Tuning Solvatochromism of Azo Dyes with Intramolecular Hydrogen Bonding in Solution and on Titanium Dioxide Nanoparticles
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, U.K.
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, U.K.; Argonne National Laboratory, 9700 S Cass Avenue, Argonne, IL 60439, U.S.A.
“Smart tuning” of optical properties in three azo dyes containing intramolecular hydrogen bonding is realized by the judicious control of solvents, when the dyes are in solution or adsorbed onto titanium dioxide nanoparticles. In solution, certain solvents destabilizing intramolecular hydrogen bonding induce a distinctive ≈70 nm “blue-shifted” absorption peak, compared with other solvents. In parallel, the optical properties of azo dye/TiO2 nanocomposites can be tuned using solvents with different hydrogen-bond accepting/donating abilities, giving insights into smart materials and dye-sensitized solar cell device design. It is proposed that intramolecular hydrogen bonding alone plays the leading role in such phenomena, which is fundamentally different to other mechanisms, such as tautomerism and cis–trans isomerization, that explain the optical control of azo dyes. Hybrid density functional theory (DFT) is employed in order to trace the origin of this optical control, and these calculations support the mechanism involving intramolecular hydrogen bonding. Two complementary studies are also reported: 1H NMR spectroscopy is conducted in order to further understand the solvent effects on intramolecular hydrogen bonding; crystal structure analysis from associated research indicates the importance of intramolecular hydrogen bonding on intramolecular charge transfer.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- USDOE Office of Science - Office of Basic Energy Sciences
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1395036
- Journal Information:
- Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 49 Vol. 117; ISSN 1932-7447
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
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