Melaminium dihydrogenpyrophosphate: synthesis, crystal packing, Hirshfeld surface analysis, and reactivity mapping: a combined experimental and theoretical study

Synthesis, characterization, crystal structures, Hirshfeld surface analysis and DFT computational studies of new Schiff Bases derived from Phenylhydrazine

Herein, a new Ni(II) carboxylate polymer, [Ni(Pyr).4H 2 O]Phth , is synthesized by the reaction of NiSO 4 .7H 2 O with equimolar amounts of phthalic acid (PhthH 2 ) as the counter-anion and pyrazine (Pyr) as an ancillary ligand in aqueous media. The crystal structure of [Ni(Pyr).4H 2 O]Phth is investigated by single crystal X-rays diffraction analysis, which inferred the ionic nature of the complex. In cation, the Ni-center is coordinated by two pyrazine rings and four water molecules to form an octahedral coordination geometry. The crystal structure exists as a one-dimensional polymeric structure. The crystal packing is stabilized by OH O and CH O bonding. The non-covalent interactions are investigated by Hirshfeld surface analysis. The enrichment ratio delivers the tendency of the interaction of the pair of chemical moieties, which are involved in the packing of crystals. Moreover, void analysis is executed to look at the packing efficiency, which helps in predicting the mechanical response of the compound.

Structural and optical properties of salicyl-N-methyl-4-stilbazolium tosylate: Thermal, DFT, MEP and Hirshfeld surface analysis

Synthesis, single crystal X-ray structure determination, Hirshfeld surface analysis, interaction energies, and density functional theory calculations of N,N'-(cyclohexane-1,4-dicarbonothioyl)bis(4-methylbenzamide)

New polymorph of N-benzoyl-morpholine-4-carbothioamide with ten crystallographically independent molecules in the asymmetric unit: Crystal structure, Hirshfeld surface analysis and Density functional theory calculations

Methyl 4-hydroxybenzoate, commonly known as methyl paraben, is an anti-microbial agent used in cosmetics and personal-care products, and as a food preservative. In this study, the single crystal X-ray structure of methyl 4-hydroxybenzoate was determined at 120 K. The crystal structure comprises three methyl 4-hydroxybenzoate molecules condensed to a 3D framework via extensive intermolecular hydrogen bonding. Hirshfeld surface analysis was performed to determine the intermolecular interactions and the crystal packing. In addition, computational calculations of methyl 4-hydroxybenzoate were obtained using the Gaussian 09W program, and by quantum mechanical methods, Hartree Fock (HF) and Density Functional Theory (DFT) with the 6–311G(d,p) basis set. The experimental FT-IR spectrum strongly correlated with the computed vibrational spectra (R2 = 0.995). The energies of the frontier orbitals, HOMO and LUMO, were used to calculate the chemical quantum parameters. The lower band gap value (ΔE) indicates the molecular determinants underlying the known pharmaceutical activity of the molecule.

Gefitinib or Iressa is an orally administered anilinoquinazoline used in cancer chemotherapy for the treatment of lung and breast cancer. It is reported to exist in two polymorphic forms, a stable form I and a metastable form II. Both of the forms belong to the triclinic P-1 space group. In this work, we report the crystallization of Gefitinib to form a methanol solvate [systematic name: N-(3-chloro-4-fluorophenyl)-7-methoxy-6-[3-(morpholin-4-yl)propoxy]quinazolin-4-amine methanol hemisolvate, C22H24ClFN4O3·0.5CH3OH] that was theoretically and experimentally investigated. The unit cell is composed of two independent Gefitinib molecules (A and B) that form a stable molecular complex with methanol in the crystal lattice. To understand the crystal lattice stabilization, a combination of techniques, namely X-ray diffraction, IR spectroscopy, thermogravimetric/differential scanning calorimetry (TG-DSC), Hirshfeld surface analysis and CLP-PIXEL methods were used. The analysis of the crystal structure of this dimer revealed a three-dimensional isostructurality with the already reported form II. The A and B molecules are connected via trifurcated C-H...O and N-H...O hydrogen bonding. In addition, the presence of the methanol molecule stabilizes the crystal structure via C-H...O, N-H...O and C-H...Cl interactions between the two monomers. The IR analysis of the dimer has shown characteristic fingerprint values when compared to the commercial form. The TG-DSC analysis of the solvated dimer is in good agreement with the patent reporting cocrystals of Gefitinib. Finally, theoretical calculations by the CLP-PIXEL method and Hirshfeld surface and two-dimensional (2D) fingerprint plot analysis were carried out in order to quantify the different intermolecular interactions and their energies in the crystal packing.

Isomeric nitro substituted symmetrical benzamides: Crystal Structures, Hirshfeld surface analysis, 3D energy frameworks, DNA binding and cell line studies

Exploring weak intermolecular interactions in two bis-1,3,4-oxadiazoles derivatives: A combined X-ray diffraction, Hirshfeld surface analysis and theoretical studies

The hybrid perovskite [NH3–(CH2)2–NH3]CdCl4 has been synthesized and characterized. Hirshfeld surface analysis was used to identify the individual types of intermolecular contacts and their impact on crystal packing. The UV–visible spectroscopy study demonstrates that the material shows an indirect optical transition with an energy gap of about 3.34 eV. The optical parameters such as refractive index (n) and extinction coefficient were deduced from reflectance spectra and discussed. The first principles calculations based on the density functional theory (DFT) were performed to investigate band structure and electronic properties. The computed band gap was found to be about 3.24 eV which is in good agreement with the experimental value and reveals the insulating behavior of the material. The calculated total (DOS) and partial (PDOS) densities of state show the contribution of different orbitals at the maximum of the valence band (MVB) and the minimum conduction band (MCB).

α-D-2'-Deoxyribonucleosides are products of the γ-irradiation of DNA under oxygen-free conditions and are constituents of anomeric DNA. They are not found as natural building blocks of canonical DNA. Reports on their conformational properties are limited. Herein, the single-crystal X-ray structure of α-D-2'-deoxyadenosine (α-dA), C10H13N5O3, and its conformational parameters were determined. In the crystalline state, α-dA forms two conformers in the asymmetric unit which are connected by hydrogen bonds. The sugar moiety of each conformer is arranged in a `clamp'-like fashion with respect to the other conformer, forming hydrogen bonds to its nucleobase and sugar residue. For both conformers, a syn conformation of the nucleobase with respect to the sugar moiety was found. This is contrary to the anti conformation usually preferred by α-nucleosides. The sugar conformation of both conformers is C2'-endo, and the 5'-hydroxyl groups are in a +sc orientation, probably due to the hydrogen bonds formed by the conformers. The formation of the supramolecular assembly of α-dA is controlled by hydrogen bonding and stacking interactions, which was verified by a Hirshfeld and curvedness surface analysis. Chains of hydrogen-bonded nucleobases extend parallel to the b direction and are linked to equivalent chains by hydrogen bonds involving the sugar moieties to form a sheet. A comparison of the solid-state structures of the anomeric 2'-deoxyadenosines revealed significant differences of their conformational parameters.

Theoretical studies, Hirshfeld surface analysis, and crystal structure determination of a newly synthesized benzothiazole copper(II) complex

A monocarbonyl analog of curcumin, (2E,5E)-2,5-bis(2-methoxybenzylidene)-cyclopentanone (B2MBCP), was prepared and characterized via spectroscopic methods (NMR, UV-Vis, FT-IR, and MS). Furthermore, density functional calculations were implemented to study the molecular structure and spectroscopic features, as well as adsorption properties. In addition, Hirshfeld surface and NBO theoretical analysis were carried out. The reduced density gradient (RDG) analysis via non-covalent interactions (NCI) and interaction region indicator (IRI) indicate the presence of extensive Van der Waals interactions. These interactions are classified in different contributions and energy stabilization from Hirshfeld surface analysis where the dominant type of contacts are H···H contacts. The molecular docking studies of B2MBCP with DNA revealed cooperative interactions that led to intercalation. The results from the cyclic voltammetry (CV) measurements agreed with the calculated energies of the frontier orbitals and the compound structure. Theoretical studies indicated that the relatively flat B2MBCP is adsorbed onto a graphene surface, with a significant adsorption energy of –41.19 kcal/mol. The results of this study provide a better overall picture of the properties of MAC with a cyclopentanone core and can be taken as a useful guide in the search for new biologically active compounds and new possible means of delivery.

Sonication-assisted synthesis of new Schiff bases derived from 3-ethoxysalicylaldehyde: Crystal structure determination, Hirshfeld surface analysis, theoretical calculations and spectroscopic studies

Isoguanine nucleosides constructed by different heterocyclic skeletons play a significant role in the context of genetic code expansion, as well as for purine-purine base pairing. However, with respect to structure analysis, only limited information is available on this class of nucleosides. In this study, the single-crystal X-ray structure of 8-ethynyl-2'-deoxyisoguanosine, C12H13N5O4·C12H13N5O4·2H2O (1), has been investigated. In the crystal of 1, the N1-H and N3-H tautomers exist together. They are connected by O3'-H to O3' hydrogen bonds. The conformation at the glycosylic bond is syn for both tautomeric forms. This conformation is stabilized by intramolecular hydrogen bonds from N3 or N3-H of the pyrimidine ring to the 5'-OH group of the sugar residue. For both tautomers, the sugar conformation adopts a C2'-endo-C3'-exo twist (2T3; S-type), with P = 165.0 and 163.9°. A synclinal orientation is observed around the C4-C5' bond. Crystal packing is controlled by a tridentate purine-purine pair of 8-ethynyl-2'-deoxyisoguanosine that is enabled by a tautomeric shift of the proton from N1 to N3 of the nucleobase. Additional stability to the 3D network is contributed by water molecules connecting different layers in the solid state. A Hirshfeld surface analysis was performed confirming the existence of the purine-purine pair and the impact of the water molecules on hydrogen bonding. To the best of our knowledge, this is the first X-ray analysis on a nucleoside with two different tautomeric forms in the crystal unit that form a purine-purine base pair.