John Hall, Boise State University, qDNA Research Group
Theoretical methods based on quantum mechanics can be used to determine the effects of structural changes in molecules on their physiochemical properties. In two studies, involving two different dye material systems, Materials Science and Engineering and qDNA Research Group PhD students Austin Biaggne and German Barcenas and their co-authors used theoretical approaches to predict the effects of dye structure changes on solvation energy and electronic properties.
What Did The Scientists Discover?
The aggregation ability and exciton dynamics of dyes are largely affected by properties of the single dye. To facilitate aggregation and improve excitonic function, dyes can be engineered with substituents or different functional groups to optimize key properties, such as hydrophobicity, static dipole moment differences (Δd), and transition dipole moments (µ). To determine how electron donating (D) and electron withdrawing (W) substituents impact solvation energy, Δd, and µ of the cyanine dye Cy5, PhD student Austin Biaggne and co-authors used density functional theory (DFT) and time-dependent (TD-) DFT calculations. The inclusion of substituents had large effects on the solvation energy of Cy5, with the most negative solvation energies correlated with greater dye solubility. Relative to pristine Cy5, substitution had little effect on µ whereas numerous W-W and D-W pair combinations increased Δd.
A different family of dyes, known as squaraines, has received considerable attention recently due to their favorable electronic and photophysical properties. In addition, these dyes have a strong propensity for aggregation, which results in emergent materials properties, such as exciton delocalization. PhD student German Barcenas and co-authors used DFT and TD-DFT methods as above to determine the effects of substituents on the electronic and photophysical properties, as well as solvation energy, for a series of nine different squaraine dyes. The role of molecular symmetry on these properties was also explored via conformers and substitution. Electron withdrawing groups impacted solvation energy, Δd, µ, and absorbance more than electron donating groups. All substituents showed a redshift (lower energy, longer wavelengths) in absorption compared to the pristine squaraine dye.
In combination, the two studies provide the initial steps toward developing design rules for Cy5 and squaraine dyes with desired properties for excitonic-related applications, such as organic photovoltaics, biological fluorescent labeling, super-resolution microscopy, and energy transport.
Knowlton, WB, Micron School of Materials Science and Engineering and Department of Electrical and Computer Engineering, Boise State University
Kolosova, OS, SSI “Institute for Single Crystals” of National Academy of Sciences of Ukraine, Kharkov
Lee, J, Micron School of Materials Science and Engineering and Department of Chemistry and Biochemistry, Boise State University
Li, L, Micron School of Materials Science and Engineering, Boise State University and Center for Advanced Energy Studies
Mass, OA, Micron School of Materials Science and Engineering, Boise State University
Obukhova, OM, SSI “Institute for Single Crystals” of the National Academy of Sciences of Ukraine
Pensack, RD, Micron School of Materials Science and Engineering, Boise State University
Tatarets, AL, SSI “Institute for Single Crystals” of National Academy of Sciences of Ukraine, Kharkov and SETA BioMedicals
Terpetschnig, E, SETA BioMedicals
Wilson, CK, Micron School of Materials Science and Engineering, Boise State University
Yurke, B, Micron School of Materials Science and Engineering and Department of Electrical and Computer Engineering, Boise State University
Biaggne, A, WB Knowlton, B Yurke, J Lee, and L Li, Substituent Effects on the Solubility and Electronic Properties of Cy5: Density Functional and Time-Dependent Density Functional Theory Calculations, Molecules, 26(3), 524 (2021). doi: 10.3390/molecules26030524.
Barcenas, G, A Biaggne, OA Mass, CK Wilson, OM Obukhova, OS Kolosova, AL Tatarets, E Terpetschnig, RD Pensack, J Lee, WB Knowlton, B Yurke, and L Li, First-Principles Studies of Substituent Effects on Squaraine Dyes, Royal Society of Chemistry Advances, Accepted (2021).
|Funding Agency||Grant Number||Role of Funding|
|Department of Navy, Office of Naval Research||N00014-19-1-2615||Primary funding for Biaggne et al.|
|U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Materials Sciences and Engineering Division, and DOE’s Established Program to Stimulate Competitive Research (EPSCoR)||DE-SC0020089||Primary funding for Barcenas et al.|
|High Performance Computing Center at Idaho National Laboratory, which is supported by the Office of Nuclear Energy of the DOE and Nuclear Science User Facilities||DE-AC07-05ID14517||Provided computational resources for both studies|
Any opinions, findings, and conclusions or recommendations expressed in this article are those of the author and do not necessarily reflect the views of the Department of Energy’s (DOE) Office of Basic Energy Sciences, Materials Sciences and Engineering Division, DOE’s EPSCoR program, DOE’s Idaho National Laboratory, and Department of the Navy’s Office of Naval Research.