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  • 1.
    Srivastava, K.
    et al.
    Physics Department, University of Lucknow, Lucknow, India.
    Khan, E.
    Physics Department, University of Lucknow, Lucknow, India.
    Shimpi, Manishkumar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Tandon, P.
    Physics Department, University of Lucknow, Lucknow, India.
    Sinha, K.
    Physics Department, University of Lucknow, Lucknow, India.
    Velaga, Sitaram
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Molecular structure and hydrogen bond interactions of a paracetamol-4,4′-bipyridine cocrystal studied using a vibrational spectroscopic and quantum chemical approach2018In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 20, no 2, p. 213-222Article in journal (Refereed)
    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. 

  • 2.
    Shimpi, Manishkumar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Giri, Lopamudra
    Indian Institute of Technology Bhubaneswar, Toshali Bhavan, Bhubaneswar.
    Rao Pedireddi, Venkateswara
    Indian Institute of Technology Bhubaneswar, Toshali Bhavan, Bhubaneswar.
    Preparation and Structure Analysis of Three New Copper Complexes of Mellitic Acid With 4,4′-Bipyridine and 1,3-bis(4-pyridyl)Propane2018In: ChemistrySelect, ISSN 2365-6549, Vol. 3, no 3, p. 855-858Article in journal (Refereed)
    Abstract [en]

    Coordination complexes, [Cu-2(H2L)(bpy)(2)].2H(2)O, (1a), [Cu(H3L)(2) (H2O)(4)].(H(2)bpypa)(2).6H(2)O, (2a) and [Cu(H3L)(4)] [Cu(H2O)(6)].(H(2)bpypa)(4).20H(2)O, (2b), of mellitic acid, H6L, with 4,4'-bipyrdine, (bpy), and 1,3-bis(4-pyridyl) propane, (bpypa), have been prepared and the three-dimensional structures are established by single crystal X-ray diffraction unequivocally. The complex 1a was prepared following hydrothermal method, while the complexes 2a and 2b were obtained concomitantly from an aqueous solution at room temperature. In the crystals of 1a, both acid and the aza-donors form coordination bonds with metal ions, while in 2a and 2b coordination bonding prevails between metal and acid molecules only, with azadonor molecules remain intact without coordinating to metal species. Further, 1a and 2b are noted to be yielding a hostguest network, whereas 2a forms planar sheets that are stacked in three-dimensional arrangemen

  • 3.
    Shimpi, Manishkumar R.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Luleå University of Technology, Department of Health Sciences, Medical Science.
    Al-Hayali, Amani
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Cavanagh, Katie L.
    Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor.
    Rodríguez- Hornedo, Nair
    Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor.
    Velaga, Sitaram
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Tadalafil-malonic acid cocrystal: Physicochemical characterization, pH-solubility and supersaturation studies2018In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to enhance the solubility and dissolution of a poorly water-soluble drug, tadalafil (TDF), by cocrystal formation with malonic acid (MOA), to characterize the cocrystal structure, and to quantify the cocrystal solution behavior. The crystal structure revealed a 1:1 stoichiometry wherein the TDF molecules form a double layered structure through N–H…O=C interactions linked to a catemeric chain of MOA molecules via O-H…O hydrogen bonds. Cocrystal solubility advantage (SA defined as Scocrystal/Sdrug) or supersaturation index was determined from eutectic point measurements to be 102 to 129 in the pH range of 1 to 3. Cocrystal dissolution generated supersaturation levels (Cmax/Sdrug) of 30 in buffer and 120 in the presence of a nucleation inhibitor, HPMC. The amorphous form of TDF generated supersaturation 3 times lower than cocrystal in buffer, and not significantly different from cocrystal in the presence of HPMC. Thus, supersaturation index is a valuable metric for assessing the risk of cocrystal conversion during kinetic studies and for predicting conditions when the usage of a precipitation inhibitor may significantly increase cocrystal exposure levels.

  • 4.
    Shimpi, Manishkumar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Velaga, Sitaram
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Pharmaceutical Crystal Engineering Using Ionic Liquid Anion–Solute Interactions2017In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 17, no 4, p. 1729-1734Article in journal (Refereed)
    Abstract [en]

    The main purpose of this work was to investigate the potential of ionic liquids (ILs) in crystal engineering. We have employed ILs with different combinations of cations and anions to study their role in directing crystal structure formation of a nicotinamide (NIC) and oxalic acid (OXA) system. A new crystal form of NIC–OXA salt (2:1) was identified and characterized using standard solid state tools such as powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and Raman and infrared spectroscopy. The crystal structure of the 2:1 salt was elucidated using single-crystal X-ray diffraction. The NIC–OXA 2:1 salt form revealed a two-dimensional layered structure, while the known 1:1 salt had a perpendicular “tape-like” structure. The 2:1 salt form could only be crystallized from the ILs possessing hydrogen bond acceptor functionality. We demonstrated that specific ILs could be selected as solvents for altering the solid-state structure of organic and inorganic materials.

  • 5.
    Ahmed, Hamzah
    et al.
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Shimpi, Manishkumar R.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Velaga, Sitaram P.
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol2017In: Drug Development and Industrial Pharmacy, ISSN 0363-9045, E-ISSN 1520-5762, Vol. 43, no 1, p. 89-97Article in journal (Refereed)
    Abstract [en]

    Objectives were to study mechanical properties of various solid forms of paracetamol and relate to their crystal structures. Paracetamol Form I (PRA), its cocrystals with oxalic acid (PRA-OXA) and 4,4-bipyridine (PRA-BPY) and hydrochloride salt (PRA-HCL) were selected. Cocrystals and salt were scaled-up using rational crystallization methods. The resulting materials were subjected to differential scanning solid-state characterization. The powders were sieved and 90-360 µm sieve fraction was considered. These powders were examined by scanning electron microscopy (SEM) and densities were determined. Tablets were made at applied pressures of 35-180 MPa under controlled conditions and the tablet height, diameter and hardness were measured. Tensile strength and porosity of the tablets were estimated using well known models. Crystal structures of these systems were visualized and slips planed were identified. Cocrystal and salt of PRA were physically pure. Sieved powders had comparable morphologies and particle size. The apparent and theoretical densities of powders were similar but no clear trends were observed. The tensile strengths of these compacts were increased with increasing pressure whereas tabletability decreased in the order oxalic acid > PRA-HCL ≈ PRA-OXA > BPY > PRA-BPY. Tablet tensile strength decreases exponentially with increasing porosity with the exception of PRY-BPY and BPY. Slip plane prediction based on attachment energies may not be independently considered. However, it was possible to explain the improved mechanical properties of powders based on the crystal structure. Cocrystallization and salt formation have introduced structural features that are responsible for improved tableting properties of PRA.

  • 6.
    Wang, Yonglei
    et al.
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Shimpi, Manishkumar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Sarman, Sten S.
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Glavatskih, Sergei
    System and Component Design, KTH, Royal Institute of Technology , Machine Design, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden, Department of Physics, Warwick University, Coventry.
    Kloo, Lars
    Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology.
    Laaksonen, Aatto
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Atomistic insight into tetraalkylphosphonium-bis(oxalato)borate ionic liquid/water mixtures: 2. Volumetric and Dynamic Properties2016In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 120, no 30, p. 7446-7455Article in journal (Refereed)
    Abstract [en]

    Atomistic simulations have been performed to investigate the microscopic structural organization of aqueous solutions of trihexyltetradecylphosphonium bis(oxalato)borate ([P6,6,6,14][BOB]) ionic liquid (IL). The evolution of the microscopic liquid structure and the local ionic organization of IL/water mixtures as a function of the water concentration is visualized and systematically analyzed via radial and spatial distribution functions, coordination numbers, hydrogen bond network, and water clustering analysis. The microscopic liquid structure in neat IL is characterized by a connected apolar network composed of the alkyl chains of [P6,6,6,14] cations and isolated polar domains consisting of the central segments of [P6,6,6,14] cations and [BOB] anions, and the corresponding local ionic environment is described by direct contact ion pairs. In IL/water mixtures with lower water mole fractions, the added water molecules are dispersed and embedded in cavities between neighboring ionic species and the local ionic structure is characterized by solvent-shared ion pairs through cation-water-anion triple complexes. With a gradual increase in the water concentration in IL/water mixtures, the added water molecules tend to aggregate and form small clusters, intermediate chain-like structures, large aggregates, and eventually a water network in water concentrated simulation systems. A further progressive dilution of IL/water mixtures leads to the formation of self-organized micelle-like aggregates characterized by a hydrophobic core and hydrophilic shell consisting of the central polar segments in [P6,6,6,14] cations and [BOB] anions in a highly branched water network. The striking structural evolution of the [P6,6,6,14][BOB] IL/water mixtures is rationalized by the competition between favorable hydrogen bonded interactions and strong electrostatic interactions between the polar segments in ionic species and the dispersion interactions between the hydrophobic alkyl chains in [P6,6,6,14] cations

  • 7.
    Prajapati, Preeti
    et al.
    Physics Department, University of Lucknow.
    Pandey, Jaja
    Physics Department, University of Lucknow.
    Shimpi, Manishkumar
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Srivastava, Anubha
    Physics Department, University of Lucknow.
    Tandon, Poonam
    Physics Department, University of Lucknow.
    Velaga, Sitaram
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Sinha, Kirti
    Physics Department, University of Lucknow.
    Combined spectroscopic and quantum chemical studies of ezetimibe2016In: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 1125, p. 193-203Article in journal (Refereed)
    Abstract [en]

    Ezetimibe (EZT) is a hypocholesterolemic agent used for the treatment of elevated blood cholesterol levels as it lowers the blood cholesterol by blocking the absorption of cholesterol in intestine. Study aims to combine experimental and computational methods to provide insights into the structural and vibrational spectroscopic properties of EZT which is important for explaining drug substance physical and biological properties. Computational study on molecular properties of ezetimibe is presented using density functional theory (DFT) with B3LYP functional and 6-311++G(d,p) basis set. A detailed vibrational assignment has been done for the observed IR and Raman spectra of EZT. In addition to the conformational study, hydrogen bonding and molecular docking studies have been also performed. For conformational studies, the double well potential energy curves have been plotted for the rotation around the six flexible bonds of the molecule. UV absorption spectrum was examined in methanol solvent and compared with calculated one in solvent environment (IEF-PCM) using TD-DFT/6-31G basis set. HOMO-LUMO energy gap of both the conformers have also been calculated in order to predict its chemical reactivity and stability. The stability of the molecule was also examined by means of natural bond analysis (NBO) analysis. To account for the chemical reactivity and site selectivity of the molecules, molecular electrostatic potential (MEPS) map has been plotted. The combination of experimental and calculated results provide an insight into the structural and vibrational spectroscopic properties of EZT. In order to give an insight for the biological activity of EZT, molecular docking of EZT with protein NPC1L1 has been done.

  • 8.
    Pandey, Jaya
    et al.
    Physics Department, University of Lucknow.
    Prajapati, Preeti
    Physics Department, University of Lucknow.
    Shimpi, Manishkumar
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Tandon, Poonam
    Physics Department, University of Lucknow.
    Velaga, Sitaram
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Srivastava, Anubha
    Physics Department, University of Lucknow.
    Sinha, Kirti
    Physics Department, University of Lucknow.
    Studies of molecular structure, hydrogen bonding and chemical activity of a nitrofurantoin-L-proline cocrystal: a combined spectroscopic and quantum chemical approach2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 78, p. 74135-74154Article in journal (Refereed)
    Abstract [en]

    Nitrofurantoin (NTF) has been used as an antibacterial drug to treat bacterial infections of the urinary tract. The purpose of this work is to predict the hydrogen bonds (potential synthons) present in the cocrystal of nitrofurantoin-L-proline (NTF-LP) through a computational approach (DFT calculations) and validate using vibrational spectroscopic studies. The present study illustrates the formation and characterization of the cocrystal of NTF-LP. The molecular structure of the NTF-LP cocrystal has been predicted by forming several models on the basis of the hydrogen bonding patterns observed in other NTF cocrystals. A conformational study and potential energy surface scan have been plotted around three flexible bonds of the cocrystal molecule and two stable conformers have been obtained. NBO analysis of the second order perturbation theory of the Fock matrix suggests that interaction n1O(39) → σ*(N13–H21) is responsible for the stabilization of the molecule. Quantum theory of atoms in molecules (QTAIM) explains that all interactions are medium and partially covalent in nature as ∇2ρBCP > 0, HBCP < 0. The molecular electrostatic potential surface (MEPS) of the cocrystal has been visualized for its most electropositive potential in the region of the NH2+ group and most electronegative potential in the vicinity of the COO− group. The HOMO and LUMO energies and electronic charge transfer (ECT) confirms that charge flows from the co-former (LP) to NTF (API). Local reactivity descriptor parameters have been used to predict the reactive sites of the cocrystal and global reactivity descriptor parameters suggest that the cocrystal is softer thus more reactive in comparison to NTF. The experimental and theoretical results support the formation of the cocrystal through the strong hydrogen bond present between the NH group of NTF and carboxylate COO− group of LP and shows that LP is present in the zwitterionic form.

  • 9.
    Shimpi, Manishkumar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Biswas, Sharmita Nandy
    Solid State and Supramolecular Structural Chemistry Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar.
    Sarkar, Sohini
    Solid State and Supramolecular Structural Chemistry Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar.
    Pedireddi, V.R.
    Solid State and Supramolecular Structural Chemistry Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar.
    Synthesis and Structural Evaluation of Five Coordination Complexes of Benzenepentacarboxylic Acid with Aza-donor Ligands2016In: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 1114, p. 38-47Article in journal (Refereed)
    Abstract [en]

    Synthesis and structural features of five new coordination assemblies, [Co(bpyH)(H2O)5](BPCH)·(bpyH2)0.5·(H2O) (1a), [{Cu(H2O)3}·{Cu0.5(bpy)0.5(H2O)0.5}2(μ-BPCH)] (1b), [{Cd0.5(BPCH)}2·{Cd0.5(bpy)(H2O)2}2]·6(H2O) (1c), [Cu(BPCH2)(bpyeaH)].2(H2O) (1d) and [Cd2 (bpyea)0.5(oxalate)0.5(μ-BPC)(H2O)]·(bpyeaH2)·2(H2O) (1e), have been reported. All the assemblies were prepared by co-crystallization of benzenepentacarboxylic acid (BPCH5) either with 4,4′-bipyridine (bpy) or 1,2-bis(4-pyridyl)ethane (bpyea) in the presence of a transition metal ion (either Co(II), Cu(II) or Cd(II)) as the case may be. All the five compounds were synthesized by hydrothermal method and structures were determined by single crystal X-ray diffraction. All the obtained compounds, 1a-1e, exhibit distinct 3-D polymeric architectures either in the form of stacked layers or host-guest networks in which water molecules play a pivotal role providing additional stabilization by coordinate bonds as well as hydrogen bonds. Other non-covalent interactions such as C–H…π and π…π stacking also participate in the formation of exotic 3-D structures of these complexes.

  • 10.
    Golets, M.
    et al.
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Shimpi, Manishkumar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Wang, Y-L
    Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Glavatskih, Sergei
    System and Component Design, KTH, Royal Institute of Technology , Machine Design, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden, Department of Physics, Warwick University, Coventry.
    Laaksonen, Aatto
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Understanding the thermal decomposition mechanism of a halogen-free chelated orthoborate-based ionic liquid: a combined computational and experimental study2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, p. 22458-22466Article in journal (Refereed)
    Abstract [en]

    In the last few decades, ionic liquids (ILs) have gained significant attention as lubricants and lubricant additives due to their polar nature, low vapour pressure and tunable physicochemical properties. In this work, quantum chemistry calculations and atomistic Molecular Dynamics (MD) simulations were employed to predict thermal degradation mechanisms of a potential lubricating agent - the tributyloctylphosphonium bis(oxalato)borate ([P4,4,4,8][BOB]) IL. It was found that the onset of decomposition of the studied IL coincides with a cleavage of the B-O bonds in the [BOB](-) anion. Consequently, a series of chemical reactions of the [P4,4,4,8](+) cation with the [BOB](-) anion was triggered yielding alkylboranes, alkenes, trialkylphosphines, CO and CO2. Another ionic system, consisting of [P4,4,4,8][Cl], was also tested for a comparison. Thermogravimetric measurements have shown a higher thermal stability of [P4,4,4,8][BOB] compared to that of [P4,4,4,8][Cl] at least at the initial stage of decomposition, in accord with the presented calculations. Quantum chemical frequency calculations also agreed with the experimental Fourier Transform Infrared (FTIR) spectroscopy results.

  • 11.
    Srivastava, Karnica
    et al.
    Physics Department, University of Lucknow.
    Shimpi, Manishkumar
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Srivastava, Anubha
    Physics Department, University of Lucknow.
    Tandon, Poonam
    Physics Department, University of Lucknow.
    Sinha, Kirti
    Physics Department, University of Lucknow.
    Velaga, Sitaram
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Vibrational analysis and chemical activity of paracetamol-oxalic acid cocrystal based on monomer and dimer calculations: DFT and AIM approach2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 12, p. 10024-10037Article in journal (Refereed)
    Abstract [en]

    The study of structural and spectral characteristics of a paracetamol-oxalic acid (PRA-OXA) cocrystal has been carried out using two models (monomer and dimer), with the aim to understand the supramolecular structure and intramolecular interactions within the cocrystal. The cocrystal has been characterized by infrared and Raman spectroscopy combined with quantum chemical calculations molecular electrostatic potential surface (MEPS), frontier orbital analysis and electronic reactivity descriptors were used to understand the role of interactions involved in affecting the chemical reactivity of individual molecules in the cocrystal. It is observed that the C=O, N-H and O-H groups of paracetamol are involved in hydrogen bonds to form cocrystals. NBO analysis suggests that the two types of interactions LP(1)(N8) -> pi*(C9-O10) and LP(2)(O10) -> sigma*(O25-H28) are responsible for the stability of the molecule. AIM analysis suggested that the non-covalent interactions are moderate in nature. The calculated HOMO-LUMO energies reveal that the charge transfer occurs within the cocrystal. Chemical reactivity parameters show that the cocrystal is more active than paracetamol.

  • 12.
    Kong, Na
    et al.
    Royal Institute of Technology, Department of Chemistry.
    Shimpi, Manishkumar
    Royal Institute of Technology, Department of Chemistry.
    Park, Jae Hyeung
    Department of Chemistry, University of Massachusetts, Lowell.
    Ramström, Olof
    Organic Chemistry, School of Chemical Science and Engineering, KTH – Royal Institute of Technology, Stockholm, Royal Institute of Technology, Department of Chemistry.
    Yan, Mingdi
    Royal Institute of Technology, Department of Chemistry.
    Carbohydrate conjugation through microwave-assisted functionalization of single-walled carbon nanotubes using perfluorophenyl azides2015In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 405, p. 33-38Article in journal (Refereed)
    Abstract [en]

    Carbohydrate-functionalized single-walled carbon nanotubes (SWNTs) were synthesized using microwave-assisted reaction of perfluorophenyl azide with the nanotubes. The results showed that microwave radiation provides a rapid and effective means to covalently attach carbohydrates to SWNTs, producing carbohydrate-SWNT conjugates for biorecognition. The carbohydrate-functionalized SWNTs were furthermore shown to interact specifically with cognate carbohydrate-specific proteins (lectins), resulting in predicted recognition patterns. The carbohydrate-presenting SWNTs constitute a new platform for sensitive protein-or cell recognition, which pave the way for glycoconjugated carbon nanomaterials in biorecognition applications.

  • 13.
    Shimpi, Manishkumar
    et al.
    Luleå University of Technology, Department of Health Sciences.
    Childs, Scott L.
    Renovo Research, Atlanta, GA.
    Boström, Dan
    Umeå universitet, Energy Technology and Thermal Process Chemistry, Umeå University.
    Velaga, Sitaram
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    New cocrystals of ezetimibe with l-proline and imidazole2014In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 16, no 38, p. 8984-8993Article in journal (Refereed)
    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

  • 14.
    Nagarajan, V.
    et al.
    School of Basic Sciences, Indian Institute of Technology Bhubaneswar.
    Pedireddia, V.R.
    School of Basic Sciences, Indian Institute of Technology Bhubaneswar.
    Shimpi, Manishkumar R.
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Hydrated and anhydrous molecular complexes of benzenepentacarboxylic acid and 4,4’-bipyridine2013In: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 1050, p. 216-221Article in journal (Refereed)
    Abstract [en]

    Supramolecular assemblies of benzenepentacarboxylic acid (BPC) and 4,4’-bipyridine (bpy) as hepta- and di- hydrates in a 2:1 and 1:1 ratios of the respective co-crystal formers, as well as an anhydrous complex of 1:2 ratio have been reported. The three supramolecular complexes [(BPC-)2(bpy2+)(H2O)7], 1a, [(BPC-)(bpy+)(bpy)], 1b and [(BPC2-)(bpy2+)(H2O)2], 1c, were obtained by carrying out co-crystallization experiments at varied conditions. 1a and 1b were obtained at ambient and hydrothermal conditions, resepctively, while 1c also was obtained at hydrothermal conditions but only in the presence of Ni(NO3)2. All the molecular complexes were characterized by single-crystal X-ray diffraction method. Molecules in all the complexes are packed in the form of stacked layers with the realization of host-guest network in 1a and 1c along a crystallographic axis, wherein the host network is formed by BPC and water molecules through different types of hydrogen bonding patterns and bpy molecules remain as guests in the voids, while in 1b, a ladder type network is observed.

  • 15.
    Marivel, Samipillai
    et al.
    Solid State & Supramolecular Structural Chemistry Unit, Division of Organic Chemistry.
    Shimpi, Manishkumar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Pedireddi, V.R.
    Solid State & Supramolecular Structural Chemistry Unit, Division of Organic Chemistry.
    Novel Supramolecular Assemblies of Coordination Polymers of Zn(II) and Bis(4-nitrophenyl)phosphoric Acid with Some Aza-Donor Compounds2007In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 7, no 9, p. 1791-1796Article in journal (Refereed)
    Abstract [en]

    Supramolecular assemblies of coordination polymers of Zn(II) and bis(4-nitrophenyl)phosphoric acid, BNPP, with aza-donor compounds, 4,4¢-bipyridine (bpy), 1,2-bis(4-pyridyl)ethane (bpyea), 1,2-bis(4-pyridyl)ethene (bpyee), and 1,3-bis(4-pyridyl)-propane (bpypa), have been reported. All the compounds are quite similar in the three-dimensional packing, irrespective of the varied dimensions of aza-donor molecules. All four compounds were synthesized by treating BNPP with corresponding aza-donor molecules in the presence of MeOH and water as the solvents. The structures were characterized by single-crystal X-ray diffraction.

  • 16.
    Shimpi, Manishkumar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Seethalekshmi, Nanappan
    Solid State & Supramolecular Structural Chemistry Unit, Division of Organic Chemistry, National Chemical Laboratory, Pune.
    Pedireddi, V.R.
    Solid State & Supramolecular Structural Chemistry Unit, Division of Organic Chemistry, National Chemical Laboratory, Pune.
    Supramolecular architecture in some 4-halophenylboronic acids2007In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 7, no 10, p. 1958-1963Article in journal (Refereed)
    Abstract [en]

    Crystal structures of 4-chloro- and 4-bromophenylboronic acids (1 and 2) and hydrates of 2 and 4-iodophenylboronic acid in two different forms (2a, 3a, and 3b), which were characterized by single-crystal X-ray diffraction methods, are reported. In structures I and 2, -B(OH)2 forms a syn-anti conformation, but it exists in syn-syn as well as anti-anti conformations in the hydrated structures 2a, 3a, and 3b. In all the structures, the molecules are held together by O-H center dot center dot center dot O interactions formed by -B(OH)2 groups. The C-H center dot center dot center dot X (X = Cl, Br, and I) interactions play an important role in crystal packing. In 2, Br center dot center dot center dot Br interactions are also observed. Interestingly, all the three hydrates form similar types of three-dimensional structures with the formation of channels, which are occupied by water molecules. The two hydrates of 4-iodophenylboronic acid (3a and 3b) are distinguishable on the basis of O center dot center dot center dot O short contacts, with an identical host lattice of the boronic acid.

  • 17.
    Pedireddi, V.R.
    et al.
    Solid State and Supramolecular Structural Chemistry Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, School of Basic Sciences, Indian Institute of Technology Bhubaneswar.
    Shimpi, Manishkumar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Yakhmi, J V
    Bhabha Atomic Research Centre, Trombay, Mumbai.
    Room-temperature ionic liquids: For a difference in the supramolecular synthesis2006In: Macromolecular Symposia, ISSN 1022-1360, E-ISSN 1521-3900, Vol. 241, no 1, p. 83-87Article in journal (Refereed)
    Abstract [en]

    Cu(I) and Ni(II) coordination polymers with 4,4'-bipyridine and 2,2'bipyridine, respectively, that have been synthesized from an ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) gave different coordination environment and supramolecular networks than the corresponding synthesis from the other solvents. The resultant complexes were characterized by single crystal x-ray diffraction methods.

1 - 17 of 17
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