Electronic Stark Effect Studies of a Porphyrin-Based Push-Pull Chromophore Displaying a Large First Hyperpolarizability: State-Specific Contributions to 
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- 作者：Laba Karki ; Fredrick W. Vance ; Joseph T. Hupp ; Steven M. LeCours ; and Michael J. Therien
- 刊名：Journal of the American Chemical Society
- 出版年：1998
- 出版时间：March 25, 1998
- 年：1998
- 卷：120
- 期：11
- 页码：2606 - 2611
- 全文大小：85K
- 年卷期：v.120,no.11(March 25, 1998)
- ISSN：1520-5126
文摘
Electroabsorption or Stark effect spectroscopy has been applied toa pair of porphyrin-basedchromophores with the aim of deriving a detailed understanding of theorigin of the remarkable firsthyperpolarizability, 
, of one of the chromophores:[5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4''-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II). Themeasurements show that significant changes in moleculardipole moment, 
, accompany excitations of x-polarizedtransitions of the aminophenyl (donor)/nitrophenyl(acceptor) functionalized chromophore, but are absent for a relatedchromophore lacking the donor and acceptorgroups. For linear chromophores, changes in dipole moment are aprerequisite to effective molecular firsthyperpolarization and incident light frequency doubling behavior.A more detailed consideration of the available
data, within the context of a conventional two-levelmodel, has yielded the following: (a) specificinformation about the roles of each of seven electronic and vibronicexcited states in defining , (b) asemiquantitative explanation for the apparent frequency independence of found in previous hyper-Rayleighscattering experiments performed at 830 and 1064 nm, and (c) anexplanation for the contrasting frequencydependence of the nonlinear optical response for the analogousCu(II)-containing chromophore. Finally, theexperimental findings are in generally good agreement with publishedZINDO calculations which had pointedtoward the exceptional effectiveness of yne linkages in coupling donorand acceptor moieties to the highlypolarizable porphyrin core assembly.
, of one of the chromophores:[5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4''-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II). Themeasurements show that significant changes in moleculardipole moment, , accompany excitations of x-polarizedtransitions of the aminophenyl (donor)/nitrophenyl(acceptor) functionalized chromophore, but are absent for a relatedchromophore lacking the donor and acceptorgroups. For linear chromophores, changes in dipole moment are aprerequisite to effective molecular firsthyperpolarization and incident light frequency doubling behavior.A more detailed consideration of the available data, within the context of a conventional two-levelmodel, has yielded the following: (a) specificinformation about the roles of each of seven electronic and vibronicexcited states in defining , (b) asemiquantitative explanation for the apparent frequency independence of found in previous hyper-Rayleighscattering experiments performed at 830 and 1064 nm, and (c) anexplanation for the contrasting frequencydependence of the nonlinear optical response for the analogousCu(II)-containing chromophore. Finally, theexperimental findings are in generally good agreement with publishedZINDO calculations which had pointedtoward the exceptional effectiveness of yne linkages in coupling donorand acceptor moieties to the highlypolarizable porphyrin core assembly.