Ultraviolet Absorption and Fluorescence Studies of 1-Methyl-2(1H)-Pyridinimine and Derivative in Polar and Non-Polar Solvents

2000 ◽  
Vol 53 (12) ◽  
pp. 951 ◽  
Author(s):  
Hassimi Traore ◽  
Michael Saunders ◽  
Scott Blasiman
Keyword(s):  
Fluorescence Spectra ◽  
Room Temperature ◽  
Potential Surface ◽  
Polar Solvents ◽  
Potential Surfaces ◽  
Fluorescence Studies ◽  
Pyridinium Cation ◽  
Vibronic Interactions ◽  
State Potential ◽  
Solute Interactions

The ultraviolet (u.v.) and fluorescence spectra and relative fluorescence intensities of 1-methyl-2(1H)-pyridinimine (1-MIP) and 1,2-dimethylpyridinimine (2-MIP) were measured in several solvents at room temperature. The solvents’ effect on the absorption and fluorescence spectra of MIP indicates that the ππ* transition shifts to higher energies (shorter wavelengths) are due to solvents’ interactions and the formation of the pyridinium cation. One major difference in the u.v. and fluorescence spectra is the small relative intensity in non-polar solvents. This was attributed to the proximity effect of ππ* and nπ* states which can lead to vibronic interactions, and to distortions of the excited-state potential surfaces. In polar solvents, however, these two states are shifted in energy due to solvent–solute interactions, which decrease the energy of the potential surface.

The specific and nonspecific solvatochromic behavior of Sudan dyes in different solvents

2015 ◽  
Vol 93 (6) ◽  
pp. 639-647 ◽  
Author(s):  
M.S. Zakerhamidi ◽  
S.M. Seyed Ahmadian ◽  
R. Kian
Keyword(s):  
Fluorescence Spectra ◽  
Room Temperature ◽  
Molecular Configuration ◽  
Sudan Dyes ◽  
Polar Solvents ◽  
Sudan Black B ◽  
Sudan Iv ◽  
Sudan Iii ◽  
Linear Solvation Energy ◽  
Solute Interactions

Absorption and fluorescence spectra of some Sudan dyes (Sudan III, Sudan IV, and Sudan Black B) were recorded in various solvents in the range of 300–800 nm at room temperature. The solvatochromic behavior of these substances and their solvent–solute interactions were analyzed by means of the linear solvation energy relationship concept suggested by Kamlet and Taft. The obtained results express the effect of solvation on the tautomerism and molecular configuration (geometry) of Sudan dyes in solvent media. Furthermore, analysis of solvent–solute interactions suggests different forms of resonance structures of Sudan dyes in polar and low-polar solvents.

Fluorescent Whitening Agents

1976 ◽  
Vol 46 (7) ◽  
pp. 539-544 ◽  
Author(s):  
L. A. Holt ◽  
I. H. Leaver ◽  
B. Milligan
Keyword(s):  
Vinyl Acetate ◽  
Polymer Films ◽  
Room Temperature ◽  
Polar Solvents ◽  
Fluorescence Studies ◽  
First Order ◽  
Absorption And Fluorescence Spectroscopy ◽  
Fluorescent Whitening Agents ◽  
Kinetics Of ◽  
Photo Decomposition

Ultraviolet absorption and fluorescence spectroscopy have been used to determine the nature and extent of photo-decomposition of fluorescent whitening agents in polymer films and in surface-whitened wool. Irradiation of the coumarin (I) in polymer films at 365 nm gives rise to a mixture of photodimers which rapidly revert to I on irradiation at wavelengths less than 320 nm. Irradiation of the stilbene (II) at 365 nm also gives a photodimer which absorbs strongly around 350 nm, but this reverts only slowly to II on irradiation. Fluorescence studies indicate that there is an increase in the degree of aggregation of I in polymer films with increasing whitener concentration, and that the kinetics of whitener photodecomposition change from first-order at low whitener concentration (0.0025%) to second-order at the higher concentration (2.5%) used in surface-whitening. The coumarin (I) is more stable to light in poly(vinyl acetate) film cast from formic acid than in films cast from less polar solvents, probably because of differences in the degree of whitener aggregation. The photostability of I in poly(vinyl acetate) film is also improved if the film is heated for short periods or stored at room temperature for longer periods.

Fluorescence of Cyclic Adducts of Fullerene

1994 ◽  
Vol 359 ◽  
Author(s):  
Tsung-I Lin ◽  
Syh-Kun Lin ◽  
Lung-Lin Shiu ◽  
Kuo-Ming Chien ◽  
Tien-Yau Luh
Keyword(s):  
Spectral Properties ◽  
Fluorescence Spectra ◽  
Room Temperature ◽  
Parent Compound ◽  
Molar Absorptivity ◽  
Absorption Bands ◽  
Polar Solvents ◽  
Peak Broadening ◽  
Stokes Shifts ◽  
Cyclic Adducts

ABSTRACTFive cyclic adducts C60C4H6, C60C5H6, C60NHCO2, C60NCO2Et, and C60CHCO2Et have been synthesized and their absorption and fluorescence spectral properties investigated and compared with those of the parent. Breaking the structural symmetry of C60 apparently resulted in enhancing the quantum yield two to three-folds in some adducts and thus made fluorescence much easier to be measured at room temperature. New absorption bands and altered fluorescence spectra were observed in the adducts. The Stokes' shifts of the adducts were small, about 4-5 nrm, compared to 68 nm for the parent compound. All the adducts exhibited a single fluorescence lifetime about the same as C60 (ca. 1.3 ns). Aliphatic solvents had little influence on the absorption or fluorescence spectral profile except on the molar absorptivity whereas aromatic and polar solvents strongly interacted with the adducts causing a peak broadening effect.

Fluorescence Quantum Yields of 2-Substituted 3-Methylquinoxalines in Liquid Solutions at Room Temperature

1991 ◽  
Vol 46 (8) ◽  
pp. 700-702
Author(s):  
A. Kawski ◽  
K. Nowaczyk ◽  
B. Kuklinski
Keyword(s):  
Quantum Yield ◽  
Fluorescence Spectra ◽  
Room Temperature ◽  
Atomic Weight ◽  
Modulation Method ◽  
Quantum Yields ◽  
Strong Decrease ◽  
Polar Solvents ◽  
Fluorescence Quantum Yields ◽  
Liquid Solutions

AbstractA sensitivity modulation method was employed to measure the fluorescence spectra and quantum yields of weakly fluorescent 2-substituted (NH2, O, OCH3, CI, Br) 3-methylquinoxalines in n-hexane and methanol at room temperature. A strong decrease in the quantum yield with increasing atomic weight of the substituents was observed in n-hexane. In polar solvents, the CI substituent is the strongest quencher although its atomic weight is 2.254 times smaller than that of Br

Infrared spectra of N-acetyl-L-α-amino-acid N'-methylamides with aliphatic side chains in non-polar solvents

1981 ◽  
Vol 46 (3) ◽  
pp. 772-780 ◽  
Author(s):  
Jorga Smolíková ◽  
Jan Pospíšek ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Conformational Changes ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Side Chains ◽  
Polar Solvents

Infrared spectra of the L-alanine (I), L-leucine (II), L-valine (III) and L-tert-leucine (IV) N-acetyl N'-methylamides were measured. Amides I-IV are not self associated in tetrachlormethane in the concentration 2 . 10-5 mol l-1 at room temperature and in tetrachloroethylene in the concentration 1.5 . 10-4 mol l-1 at temperatures above 65° C. True conformational changes are observable only with the least flexible amide IV which exists at room temperature in a C5 conformation. This conformational type is also highly populated in the valine derivative III, but is less important in the alanine and leucine derivatives I and II in which the intramolecularly bonded C7 and the distorted hydrogen-nonbonded conformations contribute seriously.

Room-temperature NaI/H2O compression icing: solute–solute interactions

2017 ◽  
Vol 19 (39) ◽  
pp. 26645-26650 ◽  
Author(s):  
Qingxin Zeng ◽  
Chuang Yao ◽  
Kai Wang ◽  
Chang Q. Sun ◽  
Bo Zou
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Bond Energy ◽  
Room Temperature ◽  
Solute Concentration ◽  
Solute Interaction ◽  
Solute Interactions

H–O bond energy governs the PCx for Na/H2O liquid–VI–VII phase transition. Solute concentration affects the path of phase transitions differently with the solute type. Solute–solute interaction lessens the PC2 sensitivity to compression. The PC1 goes along the liquid–VI boundary till the triple phase joint.

scholarly journals Spectral Properties of Hybrid of Rhodamine (6G) Dyes Doped Epoxy Resin Dissolved in Chloroform

2019 ◽  
Vol 16 (3(Suppl.)) ◽  
pp. 0764 ◽  
Author(s):  
Al-Hamdani Et al.
Keyword(s):  
Epoxy Resin ◽  
Quantum Efficiency ◽  
Fluorescence Spectra ◽  
Room Temperature ◽  
Rhodamine 6G ◽  
Energy Gap ◽  
Radiative Lifetime ◽  
Stokes Shift ◽  
Fluorescence Emission ◽  
Absorption And Fluorescence Spectra

            The research is dealing with the absorption and fluorescence spectra for the hybrid of  an Epoxy Resin doped with organic dye Rhodamine (R6G) of different concentrations (5*10-6, 5*10-5, 1*10-5, 1*10-4, 5*10-4) Mol/ℓ at room temperature. The Quantum efficiency Qfm, the rate of fluorescence emission Kfm (s-1), the non-radiative lifetime τfm (s), fluorescence lifetime τf and the Stokes shift were calculated. Also the energy gap (Eg) for each dye concentration was evaluated. The results showed that the maximum quantum efficiency 62 % and maximum stokes shift 96 nm was obtained in dye concentration 5*10-6 and 1*10-4. The energy gap ranges between 1.066 eV to 1.128 eV depending proportionally on the dye concentrations.

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