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:Treatment of 3-formyl-acetyl-acetone with the amines benzyl-amine, tert-butyl-amine and (S)-methyl-benzyl-amine led to the formation of the corresponding Schiff bases 3-[(benzyl-amino)-methyl-idene]pentane-2,4-dione, C13H15NO2 (1), 3-[(tert-butyl-amino)-methyl-idene]pentan-2,4-dione, C10H17NO2 (2) and 3-{[(S)-benz-yl(meth-yl)amino]-methyl-idene}pentane-2,4-dione, C14H17NO2 (3). The mol-ecules of all three compounds exist as enamine tautomers that contain a nearly planar amino-methyl-ene-pentane-2,4-dione core with a strong intra-molecular N-H⋯O hydrogen bridge. The R group attached to the enamine N atom has no significant influence on the bond lengths and angles of the amino-methyl-ene-pentane-2,4-dione core. The supra-molecular structures in 1-3 are mainly based on weak C-H⋯O hydrogen bonds.
| S-EPMC10439404 | biostudies-literature
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:Two Schiff bases, (E)-4-((2-chlorobenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4AAPOCB) and (E)-4-((4-chlorobenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4AAPPCB), have been synthesized and grown as single crystals. Single-crystal X-ray diffraction analysis was employed to determine the crystal structure of the compounds, and the results suggest that the compounds crystallized into an orthorhombic crystal system having P212121 and Pbca space groups, respectively. Further, the crystallinity of the compounds was analyzed by the PXRD technique. The UV-vis-NIR spectra of the compounds demonstrate excellent transmittance in the entire visible region. The lower cutoff wavelengths of the compounds were determined to be 338 and 333 nm, respectively; additionally, optical band gaps of the compounds found were 4.60 and 4.35 eV. FTIR and NMR (1H and 13C) spectral techniques were utilized to analyze the molecular structure of the compounds. The compounds emit photoluminescence with broad emission bands with centers at 401 and 418 nm. The thermal stability and phase transitions were assessed through thermogravimetric methods. The phase transition prior to melting was indicated by the endothermic event at around 190 °C in the DTA curves of both crystals, and the same was observed in the DSC curves. The second harmonic efficiencies of the powdered compounds I and II were found to be 3.52 and 1.13 times better than that of the standard reference KDP. The 4AAPOCB and 4AAPPCB compounds showed isotropic polarizability amplitudes of 46.02 × 10-24 and 46.52 × 10-24 esu, respectively. The calculation of linear polarizability and NLO second-order polarizability (β) along with other optical parameters was performed for optimized geometries. The nonzero amplitudes of the average β values for compounds 4AAPOCB and 4AAPPCB were found to be 14.74 × 10-30 and 8.10 × 10-30 esu, respectively, which show a decent potential of the synthesized molecules for NLO applications. The calculated β amplitudes were further explained based on calculated electronic parameters like molecular electrostatic potentials, frontier molecular orbitals, molecular orbital energies, transition energies, oscillator strengths, and unit spherical representation of NLO polarizability. The current analysis emphasizes the significance of synthesized compounds as prospective candidates for optical and NLO applications through the use of experiments and quantum computations.
| S-EPMC10157849 | 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 π-π stacking inter-actions under 4 Å, but in both (II) and (III), π-π 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: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: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: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: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