RESUMO
This work elucidates the potential impact of intramolecular H-bonds within the pore walls of covalent organic frameworks (COFs) on proton conductivity. Employing DaTta and TaTta as representative hosts, it was observed that their innate proton conductivities (σ) are both unsatisfactory and σ(DaTta)<σ(TaTta). Intriguingly, the performance of both imidazole-loaded products, Im@DaTta and Im@TaTta is greatly improved, and the σ of Im@DaTta (0.91×10-2 â S cm-1 ) even surpasses that of Im@TaTta (3.73×10-3 â S cm-1 ) under 100 °C and 98 % relative humidity. The structural analysis, gas adsorption tests, and activation energy calculations forecast the influence of imidazole on the H-bonded system within the framework, leading to observed changes in proton conductivity. It is hypothesized that intramolecular H-bonds within the COF framework impede efficient proton transmission. Nevertheless, the inclusion of an imidazole group disrupts these intramolecular bonds, leading to the formation of an abundance of intermolecular H-bonds within the pore channels, thus contributing to a dramatic increase in proton conductivity. The related calculation of Density Functional Theory (DFT) provides further evidence for this inference.
RESUMO
The intramolecular hydrogen bond (intra-HB) is one of the best-known examples of non-covalent interactions in molecules. Among the different types of intramolecular hydrogen bonding, the NHâ â â O hydrogen bond in amino-alcohols and amino-ethers is one of the weakest. In contrast to the strong OHâ â â N intramolecular hydrogen bond, the strength of the NHâ â â O bond can hardly be measured with conventional spectroscopic methods, even for simple amino-alcohols, since the band belonging to the NHâ â â O conformer merges with the free OH band. In this work, we developed a combination of G4 calculations, and a method based on experimental vaporization enthalpies to determine the NHâ â â O hydrogen bonding strength. The archetypal compounds for this study are 2-amino-1-ethanol and 3-amino-1-propanol as well as their respective methoxy analogs. Based on these molecules, different series were studied to investigate various factors influencing NHâ â â O intra-HB strength. In the first series, the influence of alkylation near the hydroxy or methoxy group and the amino group in sterically hindered aminoalcohols was examined. In the second series, the influence of alkylation of the amino-group was investigated. In the third series, the effect of extending the alkyl chain between functional groups was studied.
Assuntos
Amino Álcoois , Hidrogênio , Éteres , Hidrogênio/química , Ligação de Hidrogênio , TermodinâmicaRESUMO
In the title compound, C19H22N2O5, the six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation with the dimethyl-substituted C atom as the flap. The pyran ring has a flat-boat conformation. The meth-oxy-phenyl ring is orthogonal to the mean plane of the chromene moiety, with a dihedral angle of 89.97â (8)°. The amine N atom deviates from the chromene mean plane by 0.1897â (16)â Å. The methyl-amine and the nitro group are involved in an intra-molecular N-Hâ¯O hydrogen bond which generates an S(6) ring motif. They are slightly twisted out of the plane of the chromene moiety with torsion angles of C-N-C-O(pyran) = 2.2â (3)° and O(nitro)-N-C-C = -5.6â (2)°. In the crystal, there are only C-Hâ¯π inter-actions present, forming inversion-related dimers.
RESUMO
The title compound, [Cu2(C19H23N7O)(C2H3O2)4] n , was obtained via reaction of copper(II) acetate with the coordinating ligand, 6-eth-oxy-N 2,N 4-bis-[2-(pyridin-2-yl)eth-yl]-1,3,5-triazine-2,4-di-amine. The crystallized product adopts the monoclinic P21/c space group. The metal core exhibits a paddle-wheel structure typical for dicopper tetra-acetate units, with triazine and pyridyl nitro-gen atoms from different ligands coordinating to the two axial positions of the paddle wheel in an asymmetric manner. This forms a coordination polymer with the segments of the polymer created by the c-glide of the P21/c setting of the space group. The resulting chains running along the c-axis direction are held together by intra-molecular N-Hâ¯O hydrogen bonding. These chains are further packed by dispersion forces, producing an extended three-dimensional structure.
RESUMO
The title compound, C14H13ClN2O2, was obtained during an attempt to grow single crystals of 4-acetyl-phenyl 2-[(3-chloro-2-methyl-phen-yl)amino]-nicotinate in methanol, and was probably generated by alcoholysis. Two intra-molecular hydrogen bonds are formed, one between the N-H group and the carbonyl O atom of the ester and the other between the ortho sp 2CH group of the benzene ring and the pyridine N atom. Aromatic π-π stacking [shortest centroid-centroid separation = 3.598â (2)â Å] is observed in the extended structure.
RESUMO
In the title compound, C15H15NO, the configuration of the C=N bond of the Schiff base is E, and an intra-molecular O-Hâ¯N hydrogen bond is observed, forming an intra-molecular S(6) ring motif. The phenol ring is inclined by 45.73â (2)° from the plane of the aniline ring. In the crystal, mol-ecules are linked along the b axis by O-Hâ¯N and C-Hâ¯O hydrogen bonds, forming polymeric chains. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the packing arrangement are from Hâ¯H (56.9%) and Hâ¯C/Câ¯H (31.2%) inter-actions. The density functional theory (DFT) optimized structure at the B3LYP/ 6-311â G(d,p) level is compared with the experimentally determined mol-ecular structure, and the HOMO-LUMO energy gap is provided. The crystal studied was refined as an inversion twin.
RESUMO
The title compound, C20H21NO2, an example of a stable 1,2-naphtho-quinone, was determined by single-crystal X-ray diffraction analysis at 100â K. This structure illustrates steric buttressing of the adamantanyl group, forcing the N-H group into the coplanar aromatic C-H. The presence of strong delocalization between the planar N atom at the 4-position and the carbonyl group at the 2-position is indicated. In the crystal, C-Hâ¯O and C-Hâ¯π inter-actions link the mol-ecules into a three-dimensional network.
RESUMO
The title compound, C18H24N2O, is the first example of a naphtho-quinone imine derivative isolated in the 4-imine/2-amine tautomeric form having bulky alkyl substituents at the N atoms. The mol-ecular conformation is stabilized by an intra-molecular hydrogen bond between the amine and a carbonyl group and by London attraction between the two tert-butyl groups. Only van der Waals inter-actions were identified in the crystal packing.
RESUMO
In the title compound, C19H15N3O3, which crystallizes as the phenol-imine tautomer, the dihedral angle between the aromatic rings bridged by the NH unit is 47.16â (16)°. The dihedral angle between the rings bridged by the imine unit is 6.24â (15)°; this near coplanarity is reinforced by an intra-molecular O-Hâ¯N hydrogen bond, which generates an S(6) ring. In the crystal, N-Hâ¯O hydrogen bonds generate [201] C(13) chains. The chains are reinforced and cross-linked by C-Hâ¯O inter-actions to generate (001) sheets.
RESUMO
In the title compound, [AgCl(C7H7N3O2S)(C18H15P)2], the AgI ion is in a distorted tetra-hedral coordination environment formed by P atoms from two tri-phenyl-phosphane ligands, one terminal S atom from the 1-(4-nitro-phen-yl)thio-urea ligand and a chloride ion. In the crystal, bifurcated (N-H)2â¯Cl hydrogen bonds [with graph-set motif R21(6)] connect complex mol-ecules, forming zigzag chains along [001]. These chains are linked via weak C-Hâ¯O hydrogen bonds, forming a two-dimensional network parallel to (100). An intra-molecular N-Hâ¯Cl hydrogen bond forming an S(6) ring is also observed.
RESUMO
A series of 2-aryl-imidazo-pyridines/pyrazines derivatives has been designed, synthesized and evaluated for their biological activities. Among them, several investigated compounds (1a, 3b and 3d) displayed potent antiproliferative activity against HeLa cell, and also displayed comparable tubulin polymerization inhibitory activity to colchicine. These studies provided a new molecular scaffold for the further development of antitumor agents that target tubulin.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Piridinas/química , Piridinas/farmacologia , Moduladores de Tubulina/química , Moduladores de Tubulina/farmacologia , Colchicina/farmacologia , Cristalografia por Raios X , Células HeLa , Humanos , Imidazóis/química , Imidazóis/farmacologia , Modelos Moleculares , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Tubulina (Proteína)/metabolismoRESUMO
The crystal structures of bis-[2-(pyridin-2-yl)phen-yl]rhodium(III) complexes with the metal in an octahedral coordination containing chloride and aceto-nitrile ligands, namely (OC-6-42)-aceto-nitrile-chlorido-bis-[2-(pyridin-2-yl)phenyl-κ(2) N,C (1)]rhodium(III), [RhCl(C11H8N)2(CH3CN)] (1), thyminate(1-) and methanol, namely (OC-6-42)-methanol(5-methyl-2,4-dioxo-1,2,3,4-tetrahydro-pyrimidin-1-ido-κN (1))bis-[2-(pyridin-2-yl)phenyl-κ(2) N,C (1)]rhodium(III), [Rh(C11H8N)2(C5H5N2O2)(CH3OH)]·CH3OH·0.5H2O (2), and thy-min-ate(1-) and ethanol, namely (OC-6-42)-ethanol(5-methyl-2,4-dioxo-1,2,3,4-tetra-hydro-pyrimidin-1-ido-κN (1))bis[2-(pyridin-2-yl)phenyl-κ(2) N,C (1)]rhodium(III), [Rh(C11H8N)2(C5H5N2O2)(C2H5OH)]·C2H5OH (3), are reported. The aceto-nitrile complex, 1, is isostructural with the Ir(III) analog. In complexes 2 and 3, the monodeprotonated thyminate (Hthym(-)) ligand coordinates to the Rh(III) atom through the N atom, and the resulting Rh-N(Hthym) bond lengths are relatively long [2.261â (2) and 2.252â (2)â Å for 2 and 3, respectively] as compared to the Rh-N bonds in the related thyminate complexes. In each of the crystals of 2 and 3, the complexes are linked via a pair of inter-molecular N-Hâ¯O hydrogen bonds between neighbouring Hthym(-) ligands, forming an inversion dimer. A strong intra-molecular O-Hâ¯O hydrogen bond between the thyminate(1-) and alcohol ligands in mutually cis positions to each other is also observed.
RESUMO
The title compound, [Ru(C10H8N2)2(C16H12N4O)](BF4)2·3CH2Cl2, crystallizes with one complex dication, two BF4 (-) counter-anions and three di-chloro-methane solvent mol-ecules in the asymmetric unit. The central Ru(II) atom adopts a distorted octa-hedral coordination sphere with two 2,2'-bi-pyridine (bpy) and one quinoline-2-carbaldehyde (pyridine-2-carbon-yl)hydrazone (HL) ligand. The hydrazone ligand has a Z form and coordinates to the Ru(II) atom via the amide-O and imine-N atoms, affording a planar five-membered chelate ring, while its pyridine-N and quinoline-N donor atoms in the substituents are non-coordinating. The hydrazone N-H group forms an intra-molecular hydrogen bond with the quinoline-N atom. In the crystal, the quinoline moiety of HL shows the shortest π-π stacking inter-action with the pyridine substituent of HL in a neighbouring complex, the centroid-to-centroid distance being 3.793â (3)â Å.
RESUMO
In the title compound, C23H18N2O2, the pyrazole ring subtends dihedral angles of 2.01â (13) and 1.55â (10)° with the pendant benzene ring and the naphthalene ring system, respectively. The mol-ecule is almost planar (r.m.s. deviation for the 27 non-H atoms = 0.025â Å) and intra-molecular O-Hâ¯O and C-Hâ¯O hydrogen bonds both close S(6) loops. In the crystal, very weak aromatic π-π stacking inter-actions between the benzene and the pyrazole rings, with centroid-centroid distances of 3.8913â (14) and 3.9285â (15)â Å, are observed.
RESUMO
The complete mol-ecule of the title compound, C22H16N2O2, is generated by a crystallographic inversion centre at the mid-point of the central N-N bond. Two intra-molecular O-Hâ¯N hydrogen bonds occur.
RESUMO
The title compound, C17H17NO3, prepared by the condensation reaction of 2-(1,3-dioxan-2-yl)aniline and salicyl-aldehyde, has an E conformation about the C=N bond. The six-membered O-heterocycle adopts a chair conformation, with the bond to the aromatic ring located at its equatorial position. The dihedral angle between the aromatic rings is 36.54â (9)°. There is an intra-molecular N-Hâ¯O hydrogen bond forming an S(6) ring motif. In the crystal, mol-ecules are linked by C-Hâ¯O hydrogen bonds, forming chains along the a-axis direction. Within the chains, there are C-Hâ¯π inter-actions involving adjacent mol-ecules.
RESUMO
In the title compound, C15H14ClNO, which is isostructural with its bromo analogue [Tahir et al. (2012 â¶). Acta Cryst., E68, o2730], the dihedral angle between the planes of the aromatic rings is 2.71â (7)° and an intra-molecular O-Hâ¯N hydrogen bond closes an S(6) ring. In the crystal, extremely weak C-Hâ¯π inter-actions link the mol-ecules into a three-dimensional network.
RESUMO
The title compound, C17H21NO4, consists of substituted Meldrum's acid with a [4-(di-ethyl-amino)-phen-yl]methyl-idene fragment attached to the fifth position. The heterocycle assumes a distorted boat conformation. The planar part of heterocycle is almost coplanar with the benzene ring due to the presence of a long conjugated system in the mol-ecule. This leads to the formation of C-Hâ¯O-type intra-molecular contacts. As a result of the absence of hydrogen-bond donors in the structure, the crystal packing is controlled by van der Waals forces and weak C-Hâ¯O inter-actions, which associate the mol-ecules into inversion dimers.
RESUMO
In the title compound, C21H17N3O2, the 2-hy-droxy-5-methyl-phenyl ring and the phenyl ring are inclined to the mean plane of the pyrazolo-pyridine moiety (r.m.s. deviation = 0.013â Å) by 52.89â (9) and 19.63â (8)°, respectively, and to each other by 42.83â (11)°. In the mol-ecule, there are intra-molecular O-Hâ¯O and C-Hâ¯N hydrogen bonds, both enclosing an S(6) ring motif. In the crystal, mol-ecules stack along the c-axis direction, forming columns within which there are a number of π-π inter-actions [the inter-centroid distances vary from 3.5278â (10) to 3.8625â (10)â Å]. The columns are linked by C-Hâ¯π inter-actions, forming slabs parallel to (100).