Search results for "kristallografia"
showing 10 items of 64 documents
Synthesis and X-ray Crystal Structure of New Substituted 3-4′-Bipyrazole Derivatives. Hirshfeld Analysis, DFT and NBO Studies
2021
A new compounds named 3-4′-bipyrazoles 2 and 3 were synthesized in high chemical yield from a reaction of pyran-2,4-diketone 1 with aryl hydrazines under thermal conditions in MeOH. Compound 2 was unambiguously confirmed by single-crystal X-ray analysis. It crystalizes in a triclinic crystal system and space group P-1. Its crystal structure was found to be in good agreement with the spectral characterizations. With the aid of Hirshfeld calculations, the H…H (54.8–55.3%) and H…C (28.3–29.2%) intermolecular contacts are the most dominant, while the O…H (5.8–6.5%), N…H (3.8–4.6%) and C…C (3.0–4.9%) are less dominant. The compound has a polar nature with a net dipole moment of 6.388 Debye. The …
Synthesis and X-ray Crystal Structure Analysis of Substituted 1,2,4-Triazolo [4’,3’:2,3]pyridazino[4,5-b]indole and Its Precursor
2023
The hit compound 1,2,4-triazolo[4’,3’:2,3]pyridazino[4,5-b]indole 3 was synthesized from the reflux of 4-amino-5-indolyl-1,2,4-triazole-3-thione 1 with 4′-bromoacetophenone 2 in methanol catalyzed by concentrated HCl and the desired final molecule was obtained by recrystallization from methanol. The suggested structures of compounds 1 and 3 based on the spectral characterizations were confirmed by X-ray single crystal diffraction analysis. Compound 3 crystallized in the triclinic crystal system and P-1 space group with a = 5.9308(2) Å, b = 10.9695(3) Å, c = 14.7966(4) Å, α = 100.5010(10)°, β = 98.6180(10)°, and γ = 103.8180(10)°. On the other hand, the crystal system of 1 is monoclinic, whe…
Effect of a Rigid Sulfonamide Bond on Molecular Folding: A Case Study
2015
A disulfonamide compound with bulky aromatic side chains was prepared, and its properties as a potential building block for foldamers were evaluated. Two different solvate crystal forms of the compound were identified and compared to the structures of an analogous oligoamide and related disulfonamides. The disulfonamide is unfolded in one of the solvates, whereas in the other one, a loosely folded conformer stabilized by an intramolecular hydrogen bond is found. Density functional calculations indicated that the loosely folded conformer is slightly more stable than its unfolded isomer. The calculations also identified a third, more tightly folded and more extensively hydrogen bonded, confor…
Synthesis, X-ray Structure of Two Hexa-Coordinated Ni(II) Complexes with s-Triazine Hydrazine Schiff Base Ligand
2023
The hydrazine s-triazine ligand (E)-4,4’-(6-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)-1,3,5-triazine-2,4-diyl)dimorpholine (DMPT) was used to synthesize two new Ni(II) complexes via a self-assembly technique. The two complexes were synthesized by a one-pot synthesis strategy and characterized by elemental analysis, FTIR and single-crystal X-ray diffraction analysis to be [Ni(DMPT)(H2O)3](NO3)2.3H2O (1) and [Ni(DMPT)(H2O)3](NO3)2.H2O (2). The structures of both complexes were very similar regarding the coordination sphere and counter anions, but differ only in the number of the crystal water molecules. In the case of complex 1, there are three water molecules instead of one H2O molecu…
Binding of ion pairs and neutral guests by aryl-extended meso‑p-hydroxyphenyl calix[4]pyrrole : The interplay between three binding sites
2023
An aryl-extended calix[4]pyrrole with four meso‑p-hydroxyphenyl substituents was investigated as a host for chloride, acetate, and benzoate anions. Crystal structures of pyridinium and imidazolium chloride complexes were obtained in which chloride ions are hydrogen bonded exo-cavity to the upper rim hydroxyl groups, and the aromatic cations are bound to the shallow cavity of the host. Furthermore, the calix[4]pyrrole formed a hydrogen bonded dimeric capsule templated by inclusion of adiponitrile guest in the endo-cavity binding site. NMR titrations revealed the preference of the OH groups of the host to bind anionic guests in solution. Benzoate anion had the highest binding constant (4 700 …
Synthesis, X-ray Single-Crystal Analysis, and Anticancer Activity Evaluation of New Alkylsulfanyl-Pyridazino[4,5-b]indole Compounds as Multitarget In…
2022
The alkylation of 3,5-dihydro-4H-pyridazino[4,5-b]indole-4-thione with benzyl bromide, ethyl chloroacetate, and allyl bromide in the presence of potassium carbonate (K2CO3) yielded new alkylsulfanylpyridazino[4,5-b]indole derivatives (i.e., compounds 4–6). Hydrazinolysis of ester 6 resulted in hydrazide 7. The structure of compound 6 was verified by X-ray single-crystal analysis. Among the synthesized compounds, compound 6 exhibited the most promising cytotoxicity toward MCF-7 cells with an IC50 value of 12 µM. It showed potential inhibition activity toward EGFR, PI3K, and AKT in MCF-7 cells, with 0.26-, 0.49-, and 0.31-fold reductions in concentration compared to an untreated c…
Systematic Modulation of the Supramolecular Gelation Properties of Bile Acid Alkyl Amides
2018
The self-assembly properties of nine low-molecular-weight gelators (LMWGs) based on bile acid alkyl amides were studied in detail. Based on the results, the number of hydroxyl groups attached to the steroidal backbone plays a major role in the gelation, although the nature of the aliphatic side chain also modulates the gelation abilities. Of the 50 gel systems studied, 35 are based on lithocholic acid and 15 on cholic acid derivatives. The deoxycholic acid derivatives did not form any gels. The gelation occurred primarily in aromatic solvents and the gels manifested typical fibrous or spherical morphologies. The 13C cross-polarized magic angle spinning (CPMAS) NMR spectra measured on the cr…
Crystal Structures and Cytotoxicity of ent-Kaurane-Type Diterpenoids from Two Aspilia Species
2018
A phytochemical investigation of the roots of Aspilia pluriseta led to the isolation of ent-kaurane-type diterpenoids and additional phytochemicals (1⁻23). The structures of the isolated compounds were elucidated based on Nuclear Magnetic Resonance (NMR) spectroscopic and mass spectrometric analyses. The absolute configurations of seven of the ent-kaurane-type diterpenoids (3⁻6, 6b, 7 and 8) were determined by single crystal X-ray diffraction studies. Eleven of the compounds were also isolated from the roots and the aerial parts of Aspilia mossambicensis. The literature NMR assignments for compounds 1 and 5 were revised. In a cytotoxicity assay, 12α-methoxy-ent-kaur-9(11),1…
Confinement inside a Crystalline Sponge Induces Pyrrole To Form N−H⋅⋅⋅π Bonded Tetramers
2021
Based on the DFT‐level calculated molecular volume (V mol ) of pyrrole and its liquid density, pyrrole manifests the highest liquid density coefficient LD c (defined as [V mol • density • 0.6023]/FW) value of 0.7. Normal liquids have LD c < 0.63. This very high LD c is due to the strong N‐H … π interactions in solution and hence pyrrole can be considered to be a pseudo‐crystalline liquid. When trapped inside the confined space of the crystalline sponge a reorientation of the N‐H … π interaction is observed leading to specific cyclic N‐H … π tetramers and N‐H … π dimers, verified by single crystal X‐ray crystallographic and computational methods. These tetramers are of the same size as four …
Signal amplification and transduction in phytochrome photosensors
2014
[Introduction] Page 2 of 20 Sensory proteins must relay structural signals from the sensory site over large distances to regulatory output domains. Phytochromes are a major family of red-light sensing kinases that control diverse cell ular functions in plants, bacteria, and fungi. 1-9 Bacterial phytochro mes consist of a photosensory core and a C-te rminal regulatory domain. 10,11 Structures of photosensory cores are reported in the resting state 12-18 and conformational responses to light activat ion have been proposed in the vicinity of the chromophore. 19-23 However, the structure of the signalling state and the mechanism of downstream signal re lay through the photosensory core remain e…