Abstract
An IrIII-PtII heterodimetallic complex [(ppy)2Ir(dapz)PtCl2]Cl (4), together with the corresponding monometallic complexes [(dapz)PtCl2] (2) and [(ppy)2Ir(dapz)]Cl (3) was designed and prepared, where dapz is 2,5-di(N-methyl-N′-(pyrid-2-yl)amino)pyrazine and ppy is 2-phenylpyridine, respectively. Single-crystal X-ray analysis was carried out for complex 4, displaying the intermolecular Pt∙∙∙Pt and aromatic plane∙∙∙plane distances of 3.839 and 3.886 Å, respectively. The monometallic complex 2 exhibits a single emission maximum at 432 nm with a shorter excited-state lifetime (τ) of 6 ns, while complex 3 exhibits an emission band at 454 nm with a longer excited-state lifetime of 135 ns in CH3CN (N2-saturated) under ambient conditions. In contrast, the heterodimetallic complex 4 displays intriguing excitation wavelength-dependent dual singlet and triplet emissions. Theoretical calculations of the electronic structures and absorption spectra of these complexes were carried out to assist the interpretation of these experimental findings.
Highlights
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One strategy to construct dual-emissive transition metal complexes (TMCs) is by tuning the ligand electronic structures of mononuclear complexes such as introducing additional organic luminophores [17,18,24,25] or new ligand-localized charge-transfer excited states [19,26,27]
The predicted transitions is responsible for this band. This state is mainly assigned to the highest occupied molecular (HOMO) → LUMO excitation, with a character of intraligand charge transfer (ILCT) from the aminopyridine units to the central pyrazine unit of dapz
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. One strategy to construct dual-emissive TMCs is by tuning the ligand electronic structures of mononuclear complexes such as introducing additional organic luminophores [17,18,24,25] or new ligand-localized charge-transfer excited states [19,26,27]. Another strategy is the synthesis of dinuclear or multinuclear bridged complexes with the same or different metal ions, which may exhibit interesting photophysical properties by tuning the electron/energy transfer among individual metal components [28,29,30].
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