Mixed crystal formation of two gold isocyanide complexes with various ratios for continuous tuning of photophysical properties

Mixed crystals composed of two distinct gold isocyanide complexes are reported.

Tuning of the exchange interaction and the Curie temperature by mixed crystal formation of the bridging anionic ligands

A strategy to continuously tune the exchange constant J and the critical temperature Tc in the 1D coordination polymers [Co(NCS)x(NCSe)2−x(pyridine)2]n is reported. For such mixed crystals, prepared by annealing and from solution, an increase of J and Tc with increasing selenocyanate content is observed.

Modified photoreactivity due to mixed crystal formation. II. Enhanced reactivity upon conformational mimicry and cavity enlargement

The 2-cyanopropyl (β-cyanopropyl) group in the cobaloxime complex of (2-cyanopropyl)(3-methylpyridine)bis(dimethylglyoximato)cobalt(III) takes a trans conformation around the Co—C—C—CN bond in the crystal and undergoes isomerization to the 1-cyanopropyl (α-cyanopropyl) group with a low reaction rate when the powdered crystals are irradiated with a xenon lamp. When the complex was mixed with (2-cyanoethyl)(3-methylpyridine)bis(dimethylglyoximato)cobalt(III) or (2-cyanoethyl)(3-ethylpyridine)bis(dimethylglyoximato)cobalt(III), a mixed crystal, Mix-I or Mix-II, was obtained. The cell parameters of Mix-I and Mix-II were considerably different. When the crystals of Mix-I and Mix-II were irradiated with the xenon lamp, the 2-cyanopropyl group and the 2-cyanoethyl group isomerized to the 1-cyanopropyl and 1-cyanoethyl groups, respectively, in the crystalline state as well as in the solid state. The isomerization rates of the 2-cyanopropyl and 2-cyanoethyl groups of the mixed crystals became significantly higher than the corresponding rates in the component crystals. For the 2-cyanopropyl group, the conformational change from trans to cis in the mixed crystals caused reaction rates to be enhanced, and the expanded volume of the reaction cavity in the mixed crystals increased the reactivity for the 2-cyanoethyl group, when compared with the reactivity of each component crystal. A quantitative discussion of the increased rate constants is presented, which is based on the crystal structures. The shapes of the reaction cavities for the reactive groups undergoing isomerization control the conformation and configuration of the produced1-cyanoethyl and 1-cyanopropyl groups.