Short Wavelength Inner Filter Technique (SWIFT) in Designing Reactive Fluorescent Molecular Probes
摘要:
Here, we present a conceptually novel and experimentally straightforward technique for selective analyte detection that uses a combination of commercial fluorophores and simple chemicals. The technique utilizes the well-known inner filter effect (IFE); however, the fluorophore's excitation is performed at wavelengths significantly shorter than its absorption maximum. In the presence of the analyte, the "filter" appears or disappears at the excitation wavelength resulting in the fluorescence turning OFF or ON, respectively. Unlike common probes, our technique allows real-time monitoring of a fluorophore's stability as well as its recycling. We further demonstrate the applicability of this technique in continuing analyte detection as well as vapor analysis.
Dearomative (3+2) cycloaddition of 2-substituted 3,5-dinitropyridines and N-methyl azomethine ylide
作者:Maxim A. Bastrakov、Alexey K. Fedorenko、Alexey M. Starosotnikov、Vadim V. Kachala、Svyatoslav A. Shevelev
DOI:10.1007/s10593-019-02421-9
日期:2019.1
1,3-Dipolar cycloaddition of various 2-substituted 3,5-dinitropyridines and unstabilized N-methyl azomethineylide has been studied. It was found that, depending on the nature of the substituent, the reaction results in addition of one or two equivalents of 1,3-dipole to the pyridine ring. Eventually, a convenient method for the synthesis of differently substituted heterocyclic systems containing one
Dearomatization of 3,5-dinitropyridines – an atom-efficient approach to fused 3-nitropyrrolidines
作者:Maxim A. Bastrakov、Anna Yu. Kucherova、Alexey K. Fedorenko、Alexey M. Starosotnikov、Ivan V. Fedyanin、Igor L. Dalinger、Svyatoslav A. Shevelev
DOI:10.24820/ark.5550190.p010.185
日期:——
H-NMR of compound 6a S3 C-NMR of copmound 6a S3 H-NMR of compound 6b S4 C-NMR of copmound 6b S4 H-NMR of compound 6c S5 C-NMR of copmound 6c S5 H-NMR of compound 6d S6 C-NMR of copmound 6d S6 H-NMR of compound 6e S7 C-NMR of copmound 6e S7 H-NMR of compound 7a S8 C-NMR of copmound 7a S8 H-NMR of compound 7b S9 C-NMR of copmound 7b S9 H-NMR of compound 7c S10 C-NMR of copmound 7c S10 H-NMR of compound
The reaction rates of 2-chloro-3,5-dinitropyridine 1 with a series of arylthiolates 2a-h in methanol have been measured at 25 degrees C. The products are the corresponding 2-thioaryl-3,5-dinitropyridine 3a-h. Good Hammett correlation with rho Value -1.19 was obtained suggesting an elimination-addition mechanism SNAr and the formation of Meisenheimer-like intermediates. Plot of log k(2) vs. pK(a) values of arylthiols gave straight line with beta = 0.38 indicating that the Ti-bond breaking in the pyridine ring is so much advanced over bond making between the nucleophile and the carbon that bears the chlorine atom. Excellent correlation between log k(2) and log K (carbon basicity of arylthiolates) was obtained. (C) 1997 John Wiley & Sons. Inc.