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Purpose: The main goal of this research was to assess the mechanical properties of APIs' polymorphic forms at the single-crystal level (piroxicam, famotidine, nifedipine, olanzapine) in order to predict their bulk deformational attributes, which are critical for some pharmaceutical technology processes. Methods: The mechanical properties of oriented single crystals were determined using instrumented nanoindentation (continuous stiffness measurement). All polymorphic forms investigated were previously identified using a combination of calorimetric and spectroscopic techniques. Results: Mechanical properties such as Young's modulus and indentation hardness were consistent with the molecular packing of the polymorphic forms investigated with respect to crystal orientation. For mechanically interlocked structures, characteristic of most polymorphic forms, response of single crystals to indentation was isotropic. The material's bulk elastic properties can be successfully predicted by measuring Young's modulus of single crystals because a good linear correlation with a bulk parameter such as the tablets' elastic relaxation index was determined. Conclusions: The results confirm the idea that the intrinsic mechanical properties of pharmaceutical crystals (Young's modulus) largely control and anticipate their deformational behavior during tablet compression. Young's modulus and indentation hardness represent a very valuable and effective tool in preformulation studies for describing materials' mechanical attributes, which are important for technological processes in which materials are exposed to deformation. [ABSTRACT FROM AUTHOR]

The crystal structures of two monomeric copper(II) carboxylates with 2-aminopyridine have been determined by X-ray diffraction. The hexanoate complex crystallizes as its acetonitrile solvate [Cu(C[sub 6]H[sub 11]O[sub 2])[sub 2](C[sub 5]H[sub 6]N[sub 2])[sub 2]·CH[sub 3]CN] in the triclinic space group P-1 with a = 8.1020(6), b = 13.7106(9), c = 13.7673(9) Å, α = 113.79(1), β = 103.86(1), and γ = 94.38(4). The heptanoate compound shows an unsolvated structure [Cu(C[sub 7]H[sub 13]O[sub 2])[sub 2](C[sub 5]H[sub 6]N[sub 2])[sub 2]] and also crystallizes in the triclinic space group P-1 with the following cell parameters: a = 8.4487(9), b = 12.238(1), c = 13.504(2) Å, α = 87.034(9), β = 77.489(9), and γ = 71.41(1)°. Both compounds contain the CuO[sub 4]N[sub 2] chromophore, with ligands arranged around the copper center in a cis mode. 2-Aminopyridine is coordinated through the endocyclic nitrogen atom. The ortho position of the amino group, with respect to the pyridine nitrogen atom, allows the formation of both, intra- and intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

Two compounds have been prepared during the investigation of the reactivity of α-halopyruvamides. The reaction products: 3-(4-chlorophenyl)imidazo[1,2-a]pyridine-2-carboxamide (1) and 7-carbamoyl-5-phenyl-2,3-dihydro[1,3]thiazolo[4,3-b][1,3]thiazol-4-ium chloride (2) were structurally characterized by x-ray crystallography. Compound 1 crystallizes in the orthorhombic space group Pca21 with a = 28.813(2), b = 9.369(1), and c = 9.361(1) Å. The structure contains two crystallographically different molecules. Compound 2 crystallizes in the monoclinic space group P21/c with the following cell parameters: a = 8.5895(8), b = 22.499(2), c = 7.4133(6) Å, and β = 110.204(1)°. [ABSTRACT FROM AUTHOR]