Molecular design of novel luminescent complexes based on hybrid phosphine ligands for chemo- and biosensing applications

该联合项目旨在提供基于一类新的多供体杂化含磷杂环及其过渡金属配合物的新型发光系统，用于化学和生物传感以及生物成像。主要的合成努力将指向含有两个内环磷（III）原子、两个外环显色基团和两个位于内环氮原子上的可调功能的环膦配体，以在低成本框架内实现最大的合成灵活性。这些化合物将由伯胺或氨基酸与甲醛缩合反应合成，然后通过添加伯胺或氨基酸形成环。磷和氮上的显色异芳取代基为超分子组装提供了发光特性和额外的结合位点。内环氮原子上的不同取代基也将用于修饰供体中心的空间和电子性质，并同时提供微调配体的物理性质（如亲脂性、亲水性和发光性）的手段。金属配合物的光学性质取决于发色团和金属离子的类型。d6、d8和d10金属离子(Ir（III）、Pt（II）、Au（I)和Cu(I)）具有不同配位数和配位球，可以获得不同的发光参数。为了实现有效的电荷转移和高发光，应将显色基团与金属中心配合或放置在较近的位置。此外，一些显色性配体将在金属中心配位，以改变配合物的光物理性质。目标配合物的独特结构将为它们的底物诱导发光响应提供基础，而底物诱导发光响应则是由氧化还原转化或主客体配合物形成的结果。将对合成的配合物进行电子结构的量子化学研究，目的是揭示参与电子吸收和发光跃迁的轨道。在了解光谱起源及其结构-性质关系的基础上，将对各种功能和应用的发光金属配合物的发展潜力进行评估，特别是在生物成像和生物传感领域。由于配合物在水中的不溶性可能会限制它们在生物成像和生物传感方面的适用性，因此这些配合物也将被转化为水溶性亲水纳米颗粒用于这些研究。

This joint project aims to provide access to novel luminescent systems based on a new class of multidonor hybrid phosphorus-containing heterocycles and their transition metal complexes for applications in chemo- and biosensing and bioimaging. The main synthetic efforts will be directed towards cyclic phosphine ligands containing two endocyclic phosphorus(III) atoms, two exocyclic chromophoric groups, and two tunable functions located on the endocyclic nitrogen atoms to allow maximal synthetic flexibility within a low-cost framework. These compounds will be synthesized by condensation reactions of primary heteroaryl phosphines with formaldehyde and subsequent ring formation through addition of primary amines or amino acids. Chromophoric heteroaromatic substituents at phosphorus and nitrogen provide luminescence properties and additional binding sites for supramolecular assemblies. Differing substituents on the endocyclic nitrogen atoms will also be used to modify the steric and electronic properties of the donor centers, and will simultaneously provide the means to fine-tune physical properties such as ligand lipo- and hydrophilicity and luminescence. The optical properties of metal complexes depend on the type of chromophore and metal ion. A variety of luminescence parameters will be achieved by employing d6, d8, and d10 metal ions (Ir(III), Pt(II), Au(I) und Cu(I)) with different coordination numbers and coordination spheres. For effective charge transfer and high luminescence, chromophoric groups should be coordinated to the metal center or be located in near proximity. Moreover, a number of chromophoric coligands will be coordinated at the metal center to modify the photophysical properties of the complexes. The unique structure of the targeted complexes will provide a basis for their substrate-induced luminescence response, which in turn results from redox transformations or host–guest complex formation. Quantum chemical investigations of the electronic structure will be performed for the synthesized complexes with the aim of revealing the orbitals involved in the transitions responsible for electronic absorption and luminescence. On the basis of an understanding of the spectroscopic origin and their structure–property relationships, the potential for the development of luminescent metal complexes for a variety of functions and applications, especially in the field of bioimaging and biosensing, will be evaluated. As insolubility of the complexes in water might restrict their suitability for bioimaging and biosensing, these complexes will also be converted to water-soluble hydrophilic nanoparticles for these studies.