PMID- 19653674
OWN - NLM
STAT- MEDLINE
DCOM- 20100126
LR  - 20131121
IS  - 1520-5215 (Electronic)
IS  - 1089-5639 (Linking)
VI  - 113
IP  - 43
DP  - 2009 Oct 29
TI  - Is the photoinduced isomerization in retinal protonated Schiff bases a single- or 
      double-torsional process?
PG  - 11907-18
LID - 10.1021/jp903329j [doi]
AB  - Nonadiabatic photodynamical simulations are presented for the all-trans and 5-cis 
      isomers of the hepta-3,5,7-trieniminium cation (PSB4) with the goal of 
      characterizing the types of torsional modes occurring in the cis-trans 
      isomerization processes in retinal protonated Schiff base (RPSB), the rhodopsin 
      and bacteriorhodopsin chropomhore. Steric hindrance of these processes due to 
      environmental effects have been modeled by imposing different sets of mechanical 
      restrictions on PSB4 and studying its response in the photodynamics. Both the 
      mechanism toward the conical intersection and the initial phase of the hot ground 
      state dynamics has been studied in detail. A total of 600 trajectories have been 
      computed using a complete active space self-consistent field wave function. 
      Careful comparison with higher level methods has been made in order to verify the 
      accuracy of the results. The most important mechanism driving restricted PSB4 
      isomerization in the excited state is characterized by two concerted twist 
      motions (bipedal and closely related to it nonrigid bipedal) from which only one 
      torsion tends to be continued during the relaxation into the ground state. The 
      one-bond-flip is found to be important for the trans isomer as well. The main 
      isomerization trend is a torsion around C(5)C(6) (equivalent to C(11)C(12) in 
      RPSB) in the case of the cis isomer and around C(3)C(4) (C(13)C(14) in RPSB) in 
      the case of the trans isomer. The simulations show an initial 70 fs relaxation 
      into twisted regions and give an average internal conversion time of 130-140 fs, 
      timings that are fully compatible with the general picture described by 
      femtosecond transient absorption spectroscopic studies.
FAU - Szymczak, Jaroslaw J
AU  - Szymczak JJ
AD  - Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, 
      A-1090, Vienna, Austria. jaroslaw.szymczak@univie.ac.at
FAU - Barbatti, Mario
AU  - Barbatti M
FAU - Lischka, Hans
AU  - Lischka H
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Phys Chem A
JT  - The journal of physical chemistry. A
JID - 9890903
RN  - 0 (Protons)
RN  - 0 (Schiff Bases)
RN  - 53026-44-1 (Bacteriorhodopsins)
RN  - 9009-81-8 (Rhodopsin)
RN  - RR725D715M (Retinaldehyde)
SB  - IM
MH  - Algorithms
MH  - Bacteriorhodopsins/chemistry/metabolism
MH  - Molecular Conformation
MH  - Molecular Dynamics Simulation
MH  - Motion
MH  - *Photochemical Processes
MH  - *Protons
MH  - Retinaldehyde/*chemistry
MH  - Rhodopsin/chemistry/metabolism
MH  - Schiff Bases/chemistry
MH  - Stereoisomerism
MH  - Thermodynamics
EDAT- 2009/08/06 09:00
MHDA- 2010/01/27 06:00
CRDT- 2009/08/06 09:00
PHST- 2009/08/06 09:00 [entrez]
PHST- 2009/08/06 09:00 [pubmed]
PHST- 2010/01/27 06:00 [medline]
AID - 10.1021/jp903329j [doi]
PST - ppublish
SO  - J Phys Chem A. 2009 Oct 29;113(43):11907-18. doi: 10.1021/jp903329j.