Effects of Substitution on the Phosphorescence Process of Aromatic Carbonyl Compounds
Takeshi Takemura,Hiroaki Baba +1 more
TLDR
In this paper, the 3La(π,π*) state was shown to have a singlet character due to the heavy-atom effect, which accounts for the observation that the phosphorescence spectrum involves out-of-plane-polarized vibrational bands.Abstract:
Phosphorescence and absorption spectra, phosphorescence- and excitation-polarization, spectra and phosphorescence lifetimes were measured at 77°K for benzaldehyde, acetophenone and their eight derivatives with a halogen atom, or a hydroxyl, methoxyl or amino group as a substituent at the para position. In chloro- and bromo-derivatives, the phosphorescent triplet state is of the (n,π*) type, and is mixed with the 1La(π,π*) state by direct spin-orbit interaction, as in the case of the parent carbonyls. In addition, owing to the heavy-atom effect, it gains its singlet character by the mechanism (Remark: Graphics omitted.) which accounts for the observation that the phosphorescence spectrum involves out-of-plane-polarized vibrational bands. Substitution of a more electron-donating hydroxyl, methoxyl, or amino group brings about a change of the phosphorescent state from the 3(n,π*) state to the; 3La(π,π*). The following mechanisms are shown to be important to the 3La(π,π*) state: (Remark: Graphics omitted.) Th...read more
Citations
More filters
Journal ArticleDOI
Fluorescence and phosphorescence from higher excited states of organic molecules.
Journal ArticleDOI
PMDR studies of the magnetic and dynamic properties of the lowest excited triplet states of aromatic carbonyl molecules : acetophenone, benzaldehyde and their derivatives
T.H. Cheng,N. Hirota +1 more
TL;DR: In this paper, the results of the phosphorescence microwave double resonance studies of the lowest excited triplet (T 1) states of acetophenone, benzaldehyde and their derivatives in various mixed crystals are presented and analyzed.
Journal ArticleDOI
Correlation of the zero field splittings with the phosphorescence rate constants and vibronic activity in the lowest triplet state of benzaldehydes by PMDR
A.M. Nishimura,D.S. Tinti +1 more
TL;DR: In this paper, the authors measured the zero field splittings and the rate constants of individual spin levels in the lowest triplet state of benzaldehyde and several para-substituted benzaldehydes.
Journal ArticleDOI
Semi-empirical calculations of the zero-field-splitting parameters of the lowest triplet states of aromatic ketones
H. Hayashi,S. Nagakura +1 more
TL;DR: In this article, semi-empirical calculations of zero-field-splitting parameters have been performed for the lowest triplet states of aromatic ketones, the mixing between the nearly degenerate n, π* and ππ,π* triplets states through the vibronic and spin-orbit interactions being considered.
Journal ArticleDOI
Spin-orbit coupling effects in EPR spectra of lowest triplet states of aromatic carbonyl compounds
Michael Batley,Richard Bramley +1 more
TL;DR: In this article, the assignment of 3nπ* or 3ππ* character to the lowest triplet states of aromatic carbonly compounds can be made from their EPR spectra on the basis of spin-orbit induced changes to both the fine-structure parameters and theg-values.
References
More filters
Journal ArticleDOI
Spin—Orbit Coupling and the Radiationless Processes in Nitrogen Heterocyclics
TL;DR: In this paper, the matrix elements of the spin-orbit operator between the zero-order (spin-free) (n, π*) states of nitrogen heterocyclics are examined.
Journal ArticleDOI
The Triplet State and Molecular Electronic Processes in Organic Molecules
S. K. Lower,M. A. El-Sayed +1 more
Journal ArticleDOI
Polarization of the Luminescence of Phenanthrene
T. Azumi,S. P. McGlynn +1 more
TL;DR: In this article, the polarization of the fluorescence excitation spectrum, fluorescence spectrum and the phosphorescence spectrum of phenanthrene have been determined, and it was shown that fluorescence emission is primarily polarized out of plane.
Related Papers (5)
Investigation of Singlet → Triplet Transitions by the Phosphorescence Excitation Method. III. Aromatic Ketones and Aldehydes
David R. Kearns,W. Alan Case +1 more