Structural change dynamics of heteroleptic Cu(<scp>i</scp>) complexes observed by ultrafast emission spectroscopy

Sanga, Masashi; Iwamura, Michiko; Nakamura, Kôsuke; Nozaki, Koichi; Takeda, Hiroyuki; Monma, Yu; Ishitani, Osamu

doi:10.1039/d3cp01473h

Cited by 4 publications

(3 citation statements)

References 66 publications

(138 reference statements)

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“…The second time constant, τ 2 (6.2−12 ps), is assigned to intersystem crossing (ISC) from the 1 MLCT into the 3 MLCT manifold since this relaxation process is generally slower with respect to the PJT distortion. 19,24,55,73 The third time constant, τ 3 (3.1−4.5 ns), represents the MLCT excited-state lifetime and is consistent with other nonemissive heteroleptic mesPhen-containing Cu(I) phenanthrolines lacking sterically locking substituents on the secondary phenanthroline ligand. 29…”

Section: ■ Results and Discussionsupporting

confidence: 75%

“…The first component, τ 1 (0.17–0.68 ps), occurs on subpicosecond time scales and was identified as the PJT reorganization since each molecule under investigation is not sterically locked into a pseudotetrahedral-like geometry. The second time constant, τ 2 (6.2–12 ps), is assigned to intersystem crossing (ISC) from the 1 MLCT into the 3 MLCT manifold since this relaxation process is generally slower with respect to the PJT distortion. ,,, The third time constant, τ 3 (3.1–4.5 ns), represents the MLCT excited-state lifetime and is consistent with other nonemissive heteroleptic mesPhen-containing Cu(I) phenanthrolines lacking sterically locking substituents on the secondary phenanthroline ligand …”

Section: Resultsmentioning

confidence: 53%

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Enhanced Visible Light Absorption in Heteroleptic Cuprous Phenanthrolines

Rosko,

Wheeler,

Alameh

et al. 2024

Inorg. Chem.

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This work presents a series of Cu(I) heteroleptic 1,10-phenanthroline chromophores featuring enhanced UVA and visible-light-harvesting properties manifested through vectorial control of the copper-to-phenanthroline chargetransfer transitions. The molecules were prepared using the HETPHEN strategy, wherein a sterically congested 2,9-dimesityl-1,10-phenanthrolne (mesPhen) ligand was paired with a second phenanthroline ligand incorporating extended π-systems in their 4,7-positions. The combination of electrochemistry, static and timeresolved electronic spectroscopy, 77 K photoluminescence spectra, and timedependent density functional theory calculations corroborated all of the experimental findings. The model chromophore, [Cu(mesPhen)(phen)] + (1), lacking 4,7-substitutions preferentially reduces the mesPhen ligand in the lowest energy metal-to-ligand charge-transfer (MLCT) excited state. The remaining cuprous phenanthrolines (2−4) preferentially reduce their π-conjugated ligands in the low-lying MLCT excited state. The absorption cross sections of 2−4 were enhanced (ε MLCTmax = 7430−9980 M −1 cm −1 ) and significantly broadened across the UVA and visible regions of the spectrum compared to 1 (ε MLCTmax = 6494 M −1 cm −1 ). The excited-state decay mechanism mirrored those of long-lived homoleptic Cu(I) phenanthrolines, yielding three distinguishable time constants in ultrafast transient absorption experiments. These represent pseudo-Jahn−Teller distortion (τ 1 ), singlet−triplet intersystem crossing (τ 2 ), and the relaxed MLCT excited-state lifetime (τ 3 ). Effective light-harvesting from Cu(I)-based chromophores can now be rationalized within the HETPHEN strategy while achieving directionality in their respective MLCT transitions, valuable for integration into more complex donor− acceptor architectures and longer-lived photosensitizers.

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Section: ■ Results and Discussionsupporting

confidence: 75%

Section: Resultsmentioning

confidence: 53%

Enhanced Visible Light Absorption in Heteroleptic Cuprous Phenanthrolines

Rosko,

Wheeler,

Alameh

et al. 2024

Inorg. Chem.

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“…It is known that the excited state of CuPS is reductively quenched by BIH to generate OER species of CuPS , i.e., CuPS •– . ,, We expected the same reaction in this study as the initial photochemical process of CuPS in the presence of an excess of BIH. Notably, all of the irradiated 436 nm monochromatic light could be absorbed by CuPS , because the coordination-free ligands have no absorption bands over 400 nm (Figure S9), except of the systems generating [Fe II ( R 1 R 2 p ) 3 ] 2+ .…”

Section: Results and Discussionmentioning

confidence: 64%

Photocatalytic CO₂ Reduction Using Mixed Catalytic Systems Comprising an Iron Cation with Bulky Phenanthroline Ligands

Takeda,

Irimajiri,

Mizutani

et al. 2024

Inorg. Chem.

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This study reports on efficient photocatalytic CO 2 reduction reactions using mixed catalytic systems of an Fe ion source and various 1,10-phenanthroline derivatives (R 1 R 2 p) as ligands in the presence of triethanolamine (TEOA). As the relatively bulky substituents at positions 2 and 9 of R 1 R 2 p weakened the ability to coordinate to the Fe ion, the Fe ion formed TEOA complexes. The free R 1 R 2 p accepted an electron from the reduced photosensitizer through proton-coupled electron transfer (PCET) using protons of TEOA dissolved in a CH 3 CN solution in a CO 2 atmosphere as the initial step of the catalytic cycle. Although the mixed system of the nonsubstituted 1,10-phenanthroline generates a stable tris(phenanthroline)−Fe(II) complex in solution, this complex could not function as a CO 2 reduction catalyst. The mechanism in which R 1 R 2 p interacts with the Fe ion after PCET was proposed for this efficient photocatalytic CO 2 reduction. The proposed photocatalytic system using the 2,9-di-sec-butyl-phenanthroline ligand could produce CO with high efficiency (quantum yield of 8.2%) combined with a dinuclear Cu(I) complex as a photosensitizer.

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Recent advances in ultrafast dynamics in photoactive copper(I) diimine complexes, from optical and X-ray methods

Appleby,

Cowin,

Weinstein

2024

Advances in Inorganic Chemistry

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Structural change dynamics of heteroleptic Cu(i) complexes observed by ultrafast emission spectroscopy

Abstract: [Cu(I)(dmp)(P)2]+ (dmp =2,9-dimethyl-1,10-phenanthroline derivatives; P = phosphine ligand) is one of the most promising photosensitizers used in a photo-catalytic system reducing CO2, of which quantum yield is as high as...

Cited by 4 publications

References 66 publications

Enhanced Visible Light Absorption in Heteroleptic Cuprous Phenanthrolines

Enhanced Visible Light Absorption in Heteroleptic Cuprous Phenanthrolines

Photocatalytic CO₂ Reduction Using Mixed Catalytic Systems Comprising an Iron Cation with Bulky Phenanthroline Ligands

Recent advances in ultrafast dynamics in photoactive copper(I) diimine complexes, from optical and X-ray methods

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Structural change dynamics of heteroleptic Cu(i) complexes observed by ultrafast emission spectroscopy

Abstract: [Cu(I)(dmp)(P)2]+ (dmp =2,9-dimethyl-1,10-phenanthroline derivatives; P = phosphine ligand) is one of the most promising photosensitizers used in a photo-catalytic system reducing CO2, of which quantum yield is as high as...

Cited by 4 publications

References 66 publications

Enhanced Visible Light Absorption in Heteroleptic Cuprous Phenanthrolines

Enhanced Visible Light Absorption in Heteroleptic Cuprous Phenanthrolines

Photocatalytic CO2 Reduction Using Mixed Catalytic Systems Comprising an Iron Cation with Bulky Phenanthroline Ligands

Recent advances in ultrafast dynamics in photoactive copper(I) diimine complexes, from optical and X-ray methods

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Photocatalytic CO₂ Reduction Using Mixed Catalytic Systems Comprising an Iron Cation with Bulky Phenanthroline Ligands