Strongly exchange-coupled triplet pairs in an organic semiconductor

From biological complexes to devices based on organic semiconductors, spin interactions play a key role in the function of molecular systems. For instance, triplet-pair reactions impact operation of organic light-emitting diodes as well as photovoltaic devices. Conventional models for triplet pairs assume they interact only weakly. Here, using electron spin resonance, we observe long-lived, strongly-interacting triplet pairs in an organic semiconductor, generated via singlet fission. Using coherent spin-manipulation of these two-triplet states, we identify exchange-coupled (spin-2) quintet complexes co-existing with weakly coupled (spin-1) triplets. We measure strongly coupled pairs with a lifetime approaching 3 µs and a spin coherence time approaching 1 µs, at 10 K. Our results pave the way for the utilization of high-spin systems in organic semiconductors.Gates-Cambridge Trust, Winton Programme for the Physics of Sustainability, Freie Universität Berlin within the Excellence Initiative of the German Research Foundation, Engineering and Physical Sciences Research Council (Grant ID: EP/G060738/1)This is the author accepted manuscript. The final version is available from Nature Publishing Group at http://dx.doi.org/10.1038/nphys3908

Stoppen of doorgaan: vertrekkers en switchers op de HHS/THR: wie, waarom en hoe uitval te voorkomen

De Haagse Hogeschool/ TH Rijswijk (HHS/THR) wil het rendement van de door haar verzorgde opleidingen vergroten. Om dat te bewerkstelligen zoeken we in dit onderzoek naar het antwoord op de vraag: welke patronen bestaan er in het vertrek uit opleiding en/of hogeschool en zijn er mogelijkheden voor de hogeschool om vertrek te voorkomen? Hiertoe hebben we gegevens van de IB-Groep geanalyseerd en een enquête uitgezet onder vertrekkers en switchers van de HHS/THR.<br/

The spin label amino acid TOAC and its uses in studies of peptides: chemical, physicochemical, spectroscopic, and conformational aspects

We review work on the paramagnetic amino acid 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid, TOAC, and its applications in studies of peptides and peptide synthesis. TOAC was the first spin label probe incorporated in peptides by means of a peptide bond. In view of the rigid character of this cyclic molecule and its attachment to the peptide backbone via a peptide bond, TOAC incorporation has been very useful to analyze backbone dynamics and peptide secondary structure. Many of these studies were performed making use of EPR spectroscopy, but other physical techniques, such as X-ray crystallography, CD, fluorescence, NMR, and FT-IR, have been employed. The use of double-labeled synthetic peptides has allowed the investigation of their secondary structure. A large number of studies have focused on the interaction of peptides, both synthetic and biologically active, with membranes. In the latter case, work has been reported on ligands and fragments of GPCR, host defense peptides, phospholamban, and β-amyloid. EPR studies of macroscopically aligned samples have provided information on the orientation of peptides in membranes. More recent studies have focused on peptide–protein and peptide–nucleic acid interactions. Moreover, TOAC has been shown to be a valuable probe for paramagnetic relaxation enhancement NMR studies of the interaction of labeled peptides with proteins. The growth of the number of TOAC-related publications suggests that this unnatural amino acid will find increasing applications in the future

Stoppen of doorgaan: vertrekkers en switchers op de HHS/THR: wie, waarom en hoe uitval te voorkomen

De Haagse Hogeschool/ TH Rijswijk (HHS/THR) wil het rendement van de door haar verzorgde opleidingen vergroten. Om dat te bewerkstelligen zoeken we in dit onderzoek naar het antwoord op de vraag: welke patronen bestaan er in het vertrek uit opleiding en/of hogeschool en zijn er mogelijkheden voor de hogeschool om vertrek te voorkomen? Hiertoe hebben we gegevens van de IB-Groep geanalyseerd en een enquête uitgezet onder vertrekkers en switchers van de HHS/THR