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Enhancing the efficiency of two-photon absorption by metal coordination
Luca Grisanti1, Cristina Sissa, Francesca Terenziani
1Dipartimento di Chimica GIAF, Università di Parma & INSTM UdR Parma, Parco Area delle Scienze 17/A, 43100 Parma, Italy.
Physical Chemistry Chemical Physics : PCCP
|October 16, 2009
Summary
Coordination to ZnCl(2) enhances the two-photon absorption (TPA) of terpyridine ligands by doubling their intensity. This effect is explained by a three-state model involving the Zn(II) complex as a virtual acceptor, increasing the excited-state dipole moment.
Area of Science:
- Photochemistry
- Materials Science
- Spectroscopy
Background:
- Terpyridine ligands function as donor-pi-acceptor (D-pi-A) chromophores.
- Two-photon absorption (TPA) is a crucial photophysical process with applications in materials science.
Purpose of the Study:
- To investigate the effect of ZnCl(2) coordination on the TPA properties of a terpyridine ligand.
- To elucidate the underlying photophysical mechanisms responsible for changes in TPA intensity.
Main Methods:
- Analysis of linear absorption and fluorescence spectra.
- Development and application of essential-state models.
- Comparison of TPA spectra for the ligand and its Zn(II) complex.
Main Results:
- TPA intensity of the terpyridine ligand is enhanced approximately twofold upon coordination to ZnCl(2).
- A two-state model accurately describes the ligand's spectra, while a three-state model is required for the Zn(II) complex.
- The ZnCl(2) moiety acts as a virtual acceptor, increasing the excited-state dipole moment and TPA cross section.
Conclusions:
- Zn(II) coordination significantly modifies the electronic structure and TPA response of terpyridine ligands.
- The observed enhancement in TPA is attributed to the formation of a D-pi-AA(v) structure and increased excited-state dipole moment.
- This study provides insights into designing molecules with enhanced nonlinear optical properties.
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