Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, The Chinese Academy of Sciences, Beijing, China.
Phys Chem Chem Phys. 2013 May 7;15(17):6243-9. doi: 10.1039/c3cp50384d.
A series of styrylquinoxaline alkoxy derivatives, 3-(4-(alkoxy)styryl)quinoxalin-2(1H)-one substituted with different alkyl chain lengths (SQCn, n = 12, 14, 16, 18), have been synthesized. The air/water interfacial assemblies of these compounds fabricated using the Langmuir-Blodgett technique were studied. The assemblies transferred on the solid substrate showed photochemical reactions and supramolecular chirality, which depend on the length of the alkyl chain. The increment of the alkyl chain length caused the SQCn assemblies to change from an unstable molecular film to disordered and ordered arrangement in the LB films. Specifically, SQC12 could not form stable molecular films. Although SQC14 could form stable molecular films, the disordered packing of the molecules in the LB films caused the absence of supramolecular chirality as well as photodimerization. When the alkyl chain is increased to 16 or above, the SQC LB films show supramolecular chirality and topochemical photodimerization upon irradiation. These results indicated that the hydrophobic interaction between the long alkyl chains also played an important role in regulating the packing of the functional groups at the air/water interface, which would subsequently affect the photodimerization and the emergence of supramolecular chirality.
一系列苯乙烯基喹喔啉烷氧基衍生物，3-(4-(烷氧基)苯乙烯基)喹喔啉-2(1H)-酮取代了不同的烷基链长度（SQCn，n = 12、14、16、18），已经被合成出来。使用 Langmuir-Blodgett 技术制备的这些化合物的气/水界面组装体进行了研究。在固体基底上转移的组装体显示出光化学反应和超分子手性，这取决于烷基链的长度。烷基链长度的增加导致 SQCn 组装体从不稳定的分子膜转变为 LB 膜中的无序和有序排列。具体来说，SQC12 不能形成稳定的分子膜。虽然 SQC14 可以形成稳定的分子膜，但分子在 LB 膜中的无序堆积导致超分子手性和光二聚化的缺失。当烷基链增加到 16 或以上时，SQC LB 膜在照射下表现出超分子手性和拓扑光二聚化。这些结果表明，长烷基链之间的疏水相互作用也在调节功能基团在气/水界面的堆积方式方面发挥了重要作用，这将随后影响光二聚化和超分子手性的出现。
