Synthesis, characterization and optical properties of π-conjugated systems incorporating closo-dodecaborate clusters: new potential candidates for two-photon absorption processes
作者:R. Bernard、D. Cornu、P. L. Baldeck、J. Čáslavský、J.-M. Létoffé、J.-P. Scharff、P. Miele
DOI:10.1039/b504414f
日期:——
Non-centrosymmetric Ï-conjugated systems incorporating closo-dodecaborate clusters, [NCâC6H4âC(H)N(H)âB12H11]â
(2), [NCâC6H4âC(H)C(H)âC6H4âC(H)N(H)âB12H11]â
(3), and [NCâC6H4âC(H)C(H)âC6H4âC(H)C(H)âC6H4âC(H)N(H)âB12H11]â
(4) have been synthesized by reaction of the monoamino derivative of B12, [B12H11NH3]â
(1), with various arylaldehydes, RâC6H4âCHO. These Schiff base-like compounds were fully characterized by multinuclear NMR spectroscopy and mass spectrometry. In order to evaluate these boron rich Ï-systems as potential materials for two-photon absorption (TPA) processes, UV linear absorption curves were recorded for 3 and 4, and comparatively studied with those of the boron-free Ï-systems NCâC6H4âC(H)NâCH3
(5) and NCâC6H4âC(H)C(H)âC6H4âC(H)NâCH3
(6). The donor effect of the boron cluster was evidenced by a shift to the lower energy of the absorption band in the spectra of systems incorporating B12. The two photon absorption (TPA) spectrum of compound 3, obtained by the up-conversion method, shows a resonance at 720 nm with a cross-section ÏTPA of 35 Ã 10â50 cm4 s photonâ1 moleculeâ1. This value suggests the potential of B12 clusters to be used as new donor groups for the synthesis of non-linear materials.
非中心对称的Ï-共轭体系,其中包含[NCâC6H4âC(H)N(H)âB12H11]â (2),[NCâC6H4âC(H)C(H)âC6H4âC(H)N(H)âB12H11]â (3)、和[NCâC6H4âC(H)C(H)âC6H4âC(H)C(H)âC6H4âC(H)N(H)âB12H11]â (4)是通过 B12 的单氨基衍生物[B12H11NH3]â (1) 与各种芳基醛 RâC6H4âCHO 反应合成的。通过多核核磁共振波谱和质谱分析,这些类似希夫碱的化合物得到了全面的表征。为了评估这些富硼Ï-体系作为双光子吸收(TPA)过程潜在材料的价值,我们记录了 3 和 4 的紫外线性吸收曲线,并将其与无硼Ï-体系 NCâC6H4âC(H)NâCH3 (5) 和 NCâC6H4âC(H)C(H)âC6H4âC(H)NâCH3 (6) 的吸收曲线进行了比较研究。在含有 B12 的体系光谱中,硼团簇的供体效应表现为吸收带向低能量方向移动。通过上转换法获得的化合物 3 的双光子吸收(TPA)光谱显示,在 720 纳米波长处存在共振,其横截面 ÏTPA 为 35 Ã 10â50 cm4 s 光子â1 moleculeâ1。这一数值表明,B12 团簇有可能被用作合成非线性材料的新供体基团。