THE ELECTRONIC ABSORPTION SPECTRA OF DIXANTHOGENS

1961 ◽  
Vol 39 (12) ◽  
pp. 2590-2592 ◽  
Author(s):  
M. L. Shankaranarayana ◽  
C. C. Patel
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
High Intensity ◽  
Electronic Absorption Spectra ◽  
Blue Shift ◽  
Polar Solvents ◽  
Low Intensity

The electronic absorption spectra of diethyl, diisopropyl, di-n-butyl, and diisoamyl dixanthogens have been studied in polar and non-polar solvents. The compounds exhibit a low-intensity band around 365 mµ and two high-intensity bands around 285 and 242 mµ. The 365 mµ band is assigned, as a result of the solvent studies, to n → π* transition and the 285 mµ band to π → π* transition. The band around 242 mµ may be due to the n → σ* transition, since in polar solvents it shows mainly a blue shift.

Molecular interactions in the spectra of diaza-aromatics

1974 ◽  
Vol 27 (8) ◽  
pp. 1613 ◽  
Author(s):  
JR Honner ◽  
PR Nott ◽  
BK Selinger
Keyword(s):  
Hydrogen Bonding ◽  
Absorption Spectra ◽  
Molecular Interactions ◽  
Electronic Absorption ◽  
Low Temperatures ◽  
Electronic Absorption Spectra ◽  
Polar Solvents ◽  
Hydrogen Bonding Interactions ◽  
Low Concentrations

A reported variation of the electronic absorption spectra of diaza-aromatics in non-polar solvents with temperature appears to be explicable in terms of three effects. Hydrogen bonding interactions occur in all but exhaustively dried non-polar solvents. Microcrystals form readily at low temperatures at even quite low concentrations (c. 10-5M). The solutions are sensitive to exposure to light. The diaza-aromatics undergo photochemical change forming, in some cases, photoadducts with the solvent.

Excited State Polarizability of Some Polycyclic Polyenes

2017 ◽  
Vol 68 (2) ◽  
pp. 307-310 ◽  
Author(s):  
Ana Maria Ciubara ◽  
Andreea Celia Benchea ◽  
Carmen Beatrice Zelinschi ◽  
Dana Ortansa Dorohoi
Keyword(s):  
Excited State ◽  
Absorption Spectra ◽  
Excited States ◽  
Electronic Absorption ◽  
Ground State ◽  
Electronic Absorption Spectra ◽  
Photon Absorption ◽  
Absorption Process ◽  
Polar Solvents ◽  
Molecular Parameters

The electronic absorption spectra of five polycyclic polyenes were recorded in non-polar solvents in order to determine their polarizability in excited states from the strength of the dispersive interactions in their diluted solutions. The bathochromic shifts of p-p* vibronic bands prove the increase of the molecular polarizabilty in the photon absorption process. Some molecular parameters of the analyzed polyenes in their ground state were computed by using the programs from Spartan�14.

Electronic absorption spectra of substituted phthalocyanines in solution and as films

2003 ◽  
Vol 07 (08) ◽  
pp. 551-557 ◽  
Author(s):  
Hiroshi Ogata ◽  
Ryuji Higashi ◽  
Nagao Kobayashi
Keyword(s):  
Absorption Band ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Film Formation ◽  
Polar Solvents

The electronic absorption spectra of several phthalocyanines substituted at the so-called α-, β- and α and β-positions of the macrocycle have been recorded in solution and as films (α = 1,4,8,11,15,18,22, and 25 positions or 1,8 (or 11),15 (or 18), and 22 (or 25) positions, and β = 2,3,9,10,16,17,23, and 24 positions or 2,9 (or 10),16 (or 17), and 23 (or 24) positions). Phthalocyanines substituted with bulky groups at the α-positions prevent cofacial aggregation so that their Q-absorption band remains at a similar wavelength both in solution and films, although the film spectra are generally broader. Phthalocyanines substituted at the β-positions are apt to aggregate cofacially in polar solvents but in films they may show broad Q-bands which spread out to both shorter and longer wavelengths of the solution Q-band, depending on the bulkiness of the substituents. The film spectra of hexadeca-substituted phthalocyanines exhibit Q-bands at a similar wavelength as in solution, with insignificant broadening of the Q-band on film formation. However, the Soret bands for most of the substituted phthalocyanines are shifted and broadened to longer wavelength in the films.

Stereochemistry of [carbonato-bis((S)-prolinato)]cobaltate(III) anion

1984 ◽  
Vol 49 (3) ◽  
pp. 680-683 ◽  
Author(s):  
Bohumil Hájek ◽  
Dagmar Sýkorová ◽  
Jiří Chyba
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Cd Spectra

The λ-C1-cis(N), δ-C1-cis(N), λ-C2-cis(N) and δ-C2-cis(N) isomers of the complex K[Co((S)-Pro)2CO3] were chromatographically separated and characterized by their electronic absorption spectra and CD spectra.

Photocolouration of 2,4,4,6-Tetraaryl-4H-pyrans and Their Heteroanalogues: Importance of Hypervalent Photoisomers

1995 ◽  
Vol 60 (10) ◽  
pp. 1621-1633 ◽  
Author(s):  
Stanislav Böhm ◽  
Mojmír Adamec ◽  
Stanislav Nešpůrek ◽  
Josef Kuthan
Keyword(s):  
Reaction Kinetics ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Theoretical Data ◽  
Order Reaction ◽  
Bleaching Process ◽  
First Order ◽  
Photodegradation Products ◽  
Hypervalent Molecules

Molecular geometries of 2,4,4,6-tetraphenyl-4H-pyran (Ia), 4,4-(biphenyl-2,2e-diyl)-2,6-diphenyl-4H-pyran (Ib) and their heterocyclic isomers II-V were optimized by the PM3 method and used for the calculation of electronic absorption spectra by the CNDO/S-CI procedure. Comparison of the theoretical data with experimental UV-VIS absorption spectra made possible to select hypervalent molecules IIIa, IIIb, IVa and IVb being responsible for the photocolouration of 4H-pyrans Ia, Ib, while compounds Va, Vb, VI and VII come into account as possible photodegradation products. The bleaching process of the UV illuminated compound Ia is analyzed in terms of dispersive first-order reaction kinetics.

Niobocene Dichloride and Niobocene Diiodide: Electronic Absorption Spectra and Electron Spin Resonance

1998 ◽  
Vol 63 (5) ◽  
pp. 628-635 ◽  
Author(s):  
Jana Holubová ◽  
Zdeněk Černošek ◽  
Ivan Pavlík
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Point Group ◽  
Esr Spectra ◽  
Ligand Field ◽  
Orbital Interaction ◽  
Symmetry Point Group ◽  
Spin Orbital ◽  
Halide Ligands

The effect of the halide ligand on the bonding of niobium in niobocene dichloride and niobocene diiodide was investigated. The electronic absorption spectra of the two compounds in the range of d-d transitions were resolved into four bands corresponding to transitions of the d1 electron between five frontier orbitals in a molecule of symmetry point group C2v. The energies of the frontier molecular orbitals were determined relatively to the energy of the orbitals in the spherically symmetric ligand field formed by the appropriate halide ligands. The effect of the halide ligands on the spin-orbital interaction of the HOMO orbital is discussed qualitatively on the basis the ESR spectra.

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