We show that the electron spin phase memory time, the most important property of a molecular nanomagnet from the perspective of quantum information processing, can be improved dramatically by chemically engineering the molecular structure to optimize the environment of the spin. We vary systematically each structural component of the class of antiferromagnetic Cr(7)Ni rings to identify the sources of decoherence. The optimal structure exhibits a phase memory time exceeding 15  μs.

We determine the spin-selective kinetics of a carotenoid-porphyrin-fullerene triad that has previously been used to establish the principle that a photochemical reaction could form the basis of the magnetic compass sensor of migratory birds and show that its magnetic sensitivity can be understood without invoking quantum Zeno effects.

We show that optical excitation of radical triplet pair systems can produce a fourfold NMR signal enhancement in solution, without the need for microwave pumping. Development of optical hyperpolarization methods will significantly impact all NMR user groups by boosting sensitivity and reducing signal averaging times.

Within the framework of the radical pair mechanism, magnetic fields may alter the rate and yields of chemical reactions involving spin-correlated radical pairs as intermediates. Such effects have been studied in detail in a variety of chemical systems both experimentally and theoretically. In recent years, there has been growing interest in whether such magnetic field effects (MFEs) also occur in biological systems, a question driven most notably by the increasing body of evidence for the involvement of such effects in the magnetic compass sense of animals. The blue-light photoreceptor cryptochrome is placed at the centre of this debate and photoexcitation of its bound flavin cofactor has indeed been shown to result in the formation of radical pairs. Here, we review studies of MFEs on free flavins in model systems as well as in blue-light photoreceptor proteins and discuss the properties that are crucial in determining the magnetosensitivity of these systems.

l-Tryptophan (Trp), melatonin (MLT) and the Trp-peptide pentagastrin quenched the formation of azidyl radicals generated on irradiation of the anticancer complex trans,trans,trans-[Pt(pyridine)2(N3)2(OH)2] with visible light, giving rise to C3-centred indole radicals which were characterized for Trp and MLT using an EPR spin-trap.

Oxidation of zero‐valent phosphine complexes [M(PtBu3)2] (M=Pd, Pt) has been investigated in 1,2‐difluorobenzene solution using cyclic voltammetry and subsequently using the ferrocenium cation as a chemical redox agent. In the case of palladium, a mononuclear paramagnetic PdI derivative was readily isolated from solution and fully characterized (EPR, X‐ray crystallography). While in situ electrochemical measurements are consistent with initial one‐electron oxidation, the heavier congener undergoes C−H bond cyclometalation and ultimately affords the 14 valence‐electron PtII complex [Pt(κ 2 PC‐PtBu2CMe2CH2)(PtBu3)]+ with concomitant formation of [Pt(PtBu3)2H]+.

Low-field optically detected EPR spectra of photochemically formed transient radical ion pairs are reported for weak circularly and linearly polarized radiofrequency (RF) fields. The spectra are found to be strongly dependent on the polarization and frequency of the RF field and on the angle between the static magnetic field and the plane containing the RF field. The spectra are discussed in terms of resonances arising from Zeeman and hyperfine interactions; the conditions for validity of the rotating frame approximation are determined. Knowledge of the latter is important when using low-field EPR as a diagnostic test for the operation of the radical pair mechanism.

Optically detected zero-field electron paramagnetic resonance spectroscopy is used to show that weak linearly and circularly polarized radiofrequency magnetic fields affect the recombination reactions of spin-correlated radical pairs to different extents; the spectra are shown to be consistent with the radical pair mechanism.