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Roy J, Forzatti M, Arnal L, Martín A, Fuertes S, Tordera D, Sicilia V. Pyrazolate-Bridged NHC Cyclometalated [Pt 2] Complexes and [Pt 2Ag(PPh 3)] + Clusters in Electroluminescent Devices. Inorg Chem 2024; 63:7275-7285. [PMID: 38587101 DOI: 10.1021/acs.inorgchem.4c00105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
The ionic transition metal complexes (iTMCs) [{Pt(C∧C*)(μ-Rpz)}2Ag(PPh3)]X (HC∧C* = 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1H-imidazole-2-ylidene, X = ClO4/PF6; Rpz = pz 1a/2a, 4-Mepz 1b/2b, and 3,5-dppz 1c/2c) were prepared from the neutral [{Pt(C∧C*)(μ-Rpz)}2] (Rpz = pz A, 4-Mepz B, and 3,5-dppz C) and fully characterized. The "Ag(PPh3)" fragment is in between the two square-planar platinum units in an "open book" disposition and bonded through two Pt-Ag donor-acceptor bonds, as shown by X-ray diffraction (dPt-Ag ∼ 2.78 Å, 1a-1c). 195Pt{1H} and 31P{1H} NMR confirmed that these solid-state structures remain in solution. Photoluminescence studies and theoretical calculations on 1a, were performed. The diphenylpyrazolate derivatives show the highest photoluminescence quantum yield (PLQY) in the solid state. Therefore, 2c and its neutral precursor C were selected as active materials on light-emitting devices. OLEDs fabricated with C showed a turn-on voltage of 3.2 V, a luminance peak of 21,357 cd m-2 at 13 V, and a peak current efficiency of 28.8 cd A-1 (9.5% EQE). They showed a lifetime t50 of 15.7 h. OLEDs using 2c showed a maximum luminance of 114 cd m-2, while LECs exhibited a maximum luminance of 20 cd m-2 and a current efficiency of around 0.2 cd A-1, with a t50 value of 50 min.
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Affiliation(s)
- Jorge Roy
- Departamento de Química Inorgánica, Facultad de Ciencias, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC - Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza 50009, Spain
| | - Michele Forzatti
- Instituto de Ciencia Molecular, Universidad de Valencia, C/Catedrático J. Beltran, 2, Paterna 46980, Spain
| | - Lorenzo Arnal
- Departamento de Química Inorgánica, Facultad de Ciencias, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC - Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza 50009, Spain
| | - Antonio Martín
- Departamento de Química Inorgánica, Facultad de Ciencias, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC - Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza 50009, Spain
| | - Sara Fuertes
- Departamento de Química Inorgánica, Facultad de Ciencias, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC - Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza 50009, Spain
| | - Daniel Tordera
- Instituto de Ciencia Molecular, Universidad de Valencia, C/Catedrático J. Beltran, 2, Paterna 46980, Spain
| | - Violeta Sicilia
- Departamento de Química Inorgánica, Escuela de Ingeniería y Arquitectura de Zaragoza, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC - Universidad de Zaragoza, Campus Río Ebro, Edificio Torres Quevedo, Zaragoza 50018, Spain
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Kumar P, Pérez-Escribano M, van Raamsdonk DME, Escudero D. Phosphorescent Properties of Heteroleptic Ir(III) Complexes: Uncovering Their Emissive Species. J Phys Chem A 2023; 127:7241-7255. [PMID: 37597243 DOI: 10.1021/acs.jpca.3c04205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/21/2023]
Abstract
In this contribution, we assess the computational machinery to calculate the phosphorescence properties of a large pool of heteroleptic [Ir(C^N)2(N^N)]+ complexes (where N^N is an ancillary ligand and C^N is a cyclometalating ligand) including their phosphorescent rates and their emission spectra. Efficient computational protocols are next proposed. Specifically, different flavors of DFT functionals were benchmarked against DLPNO-CCSD(T) for the phosphorescence energies. The transition density matrix and decomposition analysis of the emitting triplet excited state enable us to categorize the studied complexes into different cases, from predominant triplet ligand-centered (3LC) character to predominant charge-transfer (3CT) character, either of metal-to-ligand charge transfer (3MLCT), ligand-to-ligand charge transfer (3LLCT), or a combination of the two. We have also calculated the vibronically resolved phosphorescent spectra and rates. Ir(III) complexes with predominant 3CT character are characterized by less vibronically resolved bands as compared to those with predominant 3LC character. Furthermore, some of the complexes are characterized by close-lying triplet excited states so that the calculation of their phosphorescence properties poses additional challenges. In these scenarios, it is necessary to perform geometry optimizations of higher-lying triplet excited states (i.e., Tn). We demonstrate that in the latter scenarios all of the close-lying triplet species must be considered to recover the shape of the experimental emission spectra. The global analysis of computed emission energies, shape of the computed emission spectra, computed rates, etc. enable us to unambiguously pinpoint for the first time the triplet states involved in the emission process and to provide a general classification of Ir(III) complexes with regard to their phosphorescence properties.
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Affiliation(s)
- Prashant Kumar
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | | | | | - Daniel Escudero
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
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Kumar P, Escudero D. Computational Protocol to Calculate the Phosphorescence Energy of Pt(II) Complexes: Is the Lowest Triplet Excited State Always Involved in Emission? A Comprehensive Benchmark Study. Inorg Chem 2021; 60:17230-17240. [PMID: 34702026 DOI: 10.1021/acs.inorgchem.1c02562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The reliable calculation of phosphorescence energies of phosphor materials is at the core of designing efficient phosphorescent organic light-emitting diodes (PhOLEDs). Therefore, it is of paramount importance to have a robust computational protocol to perform those calculations in a black-box manner. In this work, we use Domain-Based Local Pair Natural Orbital Coupled Cluster theory with single, double, and perturbative triple excitation (DLPNO-CCSD(T)) calculations to attain the phosphorescence energies of a large pool of Pt(II) complexes. Several approaches to incorporate relativistic effects in our calculations were tested. In addition, we have used the DLPNO-CCSD(T) values (i.e., our best theoretical values) to assess the performance of different flavors of density functional theory including pure, hybrid, meta-hybrid, and range-separated functionals. Among the tested functionals, the M06HF functional provides the best values compared with the DLPNO-CCSD(T) ones, with a mean absolute deviation (MAD) value of 0.14 eV. In its turn, and thanks to the increased accuracy achieved in the calculation of phosphorescence energies, we also demonstrate that not all of the investigated complexes emit from their lowest-lying triplet state (T1). The outlier complexes include different complex photophysical scenarios and both Kasha and anti-Kasha types of complexes. Finally, we provide a general computational protocol to pre-screen whether T1 is actually the emissive state and to accurately calculate the phosphorescence energies of Pt(II) complexes.
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Affiliation(s)
- Prashant Kumar
- Quantum Chemistry and Physical Chemistry Section, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Daniel Escudero
- Quantum Chemistry and Physical Chemistry Section, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
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Reichenauer F, Wang C, Förster C, Boden P, Ugur N, Báez-Cruz R, Kalmbach J, Carrella LM, Rentschler E, Ramanan C, Niedner-Schatteburg G, Gerhards M, Seitz M, Resch-Genger U, Heinze K. Strongly Red-Emissive Molecular Ruby [Cr(bpmp) 2] 3+ Surpasses [Ru(bpy) 3] 2. J Am Chem Soc 2021; 143:11843-11855. [PMID: 34296865 DOI: 10.1021/jacs.1c05971] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gaining chemical control over the thermodynamics and kinetics of photoexcited states is paramount to an efficient and sustainable utilization of photoactive transition metal complexes in a plethora of technologies. In contrast to energies of charge transfer states described by spatially separated orbitals, the energies of spin-flip states cannot straightforwardly be predicted as Pauli repulsion and the nephelauxetic effect play key roles. Guided by multireference quantum chemical calculations, we report a novel highly luminescent spin-flip emitter with a quantum chemically predicted blue-shifted luminescence. The spin-flip emission band of the chromium complex [Cr(bpmp)2]3+ (bpmp = 2,6-bis(2-pyridylmethyl)pyridine) shifted to higher energy from ca. 780 nm observed for known highly emissive chromium(III) complexes to 709 nm. The photoluminescence quantum yields climb to 20%, and very long excited state lifetimes in the millisecond range are achieved at room temperature in acidic D2O solution. Partial ligand deuteration increases the quantum yield to 25%. The high excited state energy of [Cr(bpmp)2]3+ and its facile reduction to [Cr(bpmp)2]2+ result in a high excited state redox potential. The ligand's methylene bridge acts as a Brønsted acid quenching the luminescence at high pH. Combined with a pH-insensitive chromium(III) emitter, ratiometric optical pH sensing is achieved with single wavelength excitation. The photophysical and ground state properties (quantum yield, lifetime, redox potential, and acid/base) of this spin-flip complex incorporating an earth-abundant metal surpass those of the classical precious metal [Ru(α-diimine)3]2+ charge transfer complexes, which are commonly employed in optical sensing and photo(redox) catalysis, underlining the bright future of these molecular ruby analogues.
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Affiliation(s)
- Florian Reichenauer
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Cui Wang
- Division Biophotonics, Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, 12489 Berlin, Germany.,Institut für Chemie und Biochemie, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Christoph Förster
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Pit Boden
- Department of Chemistry and Research Center Optimas, University Kaiserslautern, Erwin-Schrödinger-Straße, 67663 Kaiserslautern, Germany
| | - Naz Ugur
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Ricardo Báez-Cruz
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Jens Kalmbach
- Institute of Inorganic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Luca M Carrella
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Eva Rentschler
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Charusheela Ramanan
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Gereon Niedner-Schatteburg
- Department of Chemistry and Research Center Optimas, University Kaiserslautern, Erwin-Schrödinger-Straße, 67663 Kaiserslautern, Germany
| | - Markus Gerhards
- Department of Chemistry and Research Center Optimas, University Kaiserslautern, Erwin-Schrödinger-Straße, 67663 Kaiserslautern, Germany
| | - Michael Seitz
- Institute of Inorganic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Ute Resch-Genger
- Division Biophotonics, Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, 12489 Berlin, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
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Rivera M, Stojanović L, Crespo-Otero R. Role of Conical Intersections on the Efficiency of Fluorescent Organic Molecular Crystals. J Phys Chem A 2021; 125:1012-1024. [PMID: 33492964 DOI: 10.1021/acs.jpca.0c11072] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Organic molecular crystals are attractive materials for luminescent applications because of their promised tunability. However, the link between the chemical structure and emissive behavior is poorly understood because of the numerous interconnected factors which are at play in determining radiative and nonradiative behaviors at the solid-state level. In particular, the decay through conical intersection dominates the nonadiabatic regions of the potential energy surface, and thus, their accessibility is a telling indicator of the luminosity of the material. In this study, we investigate the radiative mechanism for five organic molecular crystals which display a solid-state emission, with a focus on the role of conical intersections in their photomechanisms. The objective is to situate the importance of the accessibility of conical intersections with regards to emissive behavior, taking into account other nonradiative decay channels, namely, vibrational decay, and exciton hopping. We begin by giving a brief overview of the structural patterns of the five systems within a larger pool of 13 crystals for a richer comparison. We observe that because of the prevalence of sheet like and herringbone packing in organic molecular crystals, the conformational diversity of crystal dimers is limited. Additionally, similarly spaced dimers have exciton coupling values of a similar order within a 50 meV interval. Next, we focus on three exemplary cases, where we disentangle the role of nonradiative decay mechanisms and show how rotational minimum energy conical intersections in vacuum lead to puckered ones in the crystal, increasing their instability upon crystallization in typical packing motifs. In contrast, molecules with puckered conical intersections in vacuum tend to conserve this trait upon crystallization, and therefore, their quantum yield of fluorescence is determined predominantly by other nonradiative decay mechanisms.
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Affiliation(s)
- Miguel Rivera
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Ljiljana Stojanović
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Rachel Crespo-Otero
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
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