Donor-Substituted Diphenylacetylene Derivatives Act as Electron Donors and Acceptors

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• 作者：Christine Onitsch ; Arnulf Rosspeintner ; Gonzalo Angulo ; Markus Griesser ; Milan Kivala ; Brian Frank ; Franc抬ois Diederich ; Georg Gescheidt
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：July 15, 2011
• 年：2011
• 卷：76
• 期：14
• 页码：5628-5635
• 全文大小：936K
• 年卷期：v.76,no.14(July 15, 2011)
• ISSN：1520-6904

文摘

Despite the predominant electron donor character of p-phenylenediamine, our studies on extended p-phenylenediamine derivatives show that they can not only be chemically oxidized, giving well-known Wurster-type radical cations, but also be chemically reduced, giving radical anions. Making use of EPR/ENDOR spectroscopy and supported by DFT calculations, we were able to reveal the extent of 蟺-electron delocalization in the paramagnetic species and to shed light onto the geometry and bond lengths. While for the radical anions spin was found to be mostly delocalized into the 蟺-system, the radical cations can be described as essentially N-centered. Furthermore, we performed electrochemical characterizations using cyclic voltammetry to gain insight into the thermodynamics of the redox processes. The photophysical properties of the parent extended p-phenylenediamine were investigated by absorption, emission, and excitation spectroscopy. The fluorescence quantum yield and the excited-state lifetime of the neutral precursors in hexane and acetonitrile were determined to establish elementary differences originating from solvent effects.