Regulation of Charge Delocalization in a Heteronuclear Fe sub(2)Ru System by a Stepwise Photochromic Process

• Published in: Chemistry : a European journal 2015-02, Vol.21 (8), p.3318-3326
• Main Authors: Xu, Guang-Tao, Li, Bin, Wang, Jin-Yun, Zhang, Dao-Bin, Chen, Zhong-Ning
• Format: Article
• Language: English
• Subjects: Charge; Charge preparation; Control; Conversion; Electronics; Ruthenium; Spectroscopic analysis; Spectroscopy
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201405464

Heteronuclear complexes FeCp sub(2)--DTE--CC--Ru(dp pe) sub(2)Cl (1o; dppe=1,2-bis(diphenylphosphino)ethane, Cp=cyclopentadienyl, DTE=dithienylethene) and FeCp sub(2)--DTE--CC--Ru(dp pe) sub(2)--CC--DTE--FeCp sub( 2) (2oo), with redox-active ferrocenyl and ruthenium centers separated by a photochromic DTE moiety, were prepared to achieve photoswitchable charge delocalization and FeRu electronic communication. Upon UV-light irradiation of 2oo, the FeRu heterometallic electronic interaction is increasingly facilitated with stepwise photocyclization, 2oo arrow right 2co arrow right 2cc; this is ascribed to the gradual increase in pi -conjugated systems. The near-infrared absorptions in mixed-valence species [2oo] super(+)/[2co] super(+)/[2cc] super(+) are gradually intensified following the conversion of [2oo] super(+) arrow right [2co] super(+) arrow right [2cc] super(+), which demonstrates that the extent of charge delocalization shows progressive enhancement with stepwise photocyclization. As revealed by electrochemical, spectroscopic, and theoretical studies, complex 2 exhibits nine switchable states through stepwise photochromic and reversible redox processes. How does your metal talk? Heteronuclear complexes (see scheme), with redox-active ferrocenyl and ruthenium centers separated by a photochromic dithienylethene (DTE) moiety, were prepared to achieve photoswitchable charge delocalization and FeRu electronic communication.