Electronic, Optical, and Vibrational Properties of Bridged Dithienylethylene-Based NLO Chromophores

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• 作者：M. Carmen Ruiz Delgado ; Juan Casado ; Victor Herná ; ndez ; Juan T. Ló ; pez Navarrete ; Jesú ; s Orduna ; Bel&eacute ; n Villacampa ; Raquel Alicante ; Jean-Manuel Raimundo ; Philippe Blanchard ; Je
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：February 28, 2008
• 年：2008
• 卷：112
• 期：8
• 页码：3109 - 3120
• 全文大小：523K
• 年卷期：v.112,no.8(February 28, 2008)
• ISSN：1932-7455

文摘

The vibrational, optical, and nonlinear optical (NLO) properties of a series of push-pull chromophores builtaround dithienylethylene-based -conjugating spacers have been investigated by UV-vis, IR, and Ramanspectroscopies and electric field-induced second harmonic generation (EFISH) measurements. The effects ofthe strength of the acceptor group on the molecular electronic properties of these conjugated NLO chromophoreshave been addressed. The magnitude of the intramolecular charge transfer has been tested as a function ofthe acceptor strength and of the bridging of the spacer. Density functional theory (DFT) calculations havebeen performed to help the assignment of the main electronic and vibrational features of the NLO chromophoresand to derive useful information about their molecular structures. EFISH measurements show that push-pullsystems that contain strong electron-acceptor groups connected via a rigidified dithienylene spacer exhibitlarge values of ₀. Theoretical NLO calculations are in excellent agreement with experimental results. Thegeometrical and electronic properties calculated in solution reveal that chromophores become highly polarizedas the dielectric constant of the solvent increases. The spectroscopic properties/structure relationships agreewith the observation that ₀ increases upon the covalent bridging of the spacer and with the increase of theacceptor strength.