scholarly journals Dipole Moments and Polarizabilities of Benzophenones Estimated from Spectroscopic Measurements

1981 ◽  
Vol 36 (8) ◽  
pp. 909-912
Author(s):  
M. Stori
Keyword(s):  
Absorption Spectra ◽  
Dipole Moments ◽  
Cavity Radius ◽  
Spectroscopic Measurements ◽  
Spectral Shifts

Abstract The effect of microenvironment on the absorption spectra of benzophenone and its aminoderivatives in n-heptane/n-butanol and n-heptane/benzene mixtures was investigated. The local dielectic constants, the composition of the solvatation shell, the Onsager cavity radius "a" and the values of a/a3 (α - the polarizability of solute molecules) have been evaluated from the spectral shifts.

ULTRAVIOLET ABSORPTION SPECTRA AND ACIDITIES OF ISOMERIC THIATRIAZOLE AND TETRAZOLE DERIVATIVES

1959 ◽  
Vol 37 (3) ◽  
pp. 563-574 ◽  
Author(s):  
Eugene Lieber ◽  
J. Ramachandran ◽  
C. N. R. Rao ◽  
C. N. Pillai
Keyword(s):  
Absorption Spectra ◽  
Absorption Maximum ◽  
Dipole Moments ◽  
Ring System ◽  
Ultraviolet Absorption ◽  
Characteristic Absorption ◽  
Tetrazole Derivatives

The ultraviolet absorption spectra of 5-(substituted)amino-1,2,3,4-thiatriazoles and the corresponding isomeric 1-substituted-tetrazoline-5-thiones have been studied. The spectra and the dipole moments of the 5-(substituted)amino-1,2,3,4-thiatriazoles eliminate the possibility of meso-ionic structures for these compounds. The dipole moments of 5-amino-, 5-methylamino-, and 5-dimethylamino-1,2,3,4-thiatriazole were all high but approximately of the same value (5.77 to 5.84 D). This suggests that the amino thiatriazoles are best represented by conventional covalent structures with significant ionic resonance contributions. The thiatriazole ring system exhibits a characteristic absorption maximum at 250–255 mμ and an electron-withdrawing effect approximately equal to the tetrazolyl ring system. The tetrazolinethionolyl ring system is similarly electron-withdrawing. The relative acidities of the 1-substituted-tetrazoline-5-thiones and the 5-alkylmercaptotetrazoles have also been studied and the results support the observations made on the basis of their ultraviolet absorption spectra.

scholarly journals Spectral shifts of BODIPY derivatives: a simple continuous model

2019 ◽  
Vol 18 (6) ◽  
pp. 1315-1323 ◽  
Author(s):  
Mette L. H. Sørensen ◽  
Tom Vosch ◽  
Bo W. Laursen ◽  
Thorsten Hansen
Keyword(s):  
Absorption Spectra ◽  
Continuous Model ◽  
Spectral Shifts ◽  
Linear Molecules

The photophysics of substituted BODIPY dyes, as well as the corresponding linear molecules, is captured by a simple Hückel model. The observed trend in the absorption spectra of chalcogen-substituted dyes can be rationalized in terms of the electronegativity of substituents.

Dipole moments and electronic absorption spectra of aryltricyanoethylenes

1970 ◽  
Vol 66 ◽  
pp. 769 ◽  
Author(s):  
Israel Agranat ◽  
Zvi Rappoport ◽  
Hannah Weiler-Feilchenfeld
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Dipole Moments

scholarly journals Nature of Lowest Electron Transitions in Anionic Polymethine Dyes With Keto-Containing Terminal Groups

2021 ◽  
Author(s):  
A. P. Naumenko ◽  
V. I. Borisyuk ◽  
Olexiy Kachkovsky ◽  
Yu. L. Slominskii ◽  
N. V. Obernikhina
Keyword(s):  
Absorption Spectra ◽  
Energy Gap ◽  
Dipole Moments ◽  
Spectral Band ◽  
Electron Transition ◽  
Polymethine Dyes ◽  
Polymethine Chain ◽  
Local Electron ◽  
Fluorescence Excitation ◽  
Electron Transitions

Abstract The complex quantum-chemical and spectral study of the anionic polymethine dyes with the simplest symmetrical terminal groups and with different length polymethine chain is performed. It was shown that these dyes produce the specific molecular orbitals positioned nearly the energy gap and located only within the terminal groups. By investigation of the absorption spectra, it was established that the typical highly intensive longwawelength spectral band is observed which are bathochromically shifted upon lengthening of the open conjugated chain; this polymethine band is connected with the electron transition between the frontier levels of the opposite symmetry. In the contrast, the local MOs take part in so-called quasi-local electron transitions involved also one the frontier orbital. The local transitions have small dipole moments and hence they do practically not appear in the absorption spectra, however, the local transitions cause the appearance of the non-deep minima in the spectra of the fluorescence excitation anisotropy.

Vibronic absorption spectra and excited states of acridine red dye in aqueous solution: TD-DFT/DFT study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Victor V. Kostjukov
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Hydrogen Bonds ◽  
Absorption Spectra ◽  
Excited States ◽  
Dipole Moments ◽  
Basis Set ◽  
Calculated Spectrum ◽  
Solvent Model ◽  
Acridine Red

Abstract The vibronic absorption spectra of acridine red (AR) xanthene dye in an aqueous solution using 40 hybrid functionals, the 6-31++G(d,p) basis set, and the IEFPCM solvent model were calculated. It turned out that the O3LYP functional provided the best agreement with the experiment in the positions of the main maximum and the short-wavelength subband (shoulder). The calculations showed that this shoulder is vibronic. At the same time, the shoulder intensity in the calculated spectrum turned out to be lower than in the experimental one. Apparently, insignificant dimerization, which occurs even at low concentrations of the dye in solution, contributes to the shoulder of the experimental absorption spectrum. Various parameters of the AR cation in the ground and excited states (IR spectra, atomic charges, dipole moments, and transition moment) were calculated. Maps of the distribution of electron density and electrostatic potential have been built. The influence of the strong hydrogen bonds of the dye with three water molecules on the absorption spectrum was analyzed. It has been shown that these bonds are strengthened upon AR excitation. The strengthening of two hydrogen bonds with water upon excitation leads to a lowering of the potential energy surface of the excited state, which causes a decrease in the excitation energy (i.e., an increase in the wavelength of the absorbed photon) as compared to a purely implicit specification of the water environment. Therefore, explicit assignment of waters strongly bound to the dye leads to spectrum redshift.

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