Search

Easy crystallization distinguishes xylitol from other sugars, which usually condense into a syrup from aqueous solution. Although two polymorphs, i.e. metastable monoclinic and high‐density orthorhombic, have been reported for xylitol, only the latter is in practical use. Under high pressure, the same orthorhombic phase has been obtained by both isothermal and isochoric recrystallization. The stability of the orthorhombic xylitol phase to 5.0 GPa has been correlated with a uniform compression of all hydrogen bonds and some flexibility of the molecular conformation, which cushion the pressure‐induced local strains. The anisotropic compressibility of xylitol and its thermal expansion are consistent with the rule of inverse effects of pressure and temperature. This inverse strain relationship has been correlated with the dimensions and orientation of xylitol molecules in the crystal structure. [ABSTRACT FROM AUTHOR]

The 1:2 complex of 1,4-dimethylpiperazine mono-betaine (MBPZ) with squaric acid (H2SQ) has been characterised by single-crystal X-ray analysis, FTIR and NMR spectroscopies, and by DFT calculations. The crystals are monoclinic, space groupP21/c. Two MBPZ cations and four hydrogen squarate anions (HSQ− ) are linked by strong O(1)–H…O(13) (2.525(4) Å), O(14)–H…O(21) (2.511(4) Å) and N(4)–H…O(23) (2.607(3) Å) hydrogen bonds into a cyclamer. In turn, the cyclamers are linked into a helixthrough two O(24)–H…O(11) hydrogen bonds of 2.516(4) Å. The piperazinium ring has a chair conformation with N(4)–CH3and N(1)–CH2COOH substituents in the equatorial positions, and N(1)–CH3in the axial position. The FTIR spectrum is consistent with the crystal data. Two models of the 1:2 complex of MBPZ with H2SQ have been optimised at the B3LYP/6-311++G(d,p) level of theory and have been used to calculate harmonic IR frequencies. One of the models (2) is dominated by electrostatic attraction between NH(4)+and HSQ− , whereas in the other (3) squaric acid interacts with a zwitterionic MBPZ through the O–H…O and O–H…N hydrogen bonds. [ABSTRACT FROM PUBLISHER]

Abstract: The location of H-atoms sites in carboxylic-acid dimers has been related to the crystal environment. It has been shown that the H-sites are coupled to the orientation of carboxylic-acid groups. Consequently, the H-bonds can be strained and the H-atoms destabilized and disordered by the symmetric crystal environment of symmetric molecules. The coupling results in the O⋯O distance contraction by about 0.015Å in carboxylic acids with disordered H-atoms, this magnitude calculated from H-bonds strain being consistent with that observed in crystal structures. This strain analysis provides an easy method of locating the H-atoms in hydrogen bonds between carboxyl groups, verifying experimental data determined by X-ray diffraction, calculating the magnitudes of O⋯O distance contraction and molecular reorientations induced by the H-atoms disordering structural effects, and predicting properties related to the H-atom dynamics. The survey of carboxylic-acid structures corroborates the effects of the molecular environment on the H-sites and hydrogen-bond dimensions. [Copyright &y& Elsevier]

Abstract: Intermolecular interactions and the role of fluorine substitution have been investigated for a halogenated-ethane anesthetic. 2-Bromo-2-chloro-1,1,1-trifluoroethane, BrClCHCF3 (Halothane), has been in situ pressure frozen in a diamond anvil cell and its structure determined by single-crystal X-ray diffraction at 1.85(5)GPa/296K. Crystal is triclinic, space group . In this racemic structure the enantiomorphic molecules are substitutionally disordered at the same general positions in that way that bromine and chlorine atoms occupy the same site at the 50:50 ratio. Despite the fact that only the Br and Cl atoms are disordered, the crystal packing is dominated by halogen⋯halogen and halogen⋯hydrogen interactions. This X-ray diffraction study provides structural explanation of considerably increased vapor pressure of Halothane compared to its hydrogenated analogue. [Copyright &y& Elsevier]

The competing effects of squeezed OH...O bonds, destabilizing the H-atom position, and of displaced hydrogen donor and acceptor groups, favouring the ordered H-atom sites, have been tuned by pressure in the pressure-frozen dichloroacetic acid. Its structure has been determined at 0.1, 0.7, 0.9 and 1.4 GPa: in this pressure range the crystals are stable in the monoclinic space group P21/ n. The molecules are O—H...O hydrogen bonded into dimers, which in turn interact via a unique pattern of halogen...halogen contacts. Between 0.1 and 1.4 GPa the OH...O bond is squeezed from 2.674 (13) to 2.632 (9) Å. Within the pressure range investigated the hydrogen bonds are squeezed and the shear displacement of the molecules compensate, and the H atoms remain ordered. [ABSTRACT FROM AUTHOR]

A novel anhydrous 1:1 and 2:1 complexes of quinoline betaine (QB) with perchloric acid have been prepared and their structures determined by X-ray diffraction. The 1:1 complex betaine is protonated and the carboxylate group forms a hydrogen bond with the ClO4 ion: O⋯O distance is 2.820(3) A˚. In the 2:1 complex, the carboxylate group of a pair of QB molecules are bridged by a proton to form dimeric cation in non-planar configuration, [(QB)2H]+, featuring a very strong hydrogen bond of the length 2.453(3) A˚. The FTIR spectrum of the 1:1 complex shows a strong absorption at ca. 3100 cm−1 due to the νOH vibration. Broad and intense absorption in the 1500–400 cm−1 region in the spectrum of the 2:1 complex is typical for the very short hydrogen bonds. B3LYP calculations predict slightly shorter hydrogen bonds with different orientation of the ring vs. COOH group than these observed in crystals. [Copyright &y& Elsevier]

The title compound, C7H6Cl2N4, forms a layered structure stabilized by short C—H⋯N and Cl⋯Cl contacts. [ABSTRACT FROM AUTHOR]

• Structure of 8 - hydroxyquinoline betaine monohydrate was solved by X-ray. • The one proton of disordered water molecules is shared between two half-occupied sides. • Three broad bands classify the FTIR spectrum as the ABC type. • PED are used to assign the bands in the vibrational spectrum. • Hirshfeld surface, Mulliken atomic charges, MEP, HOMO-LUMO were computed. • The assignment of 1H and 13C resonance signals are based on the 2D measurements. Molecular structure and properties of 8-hydroxyquinoline betaine monohydrate (1-carboxymethyl-8-hydroxyquinolinium inert salt monohydrate) were studied by X-ray diffraction, DFT calculations, FTIR and NMR spectra. In the crystals, 8-hydroxyquinoline betaine and water are bonded by an intermolecular and asymmetric COO···H 2 O hydrogen bond of 2.782(3) Å. The water molecules are disordered so that one of the proton is shared between two half occupied sites. The hydroxyl group of quinoline is bonded to the neighboring molecule by the O−H···OOC hydrogen bond of 2.571(3) Å. The molecular geometry, Hirshfeld surface, Mulliken atomic charge distribution, molecular electrostatic potential, frontier molecular orbitals, vibrational wavenumbers, magnetic isotropic shielding constants were determined using the density functional theory (DFT/B3LYP) with 6–311++G(d,p) basis set. The FTIR spectrum shows a characteristic ABC structure, typical of medium-short hydrogen bonds. The potential energy distribution (PED) was used to assign the bands in the vibrational spectrum. 1H and 13C NMR spectra were analyzed. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The ionophoric antibiotic lasalocid acid has been converted to a novel 6-bromohexyl ester (LASBR) and its structure has been determined in the crystal by X-ray diffraction and in solution by NMR and FT-IR methods. In the crystal two symmetry-independent LASBR molecules are present. The structure of LASBR in solution is slightly different because the strongest intramolecular C(1)Hogen bond in the pseudo-aromatic ring becomes partially broken and a new hydrogen bond between O(4)H and carbonyl group C(13)ed. LASBR forms complexes with Li+, Na+ and K+ cations of exclusively 1:1 stoichiometry. The structures of complexes have been studied and visualized using semi-empirical calculation based on results of spectrometric and spectroscopic investigation. It is demonstrated that in contrast to lasalocid acid the novel ester forms preferential complexes with Li+ cation. [Copyright &y& Elsevier]

Abstract: Effects of methylation for intermolecular interactions and lipophilicity have been studied for a series of methylated 4,5-dihydro-6-hydroxypyridazine-3-carboxylic and 6-hydroxypyridazine-3-carboxylic acids (1 and 2). In solution they exist in equilibrium of the lactam and lactim tautomers, with the reverse preferences for analogs 1 and 2, which affect the syntheses of their methylated derivatives. Carboxylic acid 2 preferably crystallizes as a hydrate, built of carboxylate anions and hydronium cations 2 − H3O+, hydrogen bonded into catemeric patterns involving both ions. In methyl 4,5-dihydro-6-oxopyridazine-3-carboxylate (4A) the molecules are NH⋯O hydrogen bonded into chains. In both structures 2 − H3O+ and 4A, there are relatively strong CH⋯O hydrogen bonds, arranging the molecules into sheets. The increased lipophilicity of the methylated derivatives has been correlated with the formation of CH⋯O bonds. [Copyright &y& Elsevier]

Abstract: The 2:2 hydrogen-bonded complex between Kemp’s triacid (KTA) and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) has been synthesised and studied by X-ray and FT-IR methods. The crystals of KTA–MTBD are orthorhombic, space group is Pbca with a= 15.3435(9)Å, b =13.0764(7)Å, c= 21.2403(14)Å, and Z =8. In the solid state two protonated MTBD and two deprotonated KTA molecules form a hydrogen-bonded dimer. The dimer structure is stabilised by two OH⋯O− middle strength and two N+H⋯Otermolecular hydrogen bonds as well as by two OO− very strong intramolecular hydrogen bonds. The existence of these three types of hydrogen bonds is well visible in the FT-IR spectrum of the complex and is discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: Synthesis of new (E)-(-)-[2-methyl (2), ethyl (3), isopropyl (4), benzyl (5) and phenyl (6)] carbonylmethylideno-17-oxosparteine by the Eschenmoser coupling reaction has been described. Stereochemistry of these compounds has been determined by 13C and 1H NMR and that of compound 2 additionally by X-ray analysis. The Haasnoot equation has been used to determine the HCCH dihedral angle in (E)-(-)-2-methyl-(methylcarbonylomethylideno)-17-oxosparteine on the basis of NMR spectroscopy. [Copyright &y& Elsevier]

Abstract: Structure of the 2:2 complex of cyclic oxaalkyl diamide of o-phthalic acid (CPhDA) with sodium perchlorate is studied by X-ray diffraction, ESI-MS, FT-IR, 1H and 13C NMR as well as PM5 semiempirical methods. The crystal space group is P2 1 /n with a =8.599(1)Å, b =14.802(2)Å, c =13.988(2)Å, β= 93.37(1)° and Z =4. In the dimeric crystal structure each sodium cation is coordinated by oxygen atoms of two CPhDA molecules. The ESI-MS measurements have proved that in the gas phase the 2:2 (or 1:1) as well as 2:1 complexes are formed. In the acetonitrile solution the equilibrium between the 2:2 and 1:1 complexes is found. The structures of the 2:2, 1:1 and 2:1 complexes of CPhDA with sodium cation are visualized using the PM5 method and discussed in detail. [Copyright &y& Elsevier]

Abstract: Intermolecular interactions in a synthesized C-acid, 4-nitrophenyl[bis(ethylsulfonyl)]methane have been analysed and its structure determined by X-ray diffraction. The molecular packing in the crystal is governed by CH…O. The dimensions of the hydrogen bonds and the shortest non-bonded distances are also determined. The possible implications in the formation of the hydrogen bonded complexes with the strong organic bases are also discussed. [Copyright &y& Elsevier]

Abstract: Crystal structure of monensin A rubidium salt dihydrate, [Rb(C36H61O11)·2H2O], has been studied by X-ray diffraction, FT-IR spectroscopy and PM5 semiempirical methods. The crystal space group is P212121 with a =12.6153(7), b =16.4841(10), c =19.4840(12) and Z =4. The Rb–O bond lengths are between 2.788(7) and 2.901(6)Å. The carboxyl group of monensin A is deprotonated and engaged in two intramolecular O(11)–H···O(1) of 2.52(1)Å and O(10)–H···O(2) of 2.60(1)Å hydrogen bonds with hydroxyl groups, accompanied with formation of a pseudo-cyclic structure. This structure is stabilised by the coordination of the Rb+ cation by oxygen atoms. Two water molecules are involved in the weak intermolecular hydrogen bond between the different species forming a supramolecule. The IR spectrum of the crystal is consistent with the results obtained by the X-ray study and provides spectroscopic evidence for the complex formation. The calculated structure and the structural parameters of the monensin A rubidium salt are comparable with those determined by the X-ray study. [Copyright &y& Elsevier]

Abstract: Crystal structure of the inclusion crystal of monensin A lithium salt with acetonitrile, Li(C36H61O11)·CH3CN, has been studied by X-ray diffraction, FT-IR spectroscopy and PM5 semiempirical methods. Monensin A lithium salt:acetonitrile (1:1) complex is isostructural with the previously studied crystals of monensin A sodium salt:acetonitrile (1:1) complex. The crystal space group is P212121 with a =12.6937(9), b =16.7689(12), c =18.4927(12) and Z =4. The Lingths are between 2.022(5) and 2.633(5)Å. The oxygen atoms of the carboxylate group are involved in two intramolecular hydrogen bonds of different strength: O(11)xb7;·O(1) of 2.582(2)Å and O(10)xb7;·O(2) of 2.636(2)Å. These two hydrogen bonds bind two ends of the monensin molecule, which in this way forms a pseudo cyclic structure wrapped around the Li+ cation. The IR spectrum of the crystal confirms the results obtained by the X-ray study and provides spectroscopic evidence for the formation of the inclusion complex. The calculated structure of the monensin A lithium salt and the structural parameters are comparable with those determined by X-rays. [Copyright &y& Elsevier]

Abstract: Crystal structure of the inclusion crystal of monensin A sodium salt with acetonitrile, Na(C36H61O11) CH3CN, has been studied by X-ray diffraction, FT-IR spectroscopy, and PM5 semiempirical methods. The space group of the crystal is P212121 with a =12.8116(5), b =16.5851(6), c =18.6807(6) and Z =4. Within the inclusion complex the Na+ cation is coordinated by six O atoms of monensin A molecule in a distorted octahedron geometry. The Na–O bond lengths are between 2.3276(13) and 2.6033(14)Å. The oxygen atoms of the carboxylate group are involved in two intramolecular hydrogen bonds of different strength: O(11)–H⋯O(1) of 2.554(2)Å and O(10)–H⋯O(2) of 2.683(2)Å. These two hydrogen bonds bind two ends of the monensin molecule, which in this way forms a pseudo cyclic structure wrapped around the Na+ cation. The IR spectrum of the crystal confirms the results obtained by the X-ray study and provides spectroscopic evidence for the formation of the inclusion complex. The calculated structure of the monensin A sodium salt and the structural parameters are comparable with those determined from the X-ray data. [Copyright &y& Elsevier]

Abstract: A novel betaine derivative, 3-(2-amino-pyridinium)-propionate monohydrate, has been synthesized and its structure studied by X-ray diffraction, FTIR, Raman, 1H and 13C NMR spectroscopies and by DFT calculations. The crystals are monoclinic, space group P21/c with a=8.0800(16), b=15.242(3), c=7.1698(14)Å, β=104.30(3)° and Z=4. Each oxygen atom of the carboxylate group is engaged in two intermolecular hydrogen bonds, one with water molecule and the other with amine group. The water molecules link the molecules of 3-(2-amino-pyridinium)-propionate into planar zigzag chains along the b axis. The screening constants for 1H and 13C atoms have been calculated by GIAO/B3LYP/6-31 G(d,p) and analyzed. Linear correlations between the experimental 1H and 13C chemical shifts and the computed screening constants have been obtained. Raman and FTIR spectra of the title betaine have been investigated. [Copyright &y& Elsevier]

Abstract: Azido-tetrazolo tautomeric conversions have been investigated by NMR, X-ray and semiempirical calculations in a series of new 7(8)-methylated azolopyridazines. The transannular effects of the triazole- and tetrazole-ring fusion with pyridazine have been compared, and the thermodynamic equilibrium of the 7- to 8-methyl conversions of the 6-azido-7(8)-methyltetrazolopyridazines monitored in the function of temperature by 1H NMR shifts of the pyridazine hydrogens. General rules governing the azido-tetrazolo conversions in azolopyridazines have been formulated and based on the molecular structure and strains induced in the pyridazine ring by its substituents. [Copyright &y& Elsevier]

Understanding the factors governing the formation of supramolecular structures and phase transitions between various forms of molecular crystals is pivotal for developing dynamic, stimuli‐responsive materials and polymorph‐controlled syntheses. Here, we investigate the pressure‐induced dynamic of both the intrinsic molecular structure and the supramolecular network of a predesigned polyhedral oxo‐centered zinc cluster incorporating monoanionic N,N'‐diphenylformamidinate and featuring N‐bonded phenyl groups in close proximity to the primary coordination sphere. We demonstrate that the model oxo cluster is prone to undergoing pressure‐induced conformational transformations of the secondary coordination sphere and simultaneous stepwise (initially every second polyhedral molecule undergoes the conformational transformations) and reversible transitions from an ambient phase α to high‐pressure phases β and γ, as single‐crystal‐to‐single‐crystal events. The observed phase transitions illustrate the key role of an interplay between the low‐energy conformation perturbations and cooperative intra‐ and intermolecular noncovalent interactions. [ABSTRACT FROM AUTHOR]

A complex of 5,5′-dibromo-2,2′-biphenol with 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene hydrobromide has been studied using X-ray diffraction, FT-IR, and 1H NMR spectroscopy. In the crystal structure, a bromide anion is hydrogen-bonded with MTBDH+ cation and two hydroxyl groups of two 5,5′-dibromo-2,2′-biphenol molecules. In the solid state, the Br− anion is an acceptor in N+–H⋯Br−, and two O–H⋯Br− intermolecular hydrogen bonds. In chloroform and acetonitrile, the structure of the complex assumes a new structure due to almost complete dissociation of protonated MTBD molecule. In chloroform, the MTBDH+ cation is hydrogen-bonded with 5,5′-dibromo-2,2′-biphenol whereas in acetonitrile it is free and solvated by the solvent. In both cases, the 5,5′-dibromo-2,2′-biphenol molecule is hydrogen-bonded to the bromide anion. [Copyright &y& Elsevier]

Isobaric freezing of 1,1,1-trichloroethane yields crystals where all the intermolecular contacts are much longer than the sums of the van der Waals radii and only in the structure compressed to ca.1.2 GPa do the first ClCl contacts become commensurate with this sum. This sheds new light on the range of intermolecular interactions that are capable of controlling molecular re-orientation and arrangement. [ABSTRACT FROM AUTHOR]

The molecular structure and spectroscopic properties of the 1:1 complex of quinuclidine (Q) with 2,6-dichloro-4-nitrophenol (DCNP) have been characterized by X-ray diffraction, B3LYP/6–311++G(d,p) calculations, UV–vis, FTIR and NMR spectroscopies. In the crystals the proton from DCNP is transferred to Q, and the ionic pair is linked by the N + H⋯O − hydrogen bond of 2.620(2) Å, while in the theoretically optimized structure a molecular complex is present. The band at 405 nm in the UV–vis spectra in ethanol provides the evidence of proton transfer. The calculated natural atomic charges (NBO) show the differences between neutral components Q and DCNP, and the corresponding cation Q + H or anion DCNP − . The potential energy distribution (PED) has been used to assign the vibrational spectra. [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 molecular structure of 1:1 complex formed between the naturally occurring polyether ionophore, called lasalocid acid (LAS) and propargylamine (PROP) is studied by X-ray, FT-IR, 1 H NMR, 13 C NMR and ESI-MS methods. The complex formed between deprotonated LAS acid and protonated PROP molecule is stabilized by intra- and inter-molecular hydrogen bonds. The protons of the protonated amine group are hydrogen bonded to etheric and hydroxyl oxygen atoms of the LAS anion. The similarity of the FT-IR spectra of the LAS–PROP complex in solid state and in solution demonstrated that the molecular structures of the complex in both states are comparable. It is shown that LAS in solution can form concurrent complexes with metal cations (M = Li + , Na + , K + ) and amine existing in equilibrium. Analysis of the structures of lasalocid complexes is important for a better understanding of the antibacterial and anticancer properties of lasalocid acid. [ABSTRACT FROM AUTHOR]

Abstract: For the first time the structure of the complex formed between N-allylamide of monensin A (M-AM2) and divalent cation (Sr2+) has been studied by X-ray crystallography and FT-IR spectroscopy. The crystal structure of this complex contains one Sr2+ cation coordinated by six O atoms of M-AM2 molecule, one oxygen atom of the perchlorate anion and the nitrogen atom of the acetonitrile molecule. The M-AM2 molecule is additionally tied by an intramolecular hydrogen-bonded chain [O(3)H⋯O(9)H⋯O(10)H⋯O(1)e crystal data, FT-IR spectra and semiempirical calculations show that the oxygen atom of the amide group is not involved in the coordination of the Sr2+ cation. In the gas phase the formation of two types of (M-AM2+Sr)2+ and (M-AM2+Sr+ClO4)+ complexes is detected using ESI mass spectrometry and their structures are visualized by PM5 semiempirical calculations. [Copyright &y& Elsevier]

The 1H and 19F NMR spectra of N-α-fluoro-β-trifluoromethylenamines and isostructural N-β-fluoro-β-trifluoromethylenamines of nucleobases dissolved in CDCl3and DMSO-d6have shown distinct differences associated with the conformational conversion between the Zand Estereoisomers. In the Estereoisomer the tetrafluoropropenyl group is rotated relative to the heteroring plane, whereas the Zstereoisomer assumes the most planar structure. The flat conformation of the Zstereoisomer is stabilised by internal hydrogen bonding between Cα–H and the carbonyl oxygen (pyrimidinic bases) or the endocyclic nitrogen (purinic bases). Large variations in the magnitudes of the chemical shifts of Cβ–H, Cα–F, C6–H and C8–H were observed, i.e.the chemical shift increased with increasing polarity and ability of DMSO-d6to establish intermolecular hydrogen bonds in competition with intramolecular hydrogen bonds. The (Z)-N4-benzoyl-N1-(1,3,3,3-tetrafluoroprop-1-enyl)cytosine crystals undergo a phase transition at 230 K induced by the tetrafluoropropenyl substituent reorientations. Between 300 and 230 K the molecules are present in two conformations, and below 230 K the molecules gradually assume five conformations, remaining in a stable equilibrium with intermolecular forces, evidenced by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Abstract: A complex between a new N-phenylamide of monensin A (M-AM1) and sodium chloride has been synthesised and studied by X-ray diffraction and FT-IR spectroscopy. The crystal structure of the complex between M-AM1 and sodium chloride with acetonitrile was examined using X-ray diffraction and discussed in detail. Its structure is stabilised by coordination of the Na+ cation with oxygen atoms. The Na–O bond lengths are between 2.382(2) and 2.562(2)Å. The chloride anion is involved in a weak intermolecular hydrogen bond between different species forming a supramolecule. The ESI-MS spectra indicate that the amide forms stable complexes of exclusively 1:1 stoichiometry with Na+ cations. The FT-IR spectrum of the crystal is consistent with the results obtained by the X-ray study and provides spectroscopic evidence for the complex formation. Due to its specific structural properties N-phenylamide of monensin A efficiently binds sodium chloride. The result of the PM5 semiempirical calculation is in agreement with the spectroscopic data and allows visualisation of the structure of the M-AM1–Na+ complex. The new amide of monensin A has been additionally tested in view of its antimicrobial properties. It shows great activity towards some strains of Gram-positive bacteria (MIC=6.25–12.5μg/ml). [Copyright &y& Elsevier]

Abstract: A new lasalocid 2-naphthylmethyl ester (NAFB) has been synthesised and studied by X-ray, 1H NMR, 13C NMR, FT-IR, UV–vis, fluorescence-spectroscopy as well as by the PM5 semiempirical method. The crystals of NAFB are monoclinic, space group P21 with a =10.120(2)Å, b =18.245(3)Å, c =12.354(3)Å, β =109.65(3)˚ and Z =2. The molecular conformation of NAFB in the solid state is stabilized by three intramolecular hydrogen bonds, and no intermolecular H-bonds are formed. The FT-IR spectrum of NAFB in chloroform indicates equilibrium between two NAFB conformers. In the first conformer the keto group forms an intramolecular hydrogen bond, while in the second one this group is not involved in any hydrogen bonds. The two structures of NAFB are calculated by the PM5 method and discussed in detail. [Copyright &y& Elsevier]

Abstract: 1,3-Bis(carboxymethyl)imidazolium bromide [(C7H9N2O4)+Br−] has been studied by X-ray diffraction, FT-IR and Raman spectroscopy. In the crystalline state, two 1,3-bis(carboxymethyl)imidazolium bromide molecules are hydrogen-bonded via carboxylic groups forming a symmetric dimer. Within the dimer structure the other carboxylic groups are hydrogen bonded to Br− anions. Both types of intermolecular hydrogen bonds are the relatively weak. In the solid state the Br− anions interact with both ring and with the aliphatic C–H protons. Furthermore, the betaine derivative form in the solid state a chain via strong homoconjugated (O–H···O)− hydrogen bonds. The nature of these hydrogen bonds is well reflected by the proton vibrations in the FT-IR spectra of the compounds studied. As follows from the ESI-MS results the compounds studied are not able to complex mono- and di-valent metal cations in the gas phase. [Copyright &y& Elsevier]

Abstract: Bis(8-oxy-1-methylquinolinium) hydroiodide has been studied by X-ray diffraction, FT-IR, 1H and 13C NMR spectroscopy. In the crystalline state a homoconjugated OH⋯O− hydrogen bond is formed. As indicated by the X-ray data this hydrogen bond is very short (2.457Å) and structurally symmetrical. The existence of this bond is manifested in the FT-IR spectra by an intense and broad band in the 1500–400cm−1 region. This type of absorption indicates that this hydrogen bond can be described by one very broad potential energy minimum in which the proton shows a large proton polarizability due to its fast fluctuations, i.e., it shows the so-called Zundel’s polarizability. [Copyright &y& Elsevier]

Abstract: 8-Hydroxy-1-methylquinolinium iodide monohydrate [(C10H10NO)+I−·H2O] has been studied by X-ray diffraction, FT-IR, 1H and 13C NMR spectroscopy. In the crystalline state, the iodide anion is hydrogen-bonded to the water molecule, which in turn is hydrogen bonded to the 8-OH group of the 8-hydroxyquinolinium ring, forming of a symmetric dimer. In acetonitrile and DMSO-d 6 the hydrate assumes a new structure due to almost complete dissociation of the water molecule from the complex structure. In acetonitrile the 8-OH group is hydrogen-bonded to the iodide anion, whereas in DMSO-d 6 it forms the hydrogen bond with the solvent molecules. This 8-OH⋯O(DMSO-d 6) hydrogen bond is the strongest within the structure of the hydrate. [Copyright &y& Elsevier]

• 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]

N- Methylpyrrolidine betaine (N- carboxymethyl- N- methyl-pyrrolidinium, inner salt, MPRB) cocrystallizes with p -hydroxybenzoic acid (HBA) at the 1:1 ratio. The complex is characterized by single-crystal X-ray diffraction, FTIR and NMR spectra. The pyrrolidinium ring adopts an envelope conformation with the methyl group in axial and the carboxymethyl substituent in the equatorial positions. In the cocrystal the COO⋯HO and COO⋯HOOC hydrogen bonds are of 2.574 (4) and 2.586 (4) Å, respectively. The molecular geometry, Hirshfeld surface, natural bond orbitals (NBO), molecular electrostatic potential (MEP), vibrational wavenumbers, magnetic isotropic shielding constants were performed using the density functional theory (DFT/B3LYP) with 6–311++G (d,p) basis set. The molecular structures of isolated 1:1 and 1:2 complexes were optimized. The potential energy distribution (PED) of the IR vibrational modes were used to assign the bands in the IR spectrum. Diagrams of the HOMO and LUMO of components and complex are presented. Theoretical and experimental results are in a good agreement. Image 1 • The 1:1 complex of N-methylpyrrolidine betaine with p -hydroxybenzoic acid was prepared. • Structure of complexes were characterized by X-ray diffraction, FTIR and NMR spectra. • The structures of 1:1 and 1:2 complexes were optimized by the B3LYP/6-311++G(d,p) approach. • The molecules are linked through the OH∙∙∙OOC and COOH∙∙∙OOC hydrogen-bonds. • The IR and NMR experimental and computed spectra were discussed. [ABSTRACT FROM AUTHOR]