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Ultrafast Excited‐State Deactivation Dynamics of Cyclotrisazobenzene—A Novel Type of UV‐B Absorber
Author(s) -
Slavov Chavdar,
Yang Chong,
Schweighauser Luca,
Wegner Hermann A.,
Dreuw Andreas,
Wachtveitl Josef
Publication year - 2017
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201700384
Subject(s) - photoswitch , photoisomerization , isomerization , ultrashort pulse , excitation , excited state , chemical physics , photochemistry , molecule , chemistry , molecular dynamics , femtosecond , materials science , computational chemistry , laser , atomic physics , physics , optics , organic chemistry , quantum mechanics , catalysis
Azobenzenes are widely utilized as molecular photoswitches for control of nanoscale processes. Their photoisomerization reaction is highly robust and is retained even in extremely rigid systems. Currently, it is not clear what geometric restrictions are required to block this isomerization successfully. We present here a combined experimental and theoretical study on the ultrafast dynamics of cyclotrisazobenzene (CTA) and demonstrate that the structural constraints in CTA prevent isomerization of the photoswitch units. In the developed molecular picture, the N=N bonds respond elastically to the motion along the isomerization coordinates, which leads to ultrafast and complete dissipation of the UV excitation as heat. Based on this property, CTA and possibly other similarly designed molecules can be utilized as UV absorbers, for example in sunscreens; other potential applications are also envisioned.