Abstract：
Selective detection of a metal ion with high selectivity is of great importance to understand its existence and its role in many chemical and biological processes. We report here the synthesis, characterization and Al3+ sensing properties of two rhodamine-based isomers, (E)-2-((2-(allyloxy)benzylidene)amino)ethyl)-3\',6\'-bis(ethylamine)-2\',7\'-dimethylspiro[isoindoline-1,9\'-xanthen]-3-one (L-2-oxy) and (E)-2-((4-(allyloxy)benzylidene)amino)ethyl)-3\',6\'-bis(ethylamine)-2\',7\'-dimethylspiro[isoindoline-1,9\'-xanthen]-3-one (L-4-oxy). L-2-oxyand L-4-oxy show pink coloration, significant enhancement in absorbance at 530 nm and fluorescence intensity at 553 nm in the presence of Al3+ among several cations. Quantum yield and lifetime of the probes increase in the presence of Al3+. LOD values have been determined as low as ∼1.0 nM for both the isomers. DFT study suggests that the cation induces opening of spirolactam ring resulting in the changes of the rhodamine dyes. Additional reason could be Chelation Enhanced Fluorescence (CHEF) effect due to the subsequent chelation of the metal ion. Between two isomers, L-2-oxy displays better sensing ability towards Al3+ in terms of fluorescence enhancement, limit of detection, lifetime enhancement. Both the probes have been utilized in cell imaging studies using rat skeletal myoblast cell line (L6 cell line).
摘要：
具有高选择性的金属离子的选择性检测对于了解其存在及其在许多化学和生物过程中的作用非常重要。我们在这里报告综合，两种罗丹明基异构体的表征和Al3+传感特性，(E)-2-((2-(烯丙基氧基)亚苄基)氨基)乙基)-3',6\'-双(乙胺)-2\'，7'-二甲基螺[异吲哚啉-1,9'-黄原]-3-酮(L-2-氧基)和(E)-2-((4-(烯丙氧基)亚苄基)氨基)乙基)-3',6\'-双(乙胺)-2\'，7'-二甲基螺[异吲哚啉-1,9'-黄原]-3-酮(L-4-氧基)。L-2-氧基和L-4-氧基呈粉红色,在几种阳离子中存在Al3时，在530nm处的吸光度和553nm处的荧光强度显着增强。在Al3+的存在下,探针的量子产率和寿命增加。已确定两种异构体的LOD值低至~1.0nM。DFT研究表明，阳离子诱导螺内酰胺环的打开，导致罗丹明染料的变化。另外的原因可能是由于金属离子的后续螯合引起的螯合增强荧光(CHEF)效应。在两种异构体之间，L-2-oxy在荧光增强方面对Al3+表现出更好的传感能力，检测限，寿命增强。两种探针均已用于使用大鼠骨骼肌成肌细胞系（L6细胞系）的细胞成像研究。
