Mariano Quintero

Solid-State Forms of Zoledronic Acid: Polymorphism in Hydrates

Solid-state forms of zoledronic acid, a nitrogen-containing bisphosphonate used for treatment of bone diseases are studied using different experimental techniques (DSC, TG, and XRD). Two degrees of hydration have been obtained, containing one and three water molecules per zoledronic acid molecule. The crystal structure of the trihydrated form is reported. Two different anhydrated forms have been obtained when the hydrated ones were heated. Besides, during the dehydration process, an amount of metastable amorphous phase appears, as a function of the dehydration rate. The stability of the obtained crystalline forms is examined under high humidity and a different trihydrated form was obtained, setting clear that the same degree of hydration (trihydrated) can be obtained in two different crystalline forms, and then very different thermal behaviors have been observed.

1-(9H-Carbazol-4-yloxy)-3-{[2-(2-methoxyphenoxy)ethyl]amino}propan-2-ol hemihydrate: a carvedilol solvatomorph.

In the title racemic hemihydrated solvatomorph of carvedilol (carv), C(24)H(26)N(2)O(4)·0.5H(2)O, the asymmetric unit contains two independent organic moieties and one water molecule. Within this 2(carv)·H(2)O unit, the molecular components are strongly linked by hydrogen bonds and the unit acts as the basic building block for the crystal structure. Interactions parallel to (10 ̅1) generate hydrogen-bonded layers which are further linked by much weaker C-H···N/O interactions. The conformations of the organic molecules, as well as the hydrogen-bonding interactions connecting them, are compared with other related structures in the literature.

Direct observation of magnetocaloric effect by differential thermal analysis: Influence of experimental parameters

Abstract The magnetocaloric effect is the isothermal change of magnetic entropy and the adiabatic temperature change induced in a magnetic material when an external magnetic field is applied. In this work, we present an experimental setup to study this effect in metamagnetic transitions, using the differential thermal analysis technique, which consists in measuring simultaneously the temperatures of the sample of interest and a reference one while an external magnetic field ramp is applied. We have tested our system to measure the magnetocaloric effect in La0.305Pr0.32Ca0.375MnO3, which presents phase separation effects at low temperatures (T

Correlation between electrical and magnetic properties of phase-separated manganites studied with a general effective medium model

Abstract We have performed electrical resistivity and DC magnetization measurements as a function of temperature, on polycrystalline samples of phase-separated La5/8−yPryCa3/8MnO3 (y=0.3). We have used the general effective medium theory to obtain theoretical resistivity vs. temperature curves corresponding to different fixed ferromagnetic (FM) volume fraction values, assuming that the sample is a mixture of typical metallic-like and insulating manganites. By comparing this data with our experimental resistivity curves we have obtained the relative FM volume fraction of our sample as a function of temperature. This result matches with the corresponding magnetization data in excellent agreement, showing that a mixed-phase scenario is the key element to explain both the magnetic and transport properties in the present compound.