Work

Tuning the Molecular Rotor Dynamics of Pyrrolo[3,4‐ b ]Pyridin‐5‐Ones: Steric and Electronic Control of Environmental Sensing

Year: 2026

Type: article

Abstract: A series of seven pyrrolo[3,4-b]pyridin-5-ones were synthesized via a one-pot process involving an Ugi-Zhu reaction followed by a cascade sequence (N-acylation/aza Diels-Alder cycloaddition/decarboxylation/dehydration) incorporating different substituents no aromatic and aromatic such as furan, tetrahydrofuran, and pyridine. The pyrrolo[3,4-b]pyridin-5-ones were optically characterized through their photoluminescence spectra, quantum yields, and fluorescence lifetimes. By combining spectroscopic measurements with DFT/TDDFT calculations, photophysical behavior was elucidated, specifically addressing solvent effects on transition magnitudes and the electronic nature of absorption and emission states. Structure-property relationship analyses revealed that steric and electronic substituent effects govern the interplay between charge-transfer (CT) and locally excited (LE) states. Finally, the most promising candidates were successfully evaluated as fluorogenic microviscosity and polarity sensors, demonstrating their potential for advanced sensing applications.

Source: Luminescence

DOI: 10.1002/bio.70655