scholarly journals Theoretical Analysis of the Effect Provoked by Bromine-Addition on the Thermolysis and Chemiexcitation of a Model Dioxetanone

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Luís Pinto da Silva ◽  
Rui F. J. Pereira ◽  
Joaquim C. G. Esteves da Silva
Keyword(s):  
Light Emission ◽  
Heavy Atom ◽  
Quantum Yields ◽  
Efficient Production ◽  
Triplet States ◽  
Singlet States ◽  
Electronically Excited ◽  
Excited Singlet States ◽  
Thermolysis Reaction ◽  
Effect Of Heavy Atom

Chemi-/bioluminescence are phenomena in which chemical energy is converted into electronically excited singlet states, which decay with light emission. Given this feature, along with high quantum yields and other beneficial characteristics, these systems have gained numerous applications in bioanalysis, in biomedicine, and in the pharmaceutical field. Singlet chemiexcitation is made possible by the formation of cyclic peroxides (as dioxetanones) as thermolysis provides a route for a ground state reaction to produce singlet excited states. However, such thermolysis can also lead to the formation of triplet states. While triplet states are not desired in the typical applications of chemi-/bioluminescence, the efficient production of such states can open the door for the use of these systems as sensitizers in photocatalysis and triplet-triplet annihilation, among other fields. Thus, the goal of this study is to assess the effect of heavy atom addition on the thermolysis and triplet chemiexcitation of a model dioxetanone. Monobromination does not affect the thermolysis reaction but can improve the efficiency of intersystem crossing, depending on the position of monobromination. Addition of bromine atoms to the triplet state reaction product has little effect on its properties, except on its electron affinity, in which monobromination can increase between 3.1 and 8.8 kcal mol−1.

scholarly journals Structures, dipole moments and excited state lifetime of isolated 4-cyanoindole in its ground and lowest electronically excited singlet states

2019 ◽  
Vol 21 (27) ◽  
pp. 14766-14774 ◽  
Author(s):  
Marie-Luise Hebestreit ◽  
Michael Schneider ◽  
Hilda Lartian ◽  
Vivienne Betz ◽  
Michael Heinrich ◽  
...  
Keyword(s):  
Excited State ◽  
Dipole Moments ◽  
Excited State Lifetime ◽  
Excited Singlet ◽  
Singlet States ◽  
Electronically Excited ◽  
Excited Singlet States

The rotationally resolved electronic Stark spectrum of 4-cyanoindole and some N-D and C-D deuterated isotopologues has been measured and analyzed.

Triplet state quantum yields for some arom atic hydrocarbons and xanthene dyes in dilute solution

1967 ◽  
Vol 299 (1458) ◽  
pp. 348-353 ◽  
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Heavy Atom ◽  
Quantum Yields ◽  
Triplet States ◽  
Dilute Solution ◽  
Perturbation Techniques ◽  
Excited Singlet ◽  
Xanthene Dyes ◽  
Extinction Coefficients

Quantum yields of triplet state formation and extinction coefficients of the triplet states have been determined by direct depletion methods for solutions of anthracene, phenanthrene, 1,2,5,6-dibenzanthracene, fluorescein, dibromofluorescein, eosin and erythrosin. The values obtained for the hydrocarbons are in reasonable agreement with those obtained by other workers using energy transfer and heavy atom perturbation techniques. In all cases which we have studied, the sum of the quantum yields of fluorescence and triplet state formation is equal to unity within the limits of experimental error, showing that radiationless transfer from the excited singlet to the ground state is negligible.

A spectroscopic study of HCP, the phosphorus analogue of hydrocyanic acid

1969 ◽  
Vol 47 (8) ◽  
pp. 893-920 ◽  
Author(s):  
J. W. C. Johns ◽  
H. F. Shurvell ◽  
J. K. Tyler
Keyword(s):  
Energy Levels ◽  
Hydrocyanic Acid ◽  
Ultraviolet Absorption Spectrum ◽  
Triplet States ◽  
Fundamental Vibration ◽  
Excited Triplet ◽  
Singlet States ◽  
State Formula ◽  
Excited Singlet States ◽  
Vibration Rotation

The ultraviolet absorption spectrum of HCP has been observed from 4100 Å to about 2350 Å, and seven electronic transitions have been identified. Three of these transitions involve excited singlet states and four of them involve excited triplet states. The symmetries, energies, and equilibrium conformations of these states are listed below:[Formula: see text]Some observations have also been made on the vibration–rotation energy levels of the ground electronic state, [Formula: see text], of HCP. The fundamental vibration frequencies (in cm−1) are ν1 = 3216.9, ν2 = 674.7, and ν3 = 1278.4.

A quantum-chemical study of structure of H3O+ in electronically excited states

1986 ◽  
Vol 51 (4) ◽  
pp. 738-745 ◽  
Author(s):  
Peter Ertl ◽  
Jaroslav Leška
Keyword(s):  
Quantum Chemical Study ◽  
Chemical Study ◽  
Electronic Distribution ◽  
Singlet States ◽  
Electronically Excited ◽  
Electron Distributions ◽  
Optimization Of Geometry ◽  
Full Optimization ◽  
Excited Singlet States ◽  
Almost All

The CNDO/2-Cl method has been used for full optimization of geometry of the H3O+ ion in all its electronically excited singlet states and for calculation of electron distribution. The electronic structure shows that H3O+ in almost all states exhibits lower tendency to split off the proton than it does in the ground state. For the first excited state the geometries and electron distributions of the isoelectronic set H3O+, NH3, CH-3 have been calculated by the INDO-Cl method in the triplet state, too. The particles only have slightly different geometry and electronic distribution from those of the first singlet state.

Photochemical Reactions of Primary Aromatic Amines with Chloromethanes in Solution. I. Spectrochemical Studies

1989 ◽  
Vol 44 (12) ◽  
pp. 1585-1588 ◽  
Author(s):  
Wojciech Boszczyk ◽  
Tadeusz Latowski
Keyword(s):  
Hydrogen Chloride ◽  
Stability Constants ◽  
Aromatic Amines ◽  
Photochemical Reactions ◽  
Quantum Yields ◽  
Excited Singlet ◽  
Singlet States ◽  
Primary Aromatic Amines ◽  
Excited Singlet States ◽  
Induced Reaction

Interactions were studied of aniline, 4-methoxyaniline and 4-ethoxyaniline with tetrachloromethane, chloroform and dichloromethane in their ground and first excited singlet states. Stability constants of the complexes of these amines with the chloromethanes in cyclohexane were determined as well as their quantum yields of fluorescence in this solvent. The quenching of fluorescence of aniline and its derivatives by the chloromethanes was ascertained and characterized. Quantum yields of the formation of hydrogen chloride, ψΗCl, were measured during photochemically induced reaction of the amines in tetrachloromethane, chloroform and dichloromethane.

scholarly journals Emission Quenching in Tetraphenylfuran Crystal: Why This Propeller-Shaped Molecule Does Not Emit in the Condensed Phase?

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 522
Author(s):  
Ljiljana Stojanović ◽  
Rachel Crespo-Otero
Keyword(s):  
Solid State ◽  
Ground State ◽  
Light Emission ◽  
Quantum Yields ◽  
Triplet States ◽  
Fluorescence Quantum Yields ◽  
The Family ◽  
Emission Quenching ◽  
Significant Attention

Due to their substantial fluorescence quantum yields in the crystalline phase, propeller-shaped molecules have recently gained significant attention as potential emissive materials for optoelectronic applications. For the family of cyclopentadiene derivatives, light-emission is highly dependent on the nature of heteroatomic substitutions. In this paper, we investigate excited state relaxation pathways in the tetraphenyl-furan molecule (TPF), which in contrast with other molecules in the family, shows emission quenching in the solid-state. For the singlet manifold, our calculations show nonradiative pathways associated with C-O elongation are blocked in both vacuum and the solid state. A fraction of the population can be transferred to the triplet manifold and, subsequently, to the ground state in both phases. This process is expected to be relatively slow due to the small spin-orbit couplings between the relevant singlet-triplet states. Emission quenching in crystalline TPF seems to be in line with more efficient exciton hopping rates. Our simulations help clarify the role of conical intersections, population of the triplet states and crystalline structure in the emissive response of propeller-shaped molecules.

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