Microheterogeneities in binary solvent mixtures studied by electronic absorption spectra of a solvatochromic merocyanine dye

Four carbanion monosubstituted p-aryl-1,2,4-triazol-1-ium methylids are subjected to a comparative study between their spectral and quantum-mechanical parameters in order to obtain more information about their structural features in hydroxyl solvents as water and ethanol and also on the nature of electronic absorption transitions from the visible range. The quantum mechanical analysis, made by the Spartan’14 program, established a series of molecular parameters of the studied ylids important for their reactivity and for intermolecular interactions with hydroxyl liquids. An extensive solvatochromic study of 1,2,4-triazol-1-ium ylids is impossible due to their limited solubility in liquids. Binary solvent mixtures of water and ethanol with known solvent parameters from the literature were used for this study. The electronic absorption spectra in binary solvents water and ethanol were used to establish the influence of intermolecular interactions on the spectral characteristics of the studied methylids and also on the composition of their first solvation shell in ternary solutions. The difference between the interaction energies in molecular pairs ylid–water and ylid–ethanol was determined based on the statistical cell model applied to the ternary solutions of the type of ylid + water + ethanol. The obtained values are very small due to the hydroxylic nature of the two solvents.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19840680 ◽

1984 ◽

Vol 49 (3) ◽

pp. 680-683 ◽

Cited By ~ 1

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.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19951621 ◽

1995 ◽

Vol 60 (10) ◽

pp. 1621-1633 ◽

Cited By ~ 9

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.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19980628 ◽

1998 ◽

Vol 63 (5) ◽

pp. 628-635 ◽

Cited By ~ 1

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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