TY - JOUR
T1 - Examining the influence of bilayer structure on energy transfer and molecular photon upconversion in metal ion linked multilayers
AU - Arcidiacono, Ashley
AU - Zhou, Yan
AU - Zhang, Wendi
AU - Ellison, Jeffrey O.
AU - Ayad, Suliman
AU - Knorr, Erica S.
AU - Peters, Autumn N.
AU - Zheng, Lianqing
AU - Yang, Wei
AU - Scott Saavedra, S.
AU - Hanson, Kenneth
N1 - Funding Information:
Photon upconversion measurements were supported by the National Science Foundation under Grant No. DMR-1752782. Structural characterization of the bilayer was supported by the Army Research Office under Grant No. W911NF-19-1-0357. All ATR data was collected in the W.M. Keck Center for Nano-Scale Imaging in the Department of Chemistry and Biochemistry at the University of Arizona. This instrument was supported as part of the Center for Interface Science: Solar-Electric Materials (CIS:SEM), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DESC0001084. A.N.P. was supported by the NSF-REU program under Grant No. CHE-1659661. Transient absorption measurements were performed on a spectrometer supported by the National Science Foundation under Grant No. CHE-1919633. MD simulation efforts were supported by the National Institute of Health under Grant R01GM111886.
Funding Information:
Photon upconversion measurements were supported by the National Science Foundation under Grant No. DMR-1752782. Structural characterization of the bilayer was supported by the Army Research Office under Grant No. W911NF-19-1-0357. All ATR data was collected in the W.M. Keck Center for Nano-Scale Imaging in the Department of Chemistry and Biochemistry at the University of Arizona. This instrument was supported as part of the Center for Interface Science: Solar-Electric Materials (CIS:SEM), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001084. A.N.P. was supported by the NSF-REU program under Grant No. CHE-1659661. Transient absorption measurements were performed on a spectrometer supported by the National Science Foundation under Grant No. CHE-1919633. MD simulation efforts were supported by the National Institute of Health under Grant R01GM111886.
Publisher Copyright:
© 2020 American Chemical Society
PY - 2020/10/29
Y1 - 2020/10/29
N2 - Metal ion linked multilayers are a unique motif to spatially control and geometrically restrict molecules on a metal oxide surface, which is of interest in a number of promising applications. Here we use a bilayer composed of a metal oxide surface, an anthracene annihilator molecule, Zn(II) linking ion, and porphyrin sensitizers to probe the influence of the position of the metal ion binding site on energy transfer, photon upconversion, and photocurrent generation. Despite being energetically similar, varying the position of the carboxy metal ion binding group (i.e., ortho, meta, para) of the Pt(II) tetraphenyl porphyrin sensitizer had a large impact on energy transfer rates and upconverted photocurrent that can be attributed to differences in their geometries. From polarized attenuated total reflectance measurements of the bilayers on ITO, we found that the orientation of the first layer (anthracene) was largely unperturbed by subsequent layers. However, the tilt angle of the porphyrin plane varies dramatically from 41° to 64° to 57° for the p-, m-, and o-COOH substituted porphyrin molecules, which is likely responsible for the variation in energy transfer rates. We go on to show using molecular dynamics simulations that there is considerable flexibility in porphyrin orientation, indicating that an average structure is insufficient to predict the ensemble behavior. Instead, even a small subset of the population with highly favorable energy transfer rates can be the primary driver in increasing the likelihood of energy transfer. Gaining control of the orientation and its distribution will be a critical step in maximizing the potential of the metal ion linked structures.
AB - Metal ion linked multilayers are a unique motif to spatially control and geometrically restrict molecules on a metal oxide surface, which is of interest in a number of promising applications. Here we use a bilayer composed of a metal oxide surface, an anthracene annihilator molecule, Zn(II) linking ion, and porphyrin sensitizers to probe the influence of the position of the metal ion binding site on energy transfer, photon upconversion, and photocurrent generation. Despite being energetically similar, varying the position of the carboxy metal ion binding group (i.e., ortho, meta, para) of the Pt(II) tetraphenyl porphyrin sensitizer had a large impact on energy transfer rates and upconverted photocurrent that can be attributed to differences in their geometries. From polarized attenuated total reflectance measurements of the bilayers on ITO, we found that the orientation of the first layer (anthracene) was largely unperturbed by subsequent layers. However, the tilt angle of the porphyrin plane varies dramatically from 41° to 64° to 57° for the p-, m-, and o-COOH substituted porphyrin molecules, which is likely responsible for the variation in energy transfer rates. We go on to show using molecular dynamics simulations that there is considerable flexibility in porphyrin orientation, indicating that an average structure is insufficient to predict the ensemble behavior. Instead, even a small subset of the population with highly favorable energy transfer rates can be the primary driver in increasing the likelihood of energy transfer. Gaining control of the orientation and its distribution will be a critical step in maximizing the potential of the metal ion linked structures.
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U2 - 10.1021/acs.jpcc.0c08715
DO - 10.1021/acs.jpcc.0c08715
M3 - Article
AN - SCOPUS:85096063967
SN - 1932-7447
VL - 124
SP - 23597
EP - 23610
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 43
ER -