Health & Environmental Research Online (HERO)

Print Feedback Export to File
Journal Article 
On the Role of Hydrogen Bonds in Photoinduced Electron-Transfer Dynamics between 9-Fluorenone and Amine Solvents 
Ghosh, HN; Adamczyk, K; Verma, S; Dreyer, J; Nibbering, ET 
In Press 
Chemistry: A European Journal
ISSN: 0947-6539
EISSN: 1521-3765 
Using ultrafast fluorescence upconversion and mid-infrared spectroscopy, we explore the role of hydrogen bonds in the photoinduced electron transfer (ET) between 9-fluorenone (FLU) and the solvents trimethylamine (TEA) and dimethylamine (DEA). FLU shows hydrogen-bond dynamics in the methanol solvent upon photoexcitation, and similar effects may be anticipated when using DEA, whereas no hydrogen bonds can occur in TEA. Photoexcitation of the electron-acceptor dye molecule FLU with a 400 nm pump pulse induces ultrafast ET from the amine solvents, which is followed by 100 fs IR probe pulses as well as fluorescence upconversion, monitoring the time evolution of marker bands of the FLU S(1) state and the FLU radical anion, and an overtone band of the amine solvent, marking the transient generation of the amine radical cation. A comparison of the experimentally determined forward charge-separation and backward charge-recombination rates for the FLU-TEA and FLU-DEA reaction systems with the driving-force dependencies calculated for the forward and backward ET rates reveals that additional degrees of freedom determine the ET reaction dynamics for the FLU-DEA system. We suggest that hydrogen bonding between the DEA molecules plays a key role in this behaviour. 
amines; donor-acceptor systems; electron transfer; hydrogen bonds; IR spectroscopy 
• Methanol (Non-Cancer)
     Search 2012
     Search Jan 30 2013