Mono- and polychromatic light diarylethene-actinometer for the visible range

Photokinetics of Dacarbazine and Nifedipine under polychromatic light irradiation and their application as new reliable actinometers for the ultraviolet range

“…The condition set out for the use of such algebraic equations is to predict, interpret and describe well the measured kinetic traces at hand 31 . This strategy has been adopted by methods based on initial-rate equations for the determination of the quantum yield (supposed wavelength-invariant) of photoreactions under polychromatic light 25 , 26 , or by proposing a proxy integrated rate-law of the reaction investigated 27 , 32 (in all cases, the algebraic equations were not analytically derived from the differential rate equations as set above). It is also interesting to notice that despite the differences in rate laws and/or descriptive algebraic equations, the methods proposed in these studies have individually shown excellent replication of the experimental kinetic data of the reactions studied.…”

On photokinetics under polychromatic light

“…(1) ). However, a qualitative observation of the overall shape of experimental and RK-calculated traces of such photoreactions indicates that they do not seem to substantially differ from those recorded for reactions subjected to monochromatic light ( Lente and Espenson, 2004 ; Fabian and Lente, 2010 ; Roibu et al, 2018 ; Volfova et al, 2019 ; Yutani et al, 2019 ; Maafi and Al Qarni, 2022a ; Maafi and Al Qarni, 2022b ; Weingartz et al, 2023 ). This observation allows one to conjecture that the kinetics under polychromatic light may well be of -order character, similar to that previously established for the photokinetics of systems exposed to monochromatic light ( Maafi, 2023 ).…”

“…One approach introduces a simplifying hypothesis to derive an explicit formula to fit the experimental data. The applicability of such an equation is, however, limited to the specific reactive system and experimental conditions it was developed for ( Lehóczki et al, 2013 ; Józsa et al, 2018 ; Frigoli et al, 2020 ; Maafi and Al Qarni, 2022a ; Maafi and Al Qarni, 2022b ). A relatively popular method promotes the use of a high enough initial reactant concentration to ensure that the impinging polychromatic light is fully absorbed by the reactive medium (where the absorbance value of the reactive medium ought to be no less than 2) ( Amouroux et al, 2019 ).…”

Sample illumination device facilitates in situ light-coupled NMR spectroscopy without fibre optics

“…To assess light intensity reaching the sample, we employed a molecular actinometer based on diarylethene (DAE) 36 – 38 , for which the closed (CF) to open form (OF) photocyclisation under visible light with known quantum yield can be used to determine photon flux, while the reverse OF → CF transition can be triggered by UV light to set the initial concentration of CF (Fig. 4a ).…”

“…Intensity of light reaching the sample in the NMRtorch tube was assessed by monitoring the reversible closed form (CF) to open form (OF) photocyclisation of the diarylethene 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene 36 – 38 (DAE). DAE was prepared at 5 mM in dichloromethane-d 2 and irradiated in situ using a lighthead containing 280 nm and 550 nm LEDs (nominal 3 W power consumption, driven at 0.7 A current each).…”