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The structure of bis(4-trimethylammoniumbenzoate) hydroiodide hydrate 1 has been studied by X-ray diffraction, B3LYP/6–311G(d,p) calculations, FTIR, Raman and NMR spectroscopic techniques. The crystal is polar in monoclinic space group Cc. Two 4-trimethylammoniumbenzoate moieties are joined by a short and asymmetric hydrogen bond of 2.45(2) Å. Water molecules are gradually released from the structure, causing shifts in the position of iodine anions, which induces their disorder. The water molecule interacts with 4-trimethylammoniumbenzoate moiety and iodide anion via two O(3)–H(1)⋯O(1) and O(3)–H(2)⋯I(1) hydrogen bonds of lengths 2.70(3) and 3.51(1) Å. Hydrogen bonds in theoretically predicted structures of 2 and 3 (in vacuum), and 4 , 5 (in DMSO) optimized by the B3LYP/6-311G(d,p) approach are slightly longer than in crystal 1 . The FTIR spectrum of 1 shows a broad and intense absorption in the 1500–400 cm −1 region, typical of short hydrogen bonds assigned to the ν as (OHO) + γ (OHO) vibrations. The correlations between the experimental 13 C and 1 H chemical shifts ( δ exp ) of the investigated compound in DMSO and the GIAO/B3LYP/6-311G(d,p) magnetic isotropic shielding constants ( σ calc ) calculated by using the screening solvation model (COSMO) are linear, δ exp = a + b σ calc , and they well reproduce the experimental chemical shifts. [ABSTRACT FROM AUTHOR]

A novel and unique crystalline three-component complex was formed of 2-(1-piperidine)ethanol, p -hydroxybenzoic acid and water at the ratio 1:1:1. Its structure has been determined by single-crystal X-ray diffraction. This is an example of a hydrogen-bonded interaction between amino alcohol and benzoic acid molecules. Water acts as a bridge between molecules. The molecules are linked through medium-strong OH⋯O hydrogen bonds from 2.665(6) to 2.813(6) Å and NH⋯O one 2.744(5) Å in length. The molecular structure of 2-(1-piperidinium)ethanol p -hydroxybenzoate hydrate has been characterized by FTIR and Raman spectra and optimized at the B3LYP/6−311++G(d,p) level of theory. The potential energy distributions (PED) have been used to assign the vibrational spectra. Charge delocalization was analyzed using the natural bond orbital (NBO) methods. [ABSTRACT FROM AUTHOR]

The 1:1 complex of piperidine-4-carboxylic acid (isonipecotic acid, P4C) with 2,6-dichloro-4-nitrophenol (DCNP), has been investigated by single-crystal X-ray analysis, Raman and FTIR spectroscopy and theoretical calculations. The hydrogen-bonded-ion-pair complex is observed in the crystalline state with the O⋯H⋯OOC hydrogen bond of 2.453(16) Å. FTIR spectrum shows a broad absorption in the 1600–400 cm −1 region characteristic of very short OHO hydrogen bond, broken by the Evans holes. The complexes are joined through N H⋯O into a H-bonding network. The N H⋯O mode appears as a broad band in the range of 3100–2000 cm −1 . In the structure optimized at the B3LYP/6–311 + +G(d,p) level of theory the proton is transferred from DCNP to P4C, and molecules are joined through the O⋯HOOC hydrogen bond of 2.640 Å. The experimental and theoretical infrared spectra are discussed. Detail interpretation of the vibrational spectra has been carried out with the use of computed Potential Energy Distribution (PED). [ABSTRACT FROM AUTHOR]

( R / S )-Piperidine-3-carboxylic acid (P3C, nipecotic acid) forms a stable 1:1 hydrogen-bonded complex with 2,6-dichloro-4-nitrophenol (DCNP). Both, in crystal and in the optimized theoretically structure by the B3LYP/6-311 + +G(d,p) approach the proton is transferred from DCNP to P3C. The ( R ) and ( S )-stereoisomersic complexes of piperidinium-3-carboxylic acid 2,6-dichloro-4-nitrophenolate, P3C + H·DCNP − , aggregate into centrosymmetric cyclic dimers through the COOH⋯O − and N + H⋯ONO hydrogen bonds of 2.57(1) and 3.06(1) Å, respectively, which in turn are linked into a ladder-type cyclamer through the C H⋯Cl hydrogen bonds of 3.71(1) Å. The title compound is characterized by single-crystal X-ray analysis, Raman and FTIR spectroscopies. The structures of the complexes of the ratio 1:1 (monomer), 2:2 (dimer) and 4:4 (cyclamer) of P3C + H·DCNP − units are optimized by the B3LYP/6-311 + + G(d,p) approach and compared with the solid-state experimental structure. Detail interpretation of the vibrational spectra has been carried out by computing Potential Energy Distribution (PED). Charge delocalization has been analyzed using the Natural Bond Orbital (NBO) method. [ABSTRACT FROM AUTHOR]

Abstract 2-(Quinuclidinium)-alkanocarboxylates co-crystallize with 2,6-dichloro-4-nitrophenol at the ratios 1:1 and 1:2 depending on the alkyl-chain lengths. The obtained complexes have been characterized by single-crystal X-ray diffraction, UV–vis, FTIR and NMR spectroscopy. The compounds 2-(quinuclidinium)-acetate and 2-(quinuclidinium)-propionate form complexes with 2,6-dichloro-4-nitrophenol at the stoichiometric ratio 1:2, while 2-(quinuclidinium)-butyrate and 2-(quinuclidinium)-valerate at ratio 1:1. Three crystal structures of compounds of these series were determined, but no single crystals of sufficient quality could be obtained of the 2-(quinuclidinium)-butyrate complex. The B3LYP/6-311++G(d,p) approach has been used to determine structures of their isolated molecules and to interpret the IR and UV–vis spectra. Diagrams of the HOMO and LUMO of molecules have been obtained. Graphical abstract Image 1 Highlights • Quiniclidinium-alkanocarboxylates form H B complexes with 2,6-dichloro-4-nitrophenol. • Lower homologues form molecular complexes at the 1:2 ratio. • Longer homologues form proton transfer 1:1 complexes. • Molecular structures were solved by X-ray diffraction and optimized by DFT methods. • UV–vis, FTIR and NMR spectra were measured. [ABSTRACT FROM AUTHOR]

The molecular structure of 1,2-di(3-hydroxymethylpyridinium)ethane dibromide ( 1 ) has been characterized by X-ray diffraction, B3LYP/6-311++G(d,p) calculations, FTIR, Raman and NMR spectra. The crystals are monoclinic, space group C2/c . 1,2-Di(3-hydroxymethylpyridinium)ethane dication and hydrogen-bonded bromide anions in crystals are located at the inversion center. The both CH 2 OH groups are engaged in two equal length hydrogen bonds with bromide anions. Two structures ( 2 ) and ( 3 ) were optimized at the B3LYP/6-311++G(d,p) level of theory. The optimized complex ( 2) resembles the crystal structure, while complex ( 3 ) is preferred energetically. The O⋯Br − hydrogen bonds distances are: 3.289(2) Å in crystals ( 1 ), but in the optimized structures ( 2 ) and ( 3 ) they are 3.303 Å and 3.461 Å, respectively. The investigated complex is additionally stabilized by the N + ⋯Br − electrostatic attractions. The potential energy distributions (PED) were used for the assignments of IR and Raman frequencies in the experimental and calculated spectra of the title compound. The FTIR spectrum of ( 1 ) is consistent with the X-ray results. Interpretation of the 1 H and 13 C NMR spectra in DMSO- d 6 has been based on 2D experiments. The calculated GIAO/B3LYP/6-311++G(d,p) magnetic shielding constants have been used to predict 1 H and 13 C chemical shifts for the optimized structures of ( 2 ) and ( 3 ). [ABSTRACT FROM AUTHOR]

The 1:2 complex ( 1 ) of dimethylphenyl betaine (DMPB) with two molecules of 2,6-dichloro-4-nitro-phenol (DCNP) was prepared and characterized by X-ray diffraction, B3LYP/6-311++G(d,p) and B3LYP-D3/6-311++G(d,p)calculations, FTIR and NMR spectroscopies. The crystal is monoclinic, space group P 2 1 / c with Z = 4. The protons at the oxygen atoms of phenols are bonded to each oxygen atoms of the DMPB carboxylate group by two nonequivalent H-bonds with the O H⋯O distances of 2.473(5) and 2.688(4) Å. Both H-bonds in the optimized structures 2 (in vacuum), 3 (in DMSO solution) and dispersion-correlated functional (D3) 4 (in vacuum) are comparable and are slightly shorter than O(6) H(O6)⋯O(2) in the crystal. The FTIR spectrum of 1 shows a broad absorption in the 3400–2000 cm −1 region corresponding to a longer hydrogen bond and a broad absorption in the 1800–500 cm −1 region caused by the shorter H-bond. The relations between the experimental 13 C and 1 H chemical shifts ( δ exp ) of the investigated compound 1 in DMSO solution and GIAO/B3LYP/6-311++G(d,p) magnetic isotropic shielding constants ( σ calc ) obtained by using the screening solvation model (COSMO) for 3 are linear and reproduce well the experimental chemical shifts described by the equation: δ exp = a + b σ calc . [ABSTRACT FROM AUTHOR]