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Distance‐Dependent Electron Transfer Kinetics in Axially Connected Silicon Phthalocyanine‐Fullerene Conjugates
ChemPhysChem ( IF 2.9 ) Pub Date : 2020-07-30 , DOI: 10.1002/cphc.202000578
Luis Martín‐Gomis 1 , Sairaman Seetharaman 2 , David Herrero 1 , Paul A. Karr 3 , Fernando Fernández‐Lázaro 1 , Francis D'Souza 2 , Ángela Sastre‐Santos 1
Affiliation  

The effect of donor‐acceptor distance in controlling the rate of electron transfer in axially linked silicon phthalocyanine‐C60 dyads has been investigated. For this, two C60‐SiPc‐C60 dyads, 1 and 2, varying in their donor‐acceptor distance, have been newly synthesized and characterized. In the case of C60‐SiPc‐C60 1 where the SiPc and C60 are separated by a phenyl spacer, faster electron transfer was observed with kcs equal to 2.7×109 s−1 in benzonitrile. However, in the case of C60‐SiPc‐C60 2, where SiPc and C60 are separated by a biphenyl spacer, a slower electron transfer rate constant, kcs=9.1×108 s−1, was recorded. The addition of an extra phenyl spacer in 2 increased the donor‐acceptor distance by ∼4.3 Å, and consequently, slowed down the electron transfer rate constant by a factor of ∼3.7. The charge separated state lasted over 3 ns, monitoring time window of our femtosecond transient spectrometer. Complimentary nanosecond transient absorption studies revealed formation of 3SiPc* as the end product and suggested the final lifetime of the charge separated state to be in the 3–20 ns range. Energy level diagrams established to comprehend these mechanistic details indicated that the comparatively high‐energy SiPc.+‐C60.− charge separated states (1.57 eV) populated the low‐lying 3SiPc* (1.26 eV) prior returning to the ground state.

中文翻译:

轴向连接的酞菁硅-富勒烯共轭物中依赖于距离的电子转移动力学

已经研究了供体-受体距离在控制轴向连接的硅酞菁-C 60双分子中电子转移速率的影响。对于这一点,两个C 60 -SiPc-C 60二价基,12,在其供体-受体距离而变化,已经被新合成和表征。在C 60 -SiPc-C 60 1的情况下,SiPc和C 60被苯基间隔物隔开,观察到更快的电子转移,在苄腈中的k cs等于2.7×10 9  s -1。但是,对于C 60 -SiPc-C 60 参照图2,其中SiPc和C 60被联苯间隔物隔开,记录了较慢的电子传递速率常数k cs= 9.1×10 8  s -1。在2中添加一个额外的苯基间隔基可以使供体-受体距离增加约4.3Å,因此,将电子传输速率常数降低了约3.7倍。电荷分离状态持续了3 ns以上,监视着我们的飞秒瞬态光谱仪的时间窗口。免费的纳秒瞬态吸收研究表明形成了3SiPc *作为最终产品,建议电荷分离状态的最终寿命为3–20 ns。为了理解这些机械细节而建立的能级图表明,相对高能量的SiPc + + C 60 .-电荷分离状态(1.57 eV)在返回基态之前填充了较低的3 SiPc *(1.26 eV)。
更新日期:2020-07-30
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