Facile Synthesis, Structure, and Luminescence Properties of Pt(diimine)bis(arylacetylide) Chromophore−Donor Dyads
2005; American Chemical Society; Volume: 44; Issue: 8 Linguagem: Inglês
10.1021/ic048886l
ISSN1520-510X
AutoresThaddeus J. Wadas, Soma Chakraborty, R.J. Lachicotte, Quan‐Ming Wang, Richard Eisenberg,
Tópico(s)Nonlinear Optical Materials Studies
ResumoThe luminescent complex Pt(dpphen)bis(arylacetylide) complex (1) (dpphen = 4,7-diphenylphenanthroline and arylacetylide = 4-ethynylbenzaldehyde) has been synthesized and characterized structurally and spectroscopically. Complex 1 has been employed in the synthesis of donor−chromophore (D−C) dyads through Schiff base condensations of different anilines to give imine-linked dyads 2−4 and through imine reduction with borohydride, to give the corresponding amine-linked dyads 2a−4a. Crystal structure determinations of 1−4 and 4a establish a distorted square-planar geometry around the Pt(II) ion in each system with cis arylacetylide ligands and a diimine-constrained N−Pt−N bond angle of ca. 79.5°. Complex 1 is strongly emissive having a relative quantum yield (φ) of 36% and an excited-state lifetime of 3.1 μs. In accord with the notion of photoinduced electron transfer from the aniline-based donor to the photoexcited chromophore, the emission of dyads 2−4 and 2a−4a is effectively quenched in all solvents tested. The intense absorption at 400 nm (30000−70000 L/mol·cm) for 2 and 2a has been assigned as an intraligand π−π* transition, whereas the lowest-energy transitions for all other dyads correspond to Pt-to-π*(diimine) MLCT transitions. Although the dyads can be synthesized in a facile manner, photolysis experiments reveal that both the imine and amine linkages are photochemically unstable, resulting in hydrolysis and regeneration of the aldehyde-containing chromophore 1.
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