Influence of Hydrophobicity on Excitonic Coupling in DNA-Templated Indolenine Squaraine Dye Aggregates
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- Micron School of Materials Science & Engineering, Boise State University, Boise, Idaho 83725, United States
- SETA BioMedicals, LLC, 2014 Silver Court East, Urbana, Illinois 61801, United States
- State Scientific Institution “Institute for Single Crystals” of National Academy of Sciences of Ukraine, Kharkiv 61072, Ukraine
- Micron School of Materials Science & Engineering, Boise State University, Boise, Idaho 83725, United States, Center for Advanced Energy Studies, Idaho Falls, Idaho 83401, United States
- Micron School of Materials Science & Engineering, Boise State University, Boise, Idaho 83725, United States, Department of Electrical & Computer Engineering, Boise State University, Boise, Idaho 83725, United States
- Micron School of Materials Science & Engineering, Boise State University, Boise, Idaho 83725, United States, Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
Control over the strength of excitonic coupling in molecular dye aggregates is a substantial factor for the development of such technologies 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 the dyes. Covalent DNA templating proved to be a versatile tool to control dye spacing on a sub-nanometer 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 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 on squaraine aggregation are also discussed. Taken together, these findings provide a deeper insight into how dye structure influences excitonic coupling in dye aggregates covalently templated via DNA, and guidance in design rules for exciton-based materials and devices.
- Research Organization:
- Boise State Univ., ID (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
- Grant/Contract Number:
- SC0020089
- OSTI ID:
- 1844436
- Alternate ID(s):
- OSTI ID: 1845132; OSTI ID: 1846367
- Journal Information:
- Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Vol. 126 Journal Issue: 7; ISSN 1932-7447
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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