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Spectrochimica acta
Pergamon
Spectrochimica acta

Pergamon

1386-1425

Spectrochimica acta/Journal Spectrochimica acta
正式出版
收录年代

    Investigating ESIPT and donor-acceptor substituent effects on the photophysical and electrochemical properties of fluorescent 3,5-diaryl-substituted 1-phenyl-2-pyrazolines

    Frizzo, Clarissa P.Iglesias, Bernardo A.Bonacorso, Helio G.Santos, Gabriel C....
    14页
    查看更多>>摘要：This paper describes the synthesis, structural study, and evaluation of electrochemical and photophysical properties by UV-Vis absorption and fluorescence emission analysis (solution and solid-state) of a series of eight 3,5-aryl-substituted 1-phenyl-2-pyrazolines (5), where 3-aryl = 2-OH-C6H4 (5a-g) or Ph (5h), and 5-aryl = Ph (a, h), 1-naphthyl (b), 4-Br-C6H4 (c), 4-F-C6H4 (d), 4-OCH3-C6H4(e), 4-NO2-C6H4 (f), 4-(N (CH3)(2))-C6H4(g). The UV-Vis absorption properties of 2-pyrazolines were evaluated in DCM, MeCN, AcOEt, EtOH, and DMSO as the solvent and showed a fluorescence shift for the polar aprotic solvents. The steady-state fluorescence emission exhibited a band in the blue region when excited at the least energetic transition of each compound, although the excited-state intramolecular proton (ESIPT) effect was not detected. In the solid state, compounds presented similar behavior regarding absorption and emission properties compared to the solution assays. With the electrochemical analyses performed for the synthesized 2-pyrazolines, it was possible to conclude that the redox potentials were influenced by the electronic and steric effects of the substituents on the aryl rings and, according to the electronic nature of the substituents, which electron-donating groups were favored. Finally, the TD-DFT analyses revealed that all compounds had delocalized electron density throughout the 2-pyrazolines unit and were not influenced by the substituent bonded at C-5. Nonetheless, LUMO orbital analysis showed that only derivatives 5b and 5f have this localized density over the substituents. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    A naphthimide-based ratiometric fluorescent probe for selective and visual detection of phosgene in solution and the gas phase

    Xu, ZhiqiangLuo, YabinHong, YuLiu, Ziru...
    7页
    查看更多>>摘要：As a colorless, highly toxic and widely used chemical reagent, phosgene poses a potentially serious threat to public health and environmental safety. Therefore, there is an urgent need to develop a simple and sen-sitive method for detecting phosgene. In this work, a ratiometric fluorescent probe (NED) for phosgene was developed by utilizing 4-substituted 1,8-naphthimide unit as the fluorophore and ethylenediamine as the recognition moiety. The probe NED undergoes intramolecular cyclization reaction with phosgene, resulting in a remarkable ratiometric fluorescence response. The probe NED displays high sensitivity (LOD = 4.9 nM), excellent ratiometric fluorescence signal, and high selectivity toward phosgene over other relevant analytes. In addition, paper test strip capable of visually detecting gaseous phosgene has also been fabricated. (c) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Development of a human serum albumin structure-based fluorescent probe for bioimaging in living cells

    Wang, QingFan, JingwenZhou, YoujunXu, Shaohu...
    8页
    查看更多>>摘要：Forming a stable complex is a prerequisite for intramolecular charge transfer (Id) probe to recognize proteins. Herein, a human serum albumin (HSA) structure-based fluorescent probe DNPM was fabricated successfully with fully considering its binding to the primary sites in HSA. Molecular simulation was used to assist the probe design. Two ICT ligands DNPM and MPM were initially designed. Both DNPM and MPM had favorable HSA binding abilities, but only DNPM had a satisfactory HSA sensitivity. Electromagnetic coupling played a key role in DNPM fluorescence enhancement. Due to the electromagnetic environment difference in protein structure, DNPM only exhibited strong sensitivity to serum albumins. DNPM could bind to Sudlow site I and site II in HSA but could not be displaced from its binding sites by common site specific drugs (e.g. phenylbutazone and ibuprofen). Besides, DNPM exhibited great potential for illumining serum albumin in living cells. The results provided a beneficial approach for designing and synthesizing high sensitive and selective fluorescent probes for proteins. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    An effective dual sensor for Cu2+ and Zn2+ with long-wavelength fluorescence in aqueous media based on biphenylacrylonitrile Schiff-base

    Zha, BowenFang, ShutingChen, HuilingGuo, Hongyu...
    7页
    查看更多>>摘要：Although some sensors for Cu2+ and Zn2+ had been reported, the sensor with long-wavelength emission in aqueous media for in-situ detecting Cu2+ and Zn2+ was always expected. Herein, a biphenylacrylonitrile Schiff-base (OPBS) with large aromatic conjugated system was designed and synthesized in yield of 82%. OPBS possessed excellent long-wavelength fluorescence at 550-750 nm in aqueous media, which selectively response to sense Cu2+ with quenched fluorescence and Zn2+ with chromotropic fluorescence from red to yellow. The detection of Cu2+ and Zn2+ were realized without mutual interference in their coexistence system by means of the assistance of ATP. The detection limits were 2.3 x 10(-7) M for Cu2+ and 1.8 x 10(-6) M for Zn2+, respectively. The sensing mechanism was elucidated by binding MS spectra, fluorescence Job's plot and H-1 NMR spectra. Moreover, OPBS exhibited good bioimaging performance and the in-situ sensing abilities for Cu2+ and Zn2+ in living cells, suggesting the application potential for detecting Cu2+ and Zn2+ in both vitro assay and vivo environment. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    D Orange emissive carbon dots for fluorescent determination of hypoxanthine in fish

    Mou, ZehuaiGao, ZhijinHu, Yaoping
    7页
    查看更多>>摘要：Sensitive determination of hypoxanthine (HX), an indicator reflecting the degradation of meat and fish, is significantly important in monitoring food freshness. Herein, we design a novel sensor consisting of orange emissive carbon dots (O-CDs), nitrotetrazolium blue chloride (NTBC), and xanthine oxidase (XOD) for fluorescence turn-off detection of HX. O-CDs, possessing a high fluorescence quantum yield of 37%, are synthesized by hydrothermal treatment of 2,3-diaminopyridine in sulfuric acid. NTBC can react with HX/XOD-generated H2O2 and O-2(-) to yield a violet-colored formazan, which remarkably quenches the orange fluorescence of O-CDs through inner filter effect. There is a linearity between the quenching efficiency and HX concentration in the range of 2-250 mu M, and the limit of detection is 0.61 mu M, lower than those of most reported HX sensors. In addition, the proposed method exhibits excellent selectivity, and can be applied to quantify HX in fish samples with satisfactory results. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Rapid identification of producing area of wheat using terahertz spectroscopy combined with chemometrics

    Shen, YinLi, BinLi, GuanglinLang, Chongchong...
    9页
    查看更多>>摘要：Wheat from different producing areas has different flavor and properties, and thus the identification of producing area of wheat is significant to assure the quality of wheat. The traditional method of producing area of wheat determination is time-consuming, complex and needs a lot of pretreatment. The purpose of this research is to develop a new method for the determination of wheat producing areas by terahertz time domain spectroscopy in combination with chemometrics. Firstly, a total of 240 wheat samples from Shandong Province, Shaanxi Province, Henan Province, Hebei Province and Anhui Province of China were collected to analyze and obtain the time-domain spectral signals, frequency-domain spectral signals, and absorption coefficient spectral signals of the samples were obtained. Then, four different preprocessing methods of Savitzky-Golay (S-G), multiplicative scatter correction (MSC), mean centering, and standard normal variate (SNV) were applied to preprocess the absorption coefficient spectral signals, and the uninformative variable elimination (UVE) was used for variable selection of THz spectra data, for developing an effective prediction model. Finally, chemometrics methods, including the partial least squares discriminant analysis (PLS-DA), back propagation neural network (BPNN) and least squares support vector machines (LS-SVM) qualitative models were used for model building and discrimination results obtained through such models were compared. According to the test results, the comprehensive discrimination accuracy of wheat from different origins by the SNV-LS-SVM model reached 96.76%, Furthermore, these results demonstrated that an accurate qualitative analysis of producing area of wheat samples could be achieved by terahertz time-domain spectroscopy combined with chemometrics, which can provide a fast and accurate solution for grain security detection and origin tracing. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Rapid detection of mussels contaminated by heavy metals using near-infrared reflectance spectroscopy and a constrained difference extreme learning machine

    Liu, YaoXu, LeleZeng, ShaogengQiao, Fu...
    10页
    查看更多>>摘要：The consumption of mussels contaminated with heavy metals can cause toxicity in humans. To realize quick, accurate, and non-destructive detection of heavy metals in mussels, a new method based on near-infrared reflection spectroscopy was developed in this study. Spectral data from 900 nm to 1700 nm of non-contaminated mussels and mussels contaminated with Cd, Zn, Pb, and Cu were collected using a near-infrared spectrometer. After pre-processing spectral data with multiplicative scatter correction, wavelength selection algorithms based on consistency measures of neighborhood rough sets were used to extract wavelengths for distinguishing non-contaminated and contaminated mussels. A constrained difference extreme learning machine was established as a classification model to detect contaminated mussels. In the proposed model, the weight and bias of the hidden layers are calculated by the difference vectors of samples between classes instead of being randomly selected. The results indicate that the proposed model performs significantly well in differentiating between non-contaminated and contaminated mussels. The average classification accuracy of 50 randomly generated test datasets reaches 97.53%, 95.67%, 99.00%, and 98.80% for the detection of Zn, Pb, Cd, and Cu contamination, respectively. This study demonstrates that near-infrared spectroscopy coupled with a constrained difference extreme learning can be used to rapidly and accurately detect mussels contaminated with heavy metals. This is of great significance for the evaluation of the quality and safety of mussels. (c) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    pH-induced highly sensitive fluorescence detection of urea and urease based on carbon dots-based nanohybrids

    Zhang, JiajingAn, JiaHu, YongqinYang, Da...
    8页
    查看更多>>摘要：Carbon quantum dots (CDs) have become one of the most popular fluorescent materials due to their intriguing performance, which are favored by many fields. However, it is difficult to synthesize CDs with high quantum yield by the simple synthesis methods. In this paper, we fabricated CDs- silicon (SiO2) spheres composites via a versatile hydrothermal route. The prepared BCD-SiO2 composites exhibited an approximately 10-fold increase in the fluorescence intensity over that of BCDs. At the same time, the purification path was simplified by the facile separation of SiO2 spheres. The prepared BCD-SiO2 composites were used to fabricate a special sensing platform for the ultrasensitive detection of urea and urease, with detection limits of 1.67 mu M and 0.002 mg/mL, respectively. Furthermore, this strategy was successfully applied to the detection of real samples. This result shows that as-prepared BCDsSiO(2) composites are promising for broad application to biological analysis. (C) 2021 Published by Elsevier B.V.
      原文链接:
    • NSTL
    • Elsevier

    Meso-aryl-substituted thiacarbocyanine dyes as spectral-fluorescent probes for DNA

    Pronkin, Pavel G.Tatikolov, Alexander S.
    11页
    查看更多>>摘要：The noncovalent interaction of meso-aryl-substituted thiacarbocyanine dyes I and II with dsDNA and ssDNA in aqueous solutions has been studied by spectral-fluorescent methods. Complexation with DNA is accompanied by both aggregation of the dyes and the formation of monomeric strongly fluorescent complexes. Experiments on molecular docking of dyes I and II with dsDNA confirm the previous assumption about the possibility of the formation of complexes of different types: intercalation between base pairs and in the grooves of the double helix of the biopolymer. The possibility of intercalation of the dyes in the complex is confirmed by experiments on thermal dissociation of dsDNA in the presence of dyes I and II, as well as experiments on the interaction of the dyes with ssDNA. An increase in the melting temperatures Tm of dsDNA is obtained in the presence of I and II, similar to that observed for the classical intercalator ethidium bromide. The limits of detection and quantification of DNA, which are important for the use of the dyes as probes for DNA, have been determined. The primary photochemical processes of the dyes in complexes with ssDNA were studied by flash photolysis technique. Complexation with ssDNA hinders photoisomerization and creates favorable conditions for the dye triplet state formation. The decay kinetics of the triplet state of the dyes were monoexponential. The rate constant of quenching of the triplet state by air oxygen was estimated for dye I complexed with ssDNA and was found to be less than the diffusion-controlled limit. This is probably a consequence of the shielding effect of the complex on the triplet quenching process. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Multiple fluorescence quenching effects mediated fluorescent sensing of captopril Based on amino Acids-Derivative carbon nanodots

    Wang, QiZhang, ZiruYang, TianHan, Yejiao...
    9页
    查看更多>>摘要：Carbon nanodots (CNDs) were facilely synthesized through a pyrolysis procedure with histamine, an amino acid rich in element carbon and nitrogen, being the precursor. Taking advantage of the favorable fluorescence performance of CNDs, a multiple fluorescence quenching effects mediated fluorescent sensor was established for captopril (CAP) detection. MnO2 NPs were firstly combined with CNDs via electrostatic attraction and subsequently quenched the fluorescence. The quenching mechanisms were concluded to be the combined effects of fluorescence resonance energy transfer (FRET) and inner filtration effect (IFE). Subsequently CAP triggered a unique redox reaction and decomposed the quencher so that renewed the fluorescence. Hence, the sensitive and selective detection of CAP was achieved through the indication of fluorescence recovery efficiency. A proportional range of 0.4 similar to 60 mu mol L-1 with the LOD of 0.31 mu mol L-1 was obtained. The sensor was further applied to the real sample detection and the satisfactory results revealed the practical value of CNDs. The facile synthesis of CNDs and brand-new sensing mechanism made it a novel fluorescent method and could improve the analysis of CAP. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier