Tervola Essi, Truong Khai-Nghi, Ward Jas S, Priimagi Arri, Rissanen Kari
Department of Chemistry, University of Jyvaskyla P.O. Box 35, Survontie 9B 40014 Jyväskylä Finland
Smart Photonic Materials, Faculty of Engineering and Natural Sciences, Tampere University P.O. Box 541 FI-33101 Tampere Finland.
RSC Adv. 2020 Aug 12;10(49):29385-29393. doi: 10.1039/d0ra04691d. eCollection 2020 Aug 5.
A study of the fluorescence enhancement of isoquinoline, acridine (benzo[]quinoline) and benzo[]quinoline is reported with six organic acids of different p values. Protonation was found to be an effective tool in the fluorescence enhancement of quinolines. A significant increase in the fluorescence intensity is observed only when strong acids are used, resulting in an over 50-fold increase in fluorescence with trifluoroacetic or benzenesulfonic acid and isoquinoline in a 1.5 : 1 ratio. The benzenesulfonic acid was found to be the most effective in the protonation of the bases despite its higher p value compared to trifluoro- and trichloroacetic acid. The X-ray crystal structures of 14 salts reveal the charge-assisted hydrogen bond O⋯N distances to vary very little, from 2.560(2)-2.714(3) Å, with the exception of the isoquinolinium benzenesulfonate where the O⋯N distance of 2.862(7) Å is caused by additional intermolecular interactions in the solid-state.
报道了一项关于异喹啉、吖啶（苯并[ ]喹啉）和苯并[ ]喹啉与六种不同pKa值的有机酸的荧光增强研究。发现质子化是喹啉荧光增强的有效手段。仅当使用强酸时才观察到荧光强度显著增加，三氟乙酸或苯磺酸与异喹啉以1.5∶1的比例使用时，荧光增强超过50倍。尽管苯磺酸的pKa值高于三氟乙酸和三氯乙酸，但发现其在碱的质子化方面最有效。14种盐的X射线晶体结构显示，电荷辅助氢键O⋯N距离变化很小，为2.560(2)-2.714(3) Å，异喹啉苯磺酸盐除外，其固态中额外的分子间相互作用导致O⋯N距离为2.862(7) Å。
