Search Results (15)

A series of three 1,3-phenylene bis-oxamides 3a–c, structurally related to the GPR35 receptor-agonist drug lodoxamide, has been synthesized by reacting the 1,3-phenylene bis-oxalamates 2a and 2b with amines. The obtained compounds were characterized by ¹H and ¹³C NMR, and IR spectroscopy, they showed characteristic signals for the aromatic, N―H, and C=O groups. Molecular structure was determined using single-crystal X-ray diffraction. The supramolecular architecture is driven by N―H···O=C, N―H···N, C—H···π, and O=C···O=C interactions depicting a supramolecular helix (3a) and tapes (3b–c). Intermolecular interactions were studied using Hirshfeld surface analysis, where N―H∙∙∙X (X = N, O) hydrogen bonding represents 30.2% to the surface of 3a and 17.8–18.8% to the surface of 3b–c. The most energetic interactions involve the amide N—H∙∙∙O hydrogen bonding, contributing in the −113.9 to −97.0 kJ mol⁻¹ range to the crystal energy, being more dispersive than electrostatic in nature. The molecular docking study was performed to evaluate the binding ability of 3a–c compounds to the GPR35 receptor, showing a favorable binding in a similar way to lodoxamide. Full article

The reaction between cadmium nitrate tetrahydrate and N,N′-bis(pyridin-3-ylmethyl)oxalamide (L) in a 1:3 molar ratio in a water/acetonitrile (1:6 v/v) mixture afforded single crystals of compound 1 suitable for X-ray diffraction analysis. Compound 1 consists of the coordination polymer (CP) [[Cd(L)₂(OH₂)₂](NO₃)₂·4H₂O]_∞, in which Cd^II ions are bridged by neutral L antiperiplanar N-ligands in a wavy ribbon fashion developed along the c-axis. Two trans-disposed water molecules complete the pseudo-octahedral coordination geometry of the metal ion. The crystal packing of 1 revealed the interplay between π–π stacking interactions and an intricate hydrogen-bonded network involving oxalamides, nitrates, and water molecules. The donor properties of L and the intermolecular interactions in compound 1 are interpreted based on hybrid-DFT calculations. Full article

Reactions of Co(OAc)₂·4H₂O, N‚N’-bis(3-pyridylmethyl)oxalamide (L) and 4,4′-sulfonyldibenzoic acid (H₂SDA) afforded four coordination polymers with the same mixed ligands, {[Co(L)(SDA)(H₂O)₂]·H₂O·CH₃OH}_n, 1, {[Co(L)_0.5(SDA)]·2H₂O·0.5L}_n, 2, {[Co(L)_1.5(SDA)(H₂O)]·H₂O}_n, 3, and {[Co₂(L)_1.5(SDA)₂(H₂O)₂]·4H₂O}_n, 4, which have been structurally characterized using single-crystal X-ray crystallography. Complexes 1–4 are 2D layers, revealing topologies of sql, 2,6L1, (4,4)Ia, and 6L12, respectively, and demonstrating that the metal-to-ligand ratio, solvent system, and reaction temperature are important in determining the structural diversity. The immersion of these complexes into various solvents shows that the structural types govern the chemical stabilities of 1–4. Reversible structural transformation is shown for complexes 1 and 2 upon solvent removal and adsorption, while those of 3 and 4 are irreversible. Full article

Reactions of N,N′-bis(3-methylpyridyl)oxalamide (L¹), N,N’-bis(3-methylpyridyl)adipoamide (L²) and N,N’-bis(3-methylpyridyl)sebacoamide (L³) with tricarboxylic acids and Cu(II) salts afforded {[Cu(L¹)(1,3,5-HBTC)]·H₂O}_n (1,3,5-H₃BTC = 1,3,5-benzenetricarboxylic acid), 1, {[Cu_1.5(L²)_1.5(1,3,5-BTC)(H₂O)₂]·6.5H₂O}_n, 2, [Cu(L²)_0.5(1,3,5-HBTB)]_n (1,3,5-H₃BTB = 1,3,5-tri(4-carboxyphenyl)benzene), 3, [Cu₄(L³)(OH)₂(1,3,5-BTC)₂]_n, 4, {[Cu₃(L³)₂(1,3,5-BTB)₂]·2.5MeOH·2H₂O}_n, 5, and {[Cu₃(L³)₂(1,3,5-BTB)₂ ]·DMF·2H₂O}_n, 6, which have been structurally characterized by using single crystal X-ray crystallography. Complexes 1–4 form a 2D layer with the {4⁴.6²}-sql topology, a 2D layer with the (4.6²)₂(4².6².8²)-bex topology, a three-fold interpenetrated 3D net with the (4¹²·6³)-pcu topology and a 3D framework with the (4¹⁰·6³²·8³)(4²·6)₂(4³·6³) topology, respectively, whereas 5 and 6 are 3D frameworks with the (6³)₂(6⁴·8²)(6⁸·8⁵·10²) topology. Complex 5 shows a better iodine adsorption factor of 290.0 mg g⁻¹ at 60 °C for 360 min than the other ones, revealing that the flexibility of the spacer ligand governs the structural diversity and the adsorption capacity. Full article

N,N′-Dipropyloxamide (1) was synthesised by the reaction between diethyloxalate and n-propylamine in ethanol. Compound 1 was fully characterised by both microanalytical (elemental analysis, melting point determination) and spectroscopic means (FT-IR and NMR spectroscopy). Crystals suitable for single crystal X-ray diffraction were isolated by the slow evaporation of a methyl alcohol solution of the compound. The resulting crystal structure shows the prominent role exerted by intermolecular hydrogen bonds in the crystal packing. Full article

(N-Alkyloxalamido)-amino acid amides 9–12 exhibit excellent gelation capacities toward some lipophilic solvents as well as toward the commercial fuels, petrol and diesel. Gelator 10 exhibits an excellent phase-selective gelation (PSG) ability and also possesses the highest gelation capacity toward petrol and diesel known to date, with minimum gelation concentration (MGC) values (%, w/v) as low as 0.012 and 0.015, respectively. The self-assembly motif of 10 in petrol and toluene gel fibres is determined from xerogel X-ray powder diffraction (XRPD) data via the simulated annealing procedure (SA) implemented in the EXPO2014 program and refined using the Rietveld method. The elucidated motif is strongly supported by the NMR (NOE and variable temperature) study of 10 toluene-d₈ gel. It is shown that the triple unidirectional hydrogen bonding between gelator molecules involving oxalamide and carboxamide groups, together with their very low solubility, results in the formation of gel fibres of a very high aspect ratio (d = 10–30 nm, l = 0.6–1.3 μm), resulting in the as-yet unprecedented capacity of gelling commercial fuels. Rheological measurements performed at low concentrations of 10 confirmed the strength of the self-assembled network with the desired thixotropic properties that are advantageous for multiple applications. Instantaneous phase-selective gelation was obtained at room temperature through the addition of the 10 solution to the biphasic mixture of diesel and water in which the carrier solvent was congealed along with the diesel phase. The superior gelling properties and PSG ability of 10 may be used for the development of more efficient marine and surface oil spill recovery and waste water treatment technologies as well as the development of safer fuel storage and transport technologies. Full article

The aim of this study was to assess the gelling potential of chiral oxalamide derivatives in vegetable oils. Special emphasis was given to the potential applications of the examined oil gels as sustained delivery systems and as fat substitutes in food products. The applicability of oil gelators is envisaged in food, cosmetics, and the pharmaceutical industry. The regulations requiring the elimination of saturated fats and rising concerns among consumers health motivated us to investigate small organic molecules capable of efficiently transforming from liquid oil to a gel state. The oxalamide organogelators showed remarkable gelation efficiency in vegetable oils, thermal and mechanical stability, self-healing properties, and a long period of stability. The physical properties of the gels were analysed by TEM microscopy, DSC calorimetry, and oscillatory rheology. The controlled release properties of acetylsalicylic acid, ibuprofen, and hydrocortisone were analysed by the LC–MS method. The influence of the oil type (sunflower, soybean, and olive oil) on gelation efficiency of diverse oxalamide derivatives was examined by oscillatory rheology. The oxalamide gelators showed thermoreversible and thixotropic properties in vegetable oils with a minimum gelation concentration of just 0.025 wt%. The substitution of palm fats with gelled sunflower oil applied in cocoa and milk spreads at gelator concentrations lower than 0.2 wt% have shown promising viscoelastic properties compared to that of the original food products. Full article

N,N′-dibutyloxamide (1) was prepared by reacting diethyloxalate with n-butylamine in ethyl alcohol and characterized by microanalytical techniques, FT-IR, and NMR spectroscopy. Crystals suitable for single crystal X-ray diffraction (SC-XRD) were obtained from an acetonitrile solution of 1, and the structural characterization showed the presence of intermolecular hydrogen bonding interactions. Full article

Mono-N-alkylated primary oxalamide derivatives with different sized branched alkyl tail-groups were excellent low molecular weight gelators for a variety of different organic solvents with different polarities and hydrogen-bonding abilities. Solvent-gelator interactions were analyzed using Hansen solubility parameters, while ¹H NMR and FTIR spectroscopy were used to probe the driving forces for the supramolecular gelation. The molecular structures of the twin tail-groups did not significantly affect the supramolecular gelation behavior in different solvents. However, for select solvents, the molecular structures of the tail-groups did have a significant effect on gel properties such as the critical gelator concentration, thermal stability, gel stiffness, gel strength, network morphology, and molecular packing. Finally, metabolic activity studies showed that the primary alkyl oxalamide gelators had no effect on the metabolic activity of mouse immune cells, which suggests that the compounds are not cytotoxic and are suitable for use in biomedical applications. Full article

In an attempt to expand the coordination chemistry of N,N′-bis(2,4-dicarboxyphenyl)-oxalamide (H₆L) ligand, we isolated and structurally characterized two new Fe(II) Metal-Organic Frameworks (MOFs), namely [Fe₂(H₂L)(H₂O)₅] (3D-Fe-MOF) and [Fe(H₄L)(H₂O)₂]∙2H₂O, (2D-Fe-MOF) by carefully adjusting the reaction conditions to achieve the optimal degree of deprotonation of the bridging ligand. Both MOFs were found stable in water, as evidenced by powder X-ray diffraction data and their ability to sorb glucose (GLU) from either an aqueous solution or artificial sweat was investigated only to show negligible sorption. A graphite paste sensor (GPE) using the 3D-Fe-MOF as a modifier was fabricated. The 3D-Fe-MOF modified GPE was assessed for non-enzymatic GLU detection in aqueous solution at pH 6 via differential pulse voltammetry and the preliminary results were discussed. Full article

Reactions of N‚N’-bis(3-pyridylmethyl)oxalamide (L¹), N‚N’-bis(4-pyridylmethyl)oxalamide (L²), or N,N’-bis(3-pyridylmethyl)adipoamide) (L³) with angular dicarboxylic acids and Ni(II) salts under hydro(solvo)thermal conditions afforded a series of coordination polymers: {[Ni(L¹)(OBA)(H₂O)]·H₂O}_n (H₂OBA = 4,4-oxydibenzoic acid), 1, {[Ni(L¹)(SDA)(H₂O)₂]·H₂O·CH₃OH}_n (H₂SDA = 4,4-sulfonyldibenzoic acid), 2, {[Ni(L²)(OBA)]·C₂H₅OH}_n, 3, {[Ni(L²)(OBA)]·CH₃OH}_n, 4, {[Ni₂(L²)(SDA)₂(H₂O)₃]·5H₂O}_n, 5, {[Ni₂(L²)(SDA)₂(H₂O)₃]·H₂O·2C₂H₅OH}_n, 6, {[Ni(L³)(OBA)(H₂O)₂]·2H₂O}_n, 7, {[Ni(L³)(SDA)(H₂O)₂]·2H₂O}_n, 8, and {[Ni(L³)₀.₅(SDA)(H₂O)₂]·0.5C₂H₅OH}_n, 9, which have been structurally characterized by using single-crystal X-ray crystallography. Complex 1 exhibits an interdigitated 2D layer with the 2,4L2 topology and 2 is a 2D layer with the sql topology, while 3 and 4 are 3D frameworks resulting from polycatenated 2D nets with the sql topology and 5 and 6 are 2-fold interpenetrated 3D frameworks with the dia topology. Complexes 7 and 8 are 1D looped chains and 9 is a 2D layer with the 3,4L13 topology. The various structural types in 1–9 indicate that the structural diversity is subject to the flexibility and donor atom position of the neutral spacer ligands and the identity of the angular dicarboxylate ligands, while the role of the solvent is uncertain. The iodine adsorption of 1–9 was also investigated, demonstrating that that the flexibility of the spacer L¹–L³ ligands can be an important factor that governs the feasibility of the iodine adsorption. Moreover, complex 9 shows a better iodine adsorption and encapsulates 166.55 mg g⁻¹ iodine in the vapor phase at 60 °C, which corresponded to 0.38 molecules of iodine per formula unit. Full article

Ginkgo biloba L. is highly adaptable and resistant to a range of abiotic stressors, allowing its growth in various environments. However, it is unclear how G. biloba responds to common environmental stresses. We explored the physiological, transcriptomic, and metabolic responses of G. biloba to short-term drought, salt, and heat stresses. Proline, H₂O₂, and ABA contents, along with CAT activity, increased under all three types of stress. SOD activity increased under salt and heat stresses, while soluble protein and IAA contents decreased under drought and salt stresses. With respect to metabolites, D-glyceric acid increased in response to drought and salt stresses, whereas isomaltose 1, oxalamide, and threonine 2 increased under drought. Piceatannol 2,4-hydroxybutyrate and 1,3-diaminopropane increased under salt stress, whereas 4-aminobutyric acid 1 and galactonic acid increased in response to heat stress. Genes regulating nitrogen assimilation were upregulated only under drought, while the GRAS gene was upregulated under all three types of stressors. ARF genes were downregulated under heat stress, whereas genes encoding HSF and SPL were upregulated. Additionally, we predicted that miR156, miR160, miR172, and their target genes participate in stress responses. Our study provides valuable data for studying the multilevel response to drought, salinity, and heat in G. biloba. Full article

Neuroinflammation and microglia-mediated neurotoxicity contribute to the pathogenesis of a broad range of neurodegenerative diseases; therefore, identifying novel compounds that can suppress adverse activation of glia is an important goal. We have previously identified a class of trisubstituted pyrazoles that possess neuroprotective and anti-inflammatory properties. Here, we describe a second generation of pyrazole analogs that were designed to improve their neuroprotective activity toward neurons under inflammatory conditions. Pyrazolyl oxalamide derivatives were designed to explore the effects of steric and electronic factors. Three in vitro assays were performed to evaluate the compounds’ anti-neurotoxic, neuroprotective, and cytotoxic activity using human THP-1, PC-3, and SH-SY5Y cells. Five compounds significantly reduced the neurotoxic secretions from immune-stimulated microglia-like human THP-1 monocytic cells. One of these compounds was also found to protect SH-SY5Y neuronal cells when they were exposed to cytotoxic THP-1 cell supernatants. While one of the analogs was discarded due to its interference with the cell viability assay, most compounds were innocuous to the cultured cells at the concentrations used (1–100 μM). The new compounds reported herein provide a design template for the future development of lead candidates as novel inhibitors of neuroinflammation and neuroprotective drugs. Full article

Infections caused by Mycobacterium tuberculosis (Mtb.) and nontuberculous mycobacteria (NTM) are considered to be a global health problem; current therapeutic options are limited. Sulfonamides have exhibited a wide range of biological activities including those against mycobacteria. Based on the activity of 4-(3-heptylureido)-N-(5-methylisoxazol-3-yl)benzenesulfonamide against NTM, we designed a series of homologous sulfamethoxazole-based n-alkyl ureas (C₁–C₁₂), as well as several related ureas and an oxalamide. Fifteen ureas and one oxalamide were synthesized by five synthetic procedures and characterized. They were screened for their activity against Mtb. and three NTM strains (M. avium, M. kansasii). All of them share antimycobacterial properties with minimum inhibitory concentration (MIC) values starting from 2 µM. The highest activity showed 4,4′-[carbonylbis(azanediyl)]bis[N-(5-methylisoxazol-3-yl)benzenesulfonamide] with MIC of 2–62.5 µM (i.e., 1.07–33.28 µg/mL). Among n-alkyl ureas, methyl group is optimal for the inhibition of both Mtb. and NTM. Generally, longer alkyls led to increased MIC values, heptyl being an exception for NTM. Some of the novel derivatives are superior to parent sulfamethoxazole. Several urea and oxalamide derivatives are promising antimycobacterial agents with low micromolar MIC values. Full article

Intramolecular hydrogen bond (HB) formation was analyzed in the model compounds N-(2-benzoylphenyl)acetamide, N-(2-benzoylphenyl)oxalamate and N¹,N²-bis(2-benzoylphenyl)oxalamide. The formation of three-center hydrogen bonds in oxalyl derivatives was demonstrated in the solid state by the X-ray diffraction analysis of the geometric parameters associated with the molecular structures. The solvent effect on the chemical shift of H6 [δH6(DMSO-d₆)–δH6(CDCl₃)] and Δδ(ΝΗ)/ΔT measurements, in DMSO-d₆ as solvent, have been used to establish the energetics associated with intramolecular hydrogen bonding. Two center intramolecular HB is not allowed in N-(2-benzoylphenyl)acetamide either in the solid state or in DMSO-d₆ solution because of the unfavorable steric effects of the o-benzoyl group. The estimated ΔHº and ΔSº values for the hydrogen bonding disruption by DMSO-d₆ of 28.3(0.1) kJ·mol⁻¹ and 69.1(0.4) J·mol⁻¹·K⁻¹ for oxalamide, are in agreement with intramolecular three-center hydrogen bonding in solution. In the solid, the benzoyl group contributes to develop 1-D and 2-D crystal networks, through C–H∙∙∙A (A = O, π) and dipolar C=O∙∙∙A (A = CO, π) interactions, in oxalyl derivatives. To the best of our knowledge, this is the first example where three-center hydrogen bond is claimed to overcome steric constraints. Full article