Materials Chemistry Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751 013, Odisha, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India.
Org Biomol Chem. 2022 May 18;20(19):3967-3979. doi: 10.1039/d2ob00194b.
Manifestation of photophysical signalling parameters in rhodamine derivatives exhibiting complexation induced spiro-ring opening is crucial for the realization of selective metal ion detection at trace levels. Substitution of various functional groups, such as alkylation to the core architecture, modulates the physico-chemical properties of such molecular probes. Despite a few studies, relationships between the extent of photophysical signal modulations and the chain lengths of -alkyl substituents are still elusive. In this investigation, a few molecular probes based on the rhodamine B (1-5) and rhodamine 6G (6-10) platform were synthesized by their derivatization with -alkyl substituents of varying chain lengths at the amino-donor of their spiro-ring end, which exhibited Fe(III)-selective absorption and fluorescence 'off-on' signal transduction along with colorization of solution. The Fe(III)-selectivity in these probes remained the same despite their structural distinctions through varied -alkyl chain lengths of the substituents; however, the quantifiable signalling parameters such as spectroscopic enhancement factors, sensitivity, the kinetics of spiro-ring opening and effectiveness of probe-Fe(III) interactions were analyzed. These parameters were also correlated in terms of the influence of different chain lengths of -alkyl substituents that efficiently contributed to their inter-componential interactive stereo-electronic environment.
表现出复杂诱导螺环开环的光物理信号参数的罗丹明衍生物对于在痕量水平实现选择性金属离子检测至关重要。取代各种官能团，如对核心结构进行烷基化，可以调节这些分子探针的物理化学性质。尽管进行了一些研究，但光物理信号调制的程度与-烷基取代基的链长之间的关系仍然难以捉摸。在这项研究中，通过在螺环末端的氨基供体上用不同链长的-烷基取代基对罗丹明 B（1-5）和罗丹明 6G（6-10）平台的几个分子探针进行衍生化，合成了这些探针，它们表现出 Fe(III)-选择性吸收和荧光“关-开”信号转导，同时溶液也发生了变色。尽管这些探针通过取代基的不同-烷基链长具有结构差异，但它们的 Fe(III)-选择性保持不变；然而，对可量化的信号参数，如光谱增强因子、灵敏度、螺环开环动力学和探针-Fe(III)相互作用的有效性进行了分析。还根据不同链长的-烷基取代基的影响对这些参数进行了相关性分析，这些取代基有效地促进了它们之间的互变立体电子环境。
