Spin density localization and accessibility of organic radicals affect liquid-state DNP efficiency

Scalar liquid DNP performance scales of a factor ∼5 depending on the spin density distribution and accessibility of the radical.

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

The chemical oxidation and reduction processes of deprotonated, direduced o-quinone-exTTF-o-quinone in protic solvents were studied by EPR spectroscopy. The formation of relatively stable paramagnetic protonated redox forms of the parent triad was very surprising. The character of spin-density distribution in the semiquinone–quinone and semiquinone–catechol redox forms indicates that the p-phenylene-extended tetrathiafulvalene connector provides a quite effective electronic communication channel between dioxolene coordination sites. It was found that the deprotonated, direduced o-quinone-exTTF-o-quinone is capable to reduction of the metal copper in solution. The radical anion species formed in this reaction exists in solution as a solvent-separated ion pair with a copper cation. A character of spin-density distribution in a radical anion species leads to the conclusion that the ligand corresponds to type III of the Robin–Day classification.

P-V Centers Behavior in Diamond C(111) Subsurface Layers

Quantum-chemical modeling is used to study the dependence of spin states, geometrical, electronic and energy characteristics of P-V center from its location on the surface of the diamond C(111). The (111) surface of diamond crystal is found to affect the geometrical parameters, charge characteristics and spin density distribution of P-V centers.

Ruthenium-tris(bipyridine) complexes with multiple redox-active amine substituents: tuning of spin density distribution and deep-red to NIR electrochromism and electrofluorochromism

Deep-red to NIR electrochromism and electrofluorochromism are demonstrated with ruthenium-tris(bipyridine) complexes with multiple amine substituents.