Optical Properties of Spiroconjugated Charge-Transfer Dyes

详细信息    查看全文

• 作者：Przemyslaw Maslak ; Anu Chopra ; Christopher R. Moylan ; Rü ; diger Wortmann ; Sonja Lebus ; Arnold L. Rheingold ; and Glenn P. A. Yap
• 刊名：Journal of the American Chemical Society
• 出版年：1996
• 出版时间：February 14, 1996
• 年：1996
• 卷：118
• 期：6
• 页码：1471 - 1481
• 全文大小：471K
• 年卷期：v.118,no.6(February 14, 1996)
• ISSN：1520-5126

文摘

A new type of intramolecular charge-transfer dye hasbeen prepared. The LUMO of the acceptor part(1,3-indandione) in these compounds is spiroconjugated with the HOMO ofthe donor part (aromatic diamine oramino thiol). The interaction between the donor and acceptor iscontrolled by the energy and symmetry of thefrontier orbitals. The ground state dipole moments of thesecompounds are aligned along the long molecular axes.In the solid state, distortions of structures are observed thatare consistent with partial electron shift from the donorto the acceptor. Much more pronounced electron density shiftsaccompany the electronic transition that is observedin the visible region of the spectrum. These transitions are ofthe charge-transfer (CT) type, as shown by solvatochromicand electrooptical studies. The excited state dipole moments arein the direction opposite to that of the ground state.These observations are consistent with the excited state havingradical ion pair character. The new dyes are modeledusing a simple Mulliken charge-transfer theory. The mixingcoefficient of neutral and ionic wave functions describingthese systems is used as a measure of spiroconjugation between thesubchromophores. The electrooptical data providean estimate of the contribution of the CT transitions to thehyperpolarizabilities () within the two-state model.Themeasured values of indicate, however, that spiro dyes have twoopposing contributions to their hyperpolarizabilities,one from the CT transition and one due to the acceptorsubchromophore.