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Synthesis and Redox and Photophysical Properties of Benzodifuran–Spiropyran Ensembles
Author(s) -
Li Hui,
Ding Jie,
Chen Songjie,
Beyer Christoph,
Liu ShiXia,
Wagenknecht HansAchim,
Hauser Andreas,
Decurtins Silvio
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201204043
Subject(s) - spiropyran , photochromism , merocyanine , photostationary state , chemistry , photochemistry , quenching (fluorescence) , irradiation , redox , quantum yield , reaction rate constant , kinetics , isomerization , photoisomerization , fluorescence , organic chemistry , physics , quantum mechanics , nuclear physics , catalysis
Two benzodifuran (BDF)‐coupled spiropyran (SP) systems and their BDF reference compounds were obtained in good yields through Huisgen–Meldal–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.