Synthesis, structural, thermal and optical studies of 1-ethyl-2,6-dimethyl-4-hydroxy pyridinium halides

4-Hy-droxy-1,2,6-tri-methyl-pyridinium chloride monohydrate

In the crystal of the title hydrated mol­ecular salt, C₈H₁₂NO⁺·Cl⁻·H₂O, the water mol­ecule makes two O—H⋯Cl hydrogen bonds, generating [010] zigzag chains of alternating water mol­ecules and chloride ions. The cation is bonded to the chain by an O—H⋯O hydrogen bond and two weak C—H⋯Cl inter­actions. Weak aromatic π–π stacking [centroid–centroid separation = 3.5175 (15) Å] occurs between the chains.

4-Hy-droxy-1,2,6-tri-methyl-pyridinium bromide monohydrate

The title salt, C₈H₁₂NO⁺·Br⁻·H₂O, is isomorphous with the chloride analogue [Seethalakshmi et al. (2013). Acta Cryst. E69, o835–o836]. In the solid state, the cations, anions and water mol­ecules are inter­linked by a network of O—H⋯O, O—H⋯Br and C—H⋯Br inter­actions. The water mol­ecule makes two O—H⋯Br hydrogen bonds, generating [010] zigzag chains of alternating water mol­ecules and bromide anions. The cation is involved in two inter­molecular C—H⋯Cl inter­actions in the chloride salt, whereas three inter­molecular C—H⋯Br inter­actions are observed in the title bromide salt. This additional inter­molecular C—H⋯Br inter­action links the adjacent water and bromide zigzag chains via cationic mol­ecules. In addition, weak π–π stacking inter­actions are observed between pyridinium rings [centroid–centroid distance = 3.5664 (13) Å].

Dibromidobis(1-ethyl-2,6-dimethylpyridinium-4-olate-κO)zinc(II)

In the bioactive title compound, [ZnBr₂(C₉H₁₃NO)₂], the Zn^II atom is coordinated in a distorted tetra­hedral arrangement by two Br⁻ anions and the O atoms of two zwitterionic organic ligands. The pyridinium rings are almost planar [maximum deviations = 0.004 (4) and 0.003 (4) Å]. The ethyl groups are approximately perpendicular to the corresponding pyridinium ring planes [N—C—C—C = 88.8 (4)° in each ligand]. The packing of the mol­ecules is controlled by π–π inter­actions, with centroid–centroid distances of 3.625 (3) and 3.711 (2) Å, forming chains approximately parallel to (102). The crystal studied was non-merohedrally twinned (twin relationship between the domains 1 0 0, 0 1 0, −0.4672 −0.1864 −1 and batch scale factor of 7.39%).

Synthesis, spectral, optical and thermal studies of 1-methyl-2,6-dimethyl-4-hydroxypyridinium chloride monohydrate and bromide monohydrate

Semiorganic 1-methyl-2,6-dimethyl-4-hydroxypyridinium chloride monohydrate (MDMPCl.H(2)O) and bromide monohydrate (MDMPBr.H(2)O) salts have been synthesized. Single crystals of MDMPCl.H(2)O and MDMPBr.H(2)O were grown by the slow evaporation method from aqueous solution at constant temperatures 30 and 32 degrees C respectively. The grown crystals were characterized by elemental analysis, FT-IR and FT-NMR techniques and their molecular structures were elucidated. Thermogravimetric, differential thermal analyses and differential scanning calorimetry reveal the presence of water molecules in the crystal lattices and thermal stabilities. Optical transmittance windows in aqueous solution were found as 300-1100 nm using UV-vis-NIR spectrophotometer.