Control over Photoinduced Energy and Electron Transfer in Supramolecular Polyads of Covalently linked azaBODIPY-Bisporphyrin 鈥楳olecular Clip鈥?Hosting Fullerene

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• 作者：Francis D鈥橲ouza ; Anu N. Amin ; Mohamed E. El-Khouly ; Navaneetha K. Subbaiyan ; Melvin E. Zandler ; Shunichi Fukuzumi
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：January 11, 2012
• 年：2012
• 卷：134
• 期：1
• 页码：654-664
• 全文大小：634K
• 年卷期：v.134,no.1(January 11, 2012)
• ISSN：1520-5126

文摘

A 鈥榤olecular clip鈥?featuring a near-IR emitting fluorophore, BF₂-chelated tetraarylazadipyrromethane (aza-BODIPY) covalently linked to two porphyrins (MP, M = 2H or Zn) has been newly synthesized to host a three-dimensional electron acceptor fullerene via a 鈥榯wo-point鈥?metal鈥搇igand axial coordination. Efficient singlet鈥搒inglet excitation transfer from ¹ZnP* to aza-BODIPY was witnessed in the dyad and triad in nonpolar and less polar solvents, such as toluene and o-dichlorobenzene, however, in polar solvents, additional electron transfer occurred along with energy transfer. A supramolecular tetrad was formed by assembling bis-pyridine functionalized fullerene via a 鈥榯wo-point鈥?metal鈥搇igand axial coordination, and the resulted complex was characterized by optical absorption and emission, computational, and electrochemical methods. Electron transfer from photoexcited zinc porphyrin to C₆₀ is witnessed in the supramolecular tetrad from the femtosecond transient absorption spectral studies. Further, the supramolecular polyads (triad or tetrad) were utilized to build photoelectrochemical cells to check their ability to convert light into electricity by fabricating FTO/SnO₂/polyad electrodes. The presence of azaBODIPY and fullerene entities of the tetrad improved the overall light energy conversion efficiency. An incident photon-to-current conversion efficiency of up to 17% has been achieved for the tetrad modified electrode.