Together with isomerisation rates, the latter can be used to identify "optimal switches" with good photochromicity and reasonable thermal stability.
authors: Freie Universität Berlin, Institut für Chemie und Biochemie, Berlin, Germany.
authors: Ying
authors: Y
authors: Luo
authors: Manuel
authors: M
authors: Utecht
authors: Jadranka
authors: J
authors: Dokić
authors: Sergey
authors: S
authors: Korchak
authors: Hans-Martin
authors: HM
authors: Vieth
authors: Rainer
authors: R
authors: Haag
authors: Peter
authors: P
authors: Saalfrank
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D001597:Benzylidene Compounds / Q000737:chemistry*; D002627:Chemistry, Physical; D003080:Cold Temperature; D007097:Imines / Q000737:chemistry*; D007536:Isomerism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008962:Models, Theoretical; D055668:Photochemical Processes / Q000528:radiation effects; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics; D014466:Ultraviolet Rays
chemical_list: D000814:Aniline Compounds; D001597:Benzylidene Compounds; D007097:Imines; D012997:Solvents; C023650:aniline