Vivancos Ureña, Ángela

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Vivancos Ureña, Ángela

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Vivancos Ureña, Ángela

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Universidad de Murcia. Departamento de Química Inorgánica

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Open Access
Data for compounds included in the article "Luminescent Platinum(II) Complexes with Terdentate N∧C∧C Ligands".
(2023) Poveda Otazo, Dionisio; Vivancos Ureña, Ángela; Bautista, Delia; González Herrero, Pablo; Química Inorgánica; Facultades de la UMU::Facultad de Química
Open Access
Data for compounds included in the article "Bimetallic platinum(ii) complexes with bridging di-NHC and N^C^C ligands: synthesis and photophysical properties"
(2026-05-22) Mariano Paredes; Vivancos Ureña, Ángela; Poveda Otazo, Dionisio; González Herrero, Pablo; Química Inorgánica; Facultades de la UMU::Facultad de Química
Open Access
Synthesis, Luminescence, and Electrochemistry of Tris-Chelate Platinum(IV) Complexes with Cyclometalated N-Heterocyclic Carbene Ligands and Aromatic Diimines
(ACS Publications, 2024-12-19) Serrano Guarinos, José; Jiménez García, Adrián; Bautista, Delia; González Herrero, Pablo; Vivancos Ureña, Ángela; Química Inorgánica; Facultades de la UMU::Facultad de Química
Dicationic, C2-symmetrical, tris-chelate Pt(IV) com plexes of general formula [Pt(trz)2(N∧N)](OTf)2, bearing two cyclometalated 4-butyl-3-methyl-1-phenyl-1H-1,2,3-triazol-5-yli- dene (trz) ligands and one aromatic diimine [N∧N = 2,2′- bipyridine (bpy, 2), 4,4′-di-tert-butyl-2,2′-bipyridine (dbbpy, 3), 4,4′-dimethoxi-2,2′-bipyridine (dMeO-bpy, 4), 1,10-phenanthro- line (phen, 5), 4,7-diphenyl-1,10-phenanthroline (bphen, 6), dipyrido[3,2-a:2′,3′-c]phenazine (dppz, 7), or 2,3- diphenylpyrazino[2,3-f ][1,10]phenanthroline (dpprzphen, 8)] are obtained through chloride abstraction from [PtCl2(trz)2] (1) using AgOTf in the presence of the corresponding diimine. Complexes 2−4 show long-lived phosphorescence from 3LC excited states involving the diimine ligand, with quantum yields that reach 0.18 in solution and 0.58 in the solid matrix at room temperature for 3. Derivatives with more extended aromatic systems show dual phosphorescent/fluorescent emissions (5, 6) or mainly fluorescence (7, 8) in solution. Comparisons with similar complexes bearing cyclometalated 2-arylpyridines instead of aryl-N-heterocyclic carbenes indicate that the {Pt(trz)2} subunit is crucial to enable efficient emissions from diimine-centered excited states. It is also shown that the introduction of protective bulky substituents on the diimine, such as the tert-butyl groups in 3, is a key strategy to reach higher emission efficiencies. The new compounds represent rare examples of luminescent Pt(IV) complexes that show quasi-reversible one-electron reductions, indicating an unusually high redox stability.
Open Access
Selective synthesis, reactivity and luminescence of unsymmetrical bis-cyclometalated Pt(IV) complexes
(Royal Society of Chemistry, 2019-09-18) Vivancos Ureña, Ángela; Poveda Otazo, Dionisio; Muñoz, Alonso; Moreno, Julia; Bautista, Delia; González Herrero, Pablo; Química Inorgánica
Pt(II) complexes cis-N,N-[PtCl(C^N)(N′^C′H)], where C^N represents a monocyclometalated 2,6-diaryl- or 2-arylpyridine ligand and N′^C′H is an N-coordinated 2-arylpyridine, are selectively obtained from bridge-cleavage reactions of dimers [Pt2(μ-Cl)2(C^N)2] with excess N′^C′H at room temperature; isolation and characterization of derivatives of this kind is reported for the first time. Oxidation with PhICl2 affords Pt(IV) complexes [PtCl2(C^N)(C′^N′)], bearing two cyclometalated ligands in an unsymmetrical arrangement. The abstraction of the two chlorides using AgOTf at 120 °C in the presence of an additional 2-arylpyridine ligand leads to mer isomers of tris-cyclometalated Pt(IV) complexes if C^N derives from a 2-arylpyridine, whereas it results in a reductive C–C coupling if C^N is a monocyclometalated 2,6-diarylpyridine. Complexes [PtCl2(C^N)(C′^N′)] show phosphorescence in frozen PrCN glasses arising from essentially 3LC excited states localized on the cyclometalated ligand with the lowest π–π* transition energy. The combined photophysical data and computational results substantiate a variable degree of MLCT admixture into the emitting state depending on the atom trans to the metalated carbon of the chromophoric ligand (Cl or N), which has an appreciable effect on the characteristics of the observed luminescence.
Open Access
Luminescent platinum (II) Complexes with Terdentate N∧C∧C Ligands
(2023-12-05) Poveda Otazo, Dionisio; Vivancos Ureña, Ángela; Bautista, Delia; González Herrero, Pablo; Química Inorgánica
The synthesis, structure, and luminescence of Pt(II) complexes of the type [Pt(N∧C∧C)(L)] are reported, where N∧C∧C is a terdentate ligand resulting from the cycloplatination of 2-(3,5-diphenoxyphenyl)pyridine or 2-(4,4″-dimethyl-[1,1′:3′,1″-terphenyl]-5′-yl)pyridine, and L represents a monodentate ancillary ligand, which can be γ-picoline, 4-pyridinecarboxaldehyde, PPh3, n-butyl or 2,6-dimethylphenyl isocyanide, CO, or the N-heterocyclic carbenes 1-butyl-3-methylimidazol-2-ylidene or 4-butyl-3-methyl-1-phenyl-1H-1,2,3-triazol-5-ylidene. Derivatives bearing CO, isocyanides, or carbenes showed the highest stabilities in solution, whereas the pyridine and PPh3 derivatives establish ligand-exchange equilibria in acetonitrile. Different supramolecular structures are observed in the solid state, which largely depend on the nature of the ancillary ligand. Isocyanides and CO favor π interactions between the aromatic rings, metallophilic Pt···Pt contacts, or a combination of both. In contrast, pyridine ligands may lead to bimolecular assemblies driven by C–H···O, C–H···Pt, or C–H/π hydrogen bonds. Luminescence was examined in fluid solution, poly(methyl methacrylate) matrices, and the solid state at 298 K, and in 2-methyltetrahydrofuran glasses at 77 K. The majority of derivatives show highly efficient emissions from 3ILCT/MLCT or 3ILCT/MLCT/LLCT excited states of monomeric species. The formation of excimers and different types of emissive aggregates are demonstrated, which lead to red-shifted emissions of different origins and characteristics depending on the
Open Access
Bimetallic platinum(II) complexes with bridging di-NHC and N^C^C ligands: synthesis and photophysical properties
(Royal Society of Chemistry, 2025-10-02) Mariano Paredes; Vivancos Ureña, Ángela; Poveda Otazo, Dionisio; González Herrero, Pablo; Química Inorgánica; Facultades de la UMU::Facultad de Química
Three new bimetallic Pt(II) compounds of the type [{Pt(dmtppy)}2{μ-(ImMe)2(CH2)n}] [n = 1 (1), 3 (2), 6 (3)], where dmtppy is the dimetalated tridentate N^C^C ligand 2-(4,4’’-dimethyl-[1,1’:3’,1’’-terphenyl]-5’-yl) pyridine and ImMe is N-methylimidazol-N-yl-2-ylidene, have been synthesized in order to explore their ability to form molecular assemblies that affect their luminescence. Restricted rotation around the Pt–carbene bond leads to mixtures of atropisomers, which hinder the growth of single crystals. The com- plexes show efficient emissions with high phosphorescence quantum yields in 2 wt% doped PMMA films at 298 K (PLQY: 73–77%). Significant modifications of their photophysical properties in fluid solution are observed upon variation of the solvent, with the highest efficiencies found in 2-methyltetrahydrofurane (up to 63% quantum yield for complex 3). In the case of complex 1, which contains the shortest linkage, the formation of excimers in MeCN and MeOH causes a significant quenching of the emission, with a substantial decrease in the quantum yield.
Open Access
Strongly luminescent Pt(IV) complexes with a Mesoionic N-Heterocyclic Carbene Ligand: tuning their photophysical properties.
(2021-02-09) Vivancos Ureña, Ángela; Jiménez García, Adrián; Bautista, Delia; González Herrero, Pablo; Química Inorgánica
The synthesis, electrochemistry, and photophysical properties of a series of bis-cyclometalated Pt(IV) complexes that combine the mesoionic aryl-NHC ligand 4-butyl-3-methyl-1-phenyl-1H-1,2,3-triazol-5-ylidene (trz) with either 1-phenylpyrazole or 2-arylpyridine (C∧N) are reported. The complexes (OC-6-54)-[PtCl2(C∧N)(trz)] bearing cyclometalating 2-arylpyridines present phosphorescent emissions in the blue to yellow color range, which essentially arise from 3LC(C∧N) states, and reach quantum yields of ca. 0.3 in fluid solutions and almost unity in poly(methyl methacrylate) (PMMA) matrices at 298 K, thus representing a class of strong emitters with tunable properties. A systematic comparison with the homologous C2-symmetrical species (OC-6-33)-[PtCl2(C∧N)2], which contains two equal 2-arylpyridine ligands, shows that the introduction of a trz ligand leads to significantly lower nonradiative decay rates and higher quantum efficiencies. Computational calculations substantiate the effect of the carbene ligand, which raises the energy of dσ* orbitals in these derivatives and results in the higher energies of nonemissive deactivating 3LMCT states. In contrast, the isomers (OC-6-42)-[PtCl2(C∧N)(trz)] are not luminescent because they present a 3LMCT state as the lowest triplet.
Open Access
Visible light driven generation and alkyne insertion reactions of stable bis-cyclometalated Pt(iv) hydrides
(2020-10-13) Poveda Otazo, Dionisio; Vivancos Ureña, Ángela; Bautista, Delia; González Herrero, Pablo; Química Inorgánica
Hydride complexes resulting from the oxidative addition of C–H bonds are intermediates in hydrocarbon activation and functionalization reactions. The discovery of metal systems that enable their direct formation through photoexcitation with visible light could lead to advantageous synthetic methodologies. In this study, easily accessible dimers [Pt2(μ-Cl)2(C^N)2] (C^N = cyclometalated 2-arylpyridine) are demonstrated as a very convenient source of Pt(C^N) subunits, which promote photooxidative C–H addition reactions with different 2-arylpyridines (N′^C′H) upon irradiation with blue light. The resulting [PtH(Cl)(C^N)(C′^N′)] complexes are the first isolable Pt(IV) hydrides arising from a cyclometalation reaction. A transcyclometalation process involving three photochemical steps is elucidated, which occurs when the C^N ligand is a monocyclometalated 2,6-diarylpyridine, and a detailed analysis of the photoreactivity associated with the Pt(C^N) moiety is provided. Alkyne insertions into the Pt–H bond of a photogenerated Pt(IV) hydride are also reported as a demonstration of the ability of this class of compounds to undergo subsequent organometallic reactions.
Open Access
Phosphorescent Tris-cyclometalated Pt(IV) Complexes with Mesoionic N‐Heterocyclic Carbene and 2‐Arylpyridine Ligands
(2022-07-21) Vivancos Ureña, Ángela; Bautista, Delia; González Herrero, Pablo; Química Inorgánica
The synthesis, structure, photophysical properties, and electrochemistry of the first series of Pt(IV) tris-chelates bearing cyclometalated aryl-NHC ligands are reported. The complexes have the general formula [Pt(trz)2(C∧N)]+, combining two units of the cyclometalated, mesoionic aryl-NHC ligand 4- butyl-3-methyl-1-phenyl-1H-1,2,3-triazol-5-ylidene (trz) with a cyclometalated 2-arylpyridine [C∧N = 2-(2,4-difluorophenyl)- pyridine (dfppy), 2-phenylpyridine (ppy), 2-(p-tolyl)pyridine (tpy), 2-(2-thienyl)pyridine (thpy), 2-(9,9-dimethylfluoren-2-yl)- pyridine (flpy)], and presenting a mer arrangement or metalated aryls. They exhibit a significant photostability under UV irradiation and long-lived phosphorescence in the blue to yellow color range, arising from 3LC excited states involving the C∧N ligands, with quantum yields of up to 0.34 in fluid solution and 0.77 in the rigid matrix at 298 K. The time-dependent density functional theory (TD-DFT) calculations reveal that nonemissive, deactivating excited states of ligand-to-metal charge-transfer (LMCT) character are pushed to high energies as a consequence of the strong σ-donating ability of the carbenic moieties, making the Pt(trz)2 subunit an essential structural component that enables efficient emissions from the chromophoric C∧N ligands, with potential application for the development of different Pt(IV) emitters with tunable properties.
Open Access
Luminescent platinum(IV) complexes bearing cyclometalated 1,2,3-triazolylidene and bi- or terdentate 2,6-diarylpyridine ligands
(Wiley, 2019-04-23) Vivancos Ureña, Ángela; Bautista, Delia; González Herrero, Pablo; Química Inorgánica
The synthesis, structure, and photophysical properties of luminescent PtIV complexes that combine cyclometalated 1,2,3-triazolylidene and bi- or terdentate 2,6-diarylpyridine ligands are reported. The targeted complexes represent the first examples of PtIV species with a cyclometalated mesoionic aryl-NHC ligand. They exhibit moderate or weak emissions in fluid solution at 298 K arising from 3LC states, which become very intense in poly(methyl methacrylate) (PMMA) matrices at 298 K. DFT and TD-DFT calculations confirm that the chromophoric ligand is the cyclometalated 2,6-diarylpyridine and show that the aryl-NHC ligand exerts a beneficial effect on the emission efficiencies of these derivatives by increasing the energy of deactivating LMCT excited states with respect to comparable PtIV complexes with cyclometalated 2-arylpyridine ligands.