Dyad 4, comprising a triphenylamine (TPA) electron donor and 1,4-pentadien-3-one (pentadienone) electron acceptor tethered by a nonconjugated linker, displays solvatofluorochromism (SFC) and dual fluorescence associated with intramolecular charge transfer (ICT) in the excited state. While the fluorescence arises from a locally excited state of 4 (LE-4*) in saturated hydrocarbon solvents, the fluorescence from the ICT state of 4 (ICT-4*) occurs in aprotic solvents. ICT-4* has a much greater dipole moment than its corresponding ground state. The results of theoretical calculations suggest that the conversion of LE-4* to ICT-4* involves a unique structural change like a leaning of the pentadienone moiety. Two factors are responsible for the significant SFC displayed by 4, the first being the high electron-donating and -accepting abilities of the respective locally excited TPA and pentadienone moieties in LE-4* and the other being a rigid ethano bridge that links the two moieties in ICT-4*. The former property facilitates photoinduced electron-transfer (PET) and the latter prevents full single electron transfer (SET) by prohibiting direct π-conjugation and the spatial approach of the two dyad components. Consequently, these electronic and geometrical features lead to SFC arising from a large dipole moment change caused by ICT and partial intramolecular SET.

中文翻译：

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具有非共轭连接子的倾斜胺-酮二联体：与分子内电荷转移相关的溶剂化荧光致变色和双重荧光†

Dyad 4包含三苯胺（TPA）电子供体和通过非共轭连接物束缚的1,4-戊二烯-3-一（戊二烯酮）电子受体，在分子中显示了溶剂化荧光致变色（SFC）和与分子内电荷转移（ICT）相关的双重荧光。兴奋的状态。虽然荧光来自饱和烃溶剂中4（LE- 4 *）的局部激发态，但来自ICT状态4（ICT- 4 *）的荧光在非质子溶剂中产生。ICT- 4 *的偶极矩比其相应的基态大得多。理论计算结果表明，LE- 4 *转换为ICT- 4 *涉及独特的结构变化，如戊二烯酮部分的倾斜。由4表示的重要SFC有两个因素，第一个是LE- 4 *中各自的局部激发的TPA和戊二烯酮部分的高电子给体和-接受能力，另一个是连接两者的刚性乙二醛桥ICT- 4 *中的部分。前者的性质有利于光致电子转移（PET），后者的性质则通过阻止直接π共轭和两个二元组成分的空间接近来防止完全单电子转移（SET）。因此，这些电子和几何特征会导致SFC，这是由ICT和部分分子内SET引起的大偶极矩变化引起的。