From Study of Catalytic Hydrogenation to Novel Ratiometric pH Indicators with Quinoline Scaffold

Abstract

Catalytic hydrogenation of 2‐phenyl‐3‐hydroxyquinolin‐4(1H)‐ones afforded their 5,6,7,8‐tetrahydroquinolin‐4(1H)‐one analogues, which gained stability under acidic as well as alkaline conditions. For some 2‐(4‐aminophenyl) derivatives, unusual N‐isopropyl group assembling was observed in various solvents and therefore was studied in more details. The prepared derivatives were studied in context of their fluorescence properties. Some of them retained the dual character of fluorescent spectra as well as quantum yields similar to their non‐reduced parent compounds and thus were studied as potential ratiometric pH indicators.