TY - JOUR
T1 - Influence of Hydrophobicity on Excitonic Coupling in DNA-Templated Indolenine Squaraine Dye Aggregates
AU - Mass, Olga A.
AU - Wilson, Christopher K.
AU - Barcenas, German
AU - Terpetschnig, Ewald A.
AU - Obukhova, Olena M.
AU - Kolosova, Olga S.
AU - Tatarets, Anatoliy L.
AU - Li, Lan
AU - Yurke, Bernard
AU - Knowlton, William B.
AU - Pensack, Ryan D.
AU - Lee, Jeunghoon
N1 - Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
PY - 2022/2/24
Y1 - 2022/2/24
N2 - Control over the strength of excitonic coupling in molecular dye aggregates is a substantial factor for the development of technologies such as light harvesting, optoelectronics, and quantum computing. According to the molecular exciton model, the strength of excitonic coupling is inversely proportional to the distance between dyes. Covalent DNA templating was proved to be a versatile tool to control dye spacing on a subnanometer scale. To further expand our ability to control photophysical properties of excitons, here, we investigated the influence of dye hydrophobicity on the strength of excitonic coupling in squaraine aggregates covalently templated by DNA Holliday Junction (DNA HJ). Indolenine squaraines were chosen for their excellent spectral properties, stability, and diversity of chemical modifications. Six squaraines of varying hydrophobicity from highly hydrophobic to highly hydrophilic were assembled in two dimer configurations and a tetramer. In general, the examined squaraines demonstrated a propensity toward face-to-face aggregation behavior observed via steady-state absorption, fluorescence, and circular dichroism spectroscopies. Modeling based on the Kühn-Renger-May approach quantified the strength of excitonic coupling in the squaraine aggregates. The strength of excitonic coupling strongly correlated with squaraine hydrophobic region. Dimer aggregates of dichloroindolenine squaraine were found to exhibit the strongest coupling strength of 132 meV (1065 cm-1). In addition, we identified the sites for dye attachment in the DNA HJ that promote the closest spacing between the dyes in their dimers. The extracted aggregate geometries, and the role of electrostatic and steric effects in squaraine aggregation are also discussed. Taken together, these findings provide a deeper insight into how dye structures influence excitonic coupling in dye aggregates covalently templated via DNA, and guidance in design rules for exciton-based materials and devices.
AB - Control over the strength of excitonic coupling in molecular dye aggregates is a substantial factor for the development of technologies such as light harvesting, optoelectronics, and quantum computing. According to the molecular exciton model, the strength of excitonic coupling is inversely proportional to the distance between dyes. Covalent DNA templating was proved to be a versatile tool to control dye spacing on a subnanometer scale. To further expand our ability to control photophysical properties of excitons, here, we investigated the influence of dye hydrophobicity on the strength of excitonic coupling in squaraine aggregates covalently templated by DNA Holliday Junction (DNA HJ). Indolenine squaraines were chosen for their excellent spectral properties, stability, and diversity of chemical modifications. Six squaraines of varying hydrophobicity from highly hydrophobic to highly hydrophilic were assembled in two dimer configurations and a tetramer. In general, the examined squaraines demonstrated a propensity toward face-to-face aggregation behavior observed via steady-state absorption, fluorescence, and circular dichroism spectroscopies. Modeling based on the Kühn-Renger-May approach quantified the strength of excitonic coupling in the squaraine aggregates. The strength of excitonic coupling strongly correlated with squaraine hydrophobic region. Dimer aggregates of dichloroindolenine squaraine were found to exhibit the strongest coupling strength of 132 meV (1065 cm-1). In addition, we identified the sites for dye attachment in the DNA HJ that promote the closest spacing between the dyes in their dimers. The extracted aggregate geometries, and the role of electrostatic and steric effects in squaraine aggregation are also discussed. Taken together, these findings provide a deeper insight into how dye structures influence excitonic coupling in dye aggregates covalently templated via DNA, and guidance in design rules for exciton-based materials and devices.
KW - dyes and pigments
KW - genetics
KW - hydrophobicity
KW - oligomers
KW - squaraine
UR - http://www.scopus.com/inward/record.url?scp=85124901736&partnerID=8YFLogxK
UR - https://scholarworks.boisestate.edu/mse_facpubs/525
U2 - 10.1021/acs.jpcc.1c08981
DO - 10.1021/acs.jpcc.1c08981
M3 - Article
SN - 1932-7447
VL - 126
SP - 3475
EP - 3488
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 7
ER -