TY - JOUR
T1 - Molecular Luminescence Studies of Flavins, II
T2 - Interactions Involving the Excited States
AU - Song, Pill Soon
AU - Moore, Thomas A.
AU - Kurtin, William E.
N1 - Funding Information:
It can be seen that the results of the four different geometries are similar *, and are consistent Requests for reprints should be sent to Prof. PILL-SOON SONG,, Department of Chemistry, Texas Tech. University, Lubbock, Texas. * This work was supported by the Robert A. Welch Foun-dation (D-182) and by the National Science Foundation (GB-21266). ** Present address: Department of Chemistry, Trinity Uni-versity, San Antonio, Texas.
PY - 1972/9/1
Y1 - 1972/9/1
N2 - The effects of experimental geometry on the theoretical polarizations of the S1←S0and S2 ← S0bands of π→π* type in riboflavin have been examined. Polarizations of these two bands are characterized by an angle between them in the range of 20 — 28° and are relatively insensitive to the input geometry. Thus the predicted polarizations are generally in agreement with fluorescence polarization spectrum of riboflavin at 77 °K. Alloxazine forms a strong complex with KI, and the fluorescence and phosphorescence from the charge transfer states have been characterized by means of luminescence and photoselection measurements. Riboflavin did not form a strong complex with KI, but it forms aggregates (dimer) more readily than alloxazine. The excited states of flavins can be populated by the weak dipole-dipole coupling mechanism of energy transfer from 1La states of indoles to the S2 state of flavins. The measured critical distances estimated from the fluorescence depolarization experiments range from 31 A for indole to 40 A for indole-2-carboxylic acid in glycerol-methanol mixture (9:1) at 263 °K.
AB - The effects of experimental geometry on the theoretical polarizations of the S1←S0and S2 ← S0bands of π→π* type in riboflavin have been examined. Polarizations of these two bands are characterized by an angle between them in the range of 20 — 28° and are relatively insensitive to the input geometry. Thus the predicted polarizations are generally in agreement with fluorescence polarization spectrum of riboflavin at 77 °K. Alloxazine forms a strong complex with KI, and the fluorescence and phosphorescence from the charge transfer states have been characterized by means of luminescence and photoselection measurements. Riboflavin did not form a strong complex with KI, but it forms aggregates (dimer) more readily than alloxazine. The excited states of flavins can be populated by the weak dipole-dipole coupling mechanism of energy transfer from 1La states of indoles to the S2 state of flavins. The measured critical distances estimated from the fluorescence depolarization experiments range from 31 A for indole to 40 A for indole-2-carboxylic acid in glycerol-methanol mixture (9:1) at 263 °K.
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U2 - 10.1515/znb-1972-0901
DO - 10.1515/znb-1972-0901
M3 - Article
C2 - 4405062
AN - SCOPUS:0015390648
VL - 27
SP - 1011
EP - 1015
JO - Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences
JF - Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences
SN - 0932-0776
IS - 9
ER -