排序方式: 共有31条查询结果,搜索用时 10 毫秒
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Santos FS Costa TM Stefani V Gonçalves PF Descalzo RR Benvenutti EV Rodembusch FS 《The journal of physical chemistry. A》2011,115(46):13390-13398
Two Schiff bases were synthesized by reaction of 2-(4'-aminophenyl)benzoxazole derivatives with 4-N,N-diethylaminobenzaldehyde. UV-visible (UV-vis) and steady-state fluorescence in solution were applied in order to characterize its photophysical behavior. The Schiff bases present absorption in the UV region with fluorescence emission in the blue-green region, with a large Stokes' shift. The UV-vis data indicates that each dye behaves as two different chromophores in solution in the ground state. The fluorescence emission spectra of the dye 5a show that an intramolecular proton transfer (ESIPT) mechanism takes place in the excited state, whereas a twisted internal charge transfer (TICT) state is observed for the dye 5b. Theoretical calculations were performed in order to study the conformation and polarity of the molecules at their ground and excited electronic states. Using density functional theory (DFT) methods at theoretical levels BLYP/Aug-SV(P) for geometry optimizations and B3LYP/6-311++G(2d,p) for single-point energy evaluations, the calculations indicate that the lowest energy conformations are in all cases nonplanar and that the dipole moments of the excited state relaxed structures are much larger than those of the ground state structures, which corroborates the experimental UV-vis absorption results. 相似文献
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García-Acosta B Comes M Bricks JL Kudinova MA Kurdyukov VV Tolmachev AI Descalzo AB Marcos MD Martínez-Máñez R Moreno A Sancenón F Soto J Villaescusa LA Rurack K Barat JM Escriche I Amorós P 《Chemical communications (Cambridge, England)》2006,(21):2239-2241
Pyrylium-containing mesoporous materials have been used for the chromo-fluorogenic sensing of biogenic amines in an aqueous environment. 相似文献
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Descalzo AB Xu HJ Xue ZL Hoffmann K Shen Z Weller MG You XZ Rurack K 《Organic letters》2008,10(8):1581-1584
A new class of boron-dipyrromethene (BDP or BODIPY) dyes was obtained by phenanthrene fusion to the beta-pyrrole positions, absorbing in the wavelength range of important laser sources. Despite a 'propeller-like' distorted structure in the crystalline state, the chromophore absorbs (log epsilon > or = 5) and fluoresces (Phif > or = 0.8) strongly and can be easily turned into a fluorescence light-up probe. Incorporation into latex beads produces bright and photostable single-dye and F?rster Resonance Energy Transfer (FRET) particles for microscopy applications. 相似文献
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Coupling selectivity with sensitivity in an integrated chemosensor framework: design of a Hg(2+)-responsive probe,operating above 500 nm 总被引:1,自引:0,他引:1
Descalzo AB Martínez-Máñez R Radeglia R Rurack K Soto J 《Journal of the American Chemical Society》2003,125(12):3418-3419
For the highly selective and sensitive sensing of Hg2+ in water, a new design concept was realized where the selectivity of the probe's binding site is amplified by electronic properties of the chromophore. The molecular architecture of this phenoxazinone-type sensor molecule combines two potential coordination sites via an amino-keto conjugative backbone. These structural prerequisites allow only the most preferred mercuric ion to bind to the dithia dioxa monoaza crown unit, while other heavy, transition, and main group metal ions as well as protons are trapped at the keto group, inducing opposite spectral effects due to interaction with either the donor (Hg2+) or the acceptor group (other cations) of the probe. Besides these advantageous features, the probe operates well within the visible range of the spectrum and displays rather intense molar absorptivities as well as fluorescence quantum yields. 相似文献
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Dr. Hai‐Jun Xu Dr. John Mack Dr. Di Wu Dr. Zhao‐Li Xue Dr. Ana B. Descalzo Dr. Knut Rurack Prof. Nagao Kobayashi Prof. Zhen Shen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(52):16844-16867
The synthesis of a series of novel core‐modified and fused‐ring‐expanded tetraphenylporphyrins is reported. Theoretical calculations and magnetic circular dichroism (MCD) and fluorescence spectroscopic measurements were used to analyze the effect of core modification with Group 16 oxygen, sulfur, selenium, and tellurium atoms on the optical properties and electronic structures of the porphyrins. Marked redshifts of the Q and B bands and accelerated intersystem‐crossing rates were observed, thus making these compounds potentially suitable for use in a variety of applications. The scope for further fine‐tuning of these optical properties based on additional structural modifications, such as the incorporation of fused benzene rings to form ABAB structures by using a thiophene precursor with a fused bicyclo[2.2.2]octadiene ring and the introduction of various substituents onto the meso‐phenyl rings, is also examined. 相似文献
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