The role of hydrogen bonds in the crystals of 2-amino-4-methyl-5-nitropyridinium trifluoroacetate monohydrate and 4-hydroxybenzenesulfonate – X-ray and spectroscopic studies

• Two new organic–organic salts, AMNP-TFA and AMNP-HBS, were obtained and characterized.
• NH⋯O bonds are formed between the acidic unit and pyridinium cation in both salts.
• OH⋯O bonds are formed between H2O molecules and COO− and NO2 groups in AMNP-TFA.
• The SO3- groups of adjacent acidic unit are linked by OH···O bonds in AMNP-HBS.
• X-ray, IR and Raman studies and DFT calculations show the existence of intramolecular NH···O bonds.

Two new organic–organic salts, 2-amino-4-methyl-5-nitropyridinium trifluoroacetate monohydrate (AMNP-TFA), and 2-amino-4-methyl-5-nitropyridinium 4-hydroxybenzenesulfonate (AMNP-HBS), were obtained and characterized by means of FT-IR, FT-Raman and single crystal X-ray crystallography. In the former crystal, the cations, anions and water molecules are linked into layers by three types of hydrogen bonds, NPH⋯O, NAH⋯O and OH⋯O. These layers are connected by weaker CH⋯O hydrogen bonds. In the latter crystal, the cations and anions form one-dimensional structure through a number of hydrogen-bonding interactions involving the OH, NH+ and NH2 groups as donors. In this case the NPH⋯O and NAH⋯O hydrogen bonds are formed. The combination of interactions between cations and anions results in the formation of columns. Additionally, there are π–π stacking interactions between the columns. The obtained X-ray structural data are related to the vibrational spectra of the studied crystals.