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Quadratic optical nonlinearities of N-methyl and N-aryl pyridinium salts

Quadratic optical nonlinearities of N-methyl and N-aryl pyridinium salts
Quadratic optical nonlinearities of N-methyl and N-aryl pyridinium salts
Four series of dyes with dimethylamino electron donor groups and N-R-pyridinium (R = methyl Me, phenyl Ph, 2,4-dinitrophenyl 2,4-DNPh, or 2-pyrimidyl 2-Pym) electron acceptors are studied as their hexafluorophosphate salts. The intramolecular charge-transfer (ICT) energies (E-max) of these compounds decrease within each of the series in the order R = Me > Ph > 2,4-DNPh > 2-Pym, as the electron-accepting ability of the pyridinium ring increases. Hyper-Rayleigh scattering with femtosecond 1300 or 800 nm lasers yields fluorescence-free first hyperpolarizabilities ?, and static first hyperpolarizabilities ?(0)[H] are obtained via the two-state model. Dipole moment changes ??(12) for the ICT transitions obtained from Stark spectroscopy afford ?(0)[S] values by using ?(0) = 3??(12)(?(12))(2)/2 (E-max)(2) (?(12) = transition dipole moment). The ?(0)[S] data show that the combination of pyridyl N-arylation with conjugation extension affords large increases in ?(0). The ?(0)[H] data generally agree with this conclusion, but resonance effects may explain some apparent anomalies. X-ray structural studies on various salts reveal that the use of tosylate anions is not a generally applicable approach to engineering noncentrosymmetric structures of pyridinium salts. However, trans-N-phenyl-4-(4-dimethylaminophenyl-4-buta-1,3-dienyl)pyridinium hexafluorophosphate adopts the polar space group Cc, and shows a very large powder second harmonic generation efficiency from a 1907 nm laser; which is similar to that of the well-studied material trans-4'-(dimethylamino)-N-methyl-4-stilbazolium tosylate (DAST).
charge transfer, chromophoric materials, nonlinear optical materials, pyridinium salts
1616-301X
347-357
Coe, B.J.
bcf93592-85df-4a69-a1cf-aea0a9152789
Harris, J.A.
1c5b576b-d42f-4099-b9c8-9df833b9366c
Asselberghs, I.
e412653b-dd82-4209-9e71-2604639360d8
Wostyn, K.
b49e83aa-9635-45c5-8d55-8c556f4ec1dd
Clays, K.
58684914-5227-4f99-a886-6991c8bf4ca7
Persoons, A.
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Brunschwig, B.S.
9a299f7b-be4d-4b06-8a45-3b9066f1a3b0
Coles, S.J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Gelbrich, T.
42309d69-eaf1-4bb7-ba2e-db61f338e370
Light, M.E.
cf57314e-6856-491b-a8d2-2dffc452e161
Hursthouse, M.B.
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Nakatani, K.
201dbb19-3b20-4f52-bd9a-04d941903db4
Coe, B.J.
bcf93592-85df-4a69-a1cf-aea0a9152789
Harris, J.A.
1c5b576b-d42f-4099-b9c8-9df833b9366c
Asselberghs, I.
e412653b-dd82-4209-9e71-2604639360d8
Wostyn, K.
b49e83aa-9635-45c5-8d55-8c556f4ec1dd
Clays, K.
58684914-5227-4f99-a886-6991c8bf4ca7
Persoons, A.
2127f91c-bd41-47f4-bc58-d78218c34c5d
Brunschwig, B.S.
9a299f7b-be4d-4b06-8a45-3b9066f1a3b0
Coles, S.J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Gelbrich, T.
42309d69-eaf1-4bb7-ba2e-db61f338e370
Light, M.E.
cf57314e-6856-491b-a8d2-2dffc452e161
Hursthouse, M.B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Nakatani, K.
201dbb19-3b20-4f52-bd9a-04d941903db4

Coe, B.J., Harris, J.A., Asselberghs, I., Wostyn, K., Clays, K., Persoons, A., Brunschwig, B.S., Coles, S.J., Gelbrich, T., Light, M.E., Hursthouse, M.B. and Nakatani, K. (2003) Quadratic optical nonlinearities of N-methyl and N-aryl pyridinium salts. Advanced Functional Materials, 13 (5), 347-357. (doi:10.1002/adfm.200300026).

Record type: Article

Abstract

Four series of dyes with dimethylamino electron donor groups and N-R-pyridinium (R = methyl Me, phenyl Ph, 2,4-dinitrophenyl 2,4-DNPh, or 2-pyrimidyl 2-Pym) electron acceptors are studied as their hexafluorophosphate salts. The intramolecular charge-transfer (ICT) energies (E-max) of these compounds decrease within each of the series in the order R = Me > Ph > 2,4-DNPh > 2-Pym, as the electron-accepting ability of the pyridinium ring increases. Hyper-Rayleigh scattering with femtosecond 1300 or 800 nm lasers yields fluorescence-free first hyperpolarizabilities ?, and static first hyperpolarizabilities ?(0)[H] are obtained via the two-state model. Dipole moment changes ??(12) for the ICT transitions obtained from Stark spectroscopy afford ?(0)[S] values by using ?(0) = 3??(12)(?(12))(2)/2 (E-max)(2) (?(12) = transition dipole moment). The ?(0)[S] data show that the combination of pyridyl N-arylation with conjugation extension affords large increases in ?(0). The ?(0)[H] data generally agree with this conclusion, but resonance effects may explain some apparent anomalies. X-ray structural studies on various salts reveal that the use of tosylate anions is not a generally applicable approach to engineering noncentrosymmetric structures of pyridinium salts. However, trans-N-phenyl-4-(4-dimethylaminophenyl-4-buta-1,3-dienyl)pyridinium hexafluorophosphate adopts the polar space group Cc, and shows a very large powder second harmonic generation efficiency from a 1907 nm laser; which is similar to that of the well-studied material trans-4'-(dimethylamino)-N-methyl-4-stilbazolium tosylate (DAST).

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Published date: 2003
Keywords: charge transfer, chromophoric materials, nonlinear optical materials, pyridinium salts

Identifiers

Local EPrints ID: 39110
URI: http://eprints.soton.ac.uk/id/eprint/39110
ISSN: 1616-301X
PURE UUID: 56464514-3e11-4f0b-a5a2-96d084081112
ORCID for S.J. Coles: ORCID iD orcid.org/0000-0001-8414-9272
ORCID for M.E. Light: ORCID iD orcid.org/0000-0002-0585-0843

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Date deposited: 21 Jun 2006
Last modified: 27 Apr 2022 01:41

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Contributors

Author: B.J. Coe
Author: J.A. Harris
Author: I. Asselberghs
Author: K. Wostyn
Author: K. Clays
Author: A. Persoons
Author: B.S. Brunschwig
Author: S.J. Coles ORCID iD
Author: T. Gelbrich
Author: M.E. Light ORCID iD
Author: M.B. Hursthouse
Author: K. Nakatani

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