L-Prolinium picrate and 2-methylpyridinium picrate

Supramolecular synthesis and characterization of crystalline solids obtained from the reaction of 5-fluorocytosine with nitro compounds

In this manuscript we introduce a broad solid-state characterization of 5-fluorocytosine (5-FC) solid forms obtained with picric (PA) and 3,5-dinitrosalicylic (DNSA) nitro acids.

Crystal structure of a second triclinic polymorph of 2-methyl-pyridinium picrate

The title mol-ecular salt, C6H8N(+)·C6H2N3O7 (-) (systematic name: 2-methyl-pyridinium 2,4,6-tri-nitro-phenolate), crystallizes with two cations and two anions in the asymmetric unit. In the crystal, the cations are linked to the anions via bifurcated N-H⋯(O,O) hydrogen bonds, generating R 1 (2)(6) graph-set motifs. Numerous C-H⋯O hydrogen bonds are observed between these cation-anion pairs, which result in a three-dimensional network. In addition, weak aromatic π-π stacking between the 2-methyl-pyridinium rings [inter-centroid distance = 3.8334 (19) Å] and very weak stacking [inter-centroid distance = 4.0281 (16) Å] between inversion-related pairs of picrate anions is observed. The title salt is a second triclinic polymorph of the structure (also with Z' = 2) reported earlier [Anita et al. (2006). Acta Cryst. C62, o567-o570; Chan et al. (2014 ▸). CrystEngComm, 16, 4508-4538]. In the title compound, the cations and anions display a chequerboard arrangement when viewed down [100], whereas in the first polymorph, (010) layers of alternating cations and anions are apparent in a [100] view. It is inter-esting that the unit-cell lengths are almost identical for the two polymorphs, although the inter-axial angles are quite different.

L-Methioninium picrate

Single crystals of l-methioninium picrate were obtained by evaporation of aqueous solution containing equimolar quantities of each component. l-Methioninium picrate crystallizes in the monoclinic system (space group P21, Z=2). The asymmetric unit contains one l-methioninium cation and one picrate anion. The carboxyl group of the cation forms an O-H⋯O hydrogen bond with the phenoxy oxygen atom and has an O⋯O distance of 2.669(3)Å. The protonated amino group of the l-methioninium cation forms N-H⋯O hydrogen bonds with the phenoxy oxygen atom of the picrate anion and the carbonyl oxygen atom of the symmetry related cation. The infrared and Raman spectra are recorded and discussed.

Hirshfeld surface analysis of crystal packing in aza-aromatic picrate salts

The structures of picrate salts of extended aza-aromatic bases have been determined and systematically analyzed using the Hirshfeld surface approach.

Vibrational spectra and natural bond orbital analysis of organic crystal L-prolinium picrate

Vibrational spectral analysis and quantum chemical computations based on density functional theory (DFT) have been performed on the organic crystal L-prolinium picrate (LPP). The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers of LPP have been investigated using B3LYP method. The calculated molecular geometry has been compared with the experimental data. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA 4 program. The various intramolecular interactions confirming the biological activity of the compound have been exposed by natural bond orbital analysis. The distribution of Mulliken atomic charges and bending of natural hybrid orbitals associated with hydrogen bonding also reflects the presence of intramolecular hydrogen bonding thereby enhancing bioactivity. The analysis of the electron density of HOMO and LUMO gives an idea of the delocalization and low value of energy gap indicates electron transport in the molecule and thereby bioactivity. Vibrational analysis reveals the presence of strong O-H···O and N-H···O interaction between L-prolinium and picrate ions providing evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity.

Three-dimensional network in piper-azine-1,4-diium-picrate-piperazine (1/2/1)

In the title compound, C₄H₁₂N₂²⁺·2C₆H₂N₃O₇⁻·C₄H₁₀N₂, the piperazine-1,4-diium cations and piperazine mol­ecules lie on crystallographic inversion centres. In the crystal structure, inter­molecular N—H⋯O and N—H⋯N hydrogen bonds link the components to form two-dimensional layers parallel to the (001) plane. These layers are, in turn, connected by weak inter­molecular C—H⋯O hydrogen bonds and π–π stacking inter­actions [centroid–centroid distance between parallel aryl rings = 3.764 (2) Å, interplanar spacing = 3.500 (2) Å and ring offset = 1.387 (2) Å], forming a three-dimensional framework.