Competitive Delocalized Charge Transfer Boosted by Solvent Induction Strategy for Survivable Colorimetric Detection of ng-Level Urea

Abstract

Achieving sensitive and robust colorimetry is of great significance for on-site chemical detection, but has always been a dilemma or at the expense of practicality. Here, from the perspective of solvent, which is commonly the indispensable medium for chemical sensing, the solvent induction strategy concerning the hydrophobic shielding and hydrophilic bonding solvent cage was proposed considering the configuration branching ratio in the reagent and the prevention of the autoxidation channel. Due to the competitive delocalized charge transfer in the probe and the effective viscous drag in the reagent, remarkable sensing signal concentrating and moisture retention capability were achieved. We expect the present strategy would facilitate the active but robust chemical reaction design and provide a universal methodology for the exploration of high-performance chemical sensors.

Solvation effect enabled visualized discrimination of multiple metal ions

“…21,22 Firstly, the solvent molecules play a decisive role in whether the reaction could happen or progress in which pathway by participating in reaction steps or by sterically "shielding" reactive sites around the reactant. 23,24 For example, the difference in the solvation free energies of dimethyl sulfoxide (DMSO) and other solvents was correlated with the reaction mechanism of the acid-catalyzed dehydration of 1,2propanediol due to the competition of DMSO and water to solvate the reaction site, causing a mechanism change to form acetone rather than propanal. 25 Moreover, the protonation ability of solvent could alter the conformation of the solute to impact its motion and corresponding luminous behavior.…”

Intermolecular through‐space charge transfer enabled by bicomponent assembly for ultrasensitive detection of synthetic cannabinoid JWH‐018

“…[19] Beneficial from the easy synthesis, spatial and temporal resolution, high sensitivity, high selectivity, and easy modification of structure to cover a wide range of absorption/emission characteristics, [20] the organic fluorescent probes have been widely applied in the fields of metal ions, [21,22] anions, [23,24] organic molecule, [25] and biosensing. [26] Upon encountering the target molecule, the reactive recognition process occurs with the chemical bond formation or cleavage, leading to the fluorescence signal variation based on the change of electron/energy transfer, for instance, intramolecular charge transfer (ICT), [27][28][29] twisted ICT, [30,31] photoinduced electron transfer (PET), [32] Föster resonance energy transfer, [33] and so forth. However, for a less reactive target like SCs without a reactive recognition site, the aforementioned active fluorescent probe design strategy with a well-established sensing mechanism doesn't work.…”

A Deep Understanding on the Effective Generation of Twisted Intramolecular Charge Transfer by Protonation in Thiazolo[5,4-d]thiazole Derivatives

“…The exploration of the photoelectric organic materials has attracted wide interest from both academic and industrial communities in enormous applications, such as molecular switches, fluorescence sensors, organic dyes, and therapeutic materials. − A deep understanding of the charge-transfer and separation processes is of great importance in modulating the photoelectrical properties of the organic materials, and the most explored ones include photoinduced electron transfer (PET), , proton-coupled electron transfer (PCET), and intramolecular charge transfer (ICT) . Among them, the ICT process can be manipulated and oriented through introducing the push–pull effect in the functionalized organic materials with the modified electron donating/withdrawing groups (EDG/EWG). − As a particular ICT form, the twisted intramolecular charge transfer (TICT) resulted by the torsional rotation of the molecular configuration, generally leads to the dramatic change of the charge density distributions and the destruction of the π-conjugated systems in the whole molecule. − Corresponding to the charge transfer, proton transfer is another typical form of energy transfer that can greatly affect the photoelectric properties. As one of the most concerned proton transfer processes, the excited-state intramolecular proton transfer (ESIPT), can present a series of unique photochemical properties through the significant phototautomerizations induced by the excitation-strengthened hydrogen bond. − It has been demonstrated that the synergistic effect of ESIPT and TICT could further efficiently stabilize the torsional configuration by reducing the molecule energy accompanied by the dissociation of the π conjugation and nearly complete charge transfer between two fragments connecting the rotation bond, thus further ensuring the preferential and efficient charge-transfer and separation. − This distinct characteristic of the ESIPT triggered TICT process has been typically investigated in a series of functionalized organic materials, such as photostable fluorophores, photosensitizers, and aggregation induced emission luminogens (AIEgens). − For instance, by regulating the polarity of the solvent, the planar local excited state of the benzotriazole based ultraviolet absorber could be preferentially stabilized by generating a highly polar twisted charger transfer state through ESIPT triggered TICT process, resulting in the enhancement of the photostability of the ultraviolet absorbers .…”