TY - JOUR
T1 - Conformational and Binding Effects on Interfacial Electron Transfer from Dual-Linker Sensitizers
AU - Yan, Han
AU - Avenoso, Joseph P.
AU - Doble, Samantha
AU - Harmer, Ryan
AU - Rego, Luis G.C.
AU - Galoppini, Elena
AU - Gundlach, Lars
N1 - Funding Information:
For the financial support, the authors are thankful to the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Office of Solar Energy Research, under award numbers DE-FG02-01ER15256 (Galoppini) and DESC0016288 (Gundlach)); spectral characterization of the compounds carried out at Rutgers Newark were collected on instrumentation funded by the National Science Foundation (award no. MRI-1726345). CNPq/Brazil and the National Laboratory for Scientific Computing (LNCC/MCTI, Brazil), and FAPESC-H2020-MSCA-RISE-2017 (OCTA, #778158) (Rego). Elena Galoppini is grateful to Rutgers University for a sabbatical leave, and Ryan Harmer thanks the Rutgers-Newark School of Graduate Studies for a 2020–2021 Dissertation Fellowship. L.G.C.R. is grateful to the Duke University and CNPq/Brazil for support during a sabbatical leave.
Publisher Copyright:
© 2021 American Chemical Society. All rights reserved.
PY - 2021/4/29
Y1 - 2021/4/29
N2 - Interfacial electron transfer (IET) between novel dual-linker perylenes and TiO2 was investigated by ultrafast spectroscopy and nonadiabatic quantum mechanics/molecular mechanics (QM/MM) simulations. The influence of the number of linkers (one vs two) and their substitution position (ortho vs peri) on IET was investigated. Perylene sensitizers derivatized with two acrylic acid linkers in the peri position, pDtBuPe(C2H2COOH)2 (bis-peri), and in the ortho position, oDtBuPe(C2H2COOH)2 (bis-ortho), were compared to their single-linker counterparts: pDtBuPeC2H2COOH (peri) and oDtBuPeC2H2COOH (ortho). MM simulations of the bis-peri and bis-ortho sensitizers predicted that, in both cases, only one linker binds covalently to the {101} surface of anatase TiO2, while the second one binds weakly via vdW or hydrogen-bonding interactions. Results from QM/MM simulations corroborated experimental injection times for all compounds, thereby supporting single-linker binding to the surface for the dual-linker sensitizers. The study showed that, surprisingly, IET from bis-peri was significantly slower than that from peri. Theory attributes this behavior to small conformational changes caused by steric interactions. The degrees of freedom that are most strongly correlated with variations in IET times were identified by principal component analysis. Comparison between bis-ortho and ortho showed, as expected, that the dual-linker sensitizer injects faster than the single-linker variant. However, the influence of the substitution position on IET was much smaller than expected based on the difference in the static electronic structure. Finally, the strong effect of conformational changes on IET was also observed experimentally in modulations of IET due to coupling to vibrational modes, in excellent agreement with the QM/MM simulations. This study shows that small conformational changes and vibrational coupling can have a significant influence on IET even on the femtosecond time scale. The addition of linkers that differ in bonding strength and serve different functions opens up new avenues for controlling IET dynamics.
AB - Interfacial electron transfer (IET) between novel dual-linker perylenes and TiO2 was investigated by ultrafast spectroscopy and nonadiabatic quantum mechanics/molecular mechanics (QM/MM) simulations. The influence of the number of linkers (one vs two) and their substitution position (ortho vs peri) on IET was investigated. Perylene sensitizers derivatized with two acrylic acid linkers in the peri position, pDtBuPe(C2H2COOH)2 (bis-peri), and in the ortho position, oDtBuPe(C2H2COOH)2 (bis-ortho), were compared to their single-linker counterparts: pDtBuPeC2H2COOH (peri) and oDtBuPeC2H2COOH (ortho). MM simulations of the bis-peri and bis-ortho sensitizers predicted that, in both cases, only one linker binds covalently to the {101} surface of anatase TiO2, while the second one binds weakly via vdW or hydrogen-bonding interactions. Results from QM/MM simulations corroborated experimental injection times for all compounds, thereby supporting single-linker binding to the surface for the dual-linker sensitizers. The study showed that, surprisingly, IET from bis-peri was significantly slower than that from peri. Theory attributes this behavior to small conformational changes caused by steric interactions. The degrees of freedom that are most strongly correlated with variations in IET times were identified by principal component analysis. Comparison between bis-ortho and ortho showed, as expected, that the dual-linker sensitizer injects faster than the single-linker variant. However, the influence of the substitution position on IET was much smaller than expected based on the difference in the static electronic structure. Finally, the strong effect of conformational changes on IET was also observed experimentally in modulations of IET due to coupling to vibrational modes, in excellent agreement with the QM/MM simulations. This study shows that small conformational changes and vibrational coupling can have a significant influence on IET even on the femtosecond time scale. The addition of linkers that differ in bonding strength and serve different functions opens up new avenues for controlling IET dynamics.
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U2 - 10.1021/acs.jpcc.0c11299
DO - 10.1021/acs.jpcc.0c11299
M3 - Article
AN - SCOPUS:85105105272
SN - 1932-7447
VL - 125
SP - 8667
EP - 8676
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 16
ER -