Combined Spectroelectrochemical and Theoretical Study of Electron-Rich Dendritic 2,5-Diaminothiophene Derivatives: N,N,N鈥?N鈥?Tetrakis-(4-diphenylamino-phenyl)-thiophene-2,5

详细信息    查看全文

• 作者：Vladim铆r Luke拧 ; Peter Rapta ; Kinga Haubner ; Marco Rosenkranz ; Horst Hartmann ; Lothar Dunsch
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：August 1, 2013
• 年：2013
• 卷：117
• 期：30
• 页码：6702-6711
• 全文大小：584K
• 年卷期：v.117,no.30(August 1, 2013)
• ISSN：1520-5215

文摘

The in situ spectroelectrochemical and electron spin resonance (ESR) behavior of the recently prepared N,N,N鈥?N鈥?tetrakis-(4-diphenylamino-phenyl)-thiophene-2,5-diamine 11 is presented. The results are compared to the ones of the parent 2,5-bis-diphenylamino-thiophene 4₁ as well as to the corresponding high-molar third dendrimer generation 8 containing the same thiophene-2,5-diamine core. The dendritic compound 11 can be reversibly oxidized in three separated steps to yield the corresponding stable monocation 11^鈥?, dication 11²⁺, and tetracation 11⁴⁺. A well resolved ESR spectrum of the corresponding cation radical 11^鈥? with dominating splittings from two nitrogen atoms and two hydrogen atoms was observed at the first oxidation peak similar to 4₁^鈥?. The shape of the SOMOs orbitals very well correlates with the proposed distribution of the unpaired electron mainly on the thiophene center and neighboring nitrogen atoms. The spin delocalization on the central thiophene moiety in the monocations for all three model compounds 4₁^鈥?, 11^鈥?, and 8^鈥? was confirmed. The computed single occupied molecular orbital (SOMO) for trication 11^鈥?+ is completely different compared to the SOMO of the corresponding monocation 11^鈥?, and it confirms a largely delocalized unpaired spin density. Dominating diamagnetic product was determined at the third oxidation peak, confirming the formation of a tetracation by a two electron oxidation of ESR silent dication. The positive charge is fully delocalized over the lateral parts of the molecule leading to the high stability of tetracation 11⁴⁺. The estimated theoretical limit energy of the lowest optical transition S₀ 鈫?S₁ is 2.90 eV, and it can be achieved for the 3D dendrimer generation.