Sonogenerated metal-hydrogen sponges for reactive hard templating.

We present sonogenerated magnesium-hydrogen sponges for effective reactive hard templating. Formation of differently organized nanomaterials is possible by variation of sonochemical parameters and solution composition: Fe2O3 nanorods or composite dendritic Fe2O3/Fe3O4 nanostructures.

Synthesis of microcrystals of the [Fe(L)(bipy)] spin crossover coordination polymer in a poly-4-vinylpyridine matrix.

Microcrystals of the spin-crossover coordination polymer [FeL(bipy)] (L=[3,3']-[1,2-phenylenebis(iminoethylidyne)]bis-(2,4-pentanedionato)(2-), bipy=4,4'-bipyridine) have been prepared in a poly(4-vinylpyridine) (P4VP) matrix. This was done by sequential addition of the iron(II) precursor complex and the bridging ligand bipy to a P4VP matrix, and by repetition of this cycle. The obtained composite material was characterized using TEM, SEM, XRPD, and SQUID measurements, and Mössbauer spectroscopy. With repeating cycles, the size of the [FeL(bipy)] crystals in the P4VP matrix increases from submicrometer to micrometer dimensions. A strong dependence on the number of cycles is observed. Above a critical size and concentration, the microcrystals show the same cooperative spin transition as the bulk material. No indication for a gradual spin transition is observed, but the remaining iron centers are either high-spin or low-spin depending on the coordination environment.

The spin state of a molecular adsorbate driven by the ferroelectric substrate polarization.

The spin state of [Fe(H2B(pz)2)2(bipy)] thin films is mediated by changes in the electric field at the interface of organic ferroelectric polyvinylidene fluoride with trifluoroethylene (PVDF-TrFE). Signatures of the molecular crossover transition are evident in changes in the unoccupied states and the related shift from diamagnetic to paramagnetic characteristics. This may point the way to the molecular magneto-electric effect on devices.

Antagonism between extreme negative linear compression and spin crossover in [Fe(dpp)(2)(NCS)(2)]⋠py.

A scissor-like geometric mechanism is responsible for the strongest negative linear compression effect yet observed in a molecular material, [Fe(dpp)(2)(NCS)(2)]⋅py (see picture; dpp=dipyrido[3,2-a:2'3'-c]phenazine), C gray, N blue, S yellow, Fe red). The same mechanism is also responsible for suppressing the high-spin to low-spin transition under pressure.