查看更多>>摘要：The dimerization processes and its thermodynamic parameters of fluoronic dyes (fluorescein (F), eosin (E), erythrosine (ER), bengal rose (BR)) in reverse micelles of AOT with different hydrodynamic radius Rh are studied. The dimerization constants and its efficiency (the degree of dimerization of dye molecules (1-X)) were determined from the experimental data. It is found that an increase in the intercombination conversion due to the heavy atom effect leads to an increase of the value of (1-X). At the same time, the heavy atom effect affects the dye dimerization process for all the studied values of R-h. The linear dependence of (1-X) on Rh is observed. The slope of this dependence is affected by both the mass of the internal heavy atom and the charge of the anionic forms of dyes. It was found that there is a different structure of dye dimers for different R-h for all the studied systems different angles alpha between the molecules in the dimer. A linear dependence of a on Rh is observed. At the same time, the growth gradients alpha(R-h) practically do not differ for F, E, and BR and they are of the greatest importance for the studied water-micellar solutions of dyes. The growth of a from Rh is insignificant for ER. The thermodynamic parameters (such as Gibbs potential DG, enthalpy DH and entropy DS) were calculated from the experimentally measured dependences of the dimerization constant on the temperature. Delta H < 0 and Delta S < 0 in micellar solutions of the studied dyes at all values of Rh, that indicates that the dimerization reaction in the studied systems is controlled by enthalpy. The obtained linear relation ship between TDS and DH indicates the existence of enthalpy-entropy compensation in the dimeric reactions of the molecules of the studied dyes. The linear correlation observed between the values of TDS and DH allowed us to establish that the higher the molecular weight of the halogen in the dye molecule, the more effectively an increase in DH contributes to the dimeric stability. (C) 2021 Elsevier B.V. All rights reserved.
Pandiyarajan, T.Mangalaraja, R., VKarthikeyan, B.Udayabhaskar, R....
10页
查看更多>>摘要：Rare earth (RE- Pr, Er and Nd) doped ZnO nanostructures were prepared through simple wet chemical precipitation route. The RE doping induced interesting morphological transition from spherical to flower like structures were analyzed. The X-ray diffraction (XRD) measurements revealed that the prepared materials were of highly crystalline in nature and RE dopant ions did not altered the crystal structure of ZnO. The microstrain of ZnO was altered with respect to the nature of dopants. In the case of the Pr doped ZnO, X-ray photoelectron spectroscopy (XPS) analysis confirmed that the dopant (Pr) ions successfully substituted in the ZnO lattice. Raman spectra revealed RE doping induced lower energy side shift and variation in intensity of the peaks related to the characteristic phonon modes of ZnO. In the case of Nd doped ZnO nanostructures, dopant induced suppression in classical Raman modes and evolution of multiphonon related modes were identified. Optical diffuse reflectance spectral (DRS) measurements, along with the characteristic excitonic band of ZnO, other bands associated to the transitions of 4f energy levels related to the RE ions were observed. The partially filled 4f orbitals led to the enhanced photocatalytic activity in RE doped ZnO nanostructures. The observed enhanced photocatalytic activity in RE doped ZnO when compared to bare ZnO was discussed. The decolorization efficiency of MB ensued the following order 96 > 94 > 86 > 78% for ZnErO, ZnNdO, ZnPrO and ZnO, respectively. (c) 2021 Elsevier B.V. All rights reserved.
Guseva, Galina B.Antina, Elena, VBerezin, Mikhail B.Ksenofontov, Alexander A....
13页
查看更多>>摘要：This paper is devoted to the design of a fluorescent probe based on meso-carboxysubstituted-BODIPY with a thioterpene fragment. The functional replacement of the methoxy group in the BODIPY molecule on a thioterpene fragment was carried out in order to find out the antiplatelet and anticoagulant action mechanisms of thioterpenoids and to assess the membrane and receptor factors contributions. The molecular structure of the conjugate was confirmed via UV/vis-, NMR- and MS-spectra. It is found that the probe is a high fluorescence quantum yield (to similar to 100%) in the blue-green region at 509-516 nm. Molecular docking of all studied molecules showed that the BODIPY with terpenoid conjugation is an excellent way to increase their affinity to platelet receptor PY12. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The folic acid (FA) level in human body can be used as an indicator for body's normal physiological activities and offer insight into the growth and reproduction of the body's cells. But the abnormal level of FA can cause some diseases. Herein, we designed a simple and convenient approach to prepare fluorescent N-doped carbon dots (N-CDs) for the FA detection. These N-CDs have excellent hydrophilicity, high photostability, and outstanding biocompatibility, as well as excitation-independent emission behavior with typical excitation/emission peaks at 295 nm/412 nm. Upon the existence of FA, the fluorescence emission spectrum of N-CDs was significantly quenched through the synergy of static quenching mechanism and internal filtering effect (IFE). Under optimal conditions, the limit of detection was 28.0 nM (S/N = 3) within the FA concentration range of 0-200.0 mu M. In addition, N-CDs were successfully employed to detect FA in real samples such as urine and fetal bovine serum (FBS), with a recovery rate of 99.6%-100.7% for quantitative addition. Furthermore, cell experiments confirmed the low toxicity and the cell imaging performance of these N-CDs, indicating that the obtained N-CDs could be served as a credible quantitative probe for FA analysis in the field of biosensing. (C) 2021 Elsevier B.V. All rights reserved.
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