Innovative Molecular Photoswitches
Photoswitches are molecules which respond to a light stimulus with a change of their structure find application in different fields, allowing for the prodution of 'smart' materials with controllable optomechanic or optoelectronic properties. Using time resolved spectroscopy, our research in this field is focussed on the understanding of the timescale and mechanisms of the light induced transformations occurring in such systems. A clear understanding of the photoswitching mechanism is indeed a key step for engineering new and improved molecules for tailor-made applications.
Donor-acceptor Stenhouse adducts (DASA) are an emerging class of photoswitches thanks to their modular nature, rapid synthesis, and large structural changes upon excitation by visible light. Upon light absorption DASAs interconvert between an open colored form to a cyclized colourless form. We have studied in detail the mechanism of DASAs photoswitching reaction, using ultrafast spectroscopy in the visible and IR regions, to identify the structure and the dynamics of formation of the reaction intermediates.
More information can be found in:
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Zulfikri H. et al, JACS, 2019, 141, 7376-7384, DOI:10.1021/jacs.9b00341
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Lerch, M.M. et al, Angewante Chemie Int Ed, 2018, 57, 8063-8068, DOI: 10.1002/anie.201803058
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Di Donato M. et al, JACS, 2017, 139, 15596-15599, DOI: 10.1021/jacs.7b09081
Iminothioindoxyls (ITIs) are new class of photoswitches, fully operated by visible light. ITIs show a band separation of over 100 nm, isomerize on the picosecond time scale and thermally relax on the millisecond time scale. We investigated the ultrafast light induced photoisomerization of ITIs using pupmp-prpbe spectroscopy. The thermal relaxation step of ITI is also very fast. occurring on the millisecond time scale. We discovered that protonation of the imine nitrogen can slow down thermal relaxation by several order of magnitude. Learn more about ITIs on:
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Hoorens M.W.H et al, Nature Communications, 2019, 10, 2390, DOI: 10.1038/s41467-019-10251-8
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Medved' M. et al, Chemical Science, 2021, 12, 4588-4598, DOI: 10.1039/d0sc07000a
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