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首页> 外文期刊>RSC Advances >Dipolar vinyl sulfur fluorescent dyes. Synthesis and photophysics of sulfide, sulfoxide and sulfone based D–π–A compounds
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Dipolar vinyl sulfur fluorescent dyes. Synthesis and photophysics of sulfide, sulfoxide and sulfone based D–π–A compounds

机译：偶极乙烯基硫荧光染料。硫化物，亚砜和砜基D–π–A化合物的合成和光物理

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New vinyl sulfides and sulfoxides were obtained in good yields using the Horner–Wadsworth–Emmons (HWE) reaction. The vinyl sulfides and sulfoxides presented preferentially the E-stereochemistry. The respective vinyl sulfones were obtained in good yields from the vinyl sulfides by a simple oxidation step using mCPBA, solely as the E isomers. These derivatives presented absorption maxima in the UV-A region with molar absorptivity coefficients and radiative rate constant values ascribed to spin and symmetry-allowed 1π–π* electronic transitions. Experimentally, a small solvatochromic effect indicated an almost absent charge transfer character in the ground-state. A fluorescence emission in the violet-green region with a significative redshift on the maxima with increasing solvent polarity was observed, which could be related to a better electron delocalization in the excited state, as a result of an intramolecular charge transfer state. DFT and TD-DFT calculations were performed at the PBE1PBE and CAM-B3LYP levels of theory. No solvatochromic effect was observed in the ground state, but a bathochromic effect was detected in the emission maxima. Starting from sulfides to sulfones, the addition of oxygen atoms improved the charge separation, enabling an ICT state, mainly in P3 and P5. This charge separation was more efficient in the triphenylamino derivatives than among the pyrene derivatives since the first one has a better electron-donating character.
机译：使用Horner-Wadsworth-Emmons（HWE）反应以高收率获得了新的乙烯基硫化物和亚砜。乙烯基硫化物和亚砜优先呈现 E -立体化学。通过使用 m CPBA的简单氧化步骤（仅作为 E 异构体）从乙烯基硫醚以高收率获得了各自的乙烯基砜。这些导数在UV-A区域呈现最大吸收，摩尔吸收系数和辐射速率常数值归因于自旋和对称允许的 1 π-π*电子跃迁。实验上，小的溶剂化变色效应表明在基态下几乎没有电荷转移特性。观察到紫绿色区域中的荧光发射，随着溶剂极性的增加，最大值出现明显的红移，这可能与分子内电荷转移状态引起的电子在激发态下更好的离域有关。 DFT和TD-DFT计算是在PBE1PBE和CAM-B3LYP理论水平上进行的。在基态中未观察到溶剂变色效应，但是在发射最大值中检测到红变色效应。从硫化物到砜，氧原子的添加改善了电荷分离，从而使ICT状态（主要在P3和P5中）成为可能。在三苯基氨基衍生物中，这种电荷分离比在derivatives衍生物中更有效，因为第一个具有更好的供电子特性。

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