Concomitant polymorphic forms of 3-cyclopropyl-5-(2-hydrazinylpyridin-3-yl)-1,2,4-oxadiazole

2020 ◽  
Vol 76 (8) ◽  
pp. 836-844 ◽  
Author(s):  
Svitlana V. Shishkina ◽  
Irina S. Konovalova ◽  
Veronika R. Karpina ◽  
Svitlana S. Kovalenko ◽  
Sergiy M. Kovalenko ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Lone Pair ◽  
Lattice Energy ◽  
Structural Motif ◽  
Stacking Interactions ◽  
Centrosymmetric Dimer ◽  
Triclinic Structure ◽  
Isopropanol Solution ◽  
Polymorphic Forms ◽  
Head Type

The dipharmacophore compound 3-cyclopropyl-5-(2-hydrazinylpyridin-3-yl)-1,2,4-oxadiazole, C10H11N5O, was studied on the assumption of its potential biological activity. Two concomitant polymorphs were obtained on crystallization from isopropanol solution and these were thoroughly studied. Identical conformations of the molecules are found in both structures despite the low difference in energy between the four possible conformers. The two polymorphs differ crucially with respect to their crystal structures. A centrosymmetric dimer formed due to both stacking interactions of the `head-to-tail' type and N—H...N(π) hydrogen bonds is the building unit in the triclinic structure. The dimeric building units form an isotropic packing. In the orthorhombic polymorphic structure, the molecules form stacking interactions of the `head-to-head' type, which results in their organization in a column as the primary basic structural motif. The formation of N—H...N(lone pair) hydrogen bonds between two neighbouring columns allows the formation of a double column as the main structural motif. The correct packing motifs in the two polymorphs could not be identified without calculations of the pairwise interaction energies. The triclinic structure has a higher density and a lower (by 0.60 kcal mol−1) lattice energy according to periodic calculations compared to the orthorhombic structure. This allows us to presume that the triclinic form of 3-cyclopropyl-5-(2-hydrazinylpyridin-3-yl)-1,2,4-oxadiazole is the more stable.

scholarly journals Isomers and polymorphs of (E,E)-1,4-bis(nitrophenyl)-2,3-diaza-1,3-butadienes

2006 ◽  
Vol 62 (4) ◽  
pp. 666-675 ◽  
Author(s):  
Christopher Glidewell ◽  
John N. Low ◽  
Janet M. S. Skakle ◽  
James L. Wardell
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Stacking Interactions ◽  
Space Group ◽  
Stacking Interaction ◽  
Space Groups ◽  
Π Stacking ◽  
Π Stacking Interaction ◽  
Polymorphic Forms

The structures of five of the possible six isomers of (E,E)-1,4-bis(nitrophenyl)-2,3-diaza-1,3-butadiene are reported, including two polymorphs of one of the isomers. (E,E)-1,4-Bis(2-nitrophenyl)-2,3-diaza-1,3-butadiene, C14H10N4O4 (I), crystallizes in two polymorphic forms (Ia) and (Ib) in which the molecules lie across centres of inversion in space groups P21/n and P21/c, respectively: the molecules in (Ia) and (Ib) are linked into chains by aromatic π...π stacking interactions and C—H...π(arene) hydrogen bonds, respectively. Molecules of (E,E)-1-(2-nitrophenyl)-4-(3-nitrophenyl)-2,3-diaza-1,3-butadiene (II) are linked into sheets by two independent C—H...O hydrogen bonds. The molecules of (E,E)-1,4-bis(3-nitrophenyl)-2,3-diaza-1,3-butadiene (III) lie across inversion centres in the space group P21/n, and a combination of a C—H...O hydrogen bond and a π...π stacking interaction links the molecules into sheets. A total of four independent C—H...O hydrogen bonds link the molecules of (E,E)-1-(3-nitrophenyl)-4-(4-nitrophenyl)-2,3-diaza-1,3-butadiene (IV) into sheets. In (E,E)-1,4-bis(4-nitrophenyl)-2,3-diaza-1,3-butadiene (V) the molecules, which lie across centres of inversion in the space group P21/n, are linked by just two independent C—H...O hydrogen bonds into a three-dimensional framework.

Conformational polymorphs of 3-cyclopropyl-5-(3-methyl-[1,2,4]triazolo[4,3-a]pyridin-7-yl)-1,2,4-oxadiazole

2021 ◽  
Vol 77 (1) ◽  
pp. 20-28
Author(s):  
Svitlana V. Shishkina ◽  
Irina S. Konovalova ◽  
Svitlana S. Kovalenko ◽  
Lyudmila L. Nikolaeva ◽  
Natalya D. Bunyatyan ◽  
...  
Keyword(s):  
Weak Interactions ◽  
Isoamyl Alcohol ◽  
Lattice Energy ◽  
Relative Energy ◽  
Polymorphic Form ◽  
Structural Motif ◽  
Strong Interactions ◽  
Monoclinic Structure ◽  
Orthorhombic Structure ◽  
Polymorphic Forms

The dipharmacophore compound 3-cyclopropyl-5-(3-methyl-[1,2,4]triazolo[4,3-a]pyridin-7-yl)-1,2,4-oxadiazole, C12H11N5O, was studied on the assumption of its potential biological activity. Two polymorphic forms differ in both their molecular and crystal structures. The monoclinic polymorphic form was crystallized from more volatile solvents and contains a conformer with a higher relative energy. The basic molecule forms an abundance of interactions with relatively close energies. The orthorhombic polymorph was crystallized very slowly from isoamyl alcohol and contains a conformer with a much lower energy. The basic molecule forms two strong interactions and a large number of weak interactions. Stacking interactions of the `head-to-head' type in the monoclinic structure and of the `head-to-tail' type in the orthorhombic structure proved to be the strongest and form stacked columns in the two polymorphs. The main structural motif of the monoclinic structure is a double column where two stacked columns interact through weak C—H...N hydrogen bonds and dispersive interactions. In the orthorhombic structure, a single stacked column is the main structural motif. Periodic calculations confirmed that the orthorhombic structure obtained by slow evaporation has a lower lattice energy (0.97 kcal mol−1) compared to the monoclinic structure.

scholarly journals The intermolecular interactions in the aminonitromethylbenzenes

2011 ◽  
Vol 9 (1) ◽  
pp. 94-105 ◽  
Author(s):  
Rafal Kruszynski ◽  
Tomasz Sieranski
Keyword(s):  
Hydrogen Bonds ◽  
Lone Pair ◽  
Quantum Mechanical ◽  
Stacking Interactions ◽  
Quantum Mechanical Calculations ◽  
Charge Redistribution ◽  
Intermolecular Hydrogen Bonds ◽  
Non Covalent Interactions ◽  
The One ◽  
Covalent Interactions

AbstractThe intermolecular non-covalent interactions in aminonitromethylbenzenes namely 2-methyl-4-nitroaniline, 4-methyl-3-nitroaniline, 2-methyl-6-nitroaniline, 4-amino-2,6-dinitrotoluene, 2-methyl-5-nitroaniline, 4-methyl-2-nitroaniline, 2,3-dimethyl-6-nitroaniline, 4,5-dimethyl-2-nitroaniline and 2-methyl-3,5-dinitroaniline were studied by quantum mechanical calculations at RHF/311++G(3df,2p) and B3LYP/311++G(3df,2p) level of theory. The calculations prove that solely geometrical study of hydrogen bonding can be very misleading because not all short distances (classified as hydrogen bonds on the basis of interaction geometry) are bonding in character. For studied compounds interaction energy ranges from 0.23 kcal mol−1 to 5.59 kcal mol−1. The creation of intermolecular hydrogen bonds leads to charge redistribution in donors and acceptors. The Natural Bonding Orbitals analysis shows that hydrogen bonds are created by transfer of electron density from the lone pair orbitals of the H-bond acceptor to the antibonding molecular orbitals of the H-bond donor and Rydberg orbitals of the hydrogen atom. The stacking interactions are the interactions of delocalized molecular π-orbitals of the one molecule with delocalized antibonding molecular π-orbitals and the antibonding molecular σ-orbital created between the carbon atoms of the second aromatic ring and vice versa.

Polymorphism of methyl 4-amino-3-phenylisothiazole-5-carboxylate: an experimental and theoretical study

2021 ◽  
Vol 77 (1) ◽  
pp. 40-48
Author(s):  
Svitlana V. Shishkina ◽  
Irina S. Konovalova ◽  
Sergiy M. Kovalenko ◽  
Dmitriy V. Kravchenko ◽  
Natalya D. Bunyatyan
Keyword(s):  
Intermolecular Interactions ◽  
Theoretical Study ◽  
Lattice Energy ◽  
Structural Motif ◽  
Stacking Interactions ◽  
Interaction Energies ◽  
Volatile Solvents ◽  
Different Types ◽  
Periodic Calculations ◽  
Centrosymmetric Structure

Being a close analogue of amflutizole, methyl 4-amino-3-phenylisothiazole-5-carboxylate (C11H10N2O2S) was assumed to be capable of forming polymorphic structures. Noncentrosymmetric and centrosymmetric polymorphs have been obtained by crystallization from a series of more volatile solvents and from denser tetrachloromethane, respectively. Identical conformations of the molecule are found in both structures. The two polymorphs differ mainly in the intermolecular interactions formed by the amino group and in the type of stacking interactions between the π-systems. The most effective method for revealing packing motifs in structures with intermolecular interactions of different types (hydrogen bonding, stacking, dispersion, etc.) is to study the pairwise interaction energies using quantum chemical calculations. Molecules form a column as the primary basic structural motif due to stacking interactions in both polymorphic structures under study. The character of a column (straight or zigzag) is determined by the orientations of the stacked molecules (in a `head-to-head' or `head-to-tail' manner). Columns bound by intermolecular N—H...O and N—H...N hydrogen bonds form a double column as the main structural motif in the noncentrosymmetric structure. Double columns in the noncentrosymmetric structure and columns in the centrosymmetric structure interact strongly within the ab crystallographic plane, forming a layer as a secondary basic structural motif. The noncentrosymmetric structure has a lower density and a lower (by 0.59 kJ mol−1) lattice energy, calculated using periodic calculations, compared to the centrosymmetric structure.

A Chemical Perspective to the Anti-Amyloid Action of Compounds and a Nanoparticle Based Assay for Screening Amyloid Inhibitors

2020 ◽  
Author(s):  
Nidhi Gour ◽  
Bharti Koshti
Keyword(s):  
Memory Loss ◽  
Cost Effective ◽  
Structural Motif ◽  
Rapid Screening ◽  
Stacking Interactions ◽  
Aromatic Rings ◽  
Amyloid Fibers ◽  
Aromatic Stacking ◽  
Cost Effective Technique ◽  
The Brain

Aggregation of amyloid beeta 1-42 (Aβ<sub>42</sub>) peptide causes the formation of clustered deposits knows as amyloid plaques in the brain which leads to neuronal dysfunction and memory loss and associated with many neurological disorders including Alzheimer’s and Parkinson’s. Aβ<sub>42</sub> has core structural motif with phenylalanine at the 19 and 20 positions. The diphenylalanine (FF) residue plays a crucial role in the formation of amyloid fibers and serves as model peptide for studying Aβ<sub>42 </sub>aggregation. FF self-assembles to well-ordered tubular morphology via aromatic pi-pi stackings. Our studies, suggest that the aromatic rings present in the anti-amyloidogenic compounds may interact with the pi-pi stacking interactions present in the FF. Even the compounds which do not have aromatic rings, like cyclodextrin and cucurbituril show anti-amyloid property due to the binding of aromatic ring inside the guest cavity. Hence, our studies also suggest that compounds which may have a functional moiety capable of interacting with the aromatic stacking interactions might be tested for their anti-amyloidogenic properties. Further, in this manuscript, we have proposed two novel nanoparticle based assays for the rapid screening of amyloid inhibitors. In the first assay, interaction between biotin-tagged FF peptide and the streptavidin labelled gold nanoparticles (s-AuNPs) were used. In another assay, thiol-Au interactions were used to develop an assay for detection of amyloid inhibitors. It is envisaged that the proposed analytical method will provide a simple, facile and cost effective technique for the screening of amyloid inhibitors and may be of immense practical implications to find the therapeutic remedies for the diseases associated with the protein aggregation.

scholarly journals Bis(thiocyanato-κN)[tris(pyridin-2-ylmethyl)amine-κ4N]iron(II)

2014 ◽  
Vol 70 (2) ◽  
pp. m35-m35
Author(s):  
Jing-Wei Dai ◽  
Zhao-Yang Li ◽  
Osamu Sato
Keyword(s):  
Hydrogen Bonds ◽  
Octahedral Geometry ◽  
Title Complex ◽  
Stacking Interactions ◽  
Supramolecular Architecture ◽  
Two Dimensional ◽  
Π Stacking ◽  
Centroid Distance ◽  
Solvent Molecules ◽  
Amine Ligand

In the title complex, [Fe(NCS)2(C18H18N4)], the FeIIcation is chelated by a tris(2-pyridylmethyl)amine ligand and coordinated by two thiocyanate anions in a distorted N6octahedral geometry. In the crystal, weak C—H...S hydrogen bonds and π–π stacking interactions between parallel pyridine rings of adjacent molecules [centroid–centroid distance = 3.653 (3) Å] link the molecules into a two-dimensional supramolecular architecture. The structure contains voids of 124 (9) Å3, which are free of solvent molecules.

scholarly journals Crystal structure of 2-bromo-1,4-dihydroxy-9,10-anthraquinone

2014 ◽  
Vol 70 (10) ◽  
pp. o1130-o1130 ◽  
Author(s):  
Wataru Furukawa ◽  
Munenori Takehara ◽  
Yoshinori Inoue ◽  
Chitoshi Kitamura
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Three Dimensional ◽  
Stacking Interactions ◽  
Compound C ◽  
Π Stacking ◽  
Dimensional Network

In an attempt to brominate 1,4-dipropoxy-9,10-anthraquinone, a mixture of products, including the title compound, C14H7BrO4, was obtained. The molecule is essentially planar (r.m.s. deviation = 0.029 Å) and two intramolecular O—H...O hydrogen bonds occur. In the crystal, the molecules are linked by weak C—H...O hydrogen bonds, Br...O contacts [3.240 (5) Å], and π–π stacking interactions [shortest centroid–centroid separation = 3.562 (4) Å], generating a three-dimensional network.

scholarly journals Di-μ-chlorido-bis[(2,2′-bipyridine-5,5′-dicarboxylic acid-κ2N,N′)chloridocopper(II)] dimethylformamide tetrasolvate

2013 ◽  
Vol 69 (2) ◽  
pp. m73-m74 ◽  
Author(s):  
Sigurd Øien ◽  
David Stephen Wragg ◽  
Karl Petter Lillerud ◽  
Mats Tilset
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Cooh Group ◽  
Stacking Interactions ◽  
Coordination Geometry ◽  
Complex Molecules ◽  
Centroid Distance ◽  
Solvent Molecules ◽  
Hydrogen Bonded

In the title compound, [Cu2Cl4(C12H8N2O4)2]·4C3H7NO, which contains a chloride-bridged centrosymmetric CuIIdimer, the CuIIatom is in a distorted square-pyramidal 4 + 1 coordination geometry defined by the N atoms of the chelating 2,2′-bipyridine ligand, a terminal chloride and two bridging chloride ligands. Of the two independent dimethylformamide molecules, one is hydrogen bonded to a single –COOH group, while one links two adjacent –COOH groupsviaa strong accepted O—H...O and a weak donated C(O)—H...O hydrogen bond. Two of these last molecules and the two –COOH groups form a centrosymmetric hydrogen-bonded ring in which the CH=O and the –COOH groups by disorder adopt two alternate orientations in a 0.44:0.56 ratio. These hydrogen bonds link the CuIIcomplex molecules and the dimethylformamide solvent molecules into infinite chains along [-111]. Slipped π–π stacking interactions between two centrosymmetric pyridine rings (centroid–centroid distance = 3.63 Å) contribute to the coherence of the structure along [0-11].

Iodo-nitroarenesulfonamides: interplay of hard and soft hydrogen bonds, I...O interactions and aromatic π...π stacking interactions

2001 ◽  
Vol 58 (1) ◽  
pp. 94-108 ◽  
Author(s):  
Craig J. Kelly ◽  
Janet M. S. Skakle ◽  
James L. Wardell ◽  
Solange M. S. V. Wardell ◽  
John N. Low ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Stacking Interactions ◽  
Asymmetric Unit ◽  
Space Group ◽  
Rotation Axes ◽  
Π Stacking ◽  
Structural Database ◽  
A Chain

Molecules of N-(4′-iodophenylsulfonyl)-4-nitroaniline, 4-O2NC6H4NHSO2C6H4I-4′ (1), are linked by three-centre I...O2N interactions into chains and these chains are linked into a three-dimensional framework by C—H...O hydrogen bonds. In the isomeric N-(4′-nitrophenylsulfonyl)-4-iodoaniline, 4-IC6H4NHSO2C6H4NO2-4′ (2), the chains generated by the I...O2N interactions are again linked into a three-dimensional framework by C—H...O hydrogen bonds. Molecules of N,N-bis(3′-nitrophenylsulfonyl)-4-iodoaniline, 4-IC6H4N(SO2C6H4NO2-3′)2 (3), lie across twofold rotation axes in space group C2/c and they are linked into chains by paired I...O=S interactions: these chains are linked into sheets by a C—H...O hydrogen bond, and the sheets are linked into a three-dimensional framework by aromatic π...π stacking interactions. In N-(4′-iodophenylsulfonyl)-3-nitroaniline, 3-O2NC6H4NHSO2C6H4I-4′ (4), there are R^2_2(8) rings formed by hard N—H...O=S hydrogen bonds and R^2_2(24) rings formed by two-centre I...nitro interactions, which together generate a chain of fused rings: the combination of a C—H...O hydrogen bond and aromatic π...π stacking interactions links the chains into sheets. Molecules of N-(4′-iodophenylsulfonyl)-4-methyl-2-nitroaniline, 4-CH3-2-O2NC6H3NHSO2C6H4I-4′ (5), are linked by N—H...O=S and C—H...O(nitro) hydrogen bonds into a chain containing alternating R^2_2(8) and R^2_2(10) rings, but there are no I...O interactions of either type. There are two molecules in the asymmetric unit of N-(4′-iodophenylsulfonyl)-2-nitroaniline, 2-O2NC6H4NHSO2C6H4I-4′ (6), and the combination of an I...O=S interaction and a hard N—H...O(nitro) hydrogen bond links the two types of molecule to form a cyclic, centrosymmetric four-component aggregate. C—H...O hydrogen bonds link these four-molecule aggregates to form a molecular ladder. Comparisons are made with structures retrieved from the Cambridge Structural Database.

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