A white-light-emitting sensor array based on cucurbit[8]uril for quantitative detection of multicomponent nitroaniline isomers.

A white-light-emitting supramolecular complex through supramolecular interactions has been assembled; the white luminescent supramolecular complex exhibits two emission spectra. Based on this, a dual-channel white-light array sensor was constructed. The results show that it can quickly identify and detect nitroaniline isomer pollutants (p-nitroaniline, m-nitroaniline, o-nitroaniline). When these three nitroaniline isomers were added to the supramolecular white-light array sensor, the fluorescence intensity of the white-light complex decreased to varying degrees. Linear discriminant analysis (LDA) showed that the supramolecular white-light array sensor could recognize and distinguish three nitroaniline isomers and could classify mixtures containing different concentrations. Factor 1 of the array had a good linear relationship with the concentration of pollutants, and the detection limit (LOD) was as low as 0.7 µM. The method has good reproducibility and stability. In addition, it can also qualitatively detect the nitroaniline isomers in river water and contaminated rice seedling extract. It provides an ideal platform for constructing multiresponse sensors.

Supramolecular Fluorescence Sensor Array Based on Cucurbit[8]uril Complexes Used for the Detection of Multiplex Quaternary Ammonium Pesticides.

The simultaneous detection of multiple quaternary ammonium pesticides (QAPs) in water is a challenge due to their high solubility in water and similar structures. In this paper, we have developed a quadruple-channel supramolecular fluorescence sensor array for the simultaneous analysis of five QAPs, including paraquat (PQ), diquat (DQ), difenzoquat (DFQ), mepiquat (MQ), and chlormequat (CQ). Not only were QAP samples of different concentrations (10, 50, and 300 µM) in water distinguished with 100% accuracy but also single QAP and binary QAP mixed samples (DFQ-DQ) were sensitively quantified. Our experimental interference study confirmed that the developed array has good anti-interference ability. The array can quickly identify five QAPs in river and tap water samples. In addition, it also qualitatively detected QAP residues in Chinese cabbage and wheat seedlings extract. This array has rich output signals, low cost, easy preparation, and simple technology, demonstrating great potential in environmental analysis.

A supramolecular fluorescence array sensor for toxic heavy metal ion detection in environmental water and rice seedling extracts.

A supramolecular fluorescence array sensor based on cucurbituril-dye host-guest complexes (6-QAA@Q[7], PyY@Q[7], and TO@Q[8]) was constructed. The results showed that it can quickly identify and detect toxic heavy metal ions, such as Ag+, Cr3+, Hg2+, Ni2+, and Pb2+. When these five toxic heavy metal ions were added to the supramolecular fluorescence array sensor, different fluorescence responses were produced due to the different binding capacities of the metal ions to the cucurbituril-dye complex. Linear discriminant analysis (LDA) showed that the supramolecular fluorescence array sensor could identify and distinguish these five toxic heavy metal ions and a mixture containing different concentration ratios could be classified. The linear correlation between the metal ion concentration and factor 1 (F1) was strong, and the detection limit (LOD) was as low as 10-6-10-7 mol L-1. These five toxic heavy metal ions in environmental water and rice seedling extracts were identified using the supramolecular fluorescence array sensor. This sensor provides a quick and convenient method for monitoring toxic heavy metal ions in sewage.

A colorimetric supramolecular sensor array based on charge-transfer complexes for multiplex aniline and phenolic pollutants detection.

In order to effectively monitor toxic and harmful substances in sewage discharge, a rapid, highly sensitive detection of complex pollutants with similar structures has become an urgent problem to be solved. In this paper, a supramolecular colorimetric array sensor based on charge-transfer complex was constructed, which can quickly detect aniline and phenol pollutants (such as p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, m-aminophenol, hydroquinone, and resorcinol) with similar structures. When six anilines and phenol isomers with similar structures were added to the supramolecular colorimetric array sensor, different color changes were produced under natural light. Linear discriminant analysis (LDA) showed that the supramolecular colorimetric array sensor could recognize and distinguish these isomers, and a mixture with different concentration ratios could be well categorized. The total Euclidean distance (TED) of an array with pollutant concentrations had a good linear correlation, and the detection limit (LOD) was as low as 10-5-10-6 mol L-1. Six anilines and phenol isomers in real samples were identified by supramolecular colorimetric array sensor. 1H NMR results showed that the formation of charge transfer complexes in Q[8] cavity may be the cause of color change. This work provides a fast and convenient experimental basis for monitoring the complex structure pollutants in sewage discharge.

Lab-on-a-Molecule Probe: Multitarget Detection of Five Aromatic Pesticides Using a Supramolecular Probe under Single Wavelength Excitation.

In order to prevent and control the effects of pesticide residues on human health and the ecological environment, the rapid, highly sensitive, and selective detection of multiple pesticide residues has become an urgent problem to be solved. Herein, a lab-on-a-molecule probe based on a host-guest complex (ThT@Q[8] probe) has been developed to simultaneously analyze multiple aromatic pesticides under single wavelength excitation, such as fuberidazole, thiabendazole, carbendazim, thidiazuron, and tricyclazole. The fluorescence titration spectra of the ThT@Q[8] probe with the five pesticides mentioned above showed that the fluorescence intensity exhibited a good linear correlation with the pesticide concentration and the limit of detection was as low as 10-7 M. Because the ThT@Q[8] probe exhibits diverse fluorescence color changes to the five pesticides studied under a 365 nm ultraviolet lamp, we fabricated a single probe used to detect multiple analytes in the RGB triple channel by extracting the RGB variations. Principal component analysis and linear discriminant analysis proved that the ThT@Q[8] probe can recognize and distinguish five pesticides and can be applied at different concentrations. In real samples, the ThT@Q[8] probe recognized and distinguished five pesticides in tap water and Huaxi River water. The 1H NMR spectra results proved that a charge-transfer complex of ThT and pesticides in the Q[8] cavity may be formed. Moreover, we selected a test strip as a carrier to detect pesticides. The results indicate it can be used to quickly and conveniently detect different pesticides due to the rapid color change. Besides, the ThT@Q[8] probe has good cell permeability and can be used to detect pesticide residues in living cells. This work has laid the foundation for the qualitative and quantitative multitarget detection of pesticide residues.

Clustering emission of cucurbit[n]urils in the solid- and solution-state induced by the outer surface interactions of cucurbit[n]urils.

Atypical luminescent compounds that do not contain conventional chromophores emit light due to clustering and have important basic research value and a broad range of potential applications. To date, most atypical luminescent compounds are small molecules or polymers containing groups such as cyano, carbonyl and hydroxyl. In this work, driven by some sporadic and accidental luminescence phenomena observed for cucurbit[n]urils (Q[n]s), the luminescent properties and mechanism of Q[n]s in the solid- and solution-state were systematically studied and the clustering emission of Q[n]s confirmed. Our experiments have revealed that the self-induced outer-surface interactions of Q[n]s (OSIQ) are the most important driving force resulting in the clustering emission of Q[n]s. Substances that can weaken the effect of self-induced OSIQ, such as the presence of various aromatic compounds and anions, may weaken or quench the clustering emission of Q[n]s. This not only reveals the new characteristics and mechanism of the clustering emission of Q[n]s, but also provides new insights on how to utilize the clustering emission of Q[n]s and construct new types of macrocyclic luminescence systems.

"Turn-Off" Supramolecular Fluorescence Array Sensor for Heavy Metal Ion Identification.

A "turn-off" supramolecular fluorescence array sensor based on the host-guest complexes between fluorescence dyes and cucurbit[n]urils for sensing metal ions was developed. Three fluorescent probes (RhB@Q[7], H33342@2Q[7], and BRE@Q[7]) were used as the sensing units to construct a supramolecular fluorescence array sensor. The binding ability of the metal ions and cucurbituril-dye probes varied; therefore, the probes and metal ions produced different fluorescence responses. When combined with linear discriminant analysis (LDA), the qualitative and quantitative detection of seven metal ions was achieved. In analytical samples, the supramolecular fluorescence array sensor recognized and distinguish seven metal ions. These results provided new research ideas for the rapid analysis and real-time monitoring of different heavy metal ions.