Abstract
The proligand 4,6-di-(4-tert-butylphenyl)pyrimidine LH(2) can undergo cycloplatination with K(2)PtCl(4) at one of the two aryl rings to give, after treatment with sodium acetylacetonate, a mononuclear complex Pt(N^C-LH)(acac) (denoted Pt). If an excess of K(2)PtCl(4) is used, a dinuclear complex of the form [Pt(acac)](2){μ-(N^C-L-N^C)} (Pt(2)) is obtained instead, where the pyrimidine ring acts as a bridging unit. Alternatively, the mononuclear complex can undergo cyclometalation with a different metal ion. Thus, reaction of Pt with IrCl(3)·3H(2)O (2:1 ratio) leads, after treatment with sodium acetylacetonate, to an unprecedented mixed-metal complex of the form Ir{μ-(N^C-L-N^C)Pt(acac)}(2)(acac) (Pt(2)Ir). The mononuclear iridium complex Ir(N^C-LH)(2)(acac) (Ir) has also been prepared for comparison. The UV-visible absorption and photoluminesence properties of the four complexes and of the proligand have been investigated. The complexes are all highly luminescent, with quantum yields of around 0.5 in solution at room temperature. The introduction of the additional metal centers is found to lead to a substantial red-shift in absorption and emission, with λ(max) in the order Pt < Pt(2) < Ir < Pt(2)Ir. The trend is interpreted with the aid of electrochemical data and density functional theory calculations, which suggest that the red-shift is due primarily to a progressive stabilization of the lowest unoccupied molecular orbital (LUMO). The radiative decay constant is also increased. This versatile design strategy may offer a new approach for tuning and optimizing the luminescence properties of d-block metal complexes for contemporary applications.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.