Design, synthesis and photophysical and photochemcial [i.e. photochemical] study of photochromic metacyclophane and triarylmethane ligands and their rhenium(I) and ruthenium(II) complexes

光致發光間環芳, 三芳基甲烷配體及其錸(I) 和釕(II) 金屬配合物的設計, 合成, 光物理, 光化學性質的研究

Student thesis: Doctoral Thesis

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Author(s)

  • Hua FENG

Detail(s)

Awarding Institution
Supervisors/Advisors
Award date3 Oct 2012

Abstract

A series of photochromic pyridine- and bipyridine-containing leucotriarylmethane ligands has been successfully synthesized and incorporated into tricarbonyl rhenium(I) diimine and cyano ruthenium(II) diimine complexes. The X-ray crystal structures of some of the complexes have also been determined. All complexes are highly colored with moderately intense absorptions in the visible region, which are tentatively ascribed to MLCT [d𝞹(M) 𝞹*(diimine)] transitions. Moreover, these complexes also display photoluminescence. Based on the emission lifetimes and their energy dependence on the diimine ligands, these emissions are assigned as phosphorescence derived from 3MLCT excited state origins. All ligands and complexes show photochromism due to the reversible photo-ionization of the leucotriarylmethanes moiety. The photochromic reactivity, photophysical and electrochemical properties of these ligands and their complexes have been investigated. Through the incorporation of these ligands into Re(I) and Ru(II) complexes, the photochromic properties of these ligands could be changed significantly. Moreover, the photochromic reactivity of these ligands could also serve as reversible switch to change the emission characteristic of the transition metal complexes. A series metacyclophane-containing indole compounds were synthesized and the photoreactivity, photophysical and electrochemical properties of these ligands were investigated. The synthesis of these compounds was carefully characterized by NMR, IR and X-ray crystallography. Upon UV excitation into the dichloromethane solutions of metacyclophanes, the solution becomes much more strongly absorbing in the UV region with the evolution of some new structured absorption. Another series of metacyclophane-containing 1,10-phenathroline ligands have also been designed, synthesized and incorporated into the rhenium(I) tricarbonyl diimine complex system. Before the photocyclization, the ligands and complexes were found to display MLCT phosphorescence. The 𝞹-accepting ability of the phenanthroline ligand has a significant influence on the absorption property, especially, the introducing of decynyl group into the 3 and 8 positions in the phenanthroline. The photocyclization of these ligands and complexes was also investigated. Upon light irradiation, the metacyclophene moiety could undergo irreversible cyclization from an "open form" to a "closed form", through which the excited state and emission properties change significantly. , The ligands' original emission decrease with the growth of a new red-shifted emission band but the complexes show a contrary trend, the the newly evolved emission bands are shifted to blue. Which were believed related to the close energy of 1LC and 1MLCT excited stat

    Research areas

  • Ruthenium compounds, Rhenium compounds, Photochromic materials, Photochemistry, Ligands (Biochemistry), Cyclophanes