Chemosensors for selective and sensitive detection of analytes were developed following various structural, functional and operational design methodologies. The interaction between probe and analyte has been vital in chemosensor-based detection technologies. A pertinent question in such a system is to be convincingly addressed, that if the probes incorporating spatially-positioned multiple interaction sites offer preferences towards analyte binding for a favourable and optimal interaction. The derivatized Rhodamine based probe exhibiting proton-induced dual mode signalling here contained several protonation sites. The absorption and fluorescence signal enhancement on protonation of the probe attributed to its proton-mediated spiro-ring opening. Out of several plausible conformations of protonated probe [.H], their DFT calculations revealed the proton binding preferentially to the N-donor atom on spiro-ring of instead at other probable sites of protonation such as other hetero- donor atoms on the xanthene core or the carbonyl O- atom on the spiro-ring as the energetically favourable conformation. It was verified with the protonated probe complex's X-ray diffracted single crystal structure.

中文翻译：

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质子诱导光物理信号与衍生罗丹明探针相互作用位点的偏好


用于选择性和灵敏检测分析物的化学传感器是按照各种结构、功能和操作设计方法开发的。探针和分析物之间的相互作用在基于化学传感器的检测技术中至关重要。这种系统中的一个相关问题需要令人信服地解决，即结合空间定位的多个相互作用位点的探针是否对分析物结合提供偏好以实现有利且最佳的相互作用。此处展示质子诱导双模式信号传导的基于衍生化罗丹明的探针包含多个质子化位点。探针质子化的吸收和荧光信号增强归因于其质子介导的螺环打开。在质子化探针 [.H] 的几种可能构象中，他们的 DFT 计算揭示了质子优先与螺环上的 N 供体原子结合，而不是在其他可能的质子化位点（例如呫吨核心上的其他异质供体原子）或螺环上的羰基O-原子作为能量上有利的构象。通过质子化探针复合物的X射线衍射单晶结构验证了这一点。