Sonochemical synthesis of nano-cocrystals

Cocrystals are multicomponent solids with organic molecules assembled in combination to form a crystalline solid with properties different than the individual components. A cocrystal typically consists of a target molecule crystallized with a second molecule, or cocrystal former, employed to influence properties of the target (e.g. solubility). The conformer interacts with the target via intermolecular forces (e.g. hydrogen bonds) that hold the components together. The modularity of a cocrystal makes such solids attractive for applications where fine-tuning of properties is important (e.g. optical). In this presentation, we describe the use of sonochemistry to form cocrystals of nanoscale dimensions. In contrast to single-component solids, cocrystals present a fundamentally different challenge with respect to those reprecipitation methods used to form nanocrystals since the components of a cocrystal will tend to exhibit different solubilities. We show that sonochemistry affords nano-cocrystals with properties (e.g. reactivity) that contrast solids of macroscale dimensions. Related applications of sonochemistry to afford singlecomponent nanocrystals will also be presented. © 2013 Acoustical Society of America

Type A as a Moderator of Stressors and Job Complexity: A Comparison of Achievement Strivings and Impatience-Irritability

This study examined two components (achievement strivings and impatience-irritability) of the Type A Behavior Pattern as moderators of job stressors and job complexity on health and job satisfaction. It was predicted that achievement strivings would moderate the impact of job stressors and impatience-irritability would impact responses to job complexity. Data from 525 employed adults provided mixed support for the moderator hypotheses. Relations between job stressors and both health and job satisfaction were strongest among employees reporting high levels of achievement strivings. Impatience-irritability had no moderating effect. For job complexity, only one moderator effect was found. Mental demands were positively related to job satisfaction among those reporting low levels of impatience-irritability. Implications of these findings are discussed

Supramolecular Complexes of Sulfadiazine and Pyridines: Reconfigurable Exteriors and Chameleon-like Behavior of Tautomers at the Co-Crystal–Salt Boundary

We apply crystal engineering principles to prepare organic co-crystals and salts of sulfadiazine and pyridines. Pyridines are molecular building blocks utilized in crystal engineering that can disrupt the hydrogen bonded (amidine) N–H···N (pyrimidine) dimer within the parent sulfa drug (SD) crystals, while providing access to both co-crystals and salts. We have synthesized four co-crystals and three salts of sulfadiazine involving <i>N</i>,<i>N</i>-dimethyl-4-aminopyridine, 4-aminopyridine, 4-picoline, 4,4′-bipyridine, (<i>E</i>)-1,2-bis­(4-pyridyl)­ethylene, 1,2-bis­(4-pyridyl)­acetylene, and 4-(pyridin-4-yl)­piperazine. Single-crystal X-ray analyses reveal three hydrogen-bond motifs, namely, dyads, rings, and chains based involving either (amidine/aniline) N–H···N (pyridine/pyrimidine), (pyridinium) ⁺N–H···N^–(amidide), (aniline/piperazine) N–H···O₂S (sulfoxide) interactions, or a combination thereof. The hydrogen-bond motifs are assigned as <i>D</i>₁¹(2), <i>R</i>₂²(8), <i>R</i>₂²(20), <i>C</i>₂²(17), and <i>C</i>₂²(13) graph sets. An analysis of the Cambridge Structural Database (CSD) reveals that the S–N bond length is generally shorter in complexes based on an anionic SD, which is consistent with the sulfonamide possessing greater SN character. From an analysis of SD-based structures involving our work and the CSD, we present a heretofore not discussed role of tautomers at the co-crystal–salt boundary. Specifically, the ability of tautomeric forms of SDs to display reconfigurable exteriors, and thereby act as chameleons, enables SDs to accommodate different co-formers by assuming different geometries and adopting different regions along the co-crystal–salt boundary

Supramolecular Complexes of Sulfadiazine and Pyridines: Reconfigurable Exteriors and Chameleon-like Behavior of Tautomers at the Co-Crystal–Salt Boundary

We apply crystal engineering principles to prepare organic co-crystals and salts of sulfadiazine and pyridines. Pyridines are molecular building blocks utilized in crystal engineering that can disrupt the hydrogen bonded (amidine) N–H···N (pyrimidine) dimer within the parent sulfa drug (SD) crystals, while providing access to both co-crystals and salts. We have synthesized four co-crystals and three salts of sulfadiazine involving <i>N</i>,<i>N</i>-dimethyl-4-aminopyridine, 4-aminopyridine, 4-picoline, 4,4′-bipyridine, (<i>E</i>)-1,2-bis­(4-pyridyl)­ethylene, 1,2-bis­(4-pyridyl)­acetylene, and 4-(pyridin-4-yl)­piperazine. Single-crystal X-ray analyses reveal three hydrogen-bond motifs, namely, dyads, rings, and chains based involving either (amidine/aniline) N–H···N (pyridine/pyrimidine), (pyridinium) ⁺N–H···N^–(amidide), (aniline/piperazine) N–H···O₂S (sulfoxide) interactions, or a combination thereof. The hydrogen-bond motifs are assigned as <i>D</i>₁¹(2), <i>R</i>₂²(8), <i>R</i>₂²(20), <i>C</i>₂²(17), and <i>C</i>₂²(13) graph sets. An analysis of the Cambridge Structural Database (CSD) reveals that the S–N bond length is generally shorter in complexes based on an anionic SD, which is consistent with the sulfonamide possessing greater SN character. From an analysis of SD-based structures involving our work and the CSD, we present a heretofore not discussed role of tautomers at the co-crystal–salt boundary. Specifically, the ability of tautomeric forms of SDs to display reconfigurable exteriors, and thereby act as chameleons, enables SDs to accommodate different co-formers by assuming different geometries and adopting different regions along the co-crystal–salt boundary

Supramolecular Complexes of Sulfadiazine and Pyridines: Reconfigurable Exteriors and Chameleon-like Behavior of Tautomers at the Co-Crystal–Salt Boundary

We apply crystal engineering principles to prepare organic co-crystals and salts of sulfadiazine and pyridines. Pyridines are molecular building blocks utilized in crystal engineering that can disrupt the hydrogen bonded (amidine) N–H···N (pyrimidine) dimer within the parent sulfa drug (SD) crystals, while providing access to both co-crystals and salts. We have synthesized four co-crystals and three salts of sulfadiazine involving <i>N</i>,<i>N</i>-dimethyl-4-aminopyridine, 4-aminopyridine, 4-picoline, 4,4′-bipyridine, (<i>E</i>)-1,2-bis­(4-pyridyl)­ethylene, 1,2-bis­(4-pyridyl)­acetylene, and 4-(pyridin-4-yl)­piperazine. Single-crystal X-ray analyses reveal three hydrogen-bond motifs, namely, dyads, rings, and chains based involving either (amidine/aniline) N–H···N (pyridine/pyrimidine), (pyridinium) ⁺N–H···N^–(amidide), (aniline/piperazine) N–H···O₂S (sulfoxide) interactions, or a combination thereof. The hydrogen-bond motifs are assigned as <i>D</i>₁¹(2), <i>R</i>₂²(8), <i>R</i>₂²(20), <i>C</i>₂²(17), and <i>C</i>₂²(13) graph sets. An analysis of the Cambridge Structural Database (CSD) reveals that the S–N bond length is generally shorter in complexes based on an anionic SD, which is consistent with the sulfonamide possessing greater SN character. From an analysis of SD-based structures involving our work and the CSD, we present a heretofore not discussed role of tautomers at the co-crystal–salt boundary. Specifically, the ability of tautomeric forms of SDs to display reconfigurable exteriors, and thereby act as chameleons, enables SDs to accommodate different co-formers by assuming different geometries and adopting different regions along the co-crystal–salt boundary

Supramolecular Complexes of Sulfadiazine and Pyridines: Reconfigurable Exteriors and Chameleon-like Behavior of Tautomers at the Co-Crystal–Salt Boundary

We apply crystal engineering principles to prepare organic co-crystals and salts of sulfadiazine and pyridines. Pyridines are molecular building blocks utilized in crystal engineering that can disrupt the hydrogen bonded (amidine) N–H···N (pyrimidine) dimer within the parent sulfa drug (SD) crystals, while providing access to both co-crystals and salts. We have synthesized four co-crystals and three salts of sulfadiazine involving <i>N</i>,<i>N</i>-dimethyl-4-aminopyridine, 4-aminopyridine, 4-picoline, 4,4′-bipyridine, (<i>E</i>)-1,2-bis­(4-pyridyl)­ethylene, 1,2-bis­(4-pyridyl)­acetylene, and 4-(pyridin-4-yl)­piperazine. Single-crystal X-ray analyses reveal three hydrogen-bond motifs, namely, dyads, rings, and chains based involving either (amidine/aniline) N–H···N (pyridine/pyrimidine), (pyridinium) ⁺N–H···N^–(amidide), (aniline/piperazine) N–H···O₂S (sulfoxide) interactions, or a combination thereof. The hydrogen-bond motifs are assigned as <i>D</i>₁¹(2), <i>R</i>₂²(8), <i>R</i>₂²(20), <i>C</i>₂²(17), and <i>C</i>₂²(13) graph sets. An analysis of the Cambridge Structural Database (CSD) reveals that the S–N bond length is generally shorter in complexes based on an anionic SD, which is consistent with the sulfonamide possessing greater SN character. From an analysis of SD-based structures involving our work and the CSD, we present a heretofore not discussed role of tautomers at the co-crystal–salt boundary. Specifically, the ability of tautomeric forms of SDs to display reconfigurable exteriors, and thereby act as chameleons, enables SDs to accommodate different co-formers by assuming different geometries and adopting different regions along the co-crystal–salt boundary