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Dalmau D, Urriolabeitia EP. Luminescence and Palladium: The Odd Couple. Molecules 2023; 28:molecules28062663. [PMID: 36985639 PMCID: PMC10054068 DOI: 10.3390/molecules28062663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/06/2023] [Accepted: 03/08/2023] [Indexed: 03/18/2023] Open
Abstract
The synthesis, photophysical properties, and applications of highly fluorescent and phosphorescent palladium complexes are reviewed, covering the period 2018–2022. Despite the fact that the Pd atom appears closely related with an efficient quenching of the fluorescence of different molecules, different synthetic strategies have been recently optimized to achieve the preservation and even the amplification of the luminescent properties of several fluorophores after Pd incorporation. Beyond classical methodologies such as orthopalladation or the use of highly emissive ligands as porphyrins and related systems (for instance, biladiene), new concepts such as AIE (Aggregation Induced Emission) in metallacages or in coordination-driven supramolecular compounds (CDS) by restriction of intramolecular motions (RIM), or complexes showing TADF (Thermally Activated Delayed Fluorescence), are here described and analysed. Without pretending to be comprehensive, selected examples of applications in areas such as the fabrication of lighting devices, biological markers, photodynamic therapy, or oxygen sensing are also here reported.
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Bulygina LA, Khrushcheva NS, Nelyubina YV, Dorovatovskii P, Strelkova TV, Alexeev MS, Mandegani Z, Nabavizadeh SM, Kuznetsov NY. Bilateral metalloheterocyclic systems based on palladacycle and piperidine-2,4-dione pharmacophores. Org Biomol Chem 2023; 21:2337-2354. [PMID: 36825470 DOI: 10.1039/d3ob00022b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
The design of molecules with effective anticancer properties constructed from both dually active metal complex and organic fragments is a novel trend in medicinal chemistry. This concept suggests the impact of a drug on several biological targets or the synergistic action of both fragments as a single unit. We propose that the combination of a Pd-metallocomplex fragment and an organic unit can be an interesting model for anticancer drug discovery. The first phase in the development of such suggested molecules is the synthesis of bilateral metallosystems containing bioactive 6-substituted piperidin-2-one and a palladated N-phenylpyrazolic fragment. Both fragments were incorporated into one molecule through the fused pyrazole-piperidine-2-one unit followed by pyrazol-directed cyclopalladation of the phenyl-group with Pd(OAc)2. An effect of acceleration of the rate of the palladation by NH-lactam was observed. The synthesized hybrid palladacycles have been characterized and tested for their cytotoxic activity on three cancerous cell lines as PPh3 complexes, revealing structures with potential for further development and structural optimization.
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Affiliation(s)
- Ludmila A Bulygina
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov st. 28, 119991 Moscow, Russian Federation.
| | - Natalya S Khrushcheva
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov st. 28, 119991 Moscow, Russian Federation.
| | - Yulia V Nelyubina
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov st. 28, 119991 Moscow, Russian Federation.
| | - Pavel Dorovatovskii
- National Research Centre "Kurchatov Institute", 123182, Akademika Kurchatova pl., 1, Moscow, Russian Federation
| | - Tatiana V Strelkova
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov st. 28, 119991 Moscow, Russian Federation.
| | - Michael S Alexeev
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov st. 28, 119991 Moscow, Russian Federation. .,A.V. Topchiev Institute of Petrochemical Synthesis, Leninsky Prospect 29, 119991, Moscow, Russian Federation
| | - Zeinab Mandegani
- Professor Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | - S Masoud Nabavizadeh
- Professor Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | - Nikolai Yu Kuznetsov
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov st. 28, 119991 Moscow, Russian Federation. .,A.V. Topchiev Institute of Petrochemical Synthesis, Leninsky Prospect 29, 119991, Moscow, Russian Federation
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3
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Avan İ, Kani İ, Çalıkuşu L. Bis(dipyrrinato)zinc(II) Complexes: Synthesis and catalytic activity towards alcohol oxidation. INORG CHEM COMMUN 2023. [DOI: 10.1016/j.inoche.2023.110518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
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4
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Triplet Emitting C^N^C Cyclometalated Dibenzo[c,h]Acridine Pt(II) Complexes. Molecules 2022; 27:molecules27228054. [PMID: 36432153 PMCID: PMC9697690 DOI: 10.3390/molecules27228054] [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: 10/28/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 11/22/2022] Open
Abstract
In a series of Pt(II) complexes [Pt(dba)(L)] containing the very rigid, dianionic, bis-cyclometalating, tridentate C^N^C2− heterocyclic ligand dba2− (H2dba = dibenzo[c,h]acridine), the coligand (ancillary ligand) L = dmso, PPh3, CNtBu and Me2Imd (N,N’-dimethylimidazolydene) was varied in order to improve its luminescence properties. Beginning with the previously reported dmso complex, we synthesized the PPh3, CNtBu and Me2Imd derivatives and characterized them by elemental analysis, 1H (and 31P) NMR spectroscopy and MS. Cyclic voltammetry showed partially reversible reduction waves ranging between −1.89 and −2.10 V and increasing along the series Me2Imd < dmso ≈ PPh3 < CNtBu. With irreversible oxidation waves ranging between 0.55 (L = Me2Imd) and 1.00 V (dmso), the electrochemical gaps range between 2.65 and 2.91 eV while increasing along the series Me2Imd < CNtBu < PPh3 < dmso. All four complexes show in part vibrationally structured long-wavelength absorption bands peaking at around 530 nm. TD-DFT calculated spectra agree quite well with the experimental spectra, with only a slight redshift. The photoluminescence spectra of all four compounds are very similar. In fluid solution at 298 K, they show broad, only partially structured bands, with maxima at around 590 nm, while in frozen glassy matrices at 77 K, slightly blue-shifted (~580 nm) bands with clear vibronic progressions were found. The photoluminescence quantum yields ΦL ranged between 0.04 and 0.24, at 298 K, and between 0.80 and 0.90 at 77 K. The lifetimes τ at 298 K ranged between 60 and 14040 ns in Ar-purged solutions and increased from 17 to 43 µs at 77 K. The TD-DFT calculated emission spectra are in excellent agreement with the experimental findings. In terms of high ΦL and long τ, the dmso and PPh3 complexes outperform the CNtBu and Me2Imd derivatives. This is remarkable in view of the higher ligand strength of Me2Imd, compared with all other coligands, as concluded from the electrochemical data.
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5
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Song X, Peng L, Chen W, Gao Y, Fang W, Cui G. Thermally Activated Delayed Fluorescence of a Dinuclear Platinum(II) Compound: Mechanism and Roles of an Upper Triplet State. Chemistry 2022; 28:e202201782. [DOI: 10.1002/chem.202201782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Xiu‐Fang Song
- Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education, Chemistry College Beijing Normal University Beijing 100875 P.R. China
| | - Ling‐Ya Peng
- Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education, Chemistry College Beijing Normal University Beijing 100875 P.R. China
| | - Wen‐Kai Chen
- Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education, Chemistry College Beijing Normal University Beijing 100875 P.R. China
| | - Yuan‐Jun Gao
- Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education, Chemistry College Beijing Normal University Beijing 100875 P.R. China
| | - Wei‐Hai Fang
- Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education, Chemistry College Beijing Normal University Beijing 100875 P.R. China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education, Chemistry College Beijing Normal University Beijing 100875 P.R. China
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Zatsikha YV, Shamova LI, Shepit M, Berry SM, Thomas F, Herbert DE, van Lierop J, Nemykin VN. Radical Complexes of Nickel(II)/Copper(II) and Redox Non‐innocent MB‐DIPY Ligands: Unusual Stability and Strong Near‐Infrared Absorption at
λ
max
∼1300 nm. Chemistry 2022; 28:e202201181. [DOI: 10.1002/chem.202201181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Yuriy V. Zatsikha
- Department of Chemistry University of Manitoba Winnipeg MB R3T 2 N2 Canada
- Enamine Ltd. Chervonotkatska Street 78 Kyiv 02094 Ukraine
| | - Liliya I. Shamova
- Department of Chemistry University of Manitoba Winnipeg MB R3T 2 N2 Canada
| | - Michael Shepit
- Department of Physics and Astronomy University of Manitoba Winnipeg MB R3T 2 N2 Canada
| | - Steven M. Berry
- Department of Chemistry and Biochemistry University of Minnesota–Duluth Duluth MN 55812 USA
| | | | - David E. Herbert
- Department of Chemistry University of Manitoba Winnipeg MB R3T 2 N2 Canada
| | - Johan van Lierop
- Department of Physics and Astronomy University of Manitoba Winnipeg MB R3T 2 N2 Canada
| | - Victor N. Nemykin
- Department of Chemistry University of Manitoba Winnipeg MB R3T 2 N2 Canada
- Department of Chemistry University of Tennessee–Knoxville Knoxville TN 37996 USA
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Stück R, Krause M, Brünink D, Buss S, Doltsinis NL, Strassert CA, Klein A. Luminescent Pd(II) Complexes with Tridentate
−
Aryl‐pyridine‐(benzo)thiazole Ligands. Z Anorg Allg Chem 2021. [DOI: 10.1002/zaac.202100278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- René Stück
- Universität zu Köln Mathematisch-Naturwissenschaftliche Fakultät Department für Chemie Institut für Anorganische Chemie Greinstraße 6 D-50939 Köln
| | - Maren Krause
- Universität zu Köln Mathematisch-Naturwissenschaftliche Fakultät Department für Chemie Institut für Anorganische Chemie Greinstraße 6 D-50939 Köln
| | - Dana Brünink
- Westfälische Wilhelms-Universität Münster Institut für Festkörpertheorie and Center for Multiscale Theory and Computation Wilhelm-Klemm-Straße 10 D-48149 Münster Germany
| | - Stefan Buss
- Westfälische Wilhelms-Universität Münster Institut für Anorganische und Analytische Chemie, CiMIC, CeNTech Heisenbergstraße 11 D-48149 Münster Germany
| | - Nikos L. Doltsinis
- Westfälische Wilhelms-Universität Münster Institut für Festkörpertheorie and Center for Multiscale Theory and Computation Wilhelm-Klemm-Straße 10 D-48149 Münster Germany
| | - Cristian A. Strassert
- Westfälische Wilhelms-Universität Münster Institut für Anorganische und Analytische Chemie, CiMIC, CeNTech Heisenbergstraße 11 D-48149 Münster Germany
| | - Axel Klein
- Universität zu Köln Mathematisch-Naturwissenschaftliche Fakultät Department für Chemie Institut für Anorganische Chemie Greinstraße 6 D-50939 Köln
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8
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Kletsch L, Jordan R, Köcher AS, Buss S, Strassert CA, Klein A. Photoluminescence of Ni(II), Pd(II), and Pt(II) Complexes [M(Me 2dpb)Cl] Obtained from C‒H Activation of 1,5-Di(2-pyridyl)-2,4-dimethylbenzene (Me 2dpbH). Molecules 2021; 26:molecules26165051. [PMID: 34443649 PMCID: PMC8401505 DOI: 10.3390/molecules26165051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/06/2021] [Accepted: 08/17/2021] [Indexed: 11/16/2022] Open
Abstract
The three complexes [M(Me2dpb)Cl] (M = Ni, Pd, Pt) containing the tridentate N,C,N-cyclometalating 3,5-dimethyl-1,5-dipyridyl-phenide ligand (Me2dpb-) were synthesised using a base-assisted C‒H activation method. Oxidation potentials from cyclic voltammetry increased along the series Pt < Ni < Pd from 0.15 to 0.74 V. DFT calculations confirmed the essentially ligand-centred π*-type character of the lowest unoccupied molecular orbital (LUMO) for all three complexes in agreement with the invariant reduction processes. For the highest occupied molecular orbitals (HOMO), contributions from metal dyz, phenyl C4, C2, C1, and C6, and Cl pz orbitals were found. As expected, the dz2 (HOMO-1 for Ni) is stabilised for the Pd and Pt derivatives, while the antibonding dx2-y2 orbital is de-stabilised for Pt and Pd compared with Ni. The long-wavelength UV-vis absorption band energies increase along the series Ni < Pt < Pd. The lowest-energy TD-DFT-calculated state for the Ni complex has a pronounced dz2-type contribution to the overall metal-to-ligand charge transfer (MLCT) character. For Pt and Pd, the dz2 orbital is energetically not available and a strongly mixed Cl-to-π*/phenyl-to-π*/M(dyz)-to-π* (XLCT/ILCT/MLCT) character is found. The complex [Pd(Me2dpb)Cl] showed a structured emission band in a frozen glassy matrix at 77 K, peaking at 468 nm with a quantum yield of almost unity as observed for the previously reported Pt derivative. No emission was observed from the Ni complex at 77 or 298 K. The TD-DFT-calculated states using the TPSSh functional were in excellent agreement with the observed absorption energies and also clearly assessed the nature of the so-called "dark", i.e., d‒d*, excited configurations to lie low for the Ni complex (≥3.18 eV), promoting rapid radiationless relaxation. For the Pd(II) and Pt(II) derivatives, the "dark" states are markedly higher in energy with ≥4.41 eV (Pd) and ≥4.86 eV (Pt), which is in perfect agreement with the similar photophysical behaviour of the two complexes at low temperatures.
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Affiliation(s)
- Lukas Kletsch
- Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, D-50939 Köln, Germany; (L.K.); (R.J.); (A.S.K.)
| | - Rose Jordan
- Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, D-50939 Köln, Germany; (L.K.); (R.J.); (A.S.K.)
| | - Alicia S. Köcher
- Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, D-50939 Köln, Germany; (L.K.); (R.J.); (A.S.K.)
| | - Stefan Buss
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 28/30, D-48149 Münster, Germany;
- CeNTech, CiMIC, SoN, Westfälische Wilhelms-Universität Münster, Heisenbergstr. 11, D-48149 Münster, Germany
| | - Cristian A. Strassert
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 28/30, D-48149 Münster, Germany;
- CeNTech, CiMIC, SoN, Westfälische Wilhelms-Universität Münster, Heisenbergstr. 11, D-48149 Münster, Germany
- Correspondence: (C.A.S.); (A.K.); Tel.: +49-221-470-4006 (A.K.)
| | - Axel Klein
- Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, D-50939 Köln, Germany; (L.K.); (R.J.); (A.S.K.)
- Correspondence: (C.A.S.); (A.K.); Tel.: +49-221-470-4006 (A.K.)
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9
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Kuno A, Hirata G, Tanaka H, Kobayashi Y, Yasuda N, Maeda H. Dipyrrolyldiketone Pt II Complexes: Ion-Pairing π-Electronic Systems with Various Anion-Binding Modes. Chemistry 2021; 27:10068-10076. [PMID: 34002907 DOI: 10.1002/chem.202100855] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Indexed: 11/10/2022]
Abstract
A variety of π-electronic ion-pairing assemblies can be constructed by combining anion complexes of π-electronic systems and countercations. In this study, a series of anion-responsive π-electronic molecules, dipyrrolyldiketone PtII complexes containing a phenylpyridine ligand, were synthesized. The resulting PtII complexes exhibited phosphorescence emission, with higher emission quantum yields (0.30-0.42) and microsecond-order lifetimes, and solution-state anion binding, as revealed by our spectroscopic analyses. These PtII complexes displayed solid-state ion-pairing assemblies, exhibiting various anion-binding modes, which derived from pyrrole-inverted and pyrrole-non-inverted conformations, and packing structures, with the contribution of charge-by-charge assemblies, which were dependent on the substituents in the PtII complexes and the geometries and electronic states of their countercations.
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Affiliation(s)
- Atsuko Kuno
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan
| | - Goki Hirata
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan
| | - Hiroki Tanaka
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan
| | - Yoichi Kobayashi
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan
| | - Nobuhiro Yasuda
- Diffraction and Scattering Division, Japan Synchrotron Radiation Research Institute, Sayo, 679-5198, Japan
| | - Hiromitsu Maeda
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan
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10
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Vinogradova KA, Shekhovtsov NA, Berezin AS, Sukhikh TS, Rogovoy MI, Artem'ev AV, Bushuev MB. Coordination-induced emission enhancement in copper(I) iodide coordination polymers supported by 2-(alkylsulfanyl)pyrimidines. Dalton Trans 2021; 50:9317-9330. [PMID: 34132730 DOI: 10.1039/d1dt00826a] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
First examples of copper(i) complexes with 2-(alkylsulfanyl)pyrimidine ligands have been synthesized. Reactions of copper(i) iodide with 2-(methylsulfanyl)pyrimidine (L1) in various metal-to-ligand molar ratios in MeCN afford a ladder-type coordination polymer [Cu2L1I2]n with polymeric chains built from double-stranded (Cu2I2)n ribbons supported on both sides by μ2-N,S-L1 molecules. Although the second ligand, 2-(ethylsulfanyl)pyrimidine (L2), differs from L1 only by a methylene group, its reactions with copper(i) iodide in MeCN yield not only a congenerous coordination polymer, [Cu2L2I2]n, but also [CuL2I]n, in which a similar (Cu2I2)n ribbon is decorated by N-monodentate L2 molecules. Absorption spectra of all compounds represent an interplay of metal + iodine-to-ligand charge transfer (XMLCT) and ligand-centered (LC) and cluster-centered (CC) transitions, while the emission occurs from the excited states of XMLCT nature. The luminescence of [Cu2L1I2]n and [Cu2L2I2]n is blue-shifted and greatly enhanced in comparison with that of [CuL2I]n (quantum yields: 89% and 68% for [Cu2L1I2]n and [Cu2L2I2]nvs. 23% for [CuL2I]n at 77 K), which can be associated with a more rigid μ2-N,S coordination of 2-(alkylsulfanyl)pyrimidine ligands in [Cu2L1I2]n and [Cu2L2I2]n leading to a less distorted T1 state.
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Affiliation(s)
- Katerina A Vinogradova
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Nikita A Shekhovtsov
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Alexey S Berezin
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Taisiya S Sukhikh
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Maxim I Rogovoy
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Alexander V Artem'ev
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
| | - Mark B Bushuev
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia.
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11
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Eskelinen T, Buss S, Petrovskii SK, Grachova EV, Krause M, Kletsch L, Klein A, Strassert CA, Koshevoy IO, Hirva P. Photophysics and Excited State Dynamics of Cyclometalated [M(Phbpy)(CN)] (M = Ni, Pd, Pt) Complexes: A Theoretical and Experimental Study. Inorg Chem 2021; 60:8777-8789. [PMID: 34097403 DOI: 10.1021/acs.inorgchem.1c00680] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cyclometalated complexes [M(Phbpy)(CN)] (HPhbpy = 6-phenyl-2,2'-bipyridine) of the group 10 metals (Ni, Pd, and Pt) bearing a carbanionic -C∧N∧N pincer ligand were synthesized and studied in a combined experimental and computational DFT approach. All three complexes were crystallographically characterized showing closely packed dimers with head-to-tail stacking and short metal-metal contacts in the solid state. The computational models for geometries, excited states, and electronic transitions addressed both monomeric (Ni-mono, Pd-mono, and Pt-mono) and dimeric (Ni-dim, Pd-dim, and Pt-dim) entities. Photophysical properties and excited state dynamics of all title complexes were investigated in solution and in the solid at 298 and 77 K. [Ni(Phbpy)(CN)] and [Pd(Phbpy)(CN)] are virtually nonemissive in solution at 298 K, whereas [Pt(Phbpy)(CN)] shows phosphorescence in CH2Cl2 (DCM) solution (λem = 562 nm) stemming from a mixed 3MLCT/ILCT (metal-to-ligand charge transfer/intraligand charge transfer) state. At 77 K in a glassy frozen DCM:MeOH matrix, [Pd(Phbpy)(CN)] shows a remarkable emission (λem = 571 nm) with a photoluminescence quantum yield reaching almost unity, whereas [Ni(Phbpy)(CN)] is again nonemissive. Calculations on the monomeric models M-mono show that low-lying metal-centered states (MC, i.e., d-d* configuration) with dissociative character quench the photoluminescence. In the solid state, the complexes [M(Phbpy)(CN)] show defined photoluminescence bands (λem = 561 nm for Pd and 701 nm for Pt). Calculations on the dimeric models M-dim shows that the axial M···M interactions alter the photophysical properties of Pd-dim and Pt-dim toward MMLCT (metal-metal-to-ligand charge transfer) excited states with Pd-dim showing temperature-dependent emission lifetimes, suggesting thermally activated delayed fluorescence, whereas Pt-dim displayed phosphorescence with excimeric character. The metal-metal interactions were analyzed in detail with the quantum theory of atoms in molecules approach.
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Affiliation(s)
- Toni Eskelinen
- Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80100 Joensuu, Finland
| | - Stefan Buss
- CeNTech, CiMIC, SoN, Westfälische Wilhelms-Universität Münster, Heisenbergstr. 11, D-48149 Münster, Germany
| | - Stanislav K Petrovskii
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russia
| | - Elena V Grachova
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russia
| | - Maren Krause
- Department of Chemistry, University of Cologne, D-50939 Cologne, Germany
| | - Lukas Kletsch
- Department of Chemistry, University of Cologne, D-50939 Cologne, Germany
| | - Axel Klein
- Department of Chemistry, University of Cologne, D-50939 Cologne, Germany
| | - Cristian A Strassert
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 28/30, D-48149 Münster, Germany.,CeNTech, CiMIC, SoN, Westfälische Wilhelms-Universität Münster, Heisenbergstr. 11, D-48149 Münster, Germany
| | - Igor O Koshevoy
- Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80100 Joensuu, Finland
| | - Pipsa Hirva
- Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80100 Joensuu, Finland
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12
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DFT Investigation of the Molecular Properties of the Dimethylglyoximato Complexes [M(Hdmg)2] (M = Ni, Pd, Pt). INORGANICS 2021. [DOI: 10.3390/inorganics9060047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Important applications of the NiII, PdII and PtII complexes [M(Hdmg)2] (H2dmg = dimethylglyoxime) stem from their metal...metal stacked virtually insoluble aggregates. Given the virtual insolubility of the materials, we postulated that the rare reports on dissolved species in solution do not represent monomolecular species but oligomers. We thus studied the structural and spectral properties of the monomolecular entities of these compounds using density functional theory (DFT) and time-dependent DFT computations in dimethyl sulfoxide (DMSO) as a solvent. The molecular geometries, IR and UV-vis spectra, and frontier orbitals properties were computed using LANL2DZ ecp and def2TZVP as basis sets and M06-2X as the functional. The results are compared with the available experimental and other calculated data. The optimised molecular geometries proved the asymmetric character of the two formed O–H…O bonds which connect the two Hdmg‒ ligands in the completely planar molecules. Calculated UV-vis spectra revealed the presence of three absorptions in the range 180 to 350 nm that are red-shifted along the series Ni–Pd–Pt. They were assigned to essentially ligand-centred π−π* transitions in part with metal(d) to ligand(π*) charge transfer (MLCT) contributions. The notorious d‒p transitions dominating the colour and electronics of the compounds in the solid-state and oligomeric stacks are negligible in our monomolecular models strongly supporting the idea that the previously reported spectroscopic observations or biological effects in solutions are not due to monomolecular complexes but rather to oligomeric dissolved species.
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Krause M, von der Stück R, Brünink D, Buss S, Doltsinis NL, Strassert CA, Klein A. Platinum and palladium complexes of tridentate −C^N^N (phen-ide)-pyridine-thiazol ligands – A case study involving spectroelectrochemistry, photoluminescence spectroscopy and TD-DFT calculations. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2020.120093] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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