Contrast effect of hydrogen bonding on the acceptor and donor OH groups of intramolecularly hydrogen-bonded OH pairs in diols

We studied the influence of hydrogen bonding on the fundamental and overtone bands of the OH-stretching vibration of each OH group in the intramolecularly hydrogen-bonded OH(I)::OH(II) pair in 1,2-, 1,3- and 1,4-diols. The hydrogen bonding between the two OH groups significantly increases in strength from the five-membered ring of a 1,2-diol to the seven-membered ring of a 1,4-diol. Although the hydrogen bonding does not affect the vibrational property of the OH(II) (or acceptor), it significantly influences the OH(I) (or donor). As the hydrogen bonding becomes stronger from a 1,2- to a 1,4-diol, the fundamental band of the OH-stretching shifts downwards by from about 50 to 140 cm(-1), and the overtone band markedly decreases in intensity, although the effect on the intensity and bandwidth of the fundamental band varies among 1,2-, 1,3- and 1,4-diols. The quantum-mechanically calculated normal frequencies of the acceptor and donor OH groups in the hydrogen-bonded ring are in good agreement with the observed frequencies. The calculated interatomic distance between the O of an acceptor OH and the H of a donor OH is the shortest for a 1,4-diol, which is consistent with the largest frequency shift caused by the hydrogen bonding.     

Cooperativity in alkane-1,2- and 1,3-polyols: NMR,QTAIM, and IQA study of O─H…OH and C─H…OH bonding interactions

Proton nuclear magnetic resonance chemical shifts and atom–atom interaction energies for alkanepolyols with 1,2-diol and 1,3-diol repeat units, and for their 1:1 pyridine complexes, are computed by density functional theory calculations. In the 1,3-polyols, based on a tG'Gg' repeat unit, the only important intramolecular hydrogen bonding interactions are O─H^…OH. By quantum theory of atoms in molecules analysis of the electron density, unstable bond and ring critical points are found for such interactions in 1,2-polyols with tG'g repeat units, from butane-1,2,3,4-tetrol onwards and in their pyridine complexes from propane-1,2,3-triol onwards. Several features (OH proton shifts and charges, and interaction energies computed by the interacting quantum atoms approach) are used to monitor the dependence of cooperativity on chain length: This is much less regular in 1,2-polyols than in 1,3-polyols and by most criteria has a higher damping factor. Well defined C─H^…OH interactions are found in butane-1,2,3,4-tetrol and higher members of the 1,2-polyol series, as well as in their pyridine complexes: There is no evidence for cooperativity with O─H^…OH bonding. For the 1,2-polyols, there is a tenuous empirical relationship between the existence of a bond critical point for O─H^…OH hydrogen bonding and the interaction energies of competing exchange channels, but the primary/secondary ratio is always less than unity.     

Supramolecular formation of large hydrogen-bonded rings in the structures of two amino acid derivatives

Two new amino acid derivatives N-(2-oxopyrrolidin-1-ylmethyl)-l-valine (PMV) and N,N-bis(2-oxopyrrolidin-1-ylmethyl)-β-alanine (PMA) were synthesized and their structures were determined by single crystal X-ray crystallography. The geometry and conformation of both molecular aggregates and their hydrogen bond networks are not similar. In the PMV crystal structure, PMV and the solvent water molecule are linked by O–H⋯O intermolecular hydrogen bonds resulting in two ring motifs R₁₂¹²(48) and R₄⁴(22). A three-dimensional supramolecular structure is formed by hydrogen bonds N–H⋯O between the layers. In the PMA crystal structure, each water molecule connects three PMA molecules through O–H⋯O intermolecular hydrogen bonds, and a ring motif R₄⁴(24) is formed in the structure. But there is no hydrogen bond interaction between the layers, in which van der Waals' interaction is involved only.     

Intramolecular O―H⋯O and C―H⋯O hydrogen bond cooperativity in D‐glucopyranose and D‐galactopyranose—A DFT/GIAO,QTAIM/IQA,and NCI approach

Density functional theory calculations are used to compute proton nuclear magnetic resonance (NMR) chemical shifts, interatomic distances, atom–atom interaction energies, and atomic charges for partial structures and conformers of α‐D‐glucopyranose, β‐D‐glucopyranose, and α‐D‐galactopyranose built up by introducing OH groups into 2‐methyltetrahydropyran stepwisely. For the counterclockwise conformers, the most marked effects on the NMR shift and the charge on the OH1 proton are produced by OH2, those of OH3 and OH4 being somewhat smaller. This argues for a diminishing cooperative effect. The effect of OH6 depends on the configuration of the hydroxymethyl group and the position, axial or equatorial, of OH4, which controls hydrogen bonding in the 1,3‐diol motif. Variations in the interaction energies reveal that a “new” hydrogen bond is sometimes formed at the expense of a preexisting one, probably due to geometrical constraints. Whereas previous work showed that complexing a conformer with pyridine affects only the nearest neighbour, successive OH groups increase the interaction energy of the N⋯H1 hydrogen bond and reduce its length. Analogous results are obtained for the clockwise conformers. The interaction energies for C―H⋯OH hydrogen bonding between axial CH protons and OH groups in certain conformers are much smaller than for O―H⋯OH bonds but they are largely covalent, whereas those of the latter are predominantly coulombic. These interactions are modified by complexation with pyridine in the same way as O―H⋯OH interactions: the computed NMR shifts of the CH protons increase, the atom–atom distances are shorter, and interaction energies are enhanced.     

Electron density topological analysis of hydrogen bonding in glucopyranose and hydrated glucopyranose

Topological analysis of the electron density profiles and the atomic basin integration data for the most energetically favorable (4)C(1) and (1)C(4) conformers of beta-D-glucopyranose, calculated at the B3LYP/6-31+G(d), MPWlPW91/6-311+G(2d,p), and MP2/6-31+G(d) levels, demonstrates that intramolecular hydrogen bonding between adjacent ring OH groups does not occur in glucopyranose, given the need to demonstrate a bond critical point (BCP) of correct (3,-1) topology for such an interaction to be termed a hydrogen bond. On the other hand, pyranose ring OH groups separated by three, rather than just two, carbon atoms are able to form an intramolecular hydrogen bond similar in topological properties and geometry to that found for propane-1,3-diol. Vicinal, equatorial OH groups in the (4)C(1) conformer of glucopyranose are, however, able to form strong bidentate hydrogen bonds with water molecules in a cooperative manner, each water molecule acting simultaneously as both hydrogen bond donor and acceptor, and characterized by (3,-1) bond critical points with increased values for the electron density and the Laplacian of rho(r) compared to an isolated ethane-1,2-diol/water complex.     

Insights into the cooperativity between multiple interactions of dimethyl sulfoxide with carbon dioxide and water

Interactions of dimethyl sulfoxide with carbon dioxide and water molecules which induce 18 significantly stable complexes are thoroughly investigated. An addition of CO₂ or H₂O molecules into the DMSO⋯1CO₂ and DMSO⋯1H₂O systems leads to an increase in the stability of the resulting complexes, in which it is larger for a H₂O addition than a CO₂. The overall stabilization energy of the DMSO⋯1,2CO₂ is mainly contributed by the S=O⋯C Lewis acid–base interaction, whereas the O − H⋯O hydrogen bond plays a significant role in stabilizing complexes of DMSO⋯1,2H₂O and DMSO⋯1CO₂⋯1H₂O. Remarkably, the complexes of DMSO⋯2H₂O are found to be more stable than DMSO⋯1CO₂⋯1H₂O and DMSO⋯2CO₂. The level of the cooperativity of multiple interactions in ternary complexes tends to decrease in going from DMSO⋯2H₂O to DMSO⋯1CO₂⋯1H₂O and finally to DMSO⋯2CO₂. It is generally found that the red shift of the O − H bond involved in an O − H⋯O hydrogen bond increases while the blue shift of a C − H bond in a C − H⋯O hydrogen bond decreases when a cooperative effect occurs in ternary complexes as compared to those of the corresponding binary complexes. © 2018 Wiley Periodicals, Inc.     

Helical supramolecular assembly of N2,N2′‐bis[3‐(morpholin‐4‐yl)propyl]‐N1,N1′‐(1,2‐phenylene)dioxalamide dimethyl sulfoxide monosolvate

In the title compound, C₂₄H₃₆N₆O₆·C₂H₆OS, the carbonyl groups are in an antiperiplanar conformation, with O=C—C=O torsion angles of 178.59 (15) and −172.08 (16)°. An intramolecular hydrogen‐bonding pattern is depicted by four N—H...O interactions, which form two adjacent S(5)S(5) motifs, and an N—H...N interaction, which forms an S(6) ring motif. Intermolecular N—H...O hydrogen bonding and C—H...O soft interactions allow the formation of a meso‐helix. The title compound is the first example of a helical 1,2‐phenylenedioxalamide. The oxalamide traps one molecule of dimethyl sulfoxide through N—H...O hydrogen bonding. C—H...O soft interactions give rise to the two‐dimensional structure.     

Intermolecular interactions in N‐(ferrocenyl­methyl)­anthracene‐9‐carbox­amide

The title compound, [Fe(C₅H₅)(C₂₁H₁₆NO)], was synthesized from the coupling reaction of anthracene‐9‐carboxyl­ic acid and ferrocenyl­methyl­amine. The ferrocenyl (Fc) group and the anthracene ring system both lie approximately orthogonal to the amide moiety. An amide–amide interaction (along the a axis) is the principal interaction [N⋯O = 2.910 (2) Å]. A C—H⋯π(arene) interaction [C⋯centroid = 3.573 (2) Å] and a C—H⋯O interaction [C⋯O = 3.275 (3) Å] complete the hydrogen bonding; two short (Fc)C⋯C(anthracene) contacts are also present.     

Ethyl (E)‐3‐(2‐hydroxy­phenyl)‐2‐(morpholino­carbonyl)­propenoate

The title compound, C₁₆H₁₉NO₅, crystallizes as a centrosymmetric dimer through strong O—H⋯O hydrogen‐bonding interactions between the hydroxy­phenyl and morpholino­carbonyl groups. The morpholino­carbonyl group is almost perpendicular to the propenoate moiety. Electron delocalization in the N—C(=O) fragment leads to the formation of hydrogen‐bonded S(5) ring motifs through C—H⋯O interactions.     

4-(4-Chlorophenyl)-3,7,7-trimethyl-1-[2-(4-nitrobenzoyl)ethyl]-4,7,8,9-tetrahydro-1H-pyrazolo[3,4-b]quinolin-5(6H)-one–ethanol (1/1)

Molecules of the title compound, C₂₈H₂₇ClN₄O₄·C₂H₆O, form a C(6) chain via an N—H⋯O hydrogen bond along the c axis by the operation of a c-glide plane, with N⋯O = 2.761 (3) Å and N—H⋯O = 165°. The mol­ecules are further linked by a weak C—H⋯O interaction, with C⋯O = 3.344 (4) Å and C—H⋯O = 150°. Pendant hydrogen-bonded ethanol solvent mol­ecules are attached to the chains by O—H⋯N hydrogen bonds, with O⋯N = 2.904 (3) Å and O—H⋯N = 175°.     

3,5‐Di­methyl‐1,3,5‐oxadi­azane‐2,4,6‐trione: short intermolecular contacts determining the crystal packing

In the title compound, C₅H₆N₂O₄, the mol­ecules lie across a crystallographic mirror plane. The compound lacks traditional hydrogen‐bond donors, and hence crystals are held together by unusual C=O⋯O, O⋯C and weak C—H⋯O interactions, forming layers. Adjacent layers are arranged in an antiparallel manner, yielding an ABA layer sequence. The intermolecular contacts are quite short; a topological analysis of charge density based on density‐functional‐theory calculations was used for consideration of these short contacts and indicated a strong attractive bonding closed‐shell interaction between these atoms in the crystal structure.     

The Effect of Intermolecular Hydrogen Bonding on the Polyaniline Water Complex

The polyaniline water hydrogen-bonded complex was studied by first-principles calculation. The density functional theory method was used to calculate the structure characters, natural bond orbital charge distribution, infrared spectra and the frontier molecular orbital. Results showed that the H–O···H–N and C–N···H–O type intermolecular hydrogen bonds were formed. The bonds involved in the intermolecular H-bond were all influenced by the hydrogen bonding interaction. During the hydrogen bond formation, the polymer chains in the complexes were all charged, which can be an important factor contributing to the increase of electrical conductivity. The N1–H vibration was strongly influenced, and the locations as well as the intensities of N1–H absorption bands were all changed in the complexes. In the orbital transition of HOMO to LUMO, the electron density transferred from benzenoid ring to quinoid ring.     

Stereoisomers of 1,2‐diaryl‐1,3‐propanediols: erythro forms

Racemic erythro‐1,2‐diphenyl‐1,3‐propane­diol, C₁₅H₁₆O₂, is a model compound representative of erythro forms of structural elements of the 1,2‐diaryl‐1,3‐propane­diol type in lignins. In the crystal structure, the torsion angle between the bulky phenyl groups is −62.26 (11)°. Strong hydrogen bonds take part in a directed co‐operative O—H⋯O—H⋯O—H⋯O—H pattern that is assumed to have a decisive influence on the conformation. This is supported by comparisons with the geometries of related compounds.     

A supramolecular ladder motif in 2‐(2,2,6,6‐tetra­methyl­piperidin‐1‐yl­oxy)­propane‐1,3‐diol

An O—H⋯O hydrogen‐bonded step‐ladder motif was observed in the crystal structure of the title compound, C₁₂H₂₅NO₃. The ladder arrangement is typical of 1,2‐ and 1,3‐diols with a synclinal orientation of the diol functionality.     

N,N′‐Bis(2‐pyridyl)benzene‐1,2‐diamine

Hindered rotation about the partial double C—N bonds between the amine and pyridine moieties in the title mol­ecule, C₁₆H₁₄N₄, results in two different conformations of the N‐aryl‐2‐amino­pyridine units. One, assuming an E conformation, is involved in a pair of N—H⋯N hydrogen bonds that generate a centrosymmetric (8) motif. The second, adopting a Z conformation, is not engaged in any hydrogen bonding and is flattened, the dihedral angle between the benzene and pyridine rings being 12.07 (7)°. This conformation is stabilized by an intramolecular C—H⋯N interaction [C⋯N = 2.9126 (19) Å, H⋯N = 2.31 Å and C—H⋯N = 120°].     

C[triple‐bond]C—H systems as hydrogen‐bond donors and acceptors: trans‐1,2‐diethynylcyclo­hexane‐1,2‐diol and trans‐1,4‐diprop‐2‐ynylcyclo­hexane‐1,4‐diol monohydrate

The title 1,2‐diol derivative, C₁₀H₁₂O₂, crystallizes with two independent but closely similar mol­ecules in the asymmetric unit. Only two of the four OH groups are involved in classical hydrogen bonding; the mol­ecules thereby associate to form chains parallel to the short c axis. The other two OH groups are involved in O—H⋯(C[triple‐bond]C) systems. Additionally, three of the four C[triple‐bond]C—H groups act as donors in C—H⋯O inter­actions. The 1,4‐diol derivative crystallizes with two independent half‐mol­ecules of the diol (each associated with an inversion centre) and one water mol­ecule in the asymmetric unit, C₁₂H₁₆O₂·H₂O. Both OH groups and one water H atom act as classical hydrogen‐bond donors, leading to layers parallel to the ac plane. The second water H atom is involved in a three‐centre contact to two C[triple‐bond]C bonds. One acetyl­enic H atom makes a very short `weak' hydrogen bond to a hydr­oxy O atom, and the other is part of a three‐centre system in which the acceptors are a hydroxy O atom and a C[triple‐bond]C bond.     

2‐(2‐Oxazolin‐2‐yl)benzene‐1,4‐diol: X‐ray and density functional theory studies

In the crystal structure of the title compound, C₉H₉NO₃, there are strong intra­molecular O—H⋯N and inter­molecular O—H⋯O hydrogen bonds which, together with weak inter­molecular C—H⋯O hydrogen bonds, lead to the formation of infinite chains of mol­ecules. The calculated inter­molecular hydrogen‐bond energies are −11.3 and −2.7 kJ mol⁻¹, respectively, showing the dominant role of the O—H⋯O hydrogen bonding. A natural bond orbital analysis revealed the electron contribution of the lone pairs of the oxazoline N and O atoms, and of the two hydr­oxy O atoms, to the order of the relevant bonds.     

2‐Amino‐5‐nitro­thia­zole monoethanol solvate: triply‐interwoven hydrogen‐bonded sheets containing centrosymmetric R(8) and R(38) rings

2‐Amino‐5‐nitro­thia­zole crystallizes from solution in ethanol as a monosolvate, C₃H₃N₃O₂S·C₂H₆O, in which the thia­zole component has a strongly polarized molecular–electronic structure. The thia­zole mol­ecules are linked into centrosymmetric dimers by paired N—H⋯N hydrogen bonds [H⋯N = 2.09 Å, N⋯N = 2.960 (6) Å and N—H⋯N = 169°], and these dimers are linked by the ethanol mol­ecules, via a two‐centred N—H⋯O hydrogen bond [H⋯O = 1.98 Å, N⋯O = 2.838 (5) Å and N—H⋯O = 164°] and a planar asymmetric three‐centred O—H⋯(O)₂ hydrogen bond [H⋯O = 2.07 and 2.53 Å, O⋯O = 2.900 (5) and 3.188 (5) Å, O—H⋯O = 169 and 136°, and O⋯H⋯O = 55°], into sheets built from alternating (8) and (38) rings. These sheets are triply interwoven.     

A novel tubular hydrogen‐bond pattern in a new diazaphosphole oxide: a combination of X‐ray crystallography and theoretical study of hydrogen bonds

In the structure of 2‐(4‐chloroanilino)‐1,3,2λ⁴‐diazaphosphol‐2‐one, C₁₂H₁₁ClN₃OP, each molecule is connected with four neighbouring molecules through (N—H)₂…O hydrogen bonds. These hydrogen bonds form a tubular arrangement along the [001] direction built from R ³₃(12) and R ₄³(14) hydrogen‐bond ring motifs, combined with a C (4) chain motif. The hole constructed in the tubular architecture includes a 12‐atom arrangement (three P, three N, three O and three H atoms) belonging to three adjacent molecules hydrogen bonded to each other. One of the N—H groups of the diazaphosphole ring, not co‐operating in classical hydrogen bonding, takes part in an N—H…π interaction. This interaction occurs within the tubular array and does not change the dimension of the hydrogen‐bond pattern. The energies of the N—H…O and N—H…π hydrogen bonds were studied by NBO (natural bond orbital) analysis, using the experimental hydrogen‐bonded cluster of molecules as the input file for the chemical calculations. In the ¹H NMR experiment, the nitrogen‐bound proton of the diazaphosphole ring has a high value of 17.2 Hz for the ²J _H–P coupling constant.     

Boron trifluoride facilitated transesterification of dioxaborolanes

The direct transesterification of dioxaborolanes (alkane-1,2-diol based boronate esters) was explored. Using BF₃·OEt₂, alkane-1,2-diol based mono- and bis-boronate esters (i.e., pinacol and ethylene glycol) have been converted quantitatively to either benzene-1,2-diol or alkane-1,3-diol based boronate esters. In the case of pinacol esters, esterification is facilitated by the accompanying pinacol rearrangement, thus shifting the reaction equilibrium.