Characterisation of redox states of metal-organic frameworks by growth on modified thin-film electrodes.

The application of metal-organic framework (MOF) materials in electrochemical and electrochromic devices remains rare. One of the main reasons for this is the inability to readily access their detailed electrochemistry. The inherent insolubility of these materials does not allow interrogation by traditional solution-based electrochemical or spectroscopic methods.

Tailoring the Shape Memory Properties of Segmented Poly(ester urethanes) via Blending.

Thermoplastic segmented polyurethanes (PUs) can exhibit shape memory behavior, if they feature multiple kinds of physical cross-links that can be dissociated at different temperatures. This is the case if the hydrogen-bonded hard phase is joined with soft segments that can partially crystallize, so that the melting transition acts as the memory switch. For applications in the biomedical field, it is important that the fixation and recovery temperatures can be minutely controlled.

Heterobimetallic [NiFe] Complexes Containing Mixed CO/CN Ligands: Analogs of the Active Site of the [NiFe] Hydrogenases.

The development of synthetic analogs of the active sites of [NiFe] hydrogenases remains challenging, and, in spite of the number of complexes featuring a [NiFe] center, those featuring CO and CN ligands at the Fe center are under-represented. We report herein the synthesis of three bimetallic [NiFe] complexes [Ni( N S)Fe(CO)(CN)], [Ni( S)Fe(CO)(CN)], and [Ni( N S)Fe(CO)(CN)] that each contain a Ni center that bridges through two thiolato S donors to a {Fe(CO)(CN)} unit. X-ray crystallographic studies on [Ni( N S)Fe(CO)(CN)], supported by DFT calculations, are consistent with a solid-state structure containing distinct molecules in the singlet ( S = 0) and triplet ( S = 1) states.

Dynamic nuclear polarisation by thermal mixing: quantum theory and macroscopic simulations.

A theory of dynamic nuclear polarisation (DNP) by thermal mixing is suggested based on purely quantum considerations. A minimal 6-level microscopic model is developed to test the theory and link it to the well-known thermodynamic model. Optimal conditions for the nuclear polarization enhancement and effects of inhomogeneous broadening of the electron resonance are discussed.

A Ni(i)Fe(ii) analogue of the Ni-L state of the active site of the [NiFe] hydrogenases.

[Ni(L(1))Fe((t)BuNC)4](PF6)2 is a robust Ni(II)Fe(II) complex that undergoes a reversible one-electron reduction. Spectroscopic and theoretical studies show that [Ni(L(1))Fe((t)BuNC)4](+) is an unprecedented Ni(I)Fe(II) species that reproduces the electronic configuration of the Ni-L state of the [NiFe] hydrogenases.

The vibrational bound states of isomerising disilyne.

Full-dimensional variational calculations are reported for the isomerising disilyne molecule, Si2H2. Large-scale calculations using coordinates based on orthogonal satellite vectors permitted the computation of excited vibrational state energies and wavefunctions for all four isomeric forms: dibridged Si(H2)Si, monobridged Si(H)SiH, disilavinylidene H2SiSi, and trans-bent HSiSiH. Energies and wavefunctions have been determined for the lowest 2400 totally symmetric vibrational states; this set includes highly excited states above all three chemically relevant isomerisation barriers--up to about 8300 cm(-1) above the (dibridged) ground state.

Catalytic hydrogen production by a Ni-Ru mimic of NiFe hydrogenases involves a proton-coupled electron transfer step.

A combined electrochemical and theoretical study suggests that hydrogen evolution from weak acids catalyzed by a structural mimic of the active site of NiFe hydrogenases [Ni(xbsms)Ru(C6Me6)Cl](+) proceeds through proton-coupled electron transfer steps.

The potential energy surface of isomerising disilyne.

A (semi-)global, analytical potential energy surface is reported for the ground electronic state of the isomerising disilyne molecule, Si2H2. The surface reproduces well ab initio energies calculated at the CCSD(T) level with a cc-pV(Q+d)Z basis set for over 50 000 symmetrically unique molecular geometries. Of these ab initio points, 33 000 were used in a least-squares fit to determine the parameters of the analytical surface and the remainder to provide an independent test/validation set.