caa a22 4500 469072318 CHVBK 20180323132925.0 cr unu---uuuuu 170328e19920801xx s 000 0 eng 10.1007/BF00672795 doi (NATIONALLICENCE)springer-10.1007/BF00672795 Electronic absorption and fluorescence spectra and excited singlet-state dipole moments of biologically important pyrimidines [Elektronische Daten] [Cyril Párkányi, Christian Boniface, Jean-Jacques Aaron, Mame Gaye, Ratna Ghosh, László von Szentpály, Krishnan RaghuVeer] Electronic absorption and fluorescence emission spectra of several biologically important pyrimidines were measured at room temperature (298 K) in the following solvents: dioxane, ethyl ether, chloroform, ethyl acetate, 1-butanol, 2-propanol, methanol, dimethylformamide, acetonitrile, and dimethyl sulfoxide. The compounds studied were uracil, thymine, cytosine, 5-fluorouracil, 5-chlorouracil, 5-bromouracil, 5-iodouracil, 2-thiouracil, barbituric acid, and orotic acid. In combination with the ground-state dipole moments of the above compounds, these spectral data were used to determine their lowest excited singlet-state dipole moments using the soivatochromic method. The effects of the solvent upon the spectral properties and of the structure upon the ground and excited singlet-state dipole moments are discussed. For most of the compounds, the excited singlet-state dipole moments are higher than their ground-state counterparts. The theoretical dipole moments for all the pyrimidines listed above, as well as for pyrimidine, alloxan, and uracil-5-carboxylic acid, were calculated by two methods. One approach involved a combination of the PPP (π-LCI-SCF-MO) method for the π-contribution to the overall dipole moment and the σ-contribution obtained as a vector sum of the σ-bond moments and group moments. The second set of theoretical values was obtained by the CNDO/2 method. The results were compared with the experimental dipole moments. Plenum Publishing Corporation, 1992 Párkányi Cyril Department of Chemistry, Florida Atlantic University, 500 N.W. 20th Street, P.O. Box 3091, 33431-0991, Boca Raton, FL, USA aut Boniface Christian Department of Chemistry, Florida Atlantic University, 500 N.W. 20th Street, P.O. Box 3091, 33431-0991, Boca Raton, FL, USA aut Aaron Jean-Jacques Laboratoire de Chimie Organique Physique, Institut de Topologie et de Dynamique des Systèmes [Associé au CNRS], Université Paris VII, 1, rue Guy de la Brosse, F-75005, Paris, France aut Gaye Mame Laboratoire de Chimie Organique Physique, Institut de Topologie et de Dynamique des Systèmes [Associé au CNRS], Université Paris VII, 1, rue Guy de la Brosse, F-75005, Paris, France aut Ghosh Ratna Department of Chemistry, University of the West Indies, Mona Campus, St. Andrew, Kingston 7, Jamaica aut von Szentpály László Department of Chemistry, University of the West Indies, Mona Campus, St. Andrew, Kingston 7, Jamaica aut RaghuVeer Krishnan Center for Photochemical Sciences, Bowling Green State University, 43403, Bowling Green, OH, USA aut Structural Chemistry Kluwer Academic Publishers-Plenum Publishers 3/4(1992-08-01), 277-289 1040-0400 3:4<277 1992 3 11224 https://doi.org/10.1007/BF00672795 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00672795 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Párkányi Cyril Department of Chemistry, Florida Atlantic University, 500 N.W. 20th Street, P.O. Box 3091, 33431-0991, Boca Raton, FL, USA aut NATIONALLICENCE 700 1- Boniface Christian Department of Chemistry, Florida Atlantic University, 500 N.W. 20th Street, P.O. Box 3091, 33431-0991, Boca Raton, FL, USA aut NATIONALLICENCE 700 1- Aaron Jean-Jacques Laboratoire de Chimie Organique Physique, Institut de Topologie et de Dynamique des Systèmes [Associé au CNRS], Université Paris VII, 1, rue Guy de la Brosse, F-75005, Paris, France aut NATIONALLICENCE 700 1- Gaye Mame Laboratoire de Chimie Organique Physique, Institut de Topologie et de Dynamique des Systèmes [Associé au CNRS], Université Paris VII, 1, rue Guy de la Brosse, F-75005, Paris, France aut NATIONALLICENCE 700 1- Ghosh Ratna Department of Chemistry, University of the West Indies, Mona Campus, St. Andrew, Kingston 7, Jamaica aut NATIONALLICENCE 700 1- von Szentpály László Department of Chemistry, University of the West Indies, Mona Campus, St. Andrew, Kingston 7, Jamaica aut NATIONALLICENCE 700 1- RaghuVeer Krishnan Center for Photochemical Sciences, Bowling Green State University, 43403, Bowling Green, OH, USA aut NATIONALLICENCE 773 0- Structural Chemistry Kluwer Academic Publishers-Plenum Publishers 3/4(1992-08-01), 277-289 1040-0400 3:4<277 1992 3 11224 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer