Distorted forms of metalloporphyrins probed by methods of highly resolved spectroscopy

2009 ◽  
Vol 13 (08n09) ◽  
pp. 957-963 ◽  
Author(s):  
Aleksander Starukhin ◽  
Mikalai Kruk
Keyword(s):  
Ground State ◽  
Heavy Atom ◽  
Rare Gas ◽  
Cryogenic Temperatures ◽  
Out Of Plane ◽  
Saddle Type ◽  
Fluorescence And Phosphorescence Spectra ◽  
Atom Effect ◽  
Fluorescence And Phosphorescence ◽  
Phosphorescence Spectra

The spectral manifestations of the distorted forms of sterically unconstrained metallocomplexes of porphyrin in rare gas and Shpol'skii matrices at cryogenic temperatures were detected. The planar and two kinds of distorted conformations of the Mg - and Zn -porphyrins in rare gas matrices have been measured simultaneously in the fluorescence and phosphorescence spectra due to external heavy atom effect. The distinctly different frequencies of the vibronic transitions have been revealed for planar and distorted forms. In the phosphorescence spectra of the Pd -porphyrin the manifestation of the two forms in the ground state has been proven also, with one of them being planar and the other being saddle-type distorted. The ratio of the planar and non-planar forms was shown to depend on the deuteration of both meso-positions of the porphyrin and n-alkane matrix. The appearance of the out-of-plane modes in the phosphorescence spectra of the Pd - and Pt -porphyrin has been demonstrated.

Zur Photolumineszenz von Benzologen des Thiophens

1985 ◽  
Vol 40 (5) ◽  
pp. 497-502 ◽  
Author(s):  
Maximilian Zander
Keyword(s):  
Energy Gap ◽  
Heavy Atom ◽  
Phosphorescence Spectrum ◽  
Quantum Yields ◽  
Triplet States ◽  
Fluorescence And Phosphorescence Spectra ◽  
Atom Effect ◽  
Fluorescence And Phosphorescence ◽  
Phosphorescence Spectra ◽  
Hydrocarbon Fragment

Fluorescence and phosphorescence spectra, fluorescence and phosphorescence quantum yields and phosphorescence lifetimes of the benzologues I -V of thiophene have been measured in ethanol at 77 K. By comparing the energies of the lowest triplet states of the molecules with those of corresponding hydrocarbons it is concluded that the sulphur atoms act like substituents and are not equivalent to aromatic double bonds. The rate of the radiationless deactivation of the lowest triplet state depends on the energy gap Δ E(T1 - S0) in accordance with the Siebrand relation. An unexpected small intraannullar heavy-atom effect of the sulphur is observed in 2,2′-bis-benzo[b]thienyl (II), a strongly fluorescing compound. As the most likely explanation it is concluded from experiments that in II the interaction between the heavy-atom and the π-MO’s of the hydrocarbon fragment (1,4-biphenylbutadiene) is much smaller compared to that in other structurally related benzologues of thiophene. External heavy-atom perturbers (AgClO4, CH3J) have a strong influence on the vibronic structure of the phosphorescence spectrum of IV.

Condensed Aromatics. Part XX. Coronene

1982 ◽  
Vol 37 (12) ◽  
pp. 1359-1368 ◽  
Author(s):  
S. J. Cyvin ◽  
B. N. Cyvin ◽  
J. Brunvoll ◽  
J. C. Whitmer ◽  
P. Klaeboe
Keyword(s):  
Bond Orders ◽  
Symmetry Coordinates ◽  
Complete Assignment ◽  
Out Of Plane ◽  
Complete Set ◽  
Infrared Frequencies ◽  
Parameter Approximation ◽  
Fluorescence And Phosphorescence Spectra ◽  
Fluorescence And Phosphorescence ◽  
Phosphorescence Spectra

AbstractThe molecular vibrations of coronene, both in-plane and out-of-plane, are studied. The simple Hückel molecular orbitals are derived and the CC bond Oiders calculated. The bond orders are used to fix the CC stretching force constants. A complete set of independent symmetry coordinates is constructed. The in-plane vibrational frequencies are calculated by (a) the five-parameter approximation and (b) the Califano-Neto method; those of the out-of-plane vibrations only by the five-parameter approximation. The calculated frequencies are compared with observed values and previous calculations. A few new Raman bands are reported along with the presumably most complete set of infrared frequencies reported so far. A complete assignment of the infrared- active (E1u and A2u) fundamentals is proposed. A majority of the Raman-active frequencies (A1g, E1g and E2g) are also assigned, using Raman, fluorescence and phosphorescence spectra.

Photochemisches Verhalten und spektroskopische Eigenschaften von Anilino-naphthalinen

1976 ◽  
Vol 31 (8) ◽  
pp. 987-989 ◽  
Author(s):  
F. Fratev ◽  
O.E. Polansky ◽  
M. Zander
Keyword(s):  
Excited State ◽  
Aromatic Amines ◽  
Ring Closure ◽  
Fluorescence And Phosphorescence Spectra ◽  
Fluorescence And Phosphorescence ◽  
Phosphorescence Spectra

AbstractFrom the fluorescence and phosphorescence spectra of several aromatic amines it is concluded that the conjugation between nitrogen and aryl groups in the excited state is restricted. With this result a sterical explanation for the lack of the expected photochemical carbazole ring closure of 1-and 2-anilino naphthalene is given.

Note on the Influence of External Heavy-Atom Perturbers on the Phosphorescence Spectrum of Triphenylene

1984 ◽  
Vol 39 (11) ◽  
pp. 1145-1146 ◽  
Author(s):  
M. Zander
Keyword(s):  
Complex Formation ◽  
Methyl Iodide ◽  
Ground State ◽  
Chemical Nature ◽  
Heavy Atom ◽  
Phosphorescence Spectrum ◽  
Symmetry Reduction ◽  
Spectral Changes ◽  
Silver Perchlorate ◽  
Phosphorescence Spectra

Spectral changes in symmetry-forbidden phosphorescence spectra observed in the presence of external heavyatom perturbers may have quite different causes depending on the chemical nature of the perturber. This is exemplified using triphenylene as the phosphorescent compound and methyl iodide and silver Perchlorate respectively as the perturber. Intensification of the 0-0 band of the symmetry-forbidden phosphorescence spectrum of triphenylene by silver Perchlorate is assumed to result from symmetry-reduction of the hydrocarbon by ground-state complex formation with silver Perchlorate.

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