Design of High-Performance Pyridine/Quinoline Hydrazone Photoswitches

The design of P-type photoswitches with thermal stability the metastable form hundreds years that would efficiently transform using excitation wavelengths above 350 nm remains a challenge in field photochromism. In this regard, we designed and synthesized an extended set 13 pyridine/quinoline hydrazones systematically investigated structure-property relationships, defining their kinetic photoswitching parameters. We show operational pyridine hydrazone structural motif can be effectively shifted toward visible region without simultaneous loss high stability. Furthermore, characterized ground-state excited-state potential energy surfaces quantum-chemical calculations ultrafast transient absorption spectroscopy, which allowed us to rationalize both photochemical reaction mechanisms hydrazones. Whereas introducing electron-withdrawing pyridyl moiety benzoylpyridine leads stabilities exceeding 200 years, π-conjugation naphthoylquinoline pushes maxima spectral region. either case, compounds retain highly efficient characteristics. Our findings open route rational new family hydrazone-based application photonics or photopharmacology.