FIRST OBSERVATION OF INTRAMOLECULAR CHARGE-TRANSFER EMISSION FROM JET-COOLED (P-CYANOPHENYL)PENTAMETHYLDISILANE IN AN ISOLATED MOLECULAR CONDITION
FIRST OBSERVATION OF INTRAMOLECULAR CHARGE-TRANSFER EMISSION FROM JET-COOLED (P-CYANOPHENYL)PENTAMETHYLDISILANE IN AN ISOLATED MOLECULAR CONDITION
复制标题
首次观察隔离分子条件下喷射冷却（对氰基苯基）五甲基二硅烷的分子内电荷转移发射
DOI：
10.1021/ja971445z
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发表时间：
1997
影响因子：
15
通讯作者：
N. Mikami
中科院分区：
文献类型：
--
作者：
Y. Tajima;H. Ishikawa;T. Miyazawa;M. Kira;N. Mikami
自Lippert首次报道对二甲氨基苯甲腈（DMABN）的双荧光以来，大量研究致力于阐明分子内电荷转移（ICT）发射的机制，其中供体和受体部分通过单键连接。2扭曲的分子内CT（TICT）模型3已被广泛接受为ICT激发态的稳定机制，2其中CT激发态伴随着二甲氨基相对于芳环的90度扭曲，同时也提出了一些不同于TICT模型的其他想法，例如DMABN的quinoid型结构模型。4a然而，通过分子内稳定化（如TICT机制）形成ICT激发态通常伴随着这种高度极化激发态的不可避免的溶剂化;很难观察到仅由分子内起源诱导的ICT态。而超声分子束技术已被应用于ICT分子的光谱研究在一个孤立的分子条件下，4没有CT发射已被发现孤立的喷射冷却分子没有溶剂化或二聚体的形成，直到现在。5在ICT分子中，2苯基二硅烷，其中二硅烷基和芳基π系统分别作为电子供体和受体，是非常独特的，因为它们显示出双重荧光，一个来自局部激发（LE）状态，另一个来自ICT状态，即使在非极性溶剂中。6，7我们发现，喷射冷却的（对氰基苯基）五甲基二硅烷（CPDS），8它在苯基五甲基二硅烷（PDS）的帕拉上带有一个强的电子接受取代基，显示出ICT发射从没有溶剂化的孤立分子。此外，发现CPDS与水的簇合物CPDS-（H2O）n（n）1和2）表现出增强的和显著红移的CT发射。
Since the first report by Lippert on dual fluorescence exhibited by p-(dimethylamino) benzonitrile (DMABN), 1 a vast number of studies have been devoted to elucidation of the mechanism of the intramolecular charge transfer (ICT) emission of the molecules in which a donor and an acceptor moiety are linked by a single bond. 2 The twisted intramolecular CT (TICT) model3 has been widely accepted as the mechanism for the stabilization of the ICT excited state, 2 where the CT excited state is accompanied by a 90 twist of the dimethylamino group with respect to the aromatic ring, while some other ideas than the TICT model have also been proposedsfor example, a quinoid-type structure model for DMABN. 4a However, the formation of the ICT excited state via the intramolecular stabilization such as the TICT mechanism is usually accompanied by inevitable solvation of such a highly polarized excited state; it has been difficult to observe the ICT state induced only by the intramolecular origin. Whereas supersonic molecular beam techniques have been applied for spectroscopic studies of ICT molecules under an isolated molecular condition, 4 no CT emission has been found for isolated jet-cooled molecules without solvation or dimer formation until now. 5Among a wide variety of the ICT molecules, 2 phenyldisilanes, where the disilanyl group and the aryl π system serve as an electron donor and an acceptor, respectively, are quite unique because they show dual fluorescence, one originating from a locally excited (LE) state and the other from an ICT state, even in a nonpolar solvent. 6, 7 We have found that jet-cooled (p-cyanophenyl) pentamethyldisilane (CPDS), 8 which bears a strong electron-accepting substituent at the para position of the phenylpentamethyldisilane (PDS), shows the ICT emission from the isolated molecules without solvation. In addition, the clusters of CPDS with water, CPDS-(H2O) n (n) 1 and 2), were found to exhibit the enhanced and significantly red-shifted CT emission.