Search

• 5-(Quinolinium)-valeric acid bromide hydrates form centrosymmetric and asymmetric dimers. • Water is a bridge between 5-(quinolinium)-valeric acid cations and bromide anions. • The DFT calculations were used to optimize isolated structures of monomer and dimer. • PED are used to assign the bands in the vibrational spectrum. • The NBO, MEP and QTAIM methods were used to characterize the optimized structures. The molecular structure and properties of 5-(quinolinium)-valeric acid bromide monohydrate are characterized by X-ray diffraction, B3LYP/6–311++G(d,p) calculations, FTIR and NMR spectra. Two molecules of this compound are hydrogen bonded through two water molecules and two bromide anions into centrosymmetric dimers, which are arranged in a strongly anisotropic layered structure. The structures of monomer and dimer of the title complex are optimized at the B3LYP/6–311++G(d,p) level of theory. The conformations of the valeric acid unit in the crystalline monohydrate and in isolated molecules (monohydrates and anhydrous forms) are compared. The experimental and theoretical infrared spectra are discussed. The FTIR spectrum shows an absorption in the 3500–2700 cm−1 region attributed to the νCOOH···OH 2 and νBr−···H 2 O. The potential energy distributions (PED) are used to assign bands in the IR spectrum of the monomer. The 1H and 13C NMR chemical shifts are assigned by two-dimensional techniques, COSY, HSQC and HMBC. Charge delocalization is analyzed using the natural bond orbital (NBO) method and it is shown in molecular electrostatic potential (MEP) maps. The bent conformations of the computed structures are characterized by the QTAIM method. Image, graphical abstract [ABSTRACT FROM AUTHOR]