| 1. |
- Abu-Youssef, Morsy A. M., et al.
(författare)
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Topology Analysis Reveals Supramolecular Organisation of 96 Large Complex Ions into one Geometrical Object
- 2016
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 18:11, s. 1883-1886
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that the highly complex crystal structure of [Ag(4-(pyrrolidin-1-yl)pyridine)2]NO3·1/2H2O, 1, with 12 symmetry-independent Ag+ ions and 96 units of complex ions in a unit cell can be understood by the ubiquitous srs topology, reducing thousands of atom positions into a single geometrical object in one go.
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| 2. |
- Agthe, Michael, et al.
(författare)
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Dynamic growth modes of ordered arrays and mesocrystals during drop-casting of iron oxide nanocubes
- 2014
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 16:8, s. 1443-1450
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Tidskriftsartikel (refereegranskat)abstract
- The growth modes of self-assembled mesocrystals and ordered arrays from dispersions of iron oxide nanocubes with a mean edge length of 9.6 nm during controlled solvent removal have been investigated with a combination of visible light video microscopy, atomic force microscopy and scanning electron microscopy. Mesocrystals with translational and orientational order of sizes up to 10 mu m are formed spontaneously during the final, diffusion-controlled, drop-casting stage when the liquid film is very thin and the particle concentration is high. Convection-driven deposition of ordered nanocube arrays at the edge of the drying droplet is a manifestation of the so called coffee-ring effect. Dendritic growth or fingering of rapidly growing arrays of ordered nanocubes could also be observed in a transition regime as the growth front moves from the initial three-phase contact line towards the centre of the original droplet.
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| 3. |
- Ahuja, Dipali, et al.
(författare)
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Investigation of solid-liquid phase diagrams of the sulfamethazine-salicylic acid co-crystal
- 2019
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Ingår i: CrystEngComm. - : ROYAL SOC CHEMISTRY. - 1466-8033. ; 21:18, s. 2863-2874
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Tidskriftsartikel (refereegranskat)abstract
- The influence of temperature and solvent on the solid-liquid phase diagram of the 1 : 1 sulfamethazinesalicylic acid co-crystal has been investigated. Ternary phase diagrams of this co-crystal system have been constructed in three solvents: methanol, acetonitrile and a 7 : 3 (v/v) dimethylsulfoxide-methanol mixture, at three temperatures. The system exhibits congruent dissolution in acetonitrile and the co-crystal solubility has been determined by a gravimetric technique. The Gibbs energy of co-crystal formation from the respective solid components has been estimated from solubility data, together with the corresponding enthalpic and entropic component terms. The Gibbs energy of formation ranges from -5.7 to -7.7 kJ mol -1, with the stability increasing with temperature. In methanol and the DMSO-methanol mixture, the co-crystal dissolves incongruently. It is shown that the solubility ratio of the pure components cannot be used to predict with confidence whether the co-crystal will dissolve congruently or incongruently. The size of the region where the co-crystal is the only stable solid phase is inversely related to the pure component solubility ratio of salicylic acid and sulfamethazine.
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| 4. |
- Ahuja, Dipali, et al.
(författare)
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Solution and calorimetric thermodynamic study of a new 1:1 sulfamethazine-3-methylsalicylic acid co-crystal
- 2020
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 22:20, s. 3463-3473
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Tidskriftsartikel (refereegranskat)abstract
- A new 1:1 co-crystal of sulfamethazine (API, SMT) and 3-methylsalicylic acid (coformer, 3mSA) has been synthesized and its crystal structure solved by single crystal X-ray diffraction (XRD). The co-crystal has been thoroughly characterized by powder XRD, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The pure co-crystal could be synthesized by solvent drop grinding, cooling crystallization and slurry conversion co-crystallization. Ternary phase diagrams have been constructed in methanol and acetonitrile at 30 degrees C. The co-crystal exhibits incongruent dissolution in both solvents. The thermodynamics of co-crystal formation have been estimated from solubility data and calorimetric data, respectively, showing that formation of the SMT-3mSA co-crystal from its solid components is spontaneous and entropy-driven. The co-crystal formation is associated with a 5% increase in molecular volume. A relationship between the size of the region where the co-crystal is the most stable solid phase and the relative solubility of the co-crystal components has been uncovered. The co-crystal region becomes smaller as the solubility ratio increases.
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| 5. |
- Ahuja, D., et al.
(författare)
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Study of three solvates of sulfamethazine
- 2017
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Ingår i: CrystEngComm. - Cambridge, England : Royal Society of Chemistry (RSC). - 1466-8033. ; 19:43, s. 6481-6488
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Tidskriftsartikel (refereegranskat)abstract
- Three novel solvates of sulfamethazine (SMT), an anti-microbial and anti-infective sulfonamide drug with the solvents-dimethylacetamide, dimethylformamide and dimethyl sulfoxide have been identified and characterized by analytical techniques including differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and Raman spectroscopy. All three are 1:1 solvates. Crystal structure analysis revealed N-H-O type intermolecular hydrogen bonding interactions between SMT and the solvent imparting stability to the solvate structure. Thermal analysis measurements for the stoichiometry of the solvates were in good agreement with the single crystal data. The solubility of the solvates in their respective solvents at 25 °C has been determined.
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| 6. |
- Alhalaweh, Amjad, et al.
(författare)
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Pharmaceutical cocrystals of nitrofurantoin: screening, characterization and crystal structure analysis
- 2012
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 14:15, s. 5078-5088
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to screen and prepare cocrystals of the poorly soluble drug nitrofurantoin (NTF) with the aim of increasing its solubility. Screening for cocrystals of NTF using 47 coformers was performed by high-throughput (HT) screening using liquid assisted grinding (LAG) methods. Raman spectroscopy and powder X-ray diffraction (PXRD) were used as the primary analytical tools to identify the new crystalline solid forms. Manual LAG and reaction crystallization (RC) experiments were carried out to confirm and scale-up the hits. Seven hits were confirmed to be cocrystals. The cocrystals were characterized by PXRD, Raman and IR spectroscopy, thermal analysis (DSC and TGA) and liquid-state NMR or elemental analysis. The solution stability of the scaled-up cocrystals in water was tested by slurrying the cocrystals at 25 °C for one week. NTF forms cocrystals with a 1:1 stoichiometric ratio with urea (1), 4-hydroxybenzoic acid (2), nicotinamide (3), citric acid (4), l-proline (5) and vanillic acid (6). In addition, NTF forms a 1:2 cocrystal with vanillin (7). All but one of the NTF cocrystals transformed (dissociated) in water, resulting in NTF hydrate crystalline material or NTF hydrate plus the coformer, which indicates that the transforming cocrystals have a higher solubility than the NTF hydrate under these conditions. The crystal structures of 1:1 NTF-citric acid (4) and 1:2 NTF-vanillin (7) were solved by single-crystal X-ray diffraction. The crystal structures of these two cocrystals were analyzed in terms of their supramolecular synthons.
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| 7. |
- Ali, Hassan Refat H., et al.
(författare)
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Solid-state vibrational spectroscopic investigation of cocrystals and salt of indomethacin
- 2012
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Ingår i: CrystEngComm. - 1466-8033. ; 14:20, s. 6665-6674
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge and control of the solid forms of active pharmaceutical ingredients are important aspects of drug development in the pharmaceutical industry. In this paper, the process of the molecular self-assembly of saccharin cocrystals and the 2-amino-5-methylpyridine salt of indomethacin, in terms of the hydrogen bonding patterns, has been studied in the solid-state using vibrational spectroscopy (Raman and infrared). Interaction patterns in the respective crystalline states were obtained from the single crystal data. The effects of cocrystal and salt formation on the frequencies of the vibrational modes of motion were explained by vibrational spectroscopy and supported by quantum chemical calculations at the density functional theory level, leading to unambiguous assignment of the vibrational spectra of the starting materials and their respective products. Both Raman and infrared spectroscopies were useful, reliable tools for characterizing and distinguishing the indomethacin cocrystals and salt.
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| 8. |
- Almesåker, Ann, et al.
(författare)
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Coordination chemistry of N,N,4-tris(pyridin-2-ylmethyl)aniline, a novel flexible, multimodal ligand
- 2007
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 9:11, s. 997-1010
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Tidskriftsartikel (refereegranskat)abstract
- The ligand N, N, 4-tris(pyridin-2-ylmethyl) aniline was synthethised using a multicomponent reaction, which is applicable to the synthesis of a large library of similarly structured ligands. A range of metal complexes with copper, cobalt and manganese ions were crystallised as discrete complexes, dimers and 1D coordination polymers, illustrating the flexibility of the ligand in the preparation of diverse structures. While coordination about the metal centres is similar in each group with a common metal ion, the different structures represent materials with varying structural and packing topologies. Varying the counterions and crystallisation solvents gives rise to discrete complexes, dimers and a porous 1D coordination polymer. In the latter case, solvent molecules entrapped in the channels are replaceable and guest exchange is detected by single crystal and powder diffraction indicating interesting storage possibilities.
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| 9. |
- Altin, S., et al.
(författare)
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Synthesis of Na2Ti3O7 nanorods by a V-assisted route and investigation of their battery performance
- 2020
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 22:14, s. 2483-2490
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Tidskriftsartikel (refereegranskat)abstract
- We report the V-assisted synthesis of Na2Ti3O7 nanorods via a conventional solid state reaction technique. Energy dispersive X-ray spectroscopy (EDS) mapping showed that V-ions are not incorporated into the main structure of the nanorods but rather V behaves as a flux agent during the growth of the nanorods. The cyclic voltammetry (CV) analysis of the samples shows changes in the redox peaks as a function of V content. Our detailed ex situ X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS) analyses after 1000 cycles show that the degradation mechanism is the formation of various titanium oxide impurity phases which inhibits the Na-ion diffusion.
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| 10. |
- Aziz, Baroz, 1980-, et al.
(författare)
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Kinetic control of particle-mediated calcium carbonate crystallization
- 2011
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 13:14, s. 4641-4645
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Tidskriftsartikel (refereegranskat)abstract
- By changing the temperature, pH, stirring rate, or time for calcium carbonate crystallization, complex shapes of aggregated calcium carbonates formed. Such shapes have earlier been ascribed to specific interactions with specialized additives. Without polymeric additives, aggregates of vaterite transformed more rapidly into calcite aggregates under slow than under fast stirring. With an anionic polyelectrolyte added, vaterite was stabilized. Larger polycrystalline aggregates of vaterite formed under rapid than under slow stirring, indicative of a particle mediated growth of aggregates controlled by convective currents. The size of the underlying nanoparticles was temperature dependent, with grain sizes of similar to 20 to 50 nm at 20 degrees C and similar to 350 nm at 90 degrees C. The small differences in free energy between the anhydrous polymorphs of calcium carbonate made both kinetic and equilibrium dependencies important.
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