Synthesis and crystal structures of three Schiff bases derived from 3-formyl-acetyl-acetone and o-, m- and p-amino-benzoic acid.
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ABSTRACT:
SUBMITTER: Halz JH
PROVIDER: S-EPMC8739200 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The synthesis and structures of three isoxazole-containing Schiff bases are reported, namely, (E)-2-{[(isoxazol-3-yl)imino]methyl}phenol, C10H8N2O2, (E)-2-{[(5-methylisoxazol-3-yl)imino]methyl}phenol, C11H10N2O2, and (E)-2,4-di-tert-butyl-6-{[(isoxazol-3-yl)imino]methyl}phenol, C18H24N2O2. All three structures contain an intramolecular O-H...N hydrogen bond, alongside weaker intermolecular C-H...N and C-H...O contacts. The C-O(H) and imine C=N bond lengths were consistent with structures existing in the enol rather than the keto form. Despite having dihedral angles <25°, none of the compounds were observed to be strongly thermochromic, unlike their anil counterparts; however, all three compounds showed a visible colour change upon irradiation with UV light.
| S-EPMC7474185 | biostudies-literature
Project description:Using a general solvent-free procedure for the synthesis of chiral Schiff bases, the following compounds were synthesized and their crystal structures determined: (S)-(+)-2-{[(1-phenyl-eth-yl)imino]-meth-yl}naphthalene, C19H17N, (1), (S)-(+)-2-({[(4-methyl-phen-yl)eth-yl]imino}-meth-yl)naphthalene, C20H19N, (2), (R)-(-)-2-({[(4-meth-oxy-lphen-yl)eth-yl]imino}-meth-yl)naphthalene, C20H19NO, (3), (R)-(-)-2-({[(4-fluoro-phen-yl)eth-yl]imino}-meth-yl)naphthalene, C19H16FN, (4), (S)-(+)-2-({[(4-chloro-phen-yl)eth-yl]imino}-meth-yl)naphthalene, C19H16ClN, (5), (S)-(+)-2-({[(4-bromo-phen-yl)eth-yl]imino}-meth-yl)naphthalene, C19H16BrN, (6), (S)-(+)-2-({[1-(naphthalen-1-yl)eth-yl]imino}-meth-yl)naph-thalene, C23H19N, (7), (S)-(+)-2-{[(1-cyclo-hexyl-eth-yl)imino]-meth-yl}naph-tha-lene, C19H23N, (8), (S)-(-)-2-{[(1,2,3,4-tetra-hydro-naphthalen-1-yl)imino]meth-yl}naphthalene, C21H19N, (9), and (+)-2-({[(1S,2S,3S,5R)-2,6,6-tri-methylbi-cyclo-[3.1.1]hept-3-yl]imino}-meth-yl}naphthalene, C21H25N, (10). The moiety provided by the amine generates conformational flexibility for these imines. In the crystals, no strong inter-molecular contacts are observed, in spite of the presence of aromatic groups.
| S-EPMC4910349 | biostudies-literature
Project description:Amino acid ionic liquid-supported Schiff bases, derivatives of salicylaldehyde and various amino acids (L-threonine, L-valine, L-leucine, L-isoleucine and L-histidine) have been investigated by means of various spectroscopic techniques (NMR, UV-Vis, IR, MS) and deuterium isotope effects on ¹³C-NMR chemical shifts. The results have shown that in all studied amino acid ionic liquid-supported Schiff bases (except the L-histidine derivative) a proton transfer equilibrium exists and the presence of the COO? group stabilizes the proton transferred NH-form.
| S-EPMC6269710 | biostudies-literature
Project description:In the title compounds, N-(5-acetyl-2-methyl-phen-yl)quinoline-2-carboxamide [C19H16N2O2, (I)], N-(5-acetyl-2-bromo-phen-yl)quinoline-2-carboxamide [C18H13BrN2O2, (II)] and N-(5-acetyl-2-ethynylphen-yl)quinoline-2-carboxamide [C20H14N2O2, (III)], the quinoline ring system is essentially planar and forms a dihedral angles of 3.68?(5) (I), 5.59?(7) (II) and 1.87?(6)° (III) with the acetyl-substituted ring. The mol-ecular structures of (I) and (III) each feature an intra-molecular N-H?N hydrogen bond, forming an S(5) ring, while in (II) an intra-molecular bifurcated N-H?(N,Br) hydrogen bond forms two S(5) rings. In the crystals, weak C-H?O hydrogen bonds link mol-ecules of (I) into C(7) chains long [010], mol-ecules of (II) into chains of R22(8) rings along [110] and mol-ecules of (III) into C(8) chains along [010]. In (I), there are no significant ?-? stacking inter-actions under 4?Å, but in both (II) and (III), ?-? inter-actions link the weak hydrogen-bonded chains into layers parallel to (001) [centroid-centroid disttances of 3.748?(1)?Å in (II) and 3.577?(1), 3.784?(1) and 3.780?(1)?Å in (III)].
| S-EPMC5458296 | biostudies-literature
Project description:A series of novel Schiff bases and secondary amines were obtained in good yields, as a result of the reductive amination of alkyl 2-(2-formyl-4-nitrophenoxy)alkanoates with both aniline and 4-methoxyaniline under established mild reaction conditions. Sodium triacetoxyborohydride as well as hydrogen in the presence of palladium on carbon were used as efficient reducing agents of the Schiff bases, in both direct and stepwise reductive amination processes. The Schiff bases, amines, and amine hydrochlorides were designed as potential antibacterial agents, and structure-activity relationship could be established following in vitro assays against Gram-positive and Gram-negative bacteria. The minimal inhibitory concentration and zone of inhibition were also determined. In these tests, some of Schiff bases and secondary amine hydrochlorides showed moderate-to-good activity against Gram-positive bacteria, including S. aureus, M. luteus, and S. mutans.
| S-EPMC4513202 | biostudies-literature
Project description:Two Schiff bases, (E)-1-(4-methoxyphenyl)-N-((E)-3-(4-nitrophenyl)allylidene)methanamine (compound 1) and (E)-N-((E)-3-(4-nitrophenyl)allylidene)-2-phenylethanamine (compound 2) have been synthesized and characterized using spectroscopic methods; time of flight MS, 1H and 13C NMR, FT-IR, UV-VIS, photoluminescence and crystallographic methods. The structural and electronic properties of compounds 1 and 2 in the ground state were also examined using the DFT/B3LYP functional and 6-31 + G(d,p) basis set, while the electronic transitions for excited state calculations were carried out using the TD-DFT/6-31 + G(d,p) method. The Schiff base compounds, 1 and 2 crystallized in a monoclinic crystal system and the P21/c space group. The emission spectra of the compounds are attributed to conjugated π-bond interaction while the influence of the intra-ligand charge transfer resulted in a broad shoulder for 1 and a double emission peak for 2. The calculated transitions at 450 and 369 nm for 1 and 2 respectively are in reasonable agreement with the experimental results. The higher values of dipole moment, linear polarizability and first hyperpolarizability of 1, suggest a better optical property and better candidate for the development of nonlinear optical (NLO) materials.
| S-EPMC8046777 | biostudies-literature
Project description:The crystal structures of two erbium(III) complexes with 4-amino-benzoic acid (4-ABAH), namely bis-(?2-4-amino-benzoato-?(2) O:O')bis-[bis(4-amino-benzoato-?(2) O,O')di-aqua-erbium(III)] dihydrate, [Er2(C7H6NO2)6(H2O)4]·2H2O, (I), and 4-chloro-3-nitro-benzoic acid (CLNBAH), namely poly[hexa-kis-(?2-4-chloro-3-nitro-benzoato-?(2) O:O')bis-(dimethyl sulfoxide-?O)dierbium(III)], [Er2(C7H3ClNO4)6(C2H6OS)2] n , (II), have been determined. In the structure of solvatomorphic compound (I), the symmetry-related irregular ErO8 coordination polyhedra in the discrete centrosymmetric dinuclear complex comprise two monodentate water mol-ecules and six carboxyl-ate O-atom donors, four from two bidentate carboxyl-ate O,O'-chelate groups and two from the bis-monodentate O:O'-bridging group of the third 4-ABA anion. The Er-O bond-length range is 2.232?(3)-2.478?(3)?Å and the Er?Er separation in the dinuclear complex unit is 4.7527?(4)?Å. One of the coordinating water mol-ecules is involved in an intra-unit O-H?O hydrogen-bonding association with an inversion-related carboxyl-ate O-atom acceptor. In contrast, the anhydrous compound (II) is polymeric, based on centrosymmetric dinuclear repeat units comprising ErO7 coordination polyhedra which involve four O-atom donors from two bidentate O:O'-bridging carboxyl-ate groups, one O-atom donor from the monodentate dimethyl sulfoxide ligand and two O-atom donors from the third bridging CLNBA anion. The latter provides the inter-unit link in the one-dimensional coordination polymer extending along [100]. The Er-O bond-length range in (II) is 2.239?(6)-2.348?(6)?Å and the Er?Er separation within the dinuclear unit is 4.4620?(6)?Å. In the crystal of (I), extensive inter-dimer O-H?O and N-H?O hydrogen-bonding inter-actions involving both the coordinating water mol-ecules and the solvent water mol-ecules, as well as the amine groups of the 4-ABA anions, give an overall three-dimensional network structure. Within this structure are also weak ?-? ring inter-actions between two of the coordinating ligands [ring-centroid separations = 3.676?(3) and 3.711?(2)?Å]. With (II), only weak intra-polymer C-H?O, C-H?Cl and C-H?S inter-actions are present.
| S-EPMC4719813 | biostudies-other
Project description:In the title compound, C16H12O5, synthesized from isopthaloyl chloride and 2'-hy-droxy-aceto-phenone, the dihedral angle between the planes of the aromatic rings is 71.37?(9)°. In the crystal, carb-oxy-lic acid inversion dimers generate R 2 (2)(8) loops. The dimers are linked by C-H?O inter-actions, generating (101) sheets.
| S-EPMC4257273 | biostudies-literature
Project description:Phenoxyacetohydrazide Schiff base analogs 1-28 have been synthesized and their in vitro ?-glucouoronidase inhibition potential studied. Compounds 1 (IC50=9.20±0.32 µM), 5 (IC50=9.47±0.16 µM), 7 (IC50=14.7±0.19 µM), 8 (IC50=15.4±1.56 µM), 11 (IC50=19.6±0.62 µM), 12 (IC50=30.7±1.49 µM), 15 (IC50=12.0±0.16 µM), 21 (IC50=13.7±0.40 µM) and 22 (IC50=22.0±0.14 µM) showed promising ?-glucuronidase inhibition activity, better than the standard (D-saccharic acid-1,4-lactone, IC50=48.4±1.25 µM).
| S-EPMC6271590 | biostudies-literature
Project description:The crystal structures of two ammonium salts of 2-amino-4-nitro-benzoic acid are described, namely di-methyl-aza-nium 2-amino-4-nitro-benzoate, C2H8N+·C7H5N2O4-, (I), and di-butyl-aza-nium 2-amino-4-nitro-benzoate, C8H20N+·C7H5N2O4-, (II). The asymmetric unit of (I) comprises a single cation and a single anion. In the anion, small twists are noted for the carboxyl-ate and nitro groups from the ring to which they are connected, as indicated by the dihedral angles of 11.45?(13) and 3.71?(15)°, respectively; the dihedral angle between the substituents is 7.9?(2)°. The asymmetric unit of (II) comprises two independent pairs of cations and anions. In the cations, different conformations are noted in the side chains in that three chains have an all-trans [(+)-anti-periplanar] conformation, while one has a distinctive kink resulting in a (+)-synclinal conformation. The anions, again, exhibit twists with the dihedral angles between the carboxyl-ate and nitro groups and the ring being 12.73?(6) and 4.30?(10)°, respectively, for the first anion and 8.1?(4) and 12.6?(3)°, respectively, for the second. The difference between anions in (I) and (II) is that in the anions of (II), the terminal groups are conrotatory, forming dihedral angles of 17.02?(8) and 19.0?(5)°, respectively. In each independent anion of (I) and (II), an intra-molecular amino-N-H?O(carboxyl-ate) hydrogen bond is formed. In the crystal of (I), anions are linked into a jagged supra-molecular chain by charge-assisted amine-N-H?O(carboxyl-ate) hydrogen bonds and these are connected into layers via charge-assisted ammonium-N-H?O(carboxyl-ate) hydrogen bonds. The resulting layers stack along the a axis, being connected by nitro-N-O??(arene) and methyl-C-H?O(nitro) inter-actions. In the crystal of (II), the anions are connected into four-ion aggregates by charge-assisted amino-N-H?O(carboxyl-ate) hydrogen bonding. The formation of ammonium-N-H?O(carboxyl-ate) hydrogen bonds, involving all ammonium-N-H and carboxyl-ate O atoms leads to a three-dimensional architecture; additional C-H?O(nitro) inter-actions contribute to the packing. The Hirshfeld surface analysis confirms the importance of the hydrogen bonding in both crystal structures. Indeed, O?H/H?O inter-actions contribute nearly 50% to the entire Hirshfeld surface in (I).
| S-EPMC5137589 | biostudies-literature