UV/Vis Spectroscopy Studies of the Photoisomerization Kinetics in Self-Assembled Azobenzene-Containing Adlayers

Abstract

Direct comparative studies of the photoisomerization of azobenzene derivatives in self-assembled adlayers on Au and as free molecules in dichloromethane solution were performed using UV/vis spectroscopy. For all studied systems a highly reversible trans-cis isomerization in the adlayer is observed. Quantitative studies of the absorbance changes and photoisomerization kinetics reveal that in azobenzenes mounted as freestanding vertical groups on the surface via triazatriangulene-based molecular platforms photoswitching is nearly uninhibited by the local environment in the adlayer. The blue-shift of the π-π* transition in adlayers of these molecules is in good agreement with theoretical studies of the effect of excitonic coupling between the molecules. In contrast, in azobenzene-containing thiol self-assembled monolayers the fraction of photoswitching molecules and the photoisomerization kinetics are significantly reduced compared to free molecules in solution.

Fabrication of Photocontrolled Surfaces for Oil/Water Separation through Sulfur(VI) Fluoride Exchange

“…[36,37] To investigate the photoresponsive behavior of the CF 3 -azobenzene derivativei np olymer 6,w em easuredt he UV/Vis absorption spectrum of the sample in N,N-dimethylformamide( DMF) solution( Figure S1a). [36,37] To investigate the photoresponsive behavior of the CF 3 -azobenzene derivativei np olymer 6,w em easuredt he UV/Vis absorption spectrum of the sample in N,N-dimethylformamide( DMF) solution( Figure S1a).…”

Photoswitchable Glycolipid Mimetics: Synthesis and Photochromic Properties of Glycoazobenzene Amphiphiles

“…Table and Supporting Information) were collected with 1 nm resolution from 260 nm to 600 nm and the kinetic behavior was investigated by monitoring intensity at the E ‐isomer maximum wavelength. Detailed setup information is given in the literature . The obtained data are summarized in Table .…”

“…Detailed setup informationi sg iven in the literature. [19] The obtained data are summarized in Ta ble 1. All the absorbance data were collectedf rom 1mm solutionsi nC HCl 3 at room temperature under exclusiono fa mbient light.…”

“…To evoke E/ Z isomerization of compounds 18 to 23,aUV LED (2.7 mW cm À2 , l = 365 nm for E!Z), respectively ab lue LED (2.6 mW cm À2 , l = 455 nm for Z!E)w as used for irradiation. The E-isomer absorbance maximao fa ll compounds (18)(19)(20)(21) were measured around 355 nm and the Z-isomer absorbance maximum was determineda t3 12 nm.…”

UV-triggered shape-controllable PP fabric

“…4a, upon UV irradiation for 1 min, the strong absorption peak at around 350 nm, belonging to the π-π* transition of trans-azobenzene absorbance, disappeared compared to that without UV irradiation, which is attributable to the photo-isomerization between the trans-and cis-isomers of the azobenzene groups. [29][30][31] The UV/Vis absorption spectra of P(DEGMA-co-MOPAzo) with time evolution upon UV irradiation are shown in Fig. 4b.…”