Effect of chlorine as substituent on the photochemistry and acid-base properties of β-carboline alkaloids
The UV-absorption, fluorescence excitation and emission spectra of the 6-chloro-, 8-chloro-, 6,8-dichloro-derivatives of nor-harmane, harmane and harmine and the 8-chloro-derivative of harmol were studied. These studies were performed in EtOH and in EtOH + 1% perchloric acid solutions (pa). Furtherm...
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2006
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10111344_v82_n2_p79_Tarzi http://hdl.handle.net/20.500.12110/paper_10111344_v82_n2_p79_Tarzi |
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paper:paper_10111344_v82_n2_p79_Tarzi2023-06-08T15:59:42Z Effect of chlorine as substituent on the photochemistry and acid-base properties of β-carboline alkaloids Chloro-β-Carbolines Chloro-harmane Chloro-harmine Chloro-harmol Chloro-nor-harmane 6 chloroharmane 6 chloroharmine 6 chloronorharmane 6,8 dichloroharmane 6,8 dichloroharmine 6,8 dichloronorharmane 8 chloroharmane 8 chloroharmine 8 chloroharmol 8 chloronorharmane acetonitrile alcohol alkaloid derivative beta carboline beta carboline derivative chlorine harman perchloric acid unclassified drug acid base balance aqueous solution article calculation chemical reaction controlled study drug structure enthalpy flame photometry fluorescence analysis oscillation photochemistry priority journal proton transport quantum yield radiation absorption spectrophotometry structure analysis ultraviolet radiation Carbolines Chlorine Harmine Hydrogen-Ion Concentration Molecular Structure Photochemistry Spectrometry, Fluorescence Spectrophotometry, Ultraviolet Ultraviolet Rays Water The UV-absorption, fluorescence excitation and emission spectra of the 6-chloro-, 8-chloro-, 6,8-dichloro-derivatives of nor-harmane, harmane and harmine and the 8-chloro-derivative of harmol were studied. These studies were performed in EtOH and in EtOH + 1% perchloric acid solutions (pa). Furthermore, fluorescence quantum yields (φf) in both media and in acetonitrile and acetonitrile + 1% perchloric acid solutions at 298 K were measured. The HOMO and LUMO energy, the positions (λmax) and oscillator strength (f) of the 1S1 ← 1S0 band for all the neutral and protonated β-carbolines studied were calculated and compared with the experimental data. The pKa values in aqueous solution for for 6-chloro-, 8-chloro- and 6,8-dichloro-nor-harmane, harmane and harmine and 8-chloro-harmol were spectrophotometrically measured (pKa(H2O)). The change of the acid-base character of these compounds on going from the ground state (pKa) to the first electronic excited singlet state (pKa*) as Δ pKa = pKa* - pKa, in ethanol solution at 298 K were calculated (ΔpKa(EtOH)). Ground-state proton affinity (PA) for all the compounds studied defined as minus the enthalpy change of the reaction M + H+ → MH+ (gas state) were calculated. Basicity relative to pyridine (ΔHrPy) defined as the enthalpy change of the isodesmic reaction MH+ + Py → M + PyH+ in gas state and in water solution, were also calculated (ab initio calculations). The effect of chlorine as substituent on the photochemistry and acid-base properties of the β-carboline alkaloids is discussed. © 2005 Elsevier B.V. All rights reserved. 2006 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10111344_v82_n2_p79_Tarzi http://hdl.handle.net/20.500.12110/paper_10111344_v82_n2_p79_Tarzi |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Chloro-β-Carbolines Chloro-harmane Chloro-harmine Chloro-harmol Chloro-nor-harmane 6 chloroharmane 6 chloroharmine 6 chloronorharmane 6,8 dichloroharmane 6,8 dichloroharmine 6,8 dichloronorharmane 8 chloroharmane 8 chloroharmine 8 chloroharmol 8 chloronorharmane acetonitrile alcohol alkaloid derivative beta carboline beta carboline derivative chlorine harman perchloric acid unclassified drug acid base balance aqueous solution article calculation chemical reaction controlled study drug structure enthalpy flame photometry fluorescence analysis oscillation photochemistry priority journal proton transport quantum yield radiation absorption spectrophotometry structure analysis ultraviolet radiation Carbolines Chlorine Harmine Hydrogen-Ion Concentration Molecular Structure Photochemistry Spectrometry, Fluorescence Spectrophotometry, Ultraviolet Ultraviolet Rays Water |
| spellingShingle |
Chloro-β-Carbolines Chloro-harmane Chloro-harmine Chloro-harmol Chloro-nor-harmane 6 chloroharmane 6 chloroharmine 6 chloronorharmane 6,8 dichloroharmane 6,8 dichloroharmine 6,8 dichloronorharmane 8 chloroharmane 8 chloroharmine 8 chloroharmol 8 chloronorharmane acetonitrile alcohol alkaloid derivative beta carboline beta carboline derivative chlorine harman perchloric acid unclassified drug acid base balance aqueous solution article calculation chemical reaction controlled study drug structure enthalpy flame photometry fluorescence analysis oscillation photochemistry priority journal proton transport quantum yield radiation absorption spectrophotometry structure analysis ultraviolet radiation Carbolines Chlorine Harmine Hydrogen-Ion Concentration Molecular Structure Photochemistry Spectrometry, Fluorescence Spectrophotometry, Ultraviolet Ultraviolet Rays Water Effect of chlorine as substituent on the photochemistry and acid-base properties of β-carboline alkaloids |
| topic_facet |
Chloro-β-Carbolines Chloro-harmane Chloro-harmine Chloro-harmol Chloro-nor-harmane 6 chloroharmane 6 chloroharmine 6 chloronorharmane 6,8 dichloroharmane 6,8 dichloroharmine 6,8 dichloronorharmane 8 chloroharmane 8 chloroharmine 8 chloroharmol 8 chloronorharmane acetonitrile alcohol alkaloid derivative beta carboline beta carboline derivative chlorine harman perchloric acid unclassified drug acid base balance aqueous solution article calculation chemical reaction controlled study drug structure enthalpy flame photometry fluorescence analysis oscillation photochemistry priority journal proton transport quantum yield radiation absorption spectrophotometry structure analysis ultraviolet radiation Carbolines Chlorine Harmine Hydrogen-Ion Concentration Molecular Structure Photochemistry Spectrometry, Fluorescence Spectrophotometry, Ultraviolet Ultraviolet Rays Water |
| description |
The UV-absorption, fluorescence excitation and emission spectra of the 6-chloro-, 8-chloro-, 6,8-dichloro-derivatives of nor-harmane, harmane and harmine and the 8-chloro-derivative of harmol were studied. These studies were performed in EtOH and in EtOH + 1% perchloric acid solutions (pa). Furthermore, fluorescence quantum yields (φf) in both media and in acetonitrile and acetonitrile + 1% perchloric acid solutions at 298 K were measured. The HOMO and LUMO energy, the positions (λmax) and oscillator strength (f) of the 1S1 ← 1S0 band for all the neutral and protonated β-carbolines studied were calculated and compared with the experimental data. The pKa values in aqueous solution for for 6-chloro-, 8-chloro- and 6,8-dichloro-nor-harmane, harmane and harmine and 8-chloro-harmol were spectrophotometrically measured (pKa(H2O)). The change of the acid-base character of these compounds on going from the ground state (pKa) to the first electronic excited singlet state (pKa*) as Δ pKa = pKa* - pKa, in ethanol solution at 298 K were calculated (ΔpKa(EtOH)). Ground-state proton affinity (PA) for all the compounds studied defined as minus the enthalpy change of the reaction M + H+ → MH+ (gas state) were calculated. Basicity relative to pyridine (ΔHrPy) defined as the enthalpy change of the isodesmic reaction MH+ + Py → M + PyH+ in gas state and in water solution, were also calculated (ab initio calculations). The effect of chlorine as substituent on the photochemistry and acid-base properties of the β-carboline alkaloids is discussed. © 2005 Elsevier B.V. All rights reserved. |
| title |
Effect of chlorine as substituent on the photochemistry and acid-base properties of β-carboline alkaloids |
| title_short |
Effect of chlorine as substituent on the photochemistry and acid-base properties of β-carboline alkaloids |
| title_full |
Effect of chlorine as substituent on the photochemistry and acid-base properties of β-carboline alkaloids |
| title_fullStr |
Effect of chlorine as substituent on the photochemistry and acid-base properties of β-carboline alkaloids |
| title_full_unstemmed |
Effect of chlorine as substituent on the photochemistry and acid-base properties of β-carboline alkaloids |
| title_sort |
effect of chlorine as substituent on the photochemistry and acid-base properties of β-carboline alkaloids |
| publishDate |
2006 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10111344_v82_n2_p79_Tarzi http://hdl.handle.net/20.500.12110/paper_10111344_v82_n2_p79_Tarzi |
| _version_ |
1768543192175607808 |