Field dependent CIDNP from photochemically generated radical ion pairs in rigid bichromophoric systems

Wegner, M.; Fischer, Hanns; Grosse, Stefan; Vieth, Hans‐Martin; Oliver, Anna M.; Paddon‐Row, Michael N.

doi:10.1016/s0301-0104(01)00238-5

Cited by 43 publications

(30 citation statements)

References 65 publications

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“…Quite recently, the JCT mechanism has also been validated in the through-bond coupling mediated long-range intramolecular ET of the donor-bridge-acceptor systems by using a time-dependent density functional theory (TD-DFT) molecular orbital calculation [18]; the sign and magnitude of J were calculated to be dependent not only on the electronic energy level of charge-separated (CS) state but also on the molecular nuclear configuration of the CS state. The TD-DFT analysis well reproduced both the positive signs and the magnitudes of J in the dimethoxynaphthalene-bridgedicyanovinyl D-A systems [18,19].…”

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confidence: 62%

Diffusion-model analysis of effective CIDEP distance in solvent-separated radical-ion pair

2003

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The radical pair mechanism (RPM) of chemically induced dynamic electron polarization (CIDEP) is theoretically analyzed to determine what intermolecular separations (reŸ effectively cont¡ to the CIDEP generated from diflhsive, separated radical-ion pairs (RIP) in terms of the chargetransfer interaction in the singlet-triplet energy splitting (J) by taking into aceount the distance-dependent electronic coupling and reorganization energy. The diffusion-model analysis reveals that the hyperŸ237 RPM polarization (PwM) phase is varied with the driving force (-AGc~) for the charge-recombination (CR) process and that the boundary -AGcR between the opposite phases coincides well with the total reorganization energy around the diffusible separation distante, rct r = 1.2 nm, between the ion radicals. For the first time, the roe r is well described by the exponent parameter (13) in the distance-dependent electronic coupling, suggesting that the RPM CIDEP detection can be applied to characterize the electronic coupling in individual solvent-separated RIP systems. It has been concluded that, in contrast to the spin exchange interaction of the neutral radical pairs, the characteristic long-range charge-transfer interaction enables us to utilize the simple diffusion-model analysis to successfully evaluate the rc~ and the P~M in homogeneous liquid polar solvents.

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confidence: 62%

Diffusion-model analysis of effective CIDEP distance in solvent-separated radical-ion pair

2003

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“…Alternative mechanisms for solid-state photo-CIDNP have been examined by van den Heuvel et al (1994) and Corvaja et al (2000). A similar discussion of the photo-CIDNP effect observed with liquid NMR for rigid organic systems has been discussed by Wegner et al (1999Wegner et al ( , 2001.…”

Section: Introductionmentioning

confidence: 91%

Photo-CIDNP 13C Magic Angle Spinning NMR on Bacterial Reaction Centres: Exploring the Electronic Structure of the Special Pair and Its Surroundings

Matysik¹,

Schulten²,

Alia³

et al. 2001

Biological Chemistry

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Photochemically induced dynamic nuclear polarisation (photoCIDNP) in intact bacterial reaction centres has been observed by 13Csolid state NMR under continuous illumination with white light. Strong intensity enhancement of 13C NMR signals of the aromatic rings allows probing the electronic ground state of the two BChl cofactors of the special pair at the molecular scale with atomic selectivity. Differences between the two BChl cofactors are discussed. Several aliphatic 13C atoms of cofactors, as well as 13C atoms of the imidazole ring of histidine residue(s), show nuclearspin polarisation to the same extent as the aromatic nuclei of the cofactors. Mechanisms and applications of polarisation transfer are discussed.

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“…It was recently shown that 19 F photo‐CIDNP allows for the detection of a diluted p‐fluorophenol sample containing only 0.8 pmol/μL of the fluorinated substrate . CIDNP is field dependent but it was shown that hyperpolarization can be achieved over a wide range covering the typical field strengths of clinical MRI scanners between 1.5 and 3 T . Recently, 7 T MRI were introduced into clinical routine, and first 19 F signals were acquired from whole body 7 T scanners .…”

Section: Figurementioning

confidence: 99%

Low‐cost LED‐based Photo‐CIDNP Enables Biocompatible Hyperpolarization of ¹⁹F for NMR and MRI at 7 T and 4.7 T

et al. 2018

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Substrates containing 19F can serve as background‐free reporter molecules for NMR and MRI. However, in vivo applications are still limited due to the lower signal‐to‐noise ratio (SNR) when compared with 1H NMR. Although hyperpolarization can increase the SNR, to date, only photo‐chemically induced dynamic nuclear polarization (photo‐CIDNP) allows for hyperpolarization without harmful metal catalysts. Photo‐CIDNP was shown to significantly enhance 19F NMR signals of 3‐fluoro‐DL‐tyrosine in aqueous solution using flavins as photosensitizers. However, lasers were used for photoexcitation, which is expensive and requires appropriate protection procedures in a medical or lab environment. Herein, we report 19F MR hyperpolarization at 4.7 T and 7 T with a biocompatible system using a low‐cost and easy‐to‐handle LED‐based set‐up. First hyperpolarized 19F MR images could be acquired, because photo‐CIDNP enabled repetitive hyperpolarization without adding new substrates.

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Field dependent CIDNP from photochemically generated radical ion pairs in rigid bichromophoric systems

Cited by 43 publications

References 65 publications

Diffusion-model analysis of effective CIDEP distance in solvent-separated radical-ion pair

Diffusion-model analysis of effective CIDEP distance in solvent-separated radical-ion pair

Photo-CIDNP 13C Magic Angle Spinning NMR on Bacterial Reaction Centres: Exploring the Electronic Structure of the Special Pair and Its Surroundings

Low‐cost LED‐based Photo‐CIDNP Enables Biocompatible Hyperpolarization of ¹⁹F for NMR and MRI at 7 T and 4.7 T

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Field dependent CIDNP from photochemically generated radical ion pairs in rigid bichromophoric systems

Cited by 43 publications

References 65 publications

Diffusion-model analysis of effective CIDEP distance in solvent-separated radical-ion pair

Diffusion-model analysis of effective CIDEP distance in solvent-separated radical-ion pair

Photo-CIDNP 13C Magic Angle Spinning NMR on Bacterial Reaction Centres: Exploring the Electronic Structure of the Special Pair and Its Surroundings

Low‐cost LED‐based Photo‐CIDNP Enables Biocompatible Hyperpolarization of 19F for NMR and MRI at 7 T and 4.7 T

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Product

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Low‐cost LED‐based Photo‐CIDNP Enables Biocompatible Hyperpolarization of ¹⁹F for NMR and MRI at 7 T and 4.7 T