TY - JOUR
T1 - Understanding the Dynamics Behind the Photoisomerization of a Light-Driven Fluorene Molecular Rotary Motor
AU - Kazaryan, Andranik
AU - Kistemaker, Jos C.M.
AU - Schäfer, Lars V.
AU - Browne, Wesley R.
AU - Feringa, Ben L.
AU - Filatov, Michael
N1 - Relation: http://www.rug.nl/scheikunde/onderzoek/scholen/stratingh/index
date_submitted:2010
Rights: University of Groningen, Stratingh Institute for Chemistry
PY - 2010/4/22
Y1 - 2010/4/22
N2 - Light-driven molecular rotary motors derived from chiral overcrowded alkenes represent a broad class of compounds for which photochemical rearrangements lead to large scale motion of one part of the molecule with respect to another. It is this motion/change in molecular shape that is employed in many of their applications. A key group in this class are the molecular rotary motors that undergo unidirectional light-driven rotation about a double bond through a series of photochemical and thermal steps. In the present contribution we report a combined quantum chemical and molecular dynamics study of the mechanism of the rotational cycle of the fluorene-based molecular rotary motor 9-(2,4,7-trimethy1-2,3-dihydro-1H-inden-1-ylidene)-9H-fluorene (1). The potential energy surfaces of the ground and excited singlet states of I were calculated, and it was found that conical intersections play a central role in the mechanism of photo conversion between the stable conformer of 1 and its metastable conformer. Molecular dynamics simulations indicate that the average lifetime of the fluorene motor in the excited state is 1.40 +/- 0.10 ps when starting from the stable conformer, which increases to 1.77 +/- 0.13 ps for the reverse photoisomerization. These simulations indicate that the quantum yield of photoisomerization of the stable conformer is 0.92, whereas it is only 0.40 for the reverse photoisomerization. For the first time, a theoretical understanding of the experimentally observed photostationary state of 1 is reported that provides a detailed picture of the photoisomerization dynamics in overcrowded alkene-based molecular motor 1. The analysis of the electronic structure of the fluorene molecular motor holds considerable implications for the design of molecular motors. Importantly, the role of pyramidalization and conical intersections offer new insight into the factors that dominate the photostationary state achieved in these systems.
AB - Light-driven molecular rotary motors derived from chiral overcrowded alkenes represent a broad class of compounds for which photochemical rearrangements lead to large scale motion of one part of the molecule with respect to another. It is this motion/change in molecular shape that is employed in many of their applications. A key group in this class are the molecular rotary motors that undergo unidirectional light-driven rotation about a double bond through a series of photochemical and thermal steps. In the present contribution we report a combined quantum chemical and molecular dynamics study of the mechanism of the rotational cycle of the fluorene-based molecular rotary motor 9-(2,4,7-trimethy1-2,3-dihydro-1H-inden-1-ylidene)-9H-fluorene (1). The potential energy surfaces of the ground and excited singlet states of I were calculated, and it was found that conical intersections play a central role in the mechanism of photo conversion between the stable conformer of 1 and its metastable conformer. Molecular dynamics simulations indicate that the average lifetime of the fluorene motor in the excited state is 1.40 +/- 0.10 ps when starting from the stable conformer, which increases to 1.77 +/- 0.13 ps for the reverse photoisomerization. These simulations indicate that the quantum yield of photoisomerization of the stable conformer is 0.92, whereas it is only 0.40 for the reverse photoisomerization. For the first time, a theoretical understanding of the experimentally observed photostationary state of 1 is reported that provides a detailed picture of the photoisomerization dynamics in overcrowded alkene-based molecular motor 1. The analysis of the electronic structure of the fluorene molecular motor holds considerable implications for the design of molecular motors. Importantly, the role of pyramidalization and conical intersections offer new insight into the factors that dominate the photostationary state achieved in these systems.
KW - PHOTOACTIVE YELLOW PROTEIN
KW - DENSITY-FUNCTIONAL THEORY
KW - REFERENCED KOHN-SHAM
KW - AB-INITIO
KW - UNIDIRECTIONAL ROTATION
KW - CONICAL INTERSECTIONS
KW - ELECTRON CORRELATION
KW - SEMIEMPIRICAL METHODS
KW - VISUAL PIGMENT
KW - CHROMOPHORE
U2 - 10.1021/jp100609m
DO - 10.1021/jp100609m
M3 - Article
VL - 114
SP - 5058
EP - 5067
JO - The Journal of Physical Chemistry. A: Molecules, Spectroscopy, Kinetics, Environment, & General Theory
JF - The Journal of Physical Chemistry. A: Molecules, Spectroscopy, Kinetics, Environment, & General Theory
SN - 1089-5639
IS - 15
ER -