A Robust, Broadly Absorbing Fulgide Derivative as a Universal Chemical Actinometer for the UV to NIR Region

Abstract

A fulgide photoswitch is presented as a novel actinometer for a broad range of wavelengths from the UV to the NIR region (340–700 nm). It is easily accessible and has a robust photochemistry and high fatigue resistance. Its photophysics and photochemistry are described in detail. Quantum yields of photoswitching were measured for a series of wavelengths and standardized against known standards (ferrioxalate actinometry, calibrated photodiode). We also present a method for the precise determination of photoswitching quantum yields by global analysis of the whole spectra and an alternative quick and easy method for rapid determination of photon fluxes.

Selective Modification for Red‐Shifted Excitability: A Small Change in Structure, a Huge Change in Photochemistry

“…The decrease of starting material was monitored by HPLC with the use of an internal standard. To obtain the photon flux we used two different methods: ferrioxalate actinometry and our recently published fulgide photoswitch actinometer [29] . The quantum yields of our new PPGs are summarized in Table 2.…”

“…for HPLC analysis of the amount of starting material.I rradiation was performed with mounted ThorlabsL EDs. The photon flux was determined with af ulgide photoswitch [29] (26.8 nmol s À1 at 420 nm, 93.0 nmol s À1 at 530 nm). [a] n.d.…”

“…UV/Vis absorption was recorded using a commercially available Evolution 300 (ThermoScientific) or our custom‐made set up equipped with an Ocean Optics DH‐mini light source and USB4000 detector, a thermostatic cuvette holder (Thorlabs), all controlled by our in‐house programmed PHITS (Photoswitch Irradiator Test Suite) software, which was written in LabVIEW. For more details see Reinfelds et al [29] . This setup and software were also used for our chemical actinometry.…”

“…All absorption and fluorescence emission measurements were performed in standard quartz cuvettes (1.00 cm optical pathlength, Hellma-Analytics) with various maximum volumes. UV/Vis absorption was recorded using ac ommercially available Evolution 300 (ThermoScientific) or our custom-made set up equipped with an Ocean Optics DH-mini light source and USB4000 detector,athermostatic cuvette holder (Thorlabs), all controlled by our in-house programmed PHITS (Photoswitch Irradiator Test Suite) software, which was written in LabVIEW.F or more details see Reinfelds et al [29] This setup and software were also used for our chemical actinometry.R eference compound was an indolylfulgide photoswitch. Ac oncentrated solution of the fulgide (500-1000 mm)w as irradiated with the respective light source (Thorlabs mounted LED, l max = 420 nm or 530 nm) to convert the photoswitch from its 1Z form to 1C or the other way round.…”

Photoswitchable 2‐Phenyldiazenyl‐Purines and their Influence on DNA Hybridization

“…This includes spectra of the photostationary states and pure photoisomers, photostationary distributions, photofatigue studies, thermal relaxation of the cis-isomers and quantum yields of the photochemical processes. The quantum yield determination was carried out according to Reinfelds et al [31] For melting temperature measurements 1 mL samples were prepared with a 1 μM concentration of strand and counter strand in 1x PBSbuffer for the 5 different duplexes. The absorbance changes at 260 nm were measured in a UV/vis-spectrometer from JASCO.…”