芘基吡啶鎓盐羧酸金属配合物光调控三阶非线性的研究

The incorporation of effecting photoinduced switching into non-linear optical (NLO) materials will further increase their potential for novel applications in emerging optoelectronic and photonic technologies relevant to applications such as optical computing. In recent years, considerable effort has been devoted to the development of second-order nonlinearities photoswitchable materials. However, the photoswitching possessing the third-order NLO effects has rarely been reported to date. In the project, the study of the third-order NLO photoswitchable materials of metal complexes will be explored. We are planning to synthesize two series of photoswitchable compounds: one is a complete-π-conjugated system containing pyrenyl pyridinium carboxylates and their metal complexes, and the other is semi-π-conjugated system containing pyrenyl pyridinium carboxylates and their metal complexes. By Z-scan and time-resolved pump–probe technique, we will understand the contribution of complete-π-conjugated and semi-π-conjugated systems to NLO properties and also give the curves of third-order NLO absorption and refraction with delay time, and then confirm the mechanism of NLO absorption and refraction behaviors. Moreover, we will try to explore the change of third-order NLO properties of the two series of photoswitchable compounds under UV irradiation. In the proposal, we hope to find the change of NLO properties of the thin films and single-crystal photoswitchable compounds under UV irradiation, and a unique insight into the conversion mechanism of photoswitching process will be presented by combination of experiment results and density functional theory (DFT) calculations.

光调控非线性开关由于其在光调制器、全光通讯、光信号处理和光计算等方面的应用前景而受到人们的广泛关注。目前关于调控二阶非线性光开关的研究发展较快，对三阶非线性光开关的研究少有涉及。本项目拟开展光调控金属配合物三阶非线性光学(NLO)材料的研究。首先，拟设计合成两个系列的紫外光响应体系：一类是π电子全共轭的芘稠环结合吡啶鎓盐羧酸配体及其金属配合物，另一类是π电子半共轭的芘基吡啶鎓盐羧酸配体及其金属配合物。然后，通过纳秒、皮秒、飞秒等多尺度Z-扫描和泵浦探测技术测试三阶NLO吸收和折射，研究电子全共轭和电子半共轭对三阶NLO性质的影响。进一步，结合瞬态非线性测试及量子化学计算，确定三阶NLO性能产生的机理。最后，考察这两类光响应化合物（溶液、单晶、薄膜）在紫外光照射前后三阶NLO性质的变化，结合其物理化学性质转变，阐明光调控三阶NLO的转换机理。

光调控非线性开关由于其在光调制器、全光通讯、光信号处理和光计算等方面的应用前景而受到人们的广泛关注。将偶氮苯、苯并噻二唑和稠环芳烃等光敏基团引入到金属配合物中，获得了一系列紫外光响应的金属配合物三阶NLO新体系。解释了金属配合物三阶NLO性能产生的机理，反饱和吸收的机制是双光子诱导的激发态吸收，自聚焦效应来自于克尔诱导的激发态折射。阐明了结构与NLO性质的关系，金属与光敏基团之间的电荷转移使得整个共扼体系的电子离域性更强，从而增强甚至改变了光敏性化合物的三阶NLO特性。同时，扭曲的分子内电荷转移过程可以使具有可旋转的D-π-A结构的发光分子拥有不同的电子激发态能级，造成这些分子拥有多样的三阶NLO性质。.单晶态骨架交换反应提升金属有机框架（MOFs）材料性能已经成为后合成修饰的重要方法。MOFs材料在进行中心金属、配体和客体分子交换时，金属离子/有机物在MOFs的孔腔中来回穿梭，伴随着新配位键的形成与旧配位键的断裂，就使得MOFs材料的孔腔有了更好的“膨胀与收缩”，呈现出“呼吸效应”。“呼吸效应”是MOFs骨架功能化的一种重要方式，可以应用于有害重金属的去除。通过单晶态交换反应使得MOFs的孔腔功能化，在设计构建高效吸附材料方面有着巨大潜力。.均匀的孔径和比较大的比表面积使得MOFs材料成为开发在相对温和反应条件下具有高催化活性、高选择性和可循环使用的C-H活化催化剂的理想平台。我们提供了三种用于C-H键活化的MOFs催化剂的设计和合成，即金属节点作为催化位点、催化位点与有机单元的结合和催化活性客体分子与孔道的结合，阐明了不同催化性能的MOFs催化剂对功能与微环境的作用。