Influence of Ancillary Ligands and Isomerism on the Luminescence of Bis-cyclometalated Platinum(IV) Complexes

Juliá Hernández, Fabio; García-Legaz, María Dulce; Bautista, Delia; González Herrero, Pablo

Publication:
Influence of Ancillary Ligands and Isomerism on the Luminescence of Bis-cyclometalated Platinum(IV) Complexes

dc.contributor.author	Juliá Hernández, Fabio
dc.contributor.author	García-Legaz, María Dulce
dc.contributor.author	Bautista, Delia
dc.contributor.author	González Herrero, Pablo
dc.contributor.department	Química Inorgánica
dc.date.accessioned	2021-09-29T16:24:44Z
dc.date.available	2021-09-29T16:24:44Z
dc.date.copyright	© 2016 American Chemical Society
dc.date.issued	2016-08-01
dc.description.abstract	The synthesis, characterization, and photophysical properties of a wide variety of bis-cyclometalated Pt(IV) complexes featuring a C2-symmetrical or unsymmetrical {Pt(ppy)2} unit (sym or unsym complexes, respectively; ppy = C-deprotonated 2-phenylpyridine) and different ancillary ligands are reported. Complexes sym-[Pt(ppy)2X2] (X = OTf–, OAc–) were obtained by chloride abstraction from sym-[Pt(ppy)2Cl2] using the corresponding AgX salts, and the triflate derivative was employed to obtain homologous complexes with X = F–, Br–, I–, trifluoroacetate (TFA–). Complexes unsym-[Pt(ppy)2(Me)X] (X = OTf–, F–) were prepared by reacting unsym-[Pt(ppy)2(Me)Cl] with AgOTf or AgF, respectively, and the triflate derivative was employed as precursor for the synthesis of the homologues with X = Br–, I–, or TFA– through its reaction with the appropriate anionic ligands. The previously reported complexes unsym-[Pt(ppy)2X2] (X = Cl–, Br–, OAc–, TFA–) are included in the photophysical study to assess the influence of the arrangement of the cyclometalated ligands. Density functional theory (DFT) and time-dependent DFT calculations on selected derivatives were performed for a better interpretation of the observed excited-state properties. Complexes sym-[Pt(ppy)2X2] (except X = I–) exhibit phosphorescent emissions in fluid solutions at 298 K arising from essentially 3LC(ppy) excited states, which are very similar in shape and energy. However, their efficiencies are heavily dependent on the nature of the ancillary ligands, which affect the energy of deactivating ligand-to-ligand charge transfer (LLCT) or ligand-to-metal charge transfer (LMCT) states. The fluoride derivative sym-[Pt(ppy)2F2] shows the highest quantum yield of this series (Φ = 0.398), mainly because the relatively high metal-to-ligand charge transfer admixture in its emitting state leads to a high radiative rate constant. Complexes unsym-[Pt(ppy)2X2] emit from 3LC(ppy) states in frozen matrices at 77 K, but their emissions are totally quenched in fluid solution at 298 K because of the presence of low-lying, dissociative LMCT excited states, which also cause photoisomerization reactions. Complexes unsym-[Pt(ppy)2(Me)X] (X = F–, Cl–, Br–, TFA–) show strong emissions in fluid solutions at 298 K (Φ = 0.52–0.63) because deactivating LMCT states lie at high energies. However, derivative unsym-[Pt(ppy)2(Me)I] is only weakly emissive at 298 K because of the presence of low-lying LLCT [p(I) → π*(ppy)] states.
dc.format	application/pdf	es
dc.format.extent	48	es
dc.identifier.citation	Inorganic Chemistry 2016, 55(15), 7647-7660
dc.identifier.doi	https://doi.org/10.1021/acs.inorgchem.6b01100
dc.identifier.issn	0020-1669
dc.identifier.uri	http://hdl.handle.net/10201/112443
dc.language	eng	es
dc.publisher	ACS	es
dc.relation	This work was supported by Ministerio de Economía y Competitividad, Spain (Grant No. CTQ2011-24016, with FEDER support), Ministerio de Educación, Cultura y Deporte, Spain (FPU Grant to F. J), Fundación Séneca (Grant No. 19890/GERM/15) and Universidad de Murcia.
dc.rights	info:eu-repo/semantics/openAccess	es
dc.rights	Attribution-NonCommercial-NoDerivatives 4.0 Internacional	*
dc.rights.uri	http://creativecommons.org/licenses/by-nc-nd/4.0/	*
dc.subject	Platino	es
dc.subject	Luminiscencia
dc.subject	Complejos ciclometalados
dc.title	Influence of Ancillary Ligands and Isomerism on the Luminescence of Bis-cyclometalated Platinum(IV) Complexes	es
dc.type	info:eu-repo/semantics/article	es
dc.type.version	info:eu-repo/semantics/acceptedVersion
dspace.entity.type	Publication	es
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