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      Ionization energies, electron affinities and excitation energies of some steroid hormones calculated with the semiempirical HAM/3 method

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          Abstract

          Ionization energies, electron affinities and excitation energies of human sexual hormones such as testosterone, estradiol and related hormones were calculated with the semiempirical HAM/3 method. Observed photoelectron spectrum of androst-4-ene-3,17-dione was assigned using the calculated ionization energies. Spectra of electronic excitations in the region between 50 and 350nm of the molecules were simulated using the calculated values. There is a characteristic, high intensity, excitation band in the region between 75nm and 100nm in all of the steroids studied. The transition spectra above 150nm region are different from molecule to molecule.

          Translated abstract

          Potenciais de ionização, afinidades eletrônicas e energias de excitação de hormônios sexuais humanos, tais como testosterona, estradiol, além de outros hormônios relacionados foram calculados pelo método semiempírico HAM/3. O espectro fotoeletrônico observado de um esteróide, a androst-4-eno-3,17-diona, foi analisado por comparação com as energias de ionização calculadas. Os espectros eletrônicos de excitação na região entre 50 e 350 nm foram simulados utilizando os valores calculados. Existe uma banda de excitação característica, de alta intensidade, na região entre 75 e 100 nm em todos os esteróides estudados. Os espectros de transição na região acima de 150 nm são diferentes de uma molécula para outra.

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          Most cited references19

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          Time-resolved infrared spectroscopy of the lowest triplet state of thymine and thymidine.

          Vibrational spectra of the lowest energy triplet states of thymine and its 2'-deoxyribonucleoside, thymidine, are reported for the first time. Time-resolved infrared (TRIR) difference spectra were recorded over seven decades of time from 300 fs - 3 micros using femtosecond and nanosecond pump-probe techniques. The carbonyl stretch bands in the triplet state are seen at 1603 and ~1700 cm(-1) in room-temperature acetonitrile-d(3) solution. These bands and additional ones observed between 1300 and 1450 cm(-1) are quenched by dissolved oxygen on a nanosecond time scale. Density-functional calculations accurately predict the difference spectrum between triplet and singlet IR absorption cross sections, confirming the peak assignments and elucidating the nature of the vibrational modes. In the triplet state, the C4=O carbonyl exhibits substantial single-bond character, explaining the large (~70 cm(-1)) red shift in this vibration, relative to the singlet ground state. Femtosecond TRIR measurements unambiguously demonstrate that the triplet state is fully formed within the first 10 ps after excitation, ruling out a relaxed (1)npi* state as the triplet precursor.
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            Steroids

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              Textbook of Biochemistry with clinical correlation

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                Author and article information

                Contributors
                Role: ND
                Role: ND
                Journal
                jbchs
                Journal of the Brazilian Chemical Society
                J. Braz. Chem. Soc.
                Sociedade Brasileira de Química (São Paulo )
                1678-4790
                April 2001
                : 12
                : 2
                : 165-172
                Affiliations
                [1 ] Universidade Estadual de Campinas Brazil
                Article
                S0103-50532001000200007
                10.1590/S0103-50532001000200007
                2651c7cb-895b-4f87-a76a-a7d59564b79a

                http://creativecommons.org/licenses/by/4.0/

                History
                Product

                SciELO Brazil

                Self URI (journal page): http://www.scielo.br/scielo.php?script=sci_serial&pid=0103-5053&lng=en
                Categories
                CHEMISTRY, MULTIDISCIPLINARY

                General chemistry
                steroid,human sexual hormones,excitation spectra,photoelectron spectrum,semiempirical HAM/3 method

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