磷光软盐配合物及其光电应用研究

Phosphorescent ion-paired complexes, which consist of two oppositely charged transition metal complexes with excellent photophysical properties, are called "soft salts" because of the soft nature of the ions. In recent decades, phosphorescent soft salt complexes have gained an increasing attention and this review aims to summarize the syntheses and photophysical properties of those complexes, and recent advances of them in different optoelectronic applications. Generally, phosphorescent soft salt complexes are synthesized via salt metathesis reactions between two oppositely charged organometallic components. By changing the chemical structure of ligands or the metal centers of the different ionic complexes, the photophysical properties of soft salt complexes can be easily regulated. Moreover, most of the soft salt complexes show concentration-dependent photoluminescence (PL) spectra due to the energy transfer between positive and negative ions. Thus, white light emission can be obtained by dissolving ion-paired complex consisting of two ionic components with blue and yellow emission in solution at certain concentration. Considering the excellent photophysical properties and easy tunability of phosphorescent soft salt complexes, the application of them in diverse optoelectronic fields, such as organic light emitting diodes, bioimaging, photodynamic therapy, electrochromic luminescence devices, and so on, have been explored. For example, Thompson and co-workers utilized iridium(III) complexes based phosphorescent soft salts to fabricate organic light emitting diodes for the first time. Our group have first developed soft salts based phosphorescent probes for ratiometric and lifetime imaging of pH and oxygen changes in living cells. In addition, we have found that soft salt complexes showed an enhanced singlet oxygen generation rate due to the efficient energy transfer between two ionic components, which has great potential to act as a photosensitizer for photodynamic therapy of cancer cells. Huang and co-workers have proposed a new strategy to design electrochromic luminescence materials based on soft salt complexes, which display tunable and reversible electrochromic luminescence. In summary, phosphorescent soft salt complexes possessing excellent photophysical properties show great potential in diverse optoelectronic applications.