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Penki VSS, Chu YT, Chen HY, Sudewi S, Li CH, Huang GG, Hsu SCN. Steric and electronic influence on Cu-Cu short contacts in β-thioketiminato tricopper(I) clusters. Dalton Trans 2024; 53:13160-13173. [PMID: 39045681 DOI: 10.1039/d4dt01549e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
A series of β-thioketiminate copper(I) complex trimers [LCuI]3 were synthesized by modifying the ligand framework with electron-withdrawing groups (F and Cl) or electron-donating groups (iPr and Me) at the N-aryl ring as well as with CF3 groups on the chelating backbone. This ligand modification significantly impacts the enhancement of Cu⋯Cu short contacts, which can be rationalized by using steric and electronic factors of the chelated ligand. We observed that this intramolecular cuprophilicity among [LCuI]3 complexes is primarily governed by the size of N-aryl ortho-substituents. These findings were well supported by X-ray crystallography, Raman spectroscopy, and Mayer bond order analysis. The electronic effects induced by the ligand modification on the LCuI fragment were investigated using CO and 2,4,6-CNC6H2Me3 as probe molecules. Corroborated by the FTIR and CV measurements, our results reveal that the β-thioketiminate SN chelators induce more pronounced changes in the electronic character of the LCuI fragment due to the presence of CF3 groups on the chelating backbone in comparison with the F or Cl substituents on the N-aryl ring.
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Affiliation(s)
| | - Yu-Ting Chu
- International PhD Program for Science, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Hsing-Yin Chen
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
| | - Sri Sudewi
- Department of Pharmacy, Faculty of Mathematic and Natural Science, Universitas Sam Ratulangi, Manado 95115, Indonesia
| | - Chien-Hung Li
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
| | - Genin Gary Huang
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
| | - Sodio C N Hsu
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan
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Kim D, Rosko MC, Castellano FN, Gray TG, Teets TS. Long Excited-State Lifetimes in Three-Coordinate Copper(I) Complexes via Triplet-Triplet Energy Transfer to Pyrene-Decorated Isocyanides. J Am Chem Soc 2024; 146:19193-19204. [PMID: 38956456 DOI: 10.1021/jacs.4c04288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
There has been much effort to improve excited-state lifetimes in photosensitizers based on earth-abundant first-row transition metals. Copper(I) complexes have gained significant attention in this field, and in most cases, sterically driven approaches are used to optimize their lifetimes. This study presents a series of three-coordinate copper(I) complexes (Cu1-Cu3) where the excited-state lifetime is extended by triplet-triplet energy transfer. The heteroleptic compounds feature a cyclohexyl-substituted β-diketiminate (CyNacNacMe) paired with aryl isocyanide ligands, giving the general formula Cu(CyNacNacMe)(CN-Ar) (CN-dmp = 2,6-dimethylphenyl isocyanide for Cu1; CN-pyr = 1-pyrenyl isocyanide for Cu2; CN-dmp-pyr = 2,6-dimethyl-4-(1-pyrenyl)phenyl isocyanide for Cu3). The nature, energies, and dynamics of the low-energy triplet excited states are assessed with a combination of photoluminescence measurements at room temperature and 77 K, ultrafast transient absorption (UFTA) spectroscopy, and DFT calculations. The complexes with the pyrene-decorated isocyanides (Cu2 and Cu3) exhibit extended excited-state lifetimes resulting from triplet-triplet energy transfer (TTET) between the short-lived charge-transfer excited state (3CT) and the long-lived pyrene-centered triplet state (3pyr). This TTET process is irreversible in Cu3, producing exclusively the 3pyr state, and in Cu2, the 3CT and 3pyr states are nearly isoenergetic, enabling reversible TTET and long-lived 3CT luminescence. The improved photophysical properties in Cu2 and Cu3 result in improvements in activity for both photocatalytic stilbene E/Z isomerization via triplet energy transfer and photoredox transformations involving hydrodebromination and C-O bond activation. These results illustrate that the extended excited-state lifetimes achieved through TTET result in newly conceived photosynthetically relevant earth-abundant transition metal complexes.
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Affiliation(s)
- Dooyoung Kim
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Michael C Rosko
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Felix N Castellano
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Thomas G Gray
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Thomas S Teets
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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Kim D, Teets TS. Sterically Encumbered Aryl Isocyanides Extend Excited-State Lifetimes and Improve the Photocatalytic Performance of Three-Coordinate Copper(I) β-Diketiminate Charge-Transfer Chromophores. J Am Chem Soc 2024. [PMID: 38853542 DOI: 10.1021/jacs.4c05180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Copper(I) complexes are prominent candidates to replace noble metal-based photosensitizers. We recently introduced a three-coordinate design for copper(I) charge-transfer chromophores that pair β-diketiminate ligands with aryl isocyanides. The excited-state lifetime in these compounds can be extended using a bichromophoric "triplet reservoir" strategy, which comes at the expense of a decrease in excited-state energy and reducing power. In this work, we introduce a complementary, sterically driven strategy for increasing the excited-state lifetimes of these photosensitizers, which gives a higher-energy, more strongly reducing charge-transfer triplet state than does the bichromophore approach. The compounds presented (Cu1-Cu4) have the general formula Cu(CyNacNacMe)(CN-Ar), where CyNacNacMe is a cyclohexyl-substituted β-diketiminate and CN-Ar is an aryl isocyanide with a variable steric profile. Their structural features and electrochemical and photophysical properties are described. The complexes with sterically encumbered 2,6-diisopropylphenyl or m-terphenyl isocyanide ligands (Cu2-Cu4) exhibit prolonged excited-state lifetimes relative to those of the parent 2,6-dimethylphenyl isocyanide compound Cu1. Specifically, one of the m-terphenyl isocyanide compounds, Cu3, displays an excited-state lifetime of 276 ns, approximately 30 times longer than that of Cu1 (9.3 ns). The photoluminescence quantum yield of Cu3 (0.09) also increases by two orders of magnitude compared to that of Cu1 (0.0008). The strong excited-state reducing power (*Eox = -2.4 V vs Fc+/0) and long lifetime of Cu3 lead to higher yields in photoredox and photocatalytic isomerization reactions, which include dehalogenation and/or hydrodgenation of benzophenone substrates, C-O bond activation of a lignin model substrate, and photocatalytic E/Z isomerization of stilbene.
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Affiliation(s)
- Dooyoung Kim
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Thomas S Teets
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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A Comparative Study of the Synthesis and Hydrolysis of sym-Triaminobenzene Homologues. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238595. [PMID: 36500688 PMCID: PMC9737077 DOI: 10.3390/molecules27238595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 11/30/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Here, we investigated the synthetic processes for the methyl derivatives of sym-triaminobenzene and phloroglucinol, the essential chemical reactants coming into use in the production of dyes and pigments, and medicinal drugs for different purposes. The most eco-benign process for the synthesis of triamino derivatives involves the catalytic hydrogenation of corresponding nitroarenes. The present study investigated the hydrogenation of 2,4,6-trinitrotoluene, 2,4,6-trinitroxylene, and 2,4,6-trinitromesitylene over a Pd catalyst. A 1% Pd/Sibunit catalyst was found to be preferable to the 5% analogue with a preserved palladium loading because it shortens the reaction time and provides a higher yield of the target product. The hydrogenation in methanol (or mixed methanol/toluene) at 50-55 °C and 0.5 MPa pressure produced 2,4,6-triaminotoluene, 2,4,6-triaminoxylene, and 2,4,6-triaminomesitylene, which were isolated as sulfuric acid salts in 98, 91, and 97% yields, respectively. The hydrolysis process of the resultant salts was examined, and conditions leading to mono-, di-, and trimethyl derivatives of phloroglucinol (90, 77, and 82%, respectively,) were identified. The hydrogenation of the trinitrobenzene homologues in mixed 7:1 (v/v) acetone/water, followed by hydrolysis to the respective polyphenols, was explored. A successful result was achieved only for 2,4,6-trinitrotoluene. The catalyst activity was shown to decline negligibly throughout 10 cycles of reuse. 2-Methylphloroglucinol was synthesized in a high yield ranging from 85 to 91% calculated as 2,4,6-trinitrotoluene.
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Kinzhalov MA, Ivanov DM, Melekhova AA, Bokach NA, Gomila RM, Frontera A, Kukushkin VY. Chameleonic Metal-bound Isocyanides: π-Donating CuI-center Imparts a Nucleophilicity to the Isocyanide Carbon toward Halogen Bonding. Inorg Chem Front 2022. [DOI: 10.1039/d2qi00034b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the structures of the isostructural cocrystals [CuI3(CNXyl)3]·CHX3 (X = Br, I), two adjacent CuI-bound isocyanide groups, whose carbon lone pairs are blocked by the ligation, exhibit nucleophilic properties induced...
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Mai Y, Balzen AK, Torres RK, Callahan MP, Colson AC. A Modular Strategy for Expanding Electron-Sink Capacity in Noncanonical Cluster Assemblies. Inorg Chem 2021; 60:17733-17743. [PMID: 34748324 PMCID: PMC8653162 DOI: 10.1021/acs.inorgchem.1c02373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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A modular synthetic
strategy is described whereby organometallic
complexes exhibiting considerable electron-sink capacity may be assembled
by using only a few simple molecular components. The Fe2(PPh2)2(CO)5 fragment was selected
as a common electroactive component and was assembled around aromatic
cores bearing one, two, or three isocyanide functional groups, with
the resultant complexes possessing electron-sink capacities of two,
four, and six electrons, respectively. The latter complex is noteworthy
in that its electron-sink capacity was found to rival that of large
multinuclear clusters (e.g., [Ni32C6(CO)36]6– and [Ni38Pt6(CO)48]6–), which are often considered as benchmarks
of electron-sink behavior. Moreover, the modular assembly bearing
three Fe2(PPh2)2(CO)5 fragments
was observed to undergo reduction to a hexaanionic state over a potential
window of about −1.4 to −2.1 V (vs Fc/Fc+), the relatively compressed range being attributed to potential
inversions operative during the addition of the second, fourth, and
sixth electrons. Such complexes may be designated noncanonical
clusters because they exhibit redox properties similar to
those of large multinuclear clusters yet lack the extensive network
of metal–metal bonds and the condensed metallic cores that
typify the latter. By use of a
modular synthetic strategy and relatively few
molecular components, organometallic complexes exhibiting considerable
electron-sink capacity have been characterized. Complexes bearing
one, two, or three Fe2(PPh2)2(CO)5 fragments bound to aromatic isocyanide cores were found to
possess electron-sink capacities of two, four, and six electrons,
respectively, the latter rivaling the electron-sink capacity of large
polynuclear cluster benchmarks.
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Affiliation(s)
- Yume Mai
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
| | - Alexandria K Balzen
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
| | - Rebecca K Torres
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
| | - Michael P Callahan
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
| | - Adam C Colson
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho 83725, United States
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