Efficient Singlet-State Deactivation of Cyano-Substituted Indolines in Protic Solvents via CNHO Hydrogen Bonds

ChemPhysChem ◽  
2007 ◽  
Vol 8 (18) ◽  
pp. 2627-2635 ◽  
Author(s):  
Krisztina Pál ◽  
Mihály Kállay ◽  
Gottfried Köhler ◽  
Hong Zhang ◽  
István Bitter ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Singlet State ◽  
Protic Solvents

The influence of boron doped nanodiamonds on hydrogen bonds in suspensions of protic solvents

2016 ◽  
Author(s):  
Alexey M. Vervald ◽  
Evgeny A. Ekimov ◽  
Oleg S. Kudryavtsev ◽  
Igor I. Vlasov ◽  
Tatiana A. Dolenko
Keyword(s):  
Hydrogen Bonds ◽  
Boron Doped ◽  
Protic Solvents

Fluorescence of some simple umbelliferone derivatives

1979 ◽  
Vol 44 (2) ◽  
pp. 508-518 ◽  
Author(s):  
Vladimír Mikeš
Keyword(s):  
Excited State ◽  
Hydrogen Bonds ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Excited Singlet State ◽  
Absorption And Fluorescence Spectra ◽  
Excited Singlet ◽  
Nonpolar Medium ◽  
Phenolic Group

The absorption and fluorescence spectra of umbelliferone were studied; it was found that in the excited state the basicity of the α-pyrone part of the molecule increases to such an extent that it exceeds that of the phenolate oxygen of the molecule. This is responsible for the neutral nondissociated form of umbelliferone being only in nonpolar medium which prevents the dissociation of the phenolic group in the excited state. In nonpolar medium, umbelliferone behaves as a substance with closely lying π → π* and n → π* transitions. Hydrogen bonds affect the fluorescence of 7-methoxycoumarin so that the π → π* transition is preserved as the lowest excited singlet state.

Two-photon excitation fluorescence microscopy in living systems

1993 ◽  
Vol 51 ◽  
pp. 154-155 ◽  
Author(s):  
David W. Piston
Keyword(s):  
Confocal Microscopy ◽  
Fluorescence Microscopy ◽  
Singlet State ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation fluorescence microscopy provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In our fluorescence experiments, the final excited state is the same singlet state that is populated during a conventional fluorescence experiment. Thus, the fluorophore exhibits the same emission properties (e.g. wavelength shifts, environmental sensitivity) used in typical biological microscopy studies. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10−5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

Use of molecular overlap to predict intermolecular repulsion in N... H-O hydrogen bonds

1998 ◽  
Vol 95 (3) ◽  
pp. 525-537 ◽  
Author(s):  
I. NOBELI S. L. PRICE R. J. WHEATLEY
Keyword(s):  
Hydrogen Bonds

On symmetrical O-H-O hydrogen bonds

1964 ◽  
Vol 25 (5) ◽  
pp. 487-492 ◽  
Author(s):  
R.E. Rundle
Keyword(s):  
Hydrogen Bonds

The Gold Porphyrin First Excited Singlet State¶

2002 ◽  
Vol 76 (1) ◽  
pp. 47 ◽  
Author(s):  
Joakim Andréasson ◽  
Gerdenis Kodis ◽  
Su Lin ◽  
Ana L. Moore ◽  
Thomas A. Moore ◽  
...  
Keyword(s):  
Singlet State ◽  
Excited Singlet State ◽  
Excited Singlet
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