Alkyl chain-dependent cyano-stilbene derivative's molecular stacking, emission enhancement and fluorescent response to the mechanical force and thermal stimulus
作者:Pengchong Xue、Chunyu Zhang、Kunpeng Wang、Meng Liang、Tong Zhang
DOI:10.1016/j.dyepig.2018.12.036
日期:2019.4
One involved the antiparallel stacking of nonplanar aromatic moieties. The other consisted of coplanar molecules without π-π stacking, which were responsible for the higher luminescence yield. Moreover, the emission of the C4MPA solid was quenched under mechanical force, whereas the C8MPA solid still emitted a strong fluorescence after grinding. C8MPA lost fluorescence when heated at above 60 °C because
合成了两个带有丁基(C4MPA)和辛基(C8MPA)的氰基-苯乙烯衍生物,以研究烷基链对分子堆积,发射增强和机械荧光致变色的影响。这两种化合物在单分子状态下显示出微弱的发射,并在晶体状态下发射出增强的荧光。但是,C4MPA的荧光量子产率(19%)低于C8MPA的荧光量子产率(76%)。仅在C4MPA晶体中发现了面对面的二聚体堆叠,其中分子采用了非平面构型。C8MPA晶体呈现两种反平行的一维排列。一种涉及非平面芳族部分的反平行堆叠。另一个由没有π-π堆积的共面分子组成,这导致了更高的发光产量。而且,C4MPA固体的发射在机械力作用下淬灭,而C8MPA固体在研磨后仍然发出强荧光。C8MPA由于熔点低而在60°C以上加热时会丢失荧光,即使将样品冷却至室温10 h,也观察到没有荧光的过冷粘性液体,这意味着结晶过程非常缓慢。在机械力剪切刺激下,这种非发射性的过冷粘性液体可能会迅速转变为强发射性固体。