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Ferraro V, Bizzarri C, Bräse S. Thermally Activated Delayed Fluorescence (TADF) Materials Based on Earth-Abundant Transition Metal Complexes: Synthesis, Design and Applications. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2404866. [PMID: 38984475 DOI: 10.1002/advs.202404866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/27/2024] [Indexed: 07/11/2024]
Abstract
Materials exhibiting thermally activated delayed fluorescence (TADF) based on transition metal complexes are currently gathering significant attention due to their technological potential. Their application extends beyond optoelectronics, in particular organic light-emitting diodes (OLEDs) and light-emitting electrochemical cells (LECs), and include also photocatalysis, sensing, and X-ray scintillators. From the perspective of sustainability, earth-abundant metal centers are preferred to rarer second- and third-transition series elements, thus determining a reduction in costs and toxicity but without compromising the overall performances. This review offers an overview of earth-abundant transition metal complexes exhibiting TADF and their application as photoconversion materials. Particular attention is devoted to the types of ligands employed, helping in the design of novel systems with enhanced TADF properties.
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Affiliation(s)
- Valentina Ferraro
- Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany
| | - Claudia Bizzarri
- Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany
| | - Stefan Bräse
- Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany
- Institute of Biological and Chemical Systems-Functional Molecular Systems (IBCS-FMS), Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131, Karlsruhe, Germany
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Busch J, Rehak FR, Ferraro V, Nieger M, Kemell M, Fuhr O, Klopper W, Bräse S. From Mono- to Polynuclear 2-(Diphenylphosphino)pyridine-Based Cu(I) and Ag(I) Complexes: Synthesis, Structural Characterization, and DFT Calculations. ACS OMEGA 2024; 9:2220-2233. [PMID: 38250424 PMCID: PMC10795044 DOI: 10.1021/acsomega.3c05755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 10/21/2023] [Accepted: 10/25/2023] [Indexed: 01/23/2024]
Abstract
A series of monometallic Ag(I) and Cu(I) halide complexes bearing 2-(diphenylphosphino)pyridine (PyrPhos, L) as a ligand were synthesized and spectroscopically characterized. The structure of most of the derivatives was unambiguously established by X-ray diffraction analysis, revealing the formation of mono-, di-, and tetranuclear complexes having general formulas MXL3 (M = Cu, X = Cl, Br; M = Ag, X = Cl, Br, I), Ag2X2L3 (X = Cl, Br), and Ag4X4L4 (X = Cl, Br, I). The Ag(I) species were compared to the corresponding Cu(I) analogues from a structural point of view. The formation of Cu(I)/Ag(I) heterobimetallic complexes MM'X2L3 (M/M' = Cu, Ag; X = Cl, Br, I) was also investigated. The X-ray structure of the bromo-derivatives revealed the formation of two possible MM'Br2L3 complexes with Cu/Ag ratios, respectively, of 7:1 and 1:7. The ratio between Cu and Ag was studied by scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDX) measurements. The structure of the binuclear homo- and heterometallic derivatives was investigated using density functional theory (DFT) calculations, revealing the tendency of the PyrPhos ligands not to maintain the bridging motif in the presence of Ag(I) as the metal center.
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Affiliation(s)
- Jasmin
M. Busch
- Institute
of Organic Chemistry (IOC), Karlsruhe Institute
of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
| | - Florian R. Rehak
- Institute
of Physical Chemistry (IPC), Karlsruhe Institute
of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
| | - Valentina Ferraro
- Institute
of Organic Chemistry (IOC), Karlsruhe Institute
of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
| | - Martin Nieger
- Department
of Chemistry, University of Helsinki, A.I. Virtasen Aukio 1, P.O. Box 55, FI 00014 Helsinki, Finland
| | - Marianna Kemell
- Department
of Chemistry, University of Helsinki, A.I. Virtasen Aukio 1, P.O. Box 55, FI 00014 Helsinki, Finland
| | - Olaf Fuhr
- Institute
of Nanotechnology (INT), Karlsruhe Institute
of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
- Karlsruhe
Nano-Micro Facility (KNMFi), Karlsruhe Institute
of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
| | - Wim Klopper
- Institute
of Physical Chemistry (IPC), Karlsruhe Institute
of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
- Institute
of Nanotechnology (INT), Karlsruhe Institute
of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
| | - Stefan Bräse
- Institute
of Organic Chemistry (IOC), Karlsruhe Institute
of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
- Institute
of Biological and Chemical Systems-Functional Molecular Systems (IBCS-FMS), Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
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Kikuchi K, Imoto H, Naka K. Robust and highly emissive copper(I) halide 1D-coordination polymers with triphenylarsine and a series of bridging N-heteroaromatic co-ligands. Dalton Trans 2023; 52:11168-11175. [PMID: 37505189 DOI: 10.1039/d3dt00784g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Various 1D-coordination polymers with dinuclear rhombic {Cu2X2} cores (X = Br, I) were synthesized using a spontaneous evaporation method employing triphenylarsine (AsPh3) and six types of bidentate N-heteroaromatic co-ligands. The coordination polymers exhibited intense emission even at 298 K (quantum yield: up to 0.60), and their emission color was dependent on the N-heteroaromatic co-ligand. The emission efficiencies of these coordination polymers were higher than those of the discrete complexes with AsPh3 and monodentate N-heteroaromatic co-ligands reported in our previous work. In addition, the luminescence of these coordination polymers was more resistant to mechanical stimuli than that of the discrete ones.
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Affiliation(s)
- Kazuma Kikuchi
- Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, Gashokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
| | - Hiroaki Imoto
- Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, Gashokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
| | - Kensuke Naka
- Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, Gashokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
- Materials Innovation Lab, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
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Tetranuclear Copper(I) and Silver(I) Pyrazolate Adducts with 1,1'-Dimethyl-2,2'-bibenzimidazole: Influence of Structure on Photophysics. Molecules 2023; 28:molecules28031189. [PMID: 36770855 PMCID: PMC9920877 DOI: 10.3390/molecules28031189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/18/2023] [Accepted: 01/22/2023] [Indexed: 01/27/2023] Open
Abstract
A reaction of a cyclic trinuclear copper(I) or silver(I) pyrazolate complex ([MPz]3, M = Cu, Ag) with 1,1'-dimethyl-2,2'-bibenzimidazole (L) leads to the formation of tetranuclear adducts decorated by one or two molecules of a diimine ligand, depending on the amount of the ligand added (0.75 or 1.5 equivalents). The coordination of two L molecules stabilizes the formation of a practically idealized tetrahedral four-metal core in the case of a copper-containing complex and a distorted tetrahedron in the case of a Ag analog. In contrast, complexes containing one molecule of diimine possess two types of metals, two- and three-coordinated, forming the significantly distorted central M4 cores. The diimine ligands are twisted in these complexes with dihedral angles of ca. 50-60°. A TD-DFT analysis demonstrated the preference of a triplet state for the twisted 1,1'-dimethyl-2,2'-bibenzimidazole and a singlet state for the planar geometry. All obtained complexes demonstrated, in a solution, the blue fluorescence of the ligand-centered (LC) nature typical for free diimine. In contrast, a temperature decrease to 77 K stabilized the structure close to that observed in the solid state and activated the triplet states, leading to green phosphorescence at ca. 500 nm. The silver-containing complex Ag4Pz4L exhibited dual emission from both the singlet and triplet states, even at room temperature.
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Fluorescence vs. Phosphorescence: Which Scenario Is Preferable in Au(I) Complexes with Benzothiadiazoles? Molecules 2022; 27:molecules27238162. [PMID: 36500253 PMCID: PMC9741114 DOI: 10.3390/molecules27238162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 11/19/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
The photoluminescence of Au(I) complexes is generally characterized by long radiative lifetimes owing to the large spin-orbital coupling constant of the Au(I) ion. Herein, we report three brightly emissive Au(I) coordination compounds, 1, 2a, and 2b, that reveal unexpectedly short emission lifetimes of 10-20 ns. Polymorphs 2a and 2b exclusively exhibit fluorescence, which is quite rare for Au(I) compounds, while compound 1 reveals fluorescence as the major radiative pathway, and a minor contribution of a microsecond-scale component. The fluorescent behaviour for 1-2 is rationalized by means of quantum chemical (TD)-DFT calculations, which reveal the following: (1) S0-S1 and S0-T1 transitions mainly exhibit an intraligand nature. (2) The calculated spin-orbital coupling (SOC) between the states is small, which is a consequence of overall small metal contribution to the frontier orbitals. (3) The T1 state features much lower energy than the S1 state (by ca. 7000 cm-1), which hinders the SOC between the states. Thus, the S1 state decays in the form of fluorescence, rather than couples with T1. In the specific case of complex 1, the potential energy surfaces for the S1 and T2 states intersect, while the vibrationally resolved S1-S0 and T2-S0 calculated radiative transitions show substantial overlap. Thus, the microsecond-scale component for complex 1 can stem from the coupling between the S1 and T2 states.
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