Abstract
Through a combined quantum mechanics/molecular mechanics (QM/MM) approach, we evaluate the photodynamics of the mono- and dithiolated azobenzenes when they are chemisorbed on a gold surface. The analysis of steric effects suggests that the presence of the surface influences the photoisomerization process of the chemisorbed monothiolated azobenzene. In particular, the trans → cis quantum yields decrease, and the nπ∗ state lifetimes become longer. The approach to the twisted conical intersection needed for the isomerization is hindered when the molecule is attached to a substrate because of the van der Waals interactions with the surface. For the cis isomer, the cis → trans photoisomerization quantum yield is almost unaffected, since this isomer is not flat, and thus the interaction with the surface is less remarkable. Dithiolated azobenzene can photoisomerize both trans → cis and cis → trans, also when doubly linked to the surface, preserving the two bonds with the gold atoms: the flexibility of the central azo-moiety enables the molecule to photoisomerize without any bond breaking. The quantum yields in this case are even higher than in the monothiolated case, probably because of the strained initial conformation, which must adapt to the available distances between the anchoring sites.
| Original language | English |
|---|---|
| Pages (from-to) | 5962-5974 |
| Number of pages | 13 |
| Journal | Journal of Physical Chemistry C |
| Volume | 119 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - 1 Jan 2015 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Energy(all)
Cite this
Can azobenzene photoisomerize when chemisorbed on a gold surface? An analysis of steric effects based on nonadiabatic dynamics simulations. / Benassi, Enrico; Granucci, Giovanni; Persico, Maurizio; Corni, Stefano.
In: Journal of Physical Chemistry C, Vol. 119, No. 11, 01.01.2015, p. 5962-5974.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Can azobenzene photoisomerize when chemisorbed on a gold surface? An analysis of steric effects based on nonadiabatic dynamics simulations
AU - Benassi, Enrico
AU - Granucci, Giovanni
AU - Persico, Maurizio
AU - Corni, Stefano
PY - 2015/1/1
Y1 - 2015/1/1
N2 - Through a combined quantum mechanics/molecular mechanics (QM/MM) approach, we evaluate the photodynamics of the mono- and dithiolated azobenzenes when they are chemisorbed on a gold surface. The analysis of steric effects suggests that the presence of the surface influences the photoisomerization process of the chemisorbed monothiolated azobenzene. In particular, the trans → cis quantum yields decrease, and the nπ∗ state lifetimes become longer. The approach to the twisted conical intersection needed for the isomerization is hindered when the molecule is attached to a substrate because of the van der Waals interactions with the surface. For the cis isomer, the cis → trans photoisomerization quantum yield is almost unaffected, since this isomer is not flat, and thus the interaction with the surface is less remarkable. Dithiolated azobenzene can photoisomerize both trans → cis and cis → trans, also when doubly linked to the surface, preserving the two bonds with the gold atoms: the flexibility of the central azo-moiety enables the molecule to photoisomerize without any bond breaking. The quantum yields in this case are even higher than in the monothiolated case, probably because of the strained initial conformation, which must adapt to the available distances between the anchoring sites.
AB - Through a combined quantum mechanics/molecular mechanics (QM/MM) approach, we evaluate the photodynamics of the mono- and dithiolated azobenzenes when they are chemisorbed on a gold surface. The analysis of steric effects suggests that the presence of the surface influences the photoisomerization process of the chemisorbed monothiolated azobenzene. In particular, the trans → cis quantum yields decrease, and the nπ∗ state lifetimes become longer. The approach to the twisted conical intersection needed for the isomerization is hindered when the molecule is attached to a substrate because of the van der Waals interactions with the surface. For the cis isomer, the cis → trans photoisomerization quantum yield is almost unaffected, since this isomer is not flat, and thus the interaction with the surface is less remarkable. Dithiolated azobenzene can photoisomerize both trans → cis and cis → trans, also when doubly linked to the surface, preserving the two bonds with the gold atoms: the flexibility of the central azo-moiety enables the molecule to photoisomerize without any bond breaking. The quantum yields in this case are even higher than in the monothiolated case, probably because of the strained initial conformation, which must adapt to the available distances between the anchoring sites.
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U2 - 10.1021/jp511269p
DO - 10.1021/jp511269p
M3 - Article
VL - 119
SP - 5962
EP - 5974
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 11
ER -