Electronic Resource
College Park, Md.
:
American Institute of Physics (AIP)
The Journal of Chemical Physics
115 (2001), S. 8351-8358
ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
It is shown that the direct precursor for the formation of a photochrome in Schiff bases is a "twisted" geometry S1 state of a keto tautomer in which the O(centered ellipsis)N–H hydrogen bond is broken. In photochromic Schiff bases this state is close in energy to the ππ* state of the cis-ketone obtained from the initially optically excited enol species by an ultrafast excited-state proton transfer, in particular, in N-salicylidene-α-methylbenzylamine (SMB), it lies within 1 kcal/mol from the ππ* state of cis-ketone and ∼16 kcal/mol below the initial ππ* state of enol. The excited-state proton transfer in SMB is predicted to take ∼15 fs and to be nearly barrierless. It is also shown that the initial ππ* state of enol can decay via competing route to a twisted geometry nNπ* state of enol with the energy ∼20 kcal/mol below that state. © 2001 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1411999
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