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Li C, Zhao J. Organoplatinum Complex Exhibiting Aggregation-Enhanced Emission (AEE) and Dual-Channel Ion-Sensing Properties by Terminating the Molecular Configuration Transformation (MCT) and Excited-State Intramolecular Proton Transfer (ESIPT). Inorg Chem 2024; 63:11757-11767. [PMID: 38866593 DOI: 10.1021/acs.inorgchem.4c01357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Emitters produce weak emissions when they undergo structural changes such as molecular configuration transformation (MCT) or excited-state intramolecular proton transfer (ESIPT) but give out strong emissions after terminating these distortions. Herein, an organoplatinum complex, Pt-ppy-ABP, carrying a salicylaldehyde-based Schiff base unit is synthesized. It exhibits weak emission in dilute solutions but shows bright emission at the aggregated state or after interacting with F- and Zn2+. This suggests that it has an aggregation-enhanced emission (AEE) property and holds potential in ion detection. Supported by theoretical calculations and femtosecond transient absorption results, this complex suffers excited-state structural changes including MCT from a square-planar configuration to a tetrahedral one, as well as intramolecular rotation of a monodentate ligand and ESIPT, showing weak emission in its solutions. At the aggregated state, it releases strong yellow emissions because of the restraints of MCT and ligand rotation. Upon interacting with F- or Zn2+, it emits bright-red or -green emissions, achieving detection limits of 10-7 M. The sensing mechanism is concluded as deprotonation- and coordination-induced ESIPT terminations, respectively. Given its AEE property and ion-responsive emissions, its application in information encryption is also explored. Finally, these findings should provide valuable clues for the developments of chemosensors with dual-channel recognition abilities.
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Affiliation(s)
- Chencheng Li
- School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, Guizhou, China
| | - Jiang Zhao
- School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, Guizhou, China
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Auty AJ, Scattergood PA, Keane T, Cheng T, Wu G, Carson H, Shipp J, Sadler A, Roseveare T, Sazanovich IV, Meijer AJHM, Chekulaev D, Elliot PIP, Towrie M, Weinstein JA. A stronger acceptor decreases the rates of charge transfer: ultrafast dynamics and on/off switching of charge separation in organometallic donor-bridge-acceptor systems. Chem Sci 2023; 14:11417-11428. [PMID: 37886100 PMCID: PMC10599469 DOI: 10.1039/d2sc06409j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 09/23/2023] [Indexed: 10/28/2023] Open
Abstract
To unravel the role of driving force and structural changes in directing the photoinduced pathways in donor-bridge-acceptor (DBA) systems, we compared the ultrafast dynamics in novel DBAs which share a phenothiazine (PTZ) electron donor and a Pt(ii) trans-acetylide bridge (-C[triple bond, length as m-dash]C-Pt-C[triple bond, length as m-dash]C-), but bear different acceptors conjugated into the bridge (naphthalene-diimide, NDI; or naphthalene-monoimide, NAP). The excited state dynamics were elucidated by transient absorption, time-resolved infrared (TRIR, directly following electron density changes on the bridge/acceptor), and broadband fluorescence-upconversion (FLUP, directly following sub-picosecond intersystem crossing) spectroscopies, supported by TDDFT calculations. Direct conjugation of a strong acceptor into the bridge leads to switching of the lowest excited state from the intraligand 3IL state to the desired charge-separated 3CSS state. We observe two surprising effects of an increased strength of the acceptor in NDI vs. NAP: a ca. 70-fold slow-down of the 3CSS formation-(971 ps)-1vs. (14 ps)-1, and a longer lifetime of the 3CSS (5.9 vs. 1 ns); these are attributed to differences in the driving force ΔGet, and to distance dependence. The 100-fold increase in the rate of intersystem crossing-to sub-500 fs-by the stronger acceptor highlights the role of delocalisation across the heavy-atom containing bridge in this process. The close proximity of several excited states allows one to control the yield of 3CSS from ∼100% to 0% by solvent polarity. The new DBAs offer a versatile platform for investigating the role of bridge vibrations as a tool to control excited state dynamics.
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Affiliation(s)
- Alexander J Auty
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | | | - Theo Keane
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Tao Cheng
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Guanzhi Wu
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Heather Carson
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - James Shipp
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Andrew Sadler
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Thomas Roseveare
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Igor V Sazanovich
- Laser for Science Facility, Rutherford Appleton Laboratory, RCaH, STFC OX11 0QX UK
| | | | - Dimitri Chekulaev
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Paul I P Elliot
- Department of Chemical Sciences, University of Huddersfield HD1 3DH UK
| | - Mike Towrie
- Laser for Science Facility, Rutherford Appleton Laboratory, RCaH, STFC OX11 0QX UK
| | - Julia A Weinstein
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
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Khan AAT, Gobeze HB, Islam T, Arman HD, Schanze KS. Effect of bromine substitution on blue phosphorescent trans-(N-heterocyclic carbene)Pt(II) acetylide complexes. Dalton Trans 2023; 52:11535-11542. [PMID: 37540137 DOI: 10.1039/d3dt01483e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
N-heterocyclic carbene complexes of the type trans-(NHC)2PtII(CC-Ar)2 (where Ar = phenyl or substituted phenyl) are of interest as violet and blue phosphors. These complexes emit efficient phosphorescence in solution and in the solid state, and they have been applied as phosphors in organic light emitting diodes. This study explores the effect of bromine substitution on the trans-(NHC)2PtII(CC-Ar)2 chromophore through photophysical studies of a pair of complexes in which the phenyl groups feature either 3,5-dibromo- or 4-monobromo-substituents (IPt-DB and IPt-MB, respectively). The Br atoms were introduced as heavy atom(s) with the aim to enhance spin-orbit coupling and increase the radiative and non-radiative decay rates of the phosphorescent triplet state. Both IPt-MB and IPt-DB exhibit sky-blue phosphorescence in solution and in PMMA matrix. Interestingly, the emission quantum yield and lifetime of IPt-MB are substantially lower compared to IPt-DB in solution. This effect is attributed to a substantially larger non-radiative decay rate in the mono-bromo complex. Analysis of the photophysical data, combined with DFT and TD-DFT calculations, suggest that the difference in photophysical properties of the two complexes is related to the position of the Br-substituents on the phenyl acetylide rings. In short, in IPt-MB, the Br-substituents are located para-to the Pt-CC-unit, and this gives rise to stronger electron-vibrational coupling in the excited state, enhancing the rate of non-radiative decay.
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Affiliation(s)
- Amran A T Khan
- Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA.
| | - Habtom B Gobeze
- Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA.
| | - Tanjila Islam
- Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA.
| | - Hadi D Arman
- Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA.
| | - Kirk S Schanze
- Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA.
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Vivancos Á, Bautista D, González-Herrero P. Phosphorescent Tris-cyclometalated Pt(IV) Complexes with Mesoionic N-Heterocyclic Carbene and 2-Arylpyridine Ligands. Inorg Chem 2022; 61:12033-12042. [PMID: 35860839 PMCID: PMC9377419 DOI: 10.1021/acs.inorgchem.2c02039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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.
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Affiliation(s)
- Ángela Vivancos
- Departamento de Química Inorgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, 19, 30100 Murcia, Spain
| | - Delia Bautista
- Área Científica y Técnica de Investigación, Universidad de Murcia, Campus de Espinardo, 21, 30100 Murcia, Spain
| | - Pablo González-Herrero
- Departamento de Química Inorgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, 19, 30100 Murcia, Spain
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N-Heterocyclic Carbene Platinum-Butadiyne Click/iClick Complexes. Towards Blue-Violet Phosphorescence. J Organomet Chem 2022. [DOI: 10.1016/j.jorganchem.2022.122440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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He R, Domingues RA, Valandro S, Schanze KS. Platinum Poly-yne Featuring N-Heterocyclic Carbene Ligands: Synthesis, Properties, and Organic Light-Emitting Diode Application. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01344] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ru He
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Raquel A. Domingues
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
- Institute of Science and Technology, Federal University of São Paulo, R. Talim, 330, São José dos Campos, São Paulo 12231-280, Brazil
| | - Silvano Valandro
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Kirk S. Schanze
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
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