Polyphenols extracted from the seeds of Vitis vinifera L. cv. Shiraz berries were monitored during berry development. Initially seeds were green, plump and had pliable seed coats, but beginning at veraison the seeds browned in colour, became desiccated and the seed coats hardened. Isolated polyphenols consisted of flavan-3-ol monomers ((+)-catechin, (-)-epicatechin and (-)-epicatechin-3-O-gallate) and procyanidins. The procyanidins were maximal in the 3 weeks prior to veraison, increasing little during this period. The amounts of flavan-3-ol monomers increased 5-fold during this same period of time, indicating that the procyanidins and the flavan-3-ol monomers accumulate at different stages. Beginning at veraison, amounts of all polyphenols declined and changed in composition. The decrease in amount followed second-order kinetics. Polyphenol changes after veraison could be explained by oxidation and therefore, electron paramagnetic resonance (EPR) spectroscopy was used to follow the potential development of radical species in the developing seeds. Spectra consistent with a phenoxyl radical were observed in the developing seeds. The concentration of radicals remained low until veraison but then increased, reaching a maximum three weeks later, declining slowly thereafter. Changes in radical intensity together with other documented changes in the seed are consistent with an oxidative event occurring during fruit ripening. Abbreviations Kennedy et al. Development of seed polyphenols 245Development of seed polyphenols

Naphthalene diimides 1–4 having different N,N-disubstitution undergo single electron reduction processes either chemically or electrochemically to yield the corresponding radical anion in high yield. This study concentrates on 1, bearing pentyl side chains connected through the diimide nitrogens, and compares the results obtained against those bearing isopropyl, propargyl, and phenylalanyl side chains. Compound 1 exhibits mirror image absorption and fluorescence in the near-UV region in CH2Cl2 and dimethylformamide that is typical of monomeric N,N-dialkyl-substituted naphthalene diimides. In toluene, excimer-like emission is observed, which suggests ground-state complexes involving 1 are formed. X-Ray crystallography has been used to characterize 1 in the solid state. Cyclic voltammetry enables the reversible potentials for [NDI]0/– and [NDI]−/2– type processes to be measured. Bulk one-electron reduction of 1–4 is characterized by dramatic changes in the absorption and emission spectra. Additionally, highly structured EPR (electron paramagnetic resonance) signals from dimethylformamide solutions of the radical anions of 1–3 have been obtained and are consistent with coupling between the unpaired electron and the naphthalene diimide nitrogens and hydrogens and the NCH hydrogens of the appropriate side chains. The overall structure of the EPR spectrum is substituent-dependent. These changes in spectroscopic output upon an electronic input may be described as a simple ‘on/off’ switching mechanism with which to apply a ‘bottom-up’ approach to molecular device manufacture.

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Millimetre microwaves and pulsed magnetic fields have been used to investigate the magnetic resonances in a-Fe,O,. Above the field and temperature induced phase boundary the coupling of the two weak-ferromagnetic resonance modes has been observed. The coupling equation has been derived taking into account second anisotropy, basal plane anisotropy and magnetostriction. Below the phase boundary the antiferromagnetic resonance modes have been investigated and the resonance equat>ions derived for the field in the basal plane. The observation of the phase boundary using a conventional resonance spectrometer has been satisfactorily interpreted in terms of the large changes in susceptibility which a numerical analysis shows often occur a t or near this boundary. A small quantitative difference has been shown to exist between phenomenological theory and experiment at high magnetic fields.I n a-Fe,O, wird die magnetische Resonanz bei Millimetermikrowellen und in gepulsten Magnetfeldern untersucht. Oberhalb. der feld-und temperaturinduzierten Phasengrenze wird die Kopplung von zwei schwach ferroniagnetischen Resonanzmoden beobachtet. Die Iiopplungsgleichung wird unter Berucksichtignng der zweiten Anisotropie, der Basisebenenanisotropie und der Magnetostriktion abgeleitet. Unterhalb der Phasengrenze werden die a,ntiferromagnetischen Resonanzmoden untcrsucht und die Rcsonanzgleichungen far ein Feld in der Basisebene abgeleitet. Die Beobachtung der Phasengrenze mit einem konventionellen Resonanzspektrometer wird befriedigend mit groI3en Anderungen der Suszeptibilit a t erkllrt, die oft bei oder in der Nahe dieser Grenze auftreten, wie eine numerische Analysc zeigt. Es wird gezeigt, dal3 cine kleine quantitative Differenz zwischen der phanomenologischen Theorie und dem Experiment bei hohen Magnetfcldcrn existiert.