Dh mini light source

Absorption and fluorescence spectra were recorded in quartz glass cuvettes with either 10 mm or 2 mm optical path length (Hellma Analytics) on a Jasco V‐650 UV‐vis spectrophotometer and a Hitachi F‐4500 fluorometer. Absorption spectra were measured at an optical density (OD) close to 1. OD values for fluorescence spectra measurements were set to 0.1 to 0.15. Data for ON1 was obtained on a Tecan Infinite M200 Pro plate reader.
Uncaging quantum yields were determined using our recently published fulgide actinometry setup controlled by our in‐house programmed software PHITS (Photoswitch Irradiation Test Suite) written with LabVIEW.^[43] A concentrated indolylfulgide photoswitch solution in toluene served as a reference for the chemical actinometry. Its absorption spectrum was tracked (Ocean Optics DH‐mini light source, Ocean Optics USB4000 or Thorlabs CCS200/M detector) while converting the fulgide from its closed form to the Z‐form through irradiation with a 530 nm LED (M530 L3, Thorlabs). The caged oligonucleotide was then irradiated in the same setup with known photon flux. Last, the photolysis rate was determined by integration of the RP‐HPLC signals.

UV–vis measurements of Michael attack of BQDS were conducted by monitoring the optical absorbance of K₂Cr₂O₇ after the addition of a known quantity of BQDS. For each measurement, an aqueous solution of 2 mL of K₂Cr₂O₇ was first prepared in a polystyrene cuvette with a 10 mm path length and 1 M H₂SO₄ as supporting electrolyte; then BQDS was added to the solution and UV–vis spectra were recorded every 5 min. All UV–vis spectra were recorded at room temperature using a DH-mini light source from Ocean Insight and an HDX detector.