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Published April 9, 1997 | public
Journal Article

Stark Spectroscopy of Donor/Acceptor Substituted Polyenes

Abstract

The electronic structure of donor/acceptor polyenes (merocyanines) is studied by means of electroabsorption (Stark) spectroscopy. Molecules belonging to this class exhibit an extreme variability of their linear and nonlinear optical properties. Depending on the nature of the donor and acceptor end groups and the polarity of their solvent environment they can adopt ground state molecular structures between limits with mostly localized double bonds (polyene-like) or fully delocalized double bonds (cyanine-like). By comparing the results obtained for the change in dipole moment, Δμ, and change in polarizability, Δα, upon optical excitation of 12 donor/acceptor polyenes with theoretical predictions, each molecule's location in between these limits can be assigned. The results demonstrate that this position can be understood by considering only the relative electron donating and accepting strengths of the end groups. The solvent dependence of the electronic structure is also studied by measuring Stark spectra for two compounds in different frozen solvents. The results are consistent with a change of the molecule's ground state toward more dipolar structures in polar solvents. Taken together, the donor, acceptor, and solvent dependences of the electronic structure of donor/acceptor polyenes can be described by a simple model based on the gradual change of the molecule's ground state between polyene-like and cyanine-like structures.

Additional Information

© 1997 American Chemical Society. ReceiVed NoVember 25, 1996. We thank Dr. Fabienne Meyers for providing us with the results of the model calculations. This work was supported in part by grants from the National Science Foundation Chemistry Division (S.G.B.). The work was performed in part by the Jet Propulsion Laboratory, California Institute of Technology, as part of its Center for Space Microelectronics Technology and was supported by the Ballistic Missile Defense Organization, Innovative Science and Technology Office, through a contract with the National Aeronautics and Space Administration (NASA). Support at the Beckman Institute from the National Science Foundation (Grant No. CHE-9408701) and the Air Force Office of Scientific Research (Grant No. F49620-95-1-0178) is gratefully acknowledged. R.O. thanks the James Irvine Foundation for a postdoctoral fellowship.

Additional details

Created:
August 19, 2023
Modified:
October 25, 2023