@Article{ChemEurJ_19_6459, author = {H. Li and J. Ding and S. Chen and C. Beyer and S.-X. Liu and H.-A. Wagenknecht and A. Hauser and S. Decurtins}, title = {{Synthesis and Redox and Photophysical Properties of Benzodifuran{\frac{ }{ }}Spiropyran Ensembles}}, journal= {Chem. - Eur. J.}, ISSN = {0947-6539}, volume= {19}, number= {20}, pages = {6459-6466}, url = {http://onlinelibrary.wiley.com/doi/10.1002/chem.201204043/abstract}, eprint= {http://www.unige.ch/sciences/chifi/publis/refs_pdf/ref01340.pdf}, doi= {10.1002/chem.201204043}, keywords= {asymmetric synthesis;click chemistry;electron transfer;photochromism;redox chemistry;spiro compounds}, abstract = {{Two benzodifuran (BDF)-coupled spiropyran (SP) systems and their BDF reference compounds were obtained in good yields through Huisgen{\frac{ }{ }}Meldal{\frac{ }{ }}Sharpless “click” chemistry and then subjected to investigation of their electrochemical and photophysical properties. In both SP and merocyanine (MC) forms of the coupled molecules, the BDF-based emission is quenched to around 1 % of the quantum yield of emission from the BDF reference compounds. Based on electrochemical data, this quenching is attributed to oxidative electron-transfer quenching. Irradiation at 366 nm results in ring opening to the MC forms of the BDF-coupled SP compounds and the SP reference compound with a quantum efficiency of about 50 %. The rate constants for the thermal ring closing are approximately 3.4×10$^{-3}$ s$^{-1}$. However, in the photostationary states the MC fractions of the coupled molecules are substantially lower than that of the reference SP compound, attributed to the observed acceleration of the ring-closing reaction upon irradiation. As irradiation at 366 nm invariably also excites higher-energy transitions of the BDF units in the coupled compounds, the ring-opening reaction is accelerated relative to the SP reference, which results in lower MC fractions in the photostationary state. Reversible photochromism of these BDF-coupled SP compounds renders them promising in the field of molecular switches.}}, year = {2013} }