title: A Visible-Light-Triggered Conformational Diastereomer Photoswitch in a Bridged Azobenzene.
abstract: Ketal-substituted bridged azobenzenes have been synthesized; these display a symmetrical boat conformation with the ketal in pseudo-equatorial positions. These bridged Z-azobenzenes (Z1 ) readily photoisomerize to the E-isomer as well as another Z-conformer (Z2 ) with ketal function on the pseudo-axial position upon irradiation at 406 nm. The two diastereomeric conformers display distinct physicochemical characteristics. Spectroscopic and NMR investigations supported that interconversion of two conformers occurs via the E-isomer, with good photochemical quantum yield (ΦZ1→E =0.45±0.03, ΦE→Z1 =0.33±0.05, ΦE→Z2 =0.37±0.06 and ΦZ2→E =0.36±0.04). The system shows high photostability and no thermal equilibrium between the two stable Z1 and Z2 conformers.
authors.affiliation: PPSM, ENS Cachan, CNRS, Université Paris-Saclay, 94235, Cachan, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Deo
authors.affiliation: PPSM, ENS Cachan, CNRS, Université Paris-Saclay, 94235, Cachan, France.
authors.forename: Nicolas
authors.identifier: http://orcid.org/0000-0002-6076-2125
authors.initials: N
authors.lastname: Bogliotti
authors.affiliation: PPSM, ENS Cachan, CNRS, Université Paris-Saclay, 94235, Cachan, France.
authors.forename: Rémi
authors.identifier: http://orcid.org/0000-0001-5612-8327
authors.initials: R
authors.lastname: Métivier
authors.affiliation: Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Univ. Paris-Sud, Université Paris-Saclay, Gif-Sur-Yvette, 91198, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Retailleau
authors.affiliation: PPSM, ENS Cachan, CNRS, Université Paris-Saclay, 94235, Cachan, France. joanne.xie@ens-cachan.fr.
authors.forename: Juan
authors.identifier: http://orcid.org/0000-0001-8730-3220
authors.initials: J
authors.lastname: Xie
keywords: azo compounds; conformation; isomerization; molecular switches; photochemistry