The high-field magnetic properties and order of the gem mineral green dioptase Cu$_6[$Si$_6$O$_{18}]\cdot 6$H$_2$O have been studied by means single-crystal neutron diffraction in fields up to $21~$T magnetization measurements $30~$T. In zero field, Cu$^{2+}$-moments antiferromagnetic chains are oriented along $c$-axis with a small off-axis tilt. For field applied parallel $c$-axis, shows spin-...

Spin-crossover molecules having a low-spin ground state and a low-lying excited high-spin state are promising components for molecular electronics. We theoretically examine one-dimensional spin-crossover chain molecules of the type of Fe2+ triazole complexes. The existence of the additional low-spin/high-spin degree of freedom leads to rich behavior already in the ground state. We obtain the co...

A key step in cytochrome P450 catalysis includes the spin-state crossing from low spin to high spin upon substrate binding and subsequent reduction of the heme. Clearly, a weak perturbation in P450 enzymes triggers a spin-state crossing. However, the origin of the process whereby enzymes reorganize their active site through external perturbations, such as hydrogen bonding, is still poorly under...

The relationship between chemical structure and spin state in a transition metal complex has an important bearing on mechanistic bioinorganic chemistry, catalysis by base metals, and the design of spin crossover materials. The latter provide an ideal testbed for this question, since small changes in spin state energetics can be easily detected from shifts in the spin crossover equilibrium tempe...

The collective properties of spin-crossover chains are studied. Spin-crossover compounds contain ions with a low-spin ground state and low lying high-spin excited states and are of interest for molecular memory applications. Some of them naturally form one-dimensional chains. Elastic interaction and Ising exchange interaction are taken into account. The transfer-matrix approach is used to calcu...

The mechanism of the light-induced spin crossover of the [Fe(bpy)3](2+) complex (bpy=2,2'-bipyridine) has been studied by combining accurate electronic-structure calculations and time-dependent approaches to calculate intersystem-crossing rates. We investigate how the initially excited metal-to-ligand charge transfer (MLCT) singlet state deactivates to the final metastable high-spin state. Alth...