We describe the synthesis, structure and magnetic properties of two decanuclear Fe(III) complexes with novel core topologies, assembled using the tetra-deprotonated form of Bis-tris {2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol, H5L}.
The growth behavior, time of nucleation, and morphology of Ca(0H)' crystals formed during the hydration of Ca,SiOs at 1 5 O , 25O, and 35°C at water-solid ratios (w/s) from 0.3 to 5.0 were studied by optical microscopy. In samples with w/s >0.5 growth of Ca(0H)' in the c-axis direction is initially dominant. Growth in this direction ends after a few hours, but growth perpendicular to the c axis continues for several days and produces a dendritic morphology. Growth behavior is not so well defined for w/s <0.5, in part because of the large number of unhydrated particles engulfed. Increasing temperature resulted in an increase in the number of Ca(0H)' nuclei and a decrease in nucleation time and crystal size. Increasing the w/s ratio improved the euhedral character of the Ca(0H)' crystals, decreased the number of engulfed Ca3Si0, particles, and increased the nucleation time. Dendritic morphology was most pronounced in the samples for which w/s=l. Growth rates and the ultimate size of the Ca(OH), crystals varied within a given sample. The effects of temperature and the w/s ratio on the heat evolved during the hydration were studied by isotherma1 calorimetry. The times of nucleation of crystalline Ca(OH), estimated from calorimetry were similar to those derived from growth curves determined by optical microscopy.
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