PMID- 25178510
OWN - NLM
STAT- MEDLINE
DCOM- 20150915
LR  - 20150122
IS  - 1520-5207 (Electronic)
IS  - 1520-5207 (Linking)
VI  - 119
IP  - 3
DP  - 2015 Jan 22
TI  - Direct QM/MM excited-state dynamics of retinal protonated Schiff base in 
      isolation and methanol solution.
PG  - 704-14
LID - 10.1021/jp5038798 [doi]
AB  - We use the full multiple spawning (FMS) dynamics approach with a hybrid quantum 
      mechanics/molecular mechanics (QM/MM) reparameterized semiempirical method to 
      investigate the excited-state dynamics of retinal protonated Schiff base (RPSB) 
      in isolation, in neat methanol solution, and in methanol solution with a Cl(-) 
      counterion. The excited-state lifetime is dramatically affected by MeOH solvent, 
      which slows down the photoisomerization by an order of magnitude. We show that 
      this is due to charge migration in the RPSB chromophore and the concomitant 
      solvent friction in polar media. Simulation results are compared to experiments 
      where available, with good agreement for excited-state lifetimes, bond 
      selectivity of isomerization, and the time/energy-resolved fluorescence spectrum. 
      We find that the inclusion of a Cl(-) counterion in the simulations has little 
      effect on lifetimes, mechanism, or bond selectivity. In contrast to previous 
      studies limited to RPSB and a surrounding counterion, we find that the placement 
      of the counterion has little effect on bond selectivity. This suggests that 
      dielectric screening can spoil the effect of a counterion in directing 
      excited-state reactivity.
FAU - Punwong, Chutintorn
AU  - Punwong C
AD  - Department of Physics, Faculty of Science, and Trace Analysis and Biosensor 
      Research Center, Prince of Songkla University , Songkhla 90112, Thailand.
FAU - Owens, Jane
AU  - Owens J
FAU - Martinez, Todd J
AU  - Martinez TJ
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
DEP - 20140917
PL  - United States
TA  - J Phys Chem B
JT  - The journal of physical chemistry. B
JID - 101157530
RN  - 0 (Gases)
RN  - 0 (Protons)
RN  - 0 (Schiff Bases)
RN  - 0 (Solutions)
RN  - 4R7X1O2820 (Chlorine)
RN  - Y4S76JWI15 (Methanol)
SB  - IM
MH  - Chlorine/chemistry
MH  - Gases/chemistry
MH  - Isomerism
MH  - Kinetics
MH  - Methanol/*chemistry
MH  - Models, Molecular
MH  - Molecular Conformation
MH  - *Protons
MH  - *Quantum Theory
MH  - Retina/*chemistry
MH  - Schiff Bases/chemistry
MH  - Solutions
EDAT- 2014/09/03 06:00
MHDA- 2015/09/16 06:00
CRDT- 2014/09/03 06:00
PHST- 2014/09/03 06:00 [entrez]
PHST- 2014/09/03 06:00 [pubmed]
PHST- 2015/09/16 06:00 [medline]
AID - 10.1021/jp5038798 [doi]
PST - ppublish
SO  - J Phys Chem B. 2015 Jan 22;119(3):704-14. doi: 10.1021/jp5038798. Epub 2014 Sep 
      17.