Synthesis And Characterization Of Donor-Acceptor Stenhouse Adducts Based On Picolinamine Donor

Light-driven photoswitching molecules have attracted extensive attention in current research due to the wide applications in light-mediated catalysis,photoresponsive materials,selective drug delivery in biological systems,molecular electronics,and so on.The easy conversion between the two photoswitching forms of these molecules in the presence of UV light makes them easy to handle and selective in nature for various applications.Donor–acceptor Stenhouse adducts（DASAs）are a new class of negative photochromic molecules capable of linear-to-cyclic isomerization.We synthesized three new DASAs molecules,which are not only responsive to visible-light irradiation,but also to chemical stimuli including acidity and metal ions.The results also showed that donor groups play an important role in determining the isomerization process and tuning the relative stability of the isomers.This article will conduct research from the following five chapters:The first chapter gave a detailed introduction to the definition,classification,application scope and application prospects of photochromic compounds.In Chapters 2,3,and 4,we have synthesized three DASAs molecules,and analyzed their structural characteristics by ¹H NMR,¹³C NMR,¹H-¹HCOSY,HSQC,HRMS,IR and other characterization methods.In addition,they exhibit interesting isomerization phenomena under light and chemical stimulation,which can realize the mutual conversion of dark open ring structure and colorless closed ring structure,and the speed of this conversion depends on the position of the N atom in the pyridine ring.At the same time,the dramatic color changes of compounds have been used to selectively detect solution acidity,volatile primary amines and Cu²⁺ions.By comparing the responsiveness of these three DASAs to different stimuli,we explored the influence of different donor structures on the isomerization of DASAs.Chapter fifth made a brief summary of the work done in this paper and looked forward to the future work.