The lack of polarity sensing fluorophores with OFF-ON features when increasing the environment polarity has limited the monitoring of biological processes that involve an increase in local hydrophilicity. In this work, replacement of a hydroxyl group by a dimethylamino group transformed solvatochromic ICT naphthalimide- and quinolimide-based fluorophores into reversed solvatochromic ones, with higher emission in polar than in apolar environments. Excited-state dynamics studies, TD-DFT calculations, X-ray and NMR support the existence of a folded conformation for the 2-(dimethylamino)ethyl chain upon the imide ring in apolar solvents, where the dimethylamino group would quench the fluorescence by a PET effect, while in polar solvents the chain has an extended conformation, where the PET is hindered. These PET fluorophores have given rise to H₂O and pH sensors in organic solvents as well as to bright macrophage cytoplasm imaging probes.

当增加环境极性时，缺少具有OFF-ON功能的极性感应荧光团已限制了对涉及局部亲水性增加的生物过程的监控。在这项工作中，用二甲基氨基取代羟基将基于溶剂化变色的ICT萘二甲酰亚胺和喹啉亚胺基荧光团转变为反向的溶剂化变色的荧光团，在极性下的发射高于在非极性环境下的发射。激发态动力学研究，TD-DFT计算，X射线和NMR支持在非极性溶剂中酰亚胺环上的2-（二甲基氨基）乙基链存在折叠构象，其中二甲基氨基将通过PET效应，而在极性溶剂中，链具有延长的构象，从而阻碍了PET的形成。这些PET荧光团引起了H有机溶剂中的₂ O和pH传感器以及明亮的巨噬细胞胞质成像探针。