pH-Induced Orthogonal Photoresponse of trans-Chalcone Isomers and Related Compounds in Equilibria

Photoresponsive molecular devices can be a valuable tool to promote chemical changes in response multiple signals, such as photons and pH, deliver drugs or detect physiological conditions vivo. For example, trans-chalcones (Ct) from 4′-hydroxyflavylium (F1) 7-hydroxyflavylium (F2) undergo cis-trans isomerization by photoreaction into many different structures. The takes place at slow rate pH change; however, it done seconds photoreaction. In the investigation, confirming previous reports, 3-(2-hydroxy-phenyl)-1-(4-hydroxy-phenyl)-propenone, trans-chalcone (CtF1) F1, produces flavylium ions = 1–4.5. Then, we further discovered that quickly releases protons yield corresponding quinoidal base (A) solution of 5.2 during irradiation with 350 nm. Meanwhile, photolysis 3-(2,4-dihydroxy-phenyl)-1-phenyl-propenone, (CtF2) F2 5.6, induces photoacid behavior losing proton generate Ct2−. outcomes these nearly colorless chalcones under similar same photochemical useful when yielding colored AH+, A, Ct2− mildly acidic environment temporal spatial control using means.