Development of a Cyclic System for Chemiluminescence Detection

Efficient Discrimination of Hazardous Organophosphate Flame Retardants via Cataluminescence-Based Multidimensional Ratiometric Sensing

Emerging contaminants have recently evolved into a severe worldwide environmental issue. Organophosphate flame retardants (OPFRs) with neurotoxicity, genotoxicity, and reproductive and developmental toxicity are a class of notorious emerging contaminants that cause great concern. The development of high-efficiency and portable sensors for rapid online monitoring of OPFRs has become the primary demand for the exploration of the environmental migration and transformation of OPFRs. In this work, interestingly, the cataluminescence (CTL) phenomenon of OPFRs is first observed, and an ingenious multidimensional ratiometric CTL sensing strategy is developed for the recognition of multiple OPFRs. Three characteristic ratios are extracted from the multipeak CTL spectral curves based on energy transfer of single Tb/Eu-modified MgO sensing material, and thus a novel three-dimensional (3D) code recognition could be mapped out. This obtained 3D coordinate is found to be a unique characteristic for a given OPFR, just like an exclusive person's ID number, which can successfully discriminate and detect 10 kinds of OPFR vapors, including homologous series and isomers. More importantly, CTL mechanism investigations for OPFRs demonstrate that OPFRs undergo a series of chemical reaction processes, e.g., oxidative pyrolysis and hydroxylation, and different high-energy excited intermediates are generated, which trigger discrepant energy-transfer efficiency toward rare earth ions, leading to multipeak spectral profiles. Briefly, this proposed CTL analytical platform for OPFRs recognition initiates a new sensing principle for the efficient identification of emerging contaminants and shows significant prospects on rapid on-site detection.

Liquid-Phase Cyclic Chemiluminescence for the Identification of Cobalt Speciation

Accurate discrimination of metal species is a significant analytical challenge. Herein, we propose a novel methodology based on liquid-phase cyclic chemiluminescence (CCL) for the identification of cobalt speciation. The CCL multistage signals (In) of the luminol-H2O2 reaction catalyzed by different cobalt species have different decay coefficients k. Thereby, we can facilely identify various cobalt species according to the distinguishable k values, including the complicated and structurally similar cobalt complexes, such as analogues of [Co(NH3)5X]n+ (X = Cl-, H2O, and NH3), Co(II) porphyrins, and bis(2,4-pentanedione) cobalt(II) derivatives. Especially, the number of substituent atoms also influences the k value greatly, which allows excellent discrimination between complexes that only have a subtle difference in the substituent group. In addition, linear discriminant analysis based on In provides a complementary solution to improve the differentiating ability. We performed density functional theory calculations to investigate the interaction mode of H2O2 over cobalt species. A close negative correlation between the adsorption energy and the k value is observed. Moreover, the calculation of energy evolutions of H2O2 decomposition into a double hydroxide radical shows that a high level of consistency exists between the activation energy barrier and the k value. The results further demonstrate that the decay coefficient of the CCL multistage signal is associated with the catalytic reactivity of the cobalt species. Our work not only broadens the application of chemiluminescence but also provides a complementary technology for speciation analysis.

Chiral-Controlled Cyclic Chemiluminescence Reactions for the Analysis of Enantiomer Amino Acids

The similarity and complexity of chiral amino acids (AAs) in complex samples remain a significant challenge in their analysis. In this work, the chiral metal-organic framework (MOF)-controlled cyclic chemiluminescence (CCL) reaction is developed and utilized in the analysis of enantiomer AAs. The chiral MOF of d-Co_0.75Zn_0.25-MOF-74 is designed and prepared by modifying the Co_0.75Zn_0.25-MOF-74 with d-tartaric acid. The developed chiral bimetallic MOF can not only offer the chiral recognize sites but also act as the catalyst in the cyclic luminol-H₂O₂ reaction. Moreover, a distinguishable CCL signal can be obtained on enantiomer AAs via the luminol-H₂O₂ reaction with the control of d-Co_0.75Zn_0.25-MOF-74. The amplified difference of enantiomer AAs can be quantified by the decay coefficient (k-values) which are calculated from the exponential decay fitting of their obtained CCL signals. According to simulation results, the selective recognition of 19 pairs of AAs is controlled by the pore size of the MOF-74 and their hydrogen-bond interaction with d-tartaric acid on the chiral MOF. Furthermore, the k-values can also be used to estimate the change of chiral AAs in complex samples. Consequently, this chiral MOF-controlled CCL reaction is applied to differentiate enantiomer AAs involved in the quality monitoring of dairy products and auxiliary diagnosis, which provides a new approach for chiral studies and their potential applications.

Multifunctional MgO/HKUST-1 Composite for Capture, Catalysis, and Cyclic Cataluminescence Detection of Esters All-In-One to Rapidly Identify Scented Products

The integration of metallic oxide and metal-organic frameworks has attracted considerable attention as obtained composite materials because they show synergistic effects in applications of catalysis and sensing. Herein, we developed the hybrid MgO and HKUST-1 for efficient capture, catalysis, and cyclic cataluminescence (CCTL) detection of esters all-in-one to rapidly identify scented products. The multifunctional MgO/HKUST-1 composite with high CCTL activity was synthesized and characterized. The multifunctional MgO/HKUST-1 composite acts as an enrichment material for ester capture and serves as a catalyst, assisting the analyte to trigger multistage signals. The multistage signals of ester-containing scented products also satisfy the exponential decay equation with a certain τ-value. The τ-values obtained by the CCTL system were applied to identify the brands of essential oils. The working temperature served as the sensor element to obtain various τ-values. The τ-values constituted a digital code to label the different brands of cigarettes with the same aroma type. The multistage signals could be used to distinguish the origin regions of essential oils and tobacco. This work combines the CCTL strategy with the sample pretreatment, opening up a new direction to develop CCL and providing a new platform to rapidly identify ester-containing scented products.

A study on the cataluminescence of propylene oxide on FeNi layered double hydroxides/graphene oxide

In this work, FeNi layered double hydroxides/graphene oxide (FeNi LDH/GO) was prepared, which exhibits excellent selective cataluminescent performance towards propylene oxide.

Rapid chiral analysis based on liquid-phase cyclic chemiluminescence

Rapid chiral analysis has become one of the important aspects of academic and industrial research. Here we describe a new strategy based on liquid-phase cyclic chemiluminescence (CCL) for rapid resolution of enantiomers and determination of enantiomeric excess (ee). A single CCL measurement can acquire multistage signals that provide a unique way to examine the intermolecular interactions between chiral hosts and chiral guests, because the lifetime (τ) of the multistage signals is a concentration-independent and distinguishable constant for a given chiral host-guest system. According to the τ values, CCL allows discrimination between a wide range of enantiomeric pairs including chiral alcohols, amines and acids by using only one chiral host. Even the chiral systems hardly distinguished by nuclear magnetic resonance and fluorescence methods can be distinguished easily by CCL. Additionally, the τ value of a mixture of two enantiomers is equal to the weighted average of each enantiomer, which can be used for the direct determination of ee without the need to separate the chiral mixture and create calibration curves. This is extremely crucial for the cases without readily available enantiomerically pure samples. This strategy was successfully applied to monitoring of the Walden inversion reaction and analysis of chiral drugs. The results were in good agreement with those obtained by high-performance liquid chromatography, indicating the utility of CCL for routine quick ee analysis. Mechanism study revealed that the τ value is possibly related to the activity of the chiral substance to catalyze a luminol-H2O2 reaction. Our research provides an unprecedented and general protocol for chirality differentiation and ee determination, which is anticipated to be a useful technology that will find wide application in chirality-related fields, particularly in asymmetric synthesis and the pharmaceutical industry.

Multistage Signals Based on Cyclic Chemiluminescence for Decoding Complex Samples

Identification of complex samples presents a difficult challenge for modern analytical techniques, and the differentiation among closely similar mixtures often remains indeterminate. In this article, we designed a simplified cyclic chemiluminescence (CCL) system that is able to measure multistage signals in a single sample injection. The system was used to investigate the CCL reactions of the binary, ternary, and multicomponent mixtures. Results showed that each mixture has a unique exponential decay equation (EDE) with a constant decay coefficient (k-value) to describe the change law of its multistage signals. Further studies found that different brands of liquor, beer, toner, and baby powder have different k-values, and the same brand of the commodities between different batches have the same k-values, which allows facile identification of these complex samples. We then used different catalysts to design digital codes of the k-value for further improving the identifying ability of CCL. Moreover, the multistage signals are like fingerprints and could be used for linear discriminate analysis, which provides another complementary approach for identification of complex samples. Finally, we demonstrated that CCL shows potential applications in certification and quality assurance according to the change of the k-values of the sample. This work demonstrates that excellent discrimination ability of CCL for the identification of complex samples and provides a promising technology for quality assurance.

Cataluminescence sensing of carbon disulfide based on CeO2 hierarchical hollow microspheres

Material morphology-dependent cataluminescence (CTL) sensing characteristic and application are presented in this work. Hierarchical hollow microspheres CeO₂ were synthesized via the hydrothermal reaction of glucose and N, N-dimethyl-formamide (Glu-DMF). SEM, XRD, TEM, HRTEM and BET were used to characterize the prepared CeO₂ materials. Compared with CeO₂ cubics (CeO₂ Cubs), CeO₂ hierarchical hollow microspheres (CeO₂ HMs) show an enhanced CTL response to carbon disulfide. The response and recovery times of CeO₂ HMs-based CTL sensor towards carbon disulfide are about 8 s and 20 s, respectively. CeO₂ HMs exhibits a linear CTL response to carbon disulfide in the concentration range of 0.50~10 μg•mL^-1 with an excellent sensitivity and selectivity. These results suggest that CeO₂ HMs will be a highly promising CTL sensing material for the detection and monitoring carbon disulfide. Graphical abstract CeO₂ hierarchical hollow microspheres (CeO₂ HMs) were synthesized via the hydrothermal reaction of glucose and N, N-dimethyl-formamide (Glu-DMF). Meanwhile, the prepared CeO₂ HMs shows commendable CTL response towards carbon disulfide. Due to the excellent analytical performance of designed CeO₂ HMs-based sensor for carbon disulfide, it has potential application value in various locations.

Recent advances in cataluminescence-based optical sensing systems

Recent advances in the development of cataluminescence focused on oxygen, temperature, catalyst and instrumentation are summarized.

Simple and Excellent Selective Chemiluminescence-Based CS2 On-Line Detection System for Rapid Analysis of Sulfur-Containing Compounds in Complex Samples

To study the interesting chemical reaction phenomenon can greatly contribute to the development of an innovative analytical method. In this paper, a simple CL reaction cell was constructed to study the chemiluminescence (CL) emission from the thermal oxidation of carbon disulfide (CS2). We found that the CL detection of CS2 exhibits unique characteristics of excellent selectivity and rapid response capacity. Experimental investigations together with theoretical calculation were performed to study the mechanism behind the CL reaction. The results revealed that the main luminous intermediates generated during the thermal degradation of CS2 are SO2* and CO2*. Significantly, this CL emission phenomenon has a wide application due to many sulfur-containing compounds that can convert to CS2 under special conditions. On the basis of this scheme, a CS2-generating and detection system was developed for rapid measurement of CS2 or other compounds that can convert to CS2. The usefulness of the system was demonstrated by measuring dithiocarbamate (DTC) pesticides (selected mancozeb as a representative analyte) based on the evolution of CS2 in spiked agricultural products. Results showed that the system allows online and large volume detection of CS2 under nonequilibrium condition, which greatly reduces the analytical time. The concentrations of mancozeb in the spiked samples were well-quantified with satisfied recoveries of 76.9-97.3%. The system not only addresses the urgent need for rapid in-field screening of DTC residues in foodstuffs but also opens a new opportunity for the fast, convenient, and cost-effective detection of CS2 and some other sulfur-containing compounds in complex samples.

A sensitive cataluminescence-based sensor using a SrCO3/graphene composite for n-propanol

Adding graphene to SrCO₃ enhanced the CTL intensity of n-propanol, and the SrCO₃/graphene composite was used for sensitive detection of n-propanol.