# Second-order nonlinear optical properties of the four tetranitrotetrapropoxycalix[4]arene conformers

Kenis, Paul J.A.
and
Noordman, Oscar F.J.
and
Houbrechts, Stephan
and
Hummel, Gerrit J. van
and
Harkema, Sybolt
and
Veggel, Frank C.J.M. van
and
Clays, Koen
and
Engbersen, Johan F.J.
and
Persoons, Andre
and
Hulst, Niek F. van
and
Reinhoudt, David N.
(1998)
*Second-order nonlinear optical properties of the four tetranitrotetrapropoxycalix[4]arene conformers.*
Journal of the American Chemical Society, 120
(31).
pp. 7875-7883.
ISSN 0002-7863

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Abstract: | This paper reports a systematic experimental and theoretical study of the second-order nonlinear optical properties of multichromophoric molecules that range from dipolar symmetry to three-dimensional octupolar symmetry. The four possible conformers of tetranitrotetrapropoxycalix[4]arene (cone, pace, 1,2-air, 1,3-alt) were studied by nanosecond hyper-Rayleigh scattering and a newly developed time-resolved femtosecond hyper-Rayleigh scattering technique. The latter enables to correct for long-lived fluorescence contributions to the second harmonic scattering intensity. The depolarization ratios D-x/z prove the (partial) octupolar symmetry of the 1,2-alt and 1,3- alt conformers, and thus explain why their hyperpolarizabilities beta(FHRS) are of the same order of magnitude as those of the dipolar cone and pace conformers. The corresponding theoretical second-order nonlinear optical properties (both beta(FHRS) and D-x/z) were calculated using the conformations obtained from single-crystal X-ray diffraction, molecular mechanics (MM), and molecular dynamics (MD) calculations. In contrast with sum-over-state calculations presented in the literature, our theoretical method takes also into account octupolar contributions by linearly adding the NLO-properties of the separate chromophoric groups and using Bersohn's theory. The agreement between experimental and theoretical results is good both for the conformers having dipolar symmetry and for the conformers having (partly) three- dimensional octupolar symmetry. The 1,2-alt and 1,3-alt conformers of the tetranitrotetrapropoxycalix[4]arene represent the first examples of multichromophoric molecules that have high hyperpolarizabilities beta due to 3D octupolar symmetry. |

Item Type: | Article |

Copyright: | © 1998 American Chemical Society |

Faculty: | Science and Technology (TNW) |

Research Group: | |

Link to this item: | http://purl.utwente.nl/publications/11008 |

Official URL: | http://dx.doi.org/10.1021/ja980791t |

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