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首页> 外文期刊>Chemistry: A European journal >Squaraine Rotaxane as a Reversible Optical Chloride Sensor
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Squaraine Rotaxane as a Reversible Optical Chloride Sensor

机译：鱿鱼轮烷作为可逆的光学氯化物传感器

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A mechanically interlocked squaraine rotaxane is comprised of a deep-red fluorescent squaraine dye inside a tetralactam macrocycle. NMR studies show that Cl- binding to the rotaxane induces macrocycle translocation away from the central squaraine station, a process that is completely reversed when the Cl- is removed from the solution. Steady-state fluorescence and excited-state lifetime measurements show that this reversible machine-like motion modulates several technically useful optical properties, including a three-fold increase in deep-red fluorescence emission that is observable to the naked eye. The excited states were characterized quantitatively by time-correlated single photon counting, femtosecond transient absorption spectroscopy, and nanosecond laser flash photolysis. Cl- binding to the rotaxane increases the squaraine excited singlet state lifetime from 1.5 to 3.1 ns, and decreases the excited triplet state lifetime from >200 to 44 mu s. Apparently, the surrounding macrocycle quenches the excited singlet state of the encapsulated squaraine dye and stabilizes the excited triplet state. Prototype dipsticks were prepared by adsorbing the lipophilic rotaxane onto the ends of narrow, C18-coated, reverse-phase silica gel plates. The fluorescence intensity of a dipstick increased eighteen-fold upon dipping in an aqueous solution of tetrabutylammonium chloride (300 mm) and was subsequently reversed by washing with pure water. It is possible to develop the dipsticks for colorimetric determination of Cl- levels by the naked eye. After dipping into aqueous tetrabutyl ammonium chloride, a dipstick's color slowly fades at a rate that depends on the amount of Cl- in the aqueous solution. The fading process is due primarily to hydrolytic bleaching of the squaraine chromophore within the rotaxane. That is, association of Cl- to immobilized rotaxane induces macrocycle translocation and exposure of the electrophilic C4O2 core of the squaraine station, which is in turn attacked by the ambient moisture to produce a bleached product.
机译：机械联锁的方酸方烷烷由四内酰胺大环内部的深红色荧光方酸方染料组成。 NMR研究表明，Cl-与轮烷的结合会引起大环易位，使其远离中央方酸碱位，当从溶液中去除Cl-时，这一过程将完全逆转。稳态荧光和激发态寿命测量表明，这种可逆的类似机器的运动调节了几种技术上有用的光学性能，包括肉眼可观察到的深红色荧光发射增加了三倍。激发态通过时间相关的单光子计数，飞秒瞬态吸收光谱和纳秒激光闪光光解进行定量表征。 Cl-与轮烷的结合将方酸激发的单重态寿命从1.5 ns增加到3.1 ns，并将激发的三重态态寿命从> 200μs降低到44 s。显然，周围的大环猝灭了包封的方酸菁染料的激发单重态并稳定了激发的三重态。通过将亲脂性轮烷吸附在窄的，C18涂层的反相硅胶板的末端来制备原型量油尺。浸入四丁基氯化铵水溶液（300 mm）中后，量油尺的荧光强度增加了18倍，随后通过用纯水洗涤而反转。可以开发出用于用肉眼比色测定Cl含量的量油尺。浸入四丁基氯化铵水溶液后，量油尺的颜色以取决于水溶液中Cl-含量的速率缓慢褪色。褪色过程主要归因于轮烷中方酸生色团的水解漂白。即，Cl-与固定的轮烷的缔合引起方酸碱位的亲电C 4 O 2核的大环易位和暴露，其继而受到环境水分的攻击而产生漂白的产物。

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