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Lou X, van den Hout KP, van Houtem MHCJ, van Dongen JLJ, Vekemans JAJM, Meijer EW. Radical cation formation in characterization of novel C3-symmetric disks and their precursors by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2006; 41:659-69. [PMID: 16604573 DOI: 10.1002/jms.1025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Four C3-symmetrical tris(dipeptide) disks and their precursors were characterized using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS). The C3-symmetrical disks were based on a benzene-1,3,5-triscarboxamide core extended by oligopeptides with trialkoxyanilide tails. The results indicate that MALDI TOF MS is a powerful and straightforward analytical technique for characterizing C3-symmetrical disks and their precursors. Clear (pseudo)-molecular ion peaks could readily be identified. It is remarkable that strong radical ion signals were observed for all the compounds, including the anilines that were expected to be protonated prior to laser irradiation using acidic MALDI matrixes. Possible mechanisms for radical ion formation were investigated with the employment of radical scavengers, with various matrixes and with direct laser desorption/ionization (LDI). Most likely the radicals are formed by losing one electron from the aniline nitrogen and stabilized by conjugation through the phenyl ring. It appears that direct photo/thermal ionization of analytes is an important route for the radical ion formation of the compounds with trialkoxy aniline/anilide groups.
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Affiliation(s)
- Xianwen Lou
- Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
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Maroz A, Hermann R, Naumov S, Brede O. Ionization of Aniline and Its N-methyl and N-phenyl Substituted Derivatives by (Free) Electron Transfer to n-butyl Chloride Parent Radical Cations. J Phys Chem A 2005; 109:4690-6. [PMID: 16833809 DOI: 10.1021/jp0503056] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The electron transfer from aniline and its N-methyl as well as N-phenyl substituted derivatives (N-methylaniline, N,N-dimethylaniline, diphenylamine, triphenylamine) to parent solvent radical cations was studied by electron pulse radiolysis in n-butyl chloride solution. The ionization results in the case of aniline (ArNH2) and the secondary aromatic amines (Ar2NH, Ar(Me)NH) in the synchronous and direct formation of amine radical cations, as well as aminyl radicals, in comparable amounts. Subsequently, ArNH2*+ deprotonates in a delayed reaction with the present nucleophile Cl-, and forms further ArNH*. In contrast, tertiary aromatic amines such as triphenylamine and dimethylaniline yield primarily the corresponding amine radical cations Ar3N*+ or Ar(Me2)N*+, only. The persistent Ar3N*+ forms a charge transfer complex (dimer) with the parent amine molecule, whereas Ar(Me2)N*+ deprotonates to carbon-centered radicals Ar(Me)NCH2*.
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Affiliation(s)
- Andrej Maroz
- University of Leipzig, Interdisciplinary Group Time-Resolved Spectroscopy, Permoserstrasse 15, D-04303 Leipzig, Germany
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García C, Oyola R, Piñero LE, Arce R, Silva J, Sánchez V. Substitution and Solvent Effects on the Photophysical Properties of Several Series of 10-Alkylated Phenothiazine Derivatives. J Phys Chem A 2005; 109:3360-71. [PMID: 16833671 DOI: 10.1021/jp044530j] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The photophysical properties of several 2-substituted, 10-alkylated phenothiazines were measured in several solvents to investigate the relevance of the molecular structure in their photophysics and consequent photochemistry. Because the interaction modes of each drug and its corresponding species strongly depend on the variety of microenvironments in the cells, the properties of each one of these species must also be determined separately to understand fully the mechanism of action of the drug and the mechanism of its side effects. Information on the chemical interactions of the different species at the cellular level can be inferred from the corresponding electronic properties. In this work, we present absorption, steady-state, and time-resolved emission, laser flash photolysis, and quantum theoretical results for the ground state, the first excited singlet and triplet states, and the cation radical of promazine hydrochloride (PZ), 2-chlorpromazine hydrochloride (CPZ), 2-trifluoromethylpromazine hydrochloride (TFMPZ), 2-trifluoromethylperazine dihydrochloride (TFMP), 2-thiomethylpromazine (TMPZ), and thioridazine hydrochloride (TR). The corresponding nonalkylated phenothiazines are included as references. The photophysical properties of this drug family depend more on the solvent and the 2-substituents than on the dialkylaminopropyl chain. The largest effect was found for the triplet state of the 2-halogenated derivatives in phosphate buffer (PBS). Both the quantum yield and the lifetime of this intermediate drop to less than 5% of the corresponding value in organic solvents. The triplet state of halogenated promazines is efficiently quenched by a proton-transfer mechanism, and the rate of this quenching correlates very well with the phototoxicity of the promazine drugs. Therefore, we postulate that this species is directly related to the phototoxic side effect of neuroleptic drugs.
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Affiliation(s)
- Carmelo García
- Department of Chemistry, University of Puerto Rico-Humacao, Humacao, Puerto Rico.
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Greever JS, Turner JBM, Kauffman JF. Femtosecond Resonance-Enhanced Multiphoton Ionization of Perylene in Hexane. Electronic Excitation of the Radical Cation and Evidence of Hydrogen Abstraction from the Solvent. J Phys Chem A 2003. [DOI: 10.1021/jp014670i] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Jesse S. Greever
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211
| | | | - John F. Kauffman
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211
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García C, Oyola R, Piñero L, Cruz N, Alejandro F, Arce R, Nieves I. Photophysical, Electrochemical, and Theoretical Study of Protriptyline in Several Solvents. J Phys Chem B 2002. [DOI: 10.1021/jp0257855] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carmelo García
- Department of Chemistry, University of Puerto Rico, Humacao Campus, 100 Road 908, Humacao, Puerto Rico 00791-4300, and University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, Río Piedras, Puerto Rico 00931-3346
| | - Rolando Oyola
- Department of Chemistry, University of Puerto Rico, Humacao Campus, 100 Road 908, Humacao, Puerto Rico 00791-4300, and University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, Río Piedras, Puerto Rico 00931-3346
| | - Luis Piñero
- Department of Chemistry, University of Puerto Rico, Humacao Campus, 100 Road 908, Humacao, Puerto Rico 00791-4300, and University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, Río Piedras, Puerto Rico 00931-3346
| | - Nadya Cruz
- Department of Chemistry, University of Puerto Rico, Humacao Campus, 100 Road 908, Humacao, Puerto Rico 00791-4300, and University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, Río Piedras, Puerto Rico 00931-3346
| | - Felix Alejandro
- Department of Chemistry, University of Puerto Rico, Humacao Campus, 100 Road 908, Humacao, Puerto Rico 00791-4300, and University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, Río Piedras, Puerto Rico 00931-3346
| | - Rafael Arce
- Department of Chemistry, University of Puerto Rico, Humacao Campus, 100 Road 908, Humacao, Puerto Rico 00791-4300, and University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, Río Piedras, Puerto Rico 00931-3346
| | - Ileana Nieves
- Department of Chemistry, University of Puerto Rico, Humacao Campus, 100 Road 908, Humacao, Puerto Rico 00791-4300, and University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, Río Piedras, Puerto Rico 00931-3346
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Greever JS, Turner JBM, Kauffman JF. Multiphoton Excited Conductance Spectroscopy. 1. Application of the Born Model to Femtosecond Laser Excited Multiphoton Ionization of Nonpolar Liquids. J Phys Chem A 2001. [DOI: 10.1021/jp010692t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jesse S. Greever
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211-7600
| | - Joseph B M. Turner
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211-7600
| | - John F. Kauffman
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211-7600
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Ogawa T, Murata D, Soga H, Nakashima K. Ionization of Pyrene in Nonpolar Hydrocarbon Solvents as Studied by Simultaneous Two-Photon Ionization Spectra. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2001. [DOI: 10.1246/bcsj.74.673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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