Activation volume (.DELTA. V.dbldag.q) for energy- and electron-transfer quenching of [Cu(dpp)2+]* (dpp = 2,9-diphenyl-1,10-phenanthroline)

Crane, Daniel R.; Ford, Peter C.

doi:10.1021/ic00063a030

Cited by 16 publications

(9 citation statements)

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“…The variation in ∆V q with solvent composition is small; however, the nature of the variation and the fact that the ratedetermining step involves the extension of the cobaltchloro bond in the transition state (an I d mechanism) prompted the authors to comment on the similarity to the S N 1 mechanism for the solvolysis of tert-butyl chloride (extension of a C-Cl bond in the transition state) in the same solvent mixtures. Aquation studies [160][161][162] on this and related dichloro complex ions and Co(en) 2 (NH 3 )X 2+ where X ) Br, Cl, or NO 3 [334][335][336][337][338][339][340][341][342][343][344][345][346][347][348][349][350]. It was also noted that among the latter group of complexes ∆V q was essentially temperature independent.…”

Section: B Aquation and Solvolysismentioning

confidence: 99%

Activation and Reaction Volumes in Solution. 3

et al. 1998

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Section: B Aquation and Solvolysismentioning

confidence: 99%

Activation and Reaction Volumes in Solution. 3

et al. 1998

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“…The effects of the PJT distortions on the photophysical behavior of Cu(I) bis (phenanthrolines) have been extensively studied since the 1970s. − Once excited into the singlet metal-to-ligand charge transfer ( 1 MLCT) excited state, which effectively oxidizes Cu(I) to Cu(II), which is a d 9 configuration, the diimine ligands engage in a flattening distortion due to the unequal occupation of degenerate d orbitals . This geometric relaxation wastes the potential energy stored in the excited state.…”

Section: Introductionmentioning

confidence: 99%

Next Generation Cuprous Phenanthroline MLCT Photosensitizer Featuring Cyclohexyl Substituents

et al. 2021

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A new long-lived, visible-light-absorbing homoleptic Cu(I) metal-to-ligand charge transfer (MLCT) photosensitizer, [Cu(dchtmp) 2 ]PF 6 (dchtmp = 2,9-dicyclohexyl-3,4,7,8-tetramethyl-1,10-phenanthroline), has been synthesized, structurally characterized, and evaluated in terms of its molecular photophysics, electrochemistry, and electronic structure. Static and timeresolved transient absorption (TA) and photoluminescence (PL) spectroscopy measured on the title compound in CH 2 Cl 2 (τ = 2.6 μs, Φ PL = 5.5%), CH 3 CN (τ = 1.5 μs, Φ PL = 2.6%), and THF (τ = 2.0 μs, Φ PL = 3.7%) yielded impressive photophysical metrics even when dissolved in Lewis basic solvents. The combined static spectroscopic data along with ultrafast TA experiments revealed that the pseudo-Jahn−Teller distortion and intersystem crossing dynamics in the MLCT excited state displayed characteristics of being sterically arrested throughout its evolution. Electrochemical and static PL data illustrate that [Cu(dchtmp) 2 ]PF 6 is a potent photoreductant (−1.77 V vs Fc +/0 in CH 3 CN) equal to or greater than all previously investigated homoleptic Cu(I) diimine complexes. Although we successfully prepared the cyclopentyl analog dcptmp (2,9-dicyclopentyl-3,4,7,8tetramethyl-1,10-phenanthroline) using the same C−C radical coupling photochemistry as dchtmp, the corresponding Cu(I) complex could not be isolated due to the steric hindrance presented at the metal center. Ultimately, the successful preparation of [Cu(dchtmp) 2 ] + represents a major step forward for the design and discovery of novel earth-abundant photosensitizers made possible through a newly conceived ligand synthetic strategy.

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“…Much of the interest in the excited state properties of these compounds was motivated by the pioneering work of McMillin and co-workers, who first established that visible excitation of Cu(dmp) 2 + (dmp is 2,9-dimethyl-1,10-phenanthroline) produces room-temperature photoluminescence in dichloromethane solution . This and related copper phenanthroline compounds with alkyl or aryl substituents in the 2,9-positions of phenanthroline also have long-lived excited states and display excellent photostability. − The excited states are potent reductants that have been employed in potentially practical processes, such as the production of hydrogen gas from water and an electrical current by sensitization of wide band gap semiconductors …”

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confidence: 99%

Photodriven Electron and Energy Transfer from Copper Phenanthroline Excited States

1996

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Electron and energy transfer from copper 1,10-phenanthroline excited states is observed at room temperature in organic solvents. The copper phenanthroline excited states are metal-to-ligand charge-transfer in nature and have lifetimes of approximately 70-250 ns in dichloromethane solution if methyl or phenyl substituents are placed in the 2- and 9-positions of the phenanthroline ligand. The unsubstituted cuprous compound Cu(phen)(2)(PF(6)) is nonemissive under these conditions, and the excited state lifetime is <20 ns. The rate and efficiency of energy transfer to anthracene or electron transfer to viologens is reported. The cage escape efficiency of [Cu(dpp)(2)(2+), MV(+)(*)], where dpp is 2,9-diphenyl-1,10-phenanthroline, is close to unity within experimental error. Back electron transfer to ground state products occurs at the diffusion limit, 2 x 10(10) M(-)(1) s(-)(1).

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Activation volume (.DELTA. V.dbldag.q) for energy- and electron-transfer quenching of [Cu(dpp)2+]* (dpp = 2,9-diphenyl-1,10-phenanthroline)

Cited by 16 publications

References 0 publications

Activation and Reaction Volumes in Solution. 3

Activation and Reaction Volumes in Solution. 3

Next Generation Cuprous Phenanthroline MLCT Photosensitizer Featuring Cyclohexyl Substituents

Photodriven Electron and Energy Transfer from Copper Phenanthroline Excited States

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