Voss Jona, Hartmann Yannic, Nieland Esther, Mix Andreas, Schmidt Bernd M
Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, Düsseldorf, Germany.
Organische und Bioorganische Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld, Germany.
Chemistry. 2025 May 14;31(27):e202501047. doi: 10.1002/chem.202501047. Epub 2025 Apr 7.
The self-assembliy of red-light switchable, functionalised ortho-difluoroazobenzene isomers E-/Z-A with aliphatic diamines exhibits an alternating match/mismatch behaviour depending on the diamine's chain length. While even-numbered diamines exclusively form imine macrocycles with the Z-configured azobenzene isomer, odd-numbered diamines form photoswitchable, defined macrocycles. The formation of Z,Z-AX-type macrocycles was demonstrated with butane-1,4- (B) and hexane-1,6-diamine (H), while additionally E,E-AX-type macrocycles were obtained with propane-1,3- (Pr), pentane-1,5-diamine (Pe), and diethylene glycol bisamine (O), validated by single-crystal X-ray structures of E,E-APr and E,E-AO. The observed reactivity differences arise from the preferred conformations of the flexible diamines in solution, which alternate predictably with odd and even numbers of methylene groups, investigated by F-DOSY NMR experiments, MALDI-MS measurements, and UV/Vis spectroscopy. These findings provide detailed insight into photoresponsive self-assembled systems and highlight the potential of azobenzenes in dynamic covalent chemistry, offering new opportunities for controlling structure and function in adaptive materials.
红光可切换的功能化邻二氟偶氮苯异构体E-/Z-A与脂肪族二胺的自组装表现出交替匹配/不匹配行为，这取决于二胺的链长。偶数二胺仅与Z构型的偶氮苯异构体形成亚胺大环，而奇数二胺则形成可光切换的特定大环。用丁烷-1,4-二胺（B）和己烷-1,6-二胺（H）证明了Z,Z-AX型大环的形成，同时用丙烷-1,3-二胺（Pr）、戊烷-1,5-二胺（Pe）和二甘醇双胺（O）额外获得了E,E-AX型大环，通过E,E-APr和E,E-AO的单晶X射线结构进行了验证。通过F-DOSY NMR实验、MALDI-MS测量和紫外/可见光谱研究发现，观察到的反应性差异源于溶液中柔性二胺的优选构象，其随着亚甲基数量的奇偶性而可预测地交替。这些发现为光响应自组装系统提供了详细的见解，并突出了偶氮苯在动态共价化学中的潜力，为控制自适应材料的结构和功能提供了新的机会。
