Synthesis And Performance Study On Salicylic Aldehyde Schiff Base Derivatives With Aggregation Induced Emission Properties

In recent years, a new concept, aggregation enduced emission(AIE),attracted a wide spread attention. The kind of molecule with AIE characteristics has a phenomenon in contrast to the traditional molecular,namely in the high concentration or solid with strong fluorescence so that have the potential applications in solid-state fluorescence material. In this paper, we design and compare several compounds based on salicylaldehyde derivatives which has obvious AIE properties, and can identify Ni2+, Zn2+, Mg2+ under given conditions. Some meaningful results were obtained, as follows:1、 Introduce briefly the concept of aggregation induced emission(AIE) and the formation principle. Summarize the research on the properties of aggregation-induced emission(AIE) and on the recognition of metal ions in recent years.2、Three compounds Sch 1、Sch 2、Sch 3 with AIE properties were synthesized by salicylic aldehyde connected with o-phenylenediamine,m-phenylenediamine and p-phenylenediamine, respectively. Inspect andanalyze the effect of structure on the properties According to the results of AIE property of three molecules. under the condition of mixed solvent of ethanol/acetic acid/water(v:v:v, 5:1:19), salicylaldehyde can realize in situ identification of p-phenylenediamine. And Sch 2 can recognition Zn2+ in pure acetonitrile as solvent under the presence of other ions.3 、 Sythesis compound Sch 4 by one step reaction with5-bromosalicylaldehyde and o-phenylenediamine. The compound has favourable AIE property, and can efficient detect Mg2+ by the binding model of 1:1 in pure acetonitrile. Detection limit can reached2.31×10-5M-1. It is no obvious interference effect that the present of other metal ions.4、The Sch 5, Sch 6, Sch 7, Sch 8 were produced by the reaction of3,5-diiodosalicylal with 8-aminoquinoline 、 1-aminonaftalen 、2-aminopyridine and aniline, respectively. By changing the proportion of poor solvent and adjusting the viscosity of solution, we found that these four compounds have certain AIE properties, but the AIE properties are also different due to the influence of the structure. In pure acetonitrile,Sch 5 can detect Zn2+ with good response, the binding modes for a receptor binding with a Zn2+, and the other ions did not affect the recognition of Zn2+. Sch 6 was not able to identify metal ions, but it was found to be more sensitive to acid in the pH test.5 、 2- aminobenzothiazole was used as substrates connect 5-nitrosalicylaldehyde and 5- methyl salicylaldehyde obtain Sch 9 and Sch10, respectively. By changing the poor solvent percentage, we found that both of them have good AIE properties, and because of the different substituents, showing a different phenomenon, get through fluorescence spectra, UV fluorescence spectrum test, Tyndall effect and laser particle size(DLS) test. Though both can achieve the recognition of Ni2+ by naked eye in the conditions of EtOH/HEPES(9:1, v:v, pH=7.4), the experimental results are not the same with the effect of electron withdrawing group and electron donating group. And detection limit of Sch 9 and Sch 10 can reach 1.73*10-5 M-1 and 6.11*10-4 M-1, respectively.