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  • 1.
    Agthe, Michael
    et al.
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Wetterskog, Erik
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Salazar-Alvarez, German
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Bergström, Lennart Magnus
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Dynamic growth modes of ordered arrays and mesocrystals during drop-casting of iron oxide nanocubes2014Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 16, nr 8, s. 1443-1450Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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 μm 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.

  • 2.
    Alhalaweh, Amjad
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    George, Sumod
    Basavoju, Srinivas
    Childs, S.L.
    Renovo Research, Atlanta, GA.
    Rizvi, S.A.A.
    College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Pharmaceutical cocrystals of nitrofurantoin: Screening, characterization and crystal structure analysis2012Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 14, nr 15, s. 5078-5088Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 3.
    Ali, Hassan
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Alhalaweh, Amjad
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Mendes, N.F.C.
    Ribeiro-Claro, Paulo
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Solid-state vibrational spectroscopic investigation of cocrystals and salt of indomethacin2012Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 14, nr 20, s. 6665-6674Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 4.
    Bo, Qi-Bing
    et al.
    Institute of Chemistry and Chemical Engineering, University of Jinan.
    Sun, Zhong-Xi
    Institute of Chemistry and Chemical Engineering, University of Jinan.
    Forsling, Willis
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    A new family of 3D 3d-4f heterometallic frameworks comprising 1D inorganic lanthanide ladders and organic Cu-bipyridine chains2008Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 10, nr 2, s. 232-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new family of the 3D heterometallic coordination polymers [{Ln2(SO4)2(H2O)2(pydc)2Cu2 (bpy)2·2(H2O)}]n (Ln = Sm ( 1), Eu ( 2), Gd ( 3), Tb ( 4) and Dy ( 5); pydc = 2,6-pyridine-dicarboxylate anion; bpy= 4,4-bipyridine) have successfully been synthesized under solvothermal conditions (H2O/ethanol). All the coordination polymers obtained were characterized by elemental analysis, FT-IR analysis, differential thermal analysis/thermogravimetry (DTA/TG), fluorescent spectra and single crystal X-ray diffraction analysis. The most intriguing structural feature is that all the compounds exhibit 3D frameworks with 1D inorganic lanthanide ladders and organic CuI-bipyridine chains, which represent two types of 3d/4f coordination polymers (form I: Ln = Sm and Eu; form II: Ln = Gd, Tb and Dy) as the result of a so-called gadolinium break effect. Additionally, compounds 2 and 4 showed the characteristic emission spectra of the EuIII and TbIII ions, respectively, and appeared to have good fluorescence properties, while 1, 3 and 5 emitted fluorescence resembling CuI complexes. To our knowledge, the investigation of the

  • 5. George, Sumod
    et al.
    Lipstman, Sophia
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    Muniappan, Sankar
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    Goldberg, Israel
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    Porphyrin network solids: examples of supramolecular isomerism, noncentrosymmetric architectures and competing solvation2006Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 8, nr 5, s. 417-424Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Self-assembly of functionalized tetraarylporphyrins into 2-D and 3-D supramolecular arrays may exhibit structural isomerism when carried out in different experimental conditions. This study shows that the open 2-D hydrogen bonding quadrangular grid networks of free-base tetra(4-carboxyphenyl)porphyrin (TCPP) form an interweaved crystalline architecture, in addition to the non-interweaved offset-stacked porous arrangement observed before. In the two structures the individual arrays are similarly stabilized by multiple cyclic-dimeric (COOH)2 hydrogen bonding synthons, differing slightly in the grid shape. The Mn-metalled TCPP building blocks afford in a lipophilic environment 2-D coordination polymers by direct Mn-OOC/HOOC association between the tetra-acid metalloporphyrin units, without incorporation of any external bridging auxiliaries. This polymerization is further enforced by interporphyrin O-HO hydrogen bonding within and between the 2-D arrays, yielding a solvent-free 3-D architecture. The latter is related to an isomeric crystalline organization of similar layered Mn-TCPP coordination polymers obtained earlier from hydrophilic crystallization mixtures, wherein intercalated solvent separates the layered polymeric arrays. The non-acidic Mn(Cl)-TOHPP compound yields a chiral 3-D assembly sustained by multiple inter-porphyrin hydrogen bonding. Its formation is promoted by the non-centrosymmetric (axially polarized) shape of this porphyrin unit, as well as by the directional hydrogen bonding interactions, and it involves coordination of an additional axial ligand to the manganese ion. Effects of competing solvation, which interfere with the supramolecular aggregation of the TCPP scaffolds into network arrays, are demonstrated also by structures obtained from solvent mixtures containing dimethylsulfoxide.

  • 6.
    Goldberg, Israel
    et al.
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    Muniappan, Sankar
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    George, Sumod
    Lipstman, Sophia
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    Self-assembly of uniquely structured porphyrin network solids by charged N-HCl and N-HO hydrogen bonds2006Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 8, nr 11, s. 784-787Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    New motifs for the supramolecular assembly of crystalline porphyrin network solids directed by charged N-HCl and N-HO hydrogen bonds are presented, using the tetra(4-pyridyl)- and tetra(4-carboxyphenyl)-porphyrin building blocks.

  • 7.
    Lipstman, Sophia
    et al.
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    Muniappan, Sankar
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    George, Sumod
    Goldberg, Israel
    Tel-Aviv University, Ramat-Aviv, School of Chemistry, Sackler Faculty of Exact.
    The effects of strong Lewis-base reagents on supramolecular hydrogen bonding of meso-tetra(carboxyphenyl)porphyrins2006Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 8, nr 8, s. 601-607Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reactions of Pd-, Ru(CO)- and Cu-complexes of meso-tetra(carboxyphenyl)porphyrin with strong Lewis base reagents (as pyridine, 4-acetylpyridine or dimetylsulfoxide) avoided the formation of commonly observed 2-D or 3-D multiporphyrin arrays by direct hydrogen bonding. Structural analysis of the crystalline products indicates that this is due to preferential affinity of these reagents to associate to the carboxylic acid functions via H-bonds, in competition with the potential self-association of the porphyrin units. In the copper-porphyrin derivative all four carboxylic acid functions of a given porphyrin interact with the 4-acetylpyridine species, creating discrete 1 : 4 porphyrin : ligand pentameric assemblies. Then, in adducts of the ruthenium carbon monoxide porphyrins with pyridine or 4-acetylpyridine, two trans-related carboxylic acid groups of the porphyrin scaffold interact directly with neighboring porphyrin species via the common (COOH)2 cyclic dimeric synthon to yield 1-D hydrogen bonded chains, while the other carboxylic functions donate their protons to molecules of the polar pyridine/acetylpyridine ligand that prevent further interporphyrin lateral binding along the perpendicular direction. The pyridyl-type moieties bear a single electron lone pair on the N-atom that can act as an effective hydrogen bond acceptor, allowing for a localized hydrogen bond with the carboxylic acid. On the other hand, the dimethylsulfoxide can involve readily through its O-site (bearing two lone pairs of electrons) in two hydrogen bonds in tetrahedral directions, and can thus serve as a bridging auxiliary between the carboxylic acid groups of neighboring porphyrins. Correspondingly, its reaction with the palladium complex leads to the formation of heterogeneous porphyrin-dimethylsulfoxide linear hydrogen bonded chains. Along these chains two ligand molecules are inserted between adjacent porphyrin units on both sides, and bridge between their cis-related carboxyphenyl arms. The different motifs of hydrogen-bonding effect different crystal packing features in three dimensions, some characterized also by the presence of solvent-accessible open channels that propagate through the lattice.

  • 8.
    Shimpi, Manishkumar
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap.
    Childs, Scott L.
    Renovo Research, Atlanta, GA.
    Boström, Dan
    Umeå universitet, Energy Technology and Thermal Process Chemistry, Umeå University.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    New cocrystals of ezetimibe with l-proline and imidazole2014Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 16, nr 38, s. 8984-8993Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objectives of the study were to screen and prepare cocrystals of anti-cholesterol drug ezetimibe (EZT) with the aim of increasing its solubility and dissolution rate. Thermodynamic phase diagram based high throughput screening was performed using wet milling/grinding or solution crystallization methods. A large number of coformers were tested and the resulting solids were preliminarily characterized using X-ray powder diffraction (PXRD) and Raman spectroscopy. Potential cocrystals of EZT with l-proline and imidazole and a solvate formamide were identified in the screening experiments. The cocrystal hits were further characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), solution Proton nuclear magnetic resonance spectroscopy (1H-NMR) and single crystal XRD. The dissolution properties and stability of cocrystals were determined. Single-crystal X-ray diffraction data were obtained for EZT, EZT-IMI cocrystal and formamide solvate of ezetimibe. All three systems were crystallized in non-centrosymmetric orthorhombic space group P212121with Z = 4. Robust O-H⋯O, O-H⋯N, N-H⋯O and C-H⋯O hydrogen bonds played an important role in all these crystal structures. EZT-PRO cocrystal showed improved apparent solubility and solid state stability

  • 9.
    Srivastava, K.
    et al.
    Physics Department, University of Lucknow, Lucknow, India.
    Khan, E.
    Physics Department, University of Lucknow, Lucknow, India.
    Shimpi, Manishkumar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Tandon, P.
    Physics Department, University of Lucknow, Lucknow, India.
    Sinha, K.
    Physics Department, University of Lucknow, Lucknow, India.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Molecular structure and hydrogen bond interactions of a paracetamol-4,4′-bipyridine cocrystal studied using a vibrational spectroscopic and quantum chemical approach2018Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 20, nr 2, s. 213-222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of the current study is to perform the structural and spectroscopic characterization of paracetamol-4,4′-bipyridine (PRA-BPY) cocrystal using infrared, Raman spectroscopy and density functional theory (DFT) calculations. To reveal the interactions between PRA and BPY, two models (monomer and dimer + PRA) of a cocrystal are designed and optimized using DFT with a 6-311G (d, p) basis set. An atoms in molecule study shows that the non-covalent interactions in particular hydrogen bonds involved in forming the cocrystal are moderate in nature. Natural bond orbital analysis of the second order perturbation theory of the Fock matrix suggests that interactions LP (1) N13 → π∗(C15-O16) and LP (1) N56 → σ∗(N13-H14) are responsible for the stabilization of the molecule. 

  • 10.
    Srivastava, Karnica
    et al.
    Physics Department, University of Lucknow, Lucknow, India.
    Shukla, Anuradha
    Physics Department, University of Lucknow, Lucknow, India.
    Karthick, T.
    Physics Department, University of Lucknow, Lucknow, India;Institute of Organic Chemistry and Biochemistry, Academy of Sciences, Prague, Czech Republic.
    Velaga, Sitaram
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Tandon, Poonam
    Physics Department, University of Lucknow, Lucknow, India.
    Sinha, Kirti
    Physics Department, University of Lucknow, Lucknow, India.
    Shimpi, Manishkumar R.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Molecular structure, spectroscopic signature and reactivity analyses of paracetamol hydrochloride monohydrate salt using density functional theory calculations2019Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 21, nr 5, s. 857-865Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to understand the role of the intermolecular hydrogen bond interactions present in paracetamol hydrochloride monohydrated salt. Paracetamol hydrochloride monohydrate salt (PRA-HCl) and paracetamol (form I) were investigated via vibrational (FT-IR and FT-Raman) spectroscopy and density functional theory (DFT) to gain insight into the hydrogen bond patterns present in these crystalline materials. Two different density functionals, wB97X-D and M062X, were used for the comparison of the results. The geometrical parameters of PRA-HCl and form I obtained using these functional were compared with the crystallographic data, which proved the existence of intra-molecular and intermolecular hydrogen bonds. The C10O2 group of form I forms an intramolecular hydrogen bond, while the O1–H18 group of PRA-HCl forms an intermolecular hydrogen bond with a chloride ion (Cl), resulting in the elongation of the bond length and shift to a lower wavenumber for the O1–H18 group. To examine the potency of hydrogen bonding, quantum theory of atoms in molecules (QTAIM) calculations were performed and the results suggested that O1–H18⋯Cl22 is a strong intermolecular hydrogen bond. The chemical reactivity parameters reveal that the PRA-HCl and PRA-OXA cocrystals are more reactive and softer (low HOMO–LUMO energy gap) in comparison to paracetamol (form I).

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