15N, 13C and 119Sn NMR and other spectroscopic studies of 8-quinolinol, its O- and N-methyl derivatives, and chelate di- and tri-organotin(IV) complexes (original) (raw)
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NMR study of O and N , O -substituted 8-quinolinol derivatives
Magnetic Resonance in Chemistry, 2014
The 1 H and 13 C NMR spectral study of several biologically active derivatives of 8-quinolinol have been made through extensive NMR studies including homodecoupling and 2D-NMR experiments such as COSY-45°, NOESY, and HeteroCOSY. Electron donating resonance and electron withdrawing inductive effect of several groups showed marked changes in chemical shifts of nuclei at the seventh positions of O-substituted quinolinols (2-15). Although in N-alkyl, 8-alkoxyquinolinium halides (16-21), ring A rightly showed low frequency chemical shift values.
Structural and spectroscopic studies on some metal complexes of an 8-hydroxyquinoline derivative
Inorganica Chimica Acta, 2010
Mononuclear metal complexes of 2-[(2-hydroxyethylimino)methyl]quinolin-8-ol (H 2 L) were obtained by reaction of 8-hydroxyquinoline-2-carboxaldehyde, 2-aminoethanol and the corresponding metal(II) acetate (M = Co, Ni, Cu, Zn or Cd) in 2:2:1 molar ratios. The Schiff base ligand is acting as a monodeprotonated O,N,N-donor in the helical complex Ni(HL) 2 , which could be crystallographically characterised. This crystal structure contains homochiral chains of Ni(HL) 2 connected through double O-HÁ Á ÁO connections, which relate both non-coordinated hydroxy groups of the ethanolic arms with both phenolic O atoms of a neighbouring complex, in a ''head-to-tail" disposition. A study of the luminescence properties in methanol solution showed that the quantum yields of Zn(HL) 2 ÁH 2 O (U F = 0.02) and Cd(HL) 2 ÁH 2 O (U F = 0.04) are lower than that of 8-hydroxyquinoline-2-carboxaldehyde (U F = 0.06).
Inorganica Chimica Acta, 2008
The metal ion complexing properties of the ligand HQC (8-hydroxyquinoline-2-carboxylic acid) are reported. The structures of [Zn(HQCH) 2 ] AE 3H 2 O (1) and [Cd(HQCH) 2 ] AE 3H 2 O (2) were determined (HQCH = HQC with phenol protonated). Both 1 and 2 are triclinic, space group P 1, with Z = 2. For 1 a = 7.152 , b = 9.227(4), c = 15.629(7) Å , a = 103.978(7)°, b = 94.896(7)°, c = 108.033(8)°, R = 0.0499. For 2 a = 7.0897(5), b = 9.1674(7), c = 16.0672(11) Å , a = 105.0240(10)°, b = 93.9910(10)°, c = 107.1270(10)°, R = 0.0330. In 1 the Zn has a distorted octahedral coordination geometry, with Zn-N of 2.00 and 2.15 Å , and Zn-O to the protonated phenolic oxygens of 2.431 and 2.220 Å . The structure of 2 is similar, with Cd-N bonds of 2.220 and 2.228 Å , with Cd-O bonds to the protonated phenolate oxygens of 2.334 and 2.463 Å . The structures of 1 and 2, and isomorphous Ni(II) and Co(II) HQC complexes reported in the literature, show very interesting short (<2.5 Å ) O-O distances in H-bonds involving the protons on the coordinated phenolates and lattice water molecules. These are discussed in relation to the possible role of short low-energy H-bonds in alcohol dehydrogenase in mediating the transfer of the hydroxyl proton of the alcohol to an adjacent serine oxygen.
The UV-Vis spectra of 5-(4-X-phenyl)-azo-8-hydroxyquinoline derivatives (X = OCH3; CH3; H; SO3H; NO2) are investigated in ten organic solvents of different polarity in order to throw light on their solvatochromic behavior. An interesting discussion on the effect of the substituent (X) and hydrogen bonding on the energy of the charge transfer transitions and proton-ligand dissociation constants of the investigated compounds is introduced on the basis of electron repelling property. The different factors affecting the formation of La3+, Ce3+, Pr3+, Zr4+, Hf4+ and Th4+ complexes with the ligands under interest have been studied. The spectrophotometric and analytical characteristics of the formed complexes are determined.
Magnetic Resonance in Chemistry, 1979
The complete 'H NMR spectral analyses of quinoline and two of its derivatives (4,7-dichloroquinoline and 8-11itroqUinoline) have been performed. AU the long-range coupling constants were determined both in magnitude and sign. In determining the signs the INDOR technique was very useful and successful, allowing the resolution of transitions as close as a few hundredths of a Hz. The signs of the interring coupling constants alternate with the number of intervening bonds, according to MccoMe~'s rule, except the all-traos 6J couplings. A h e a r relationship has been found between the 'H-'H and %-' % interring coupling constants for which the spin polarization is transmitted almost exclusively via the ?r-electron system.
Analysis of two novel 1–4 quinolinone structures with bromine and nitrobenzyl ligands
Journal of Molecular Modeling
The scientific community has shown particular interest in the study of quinolinones-a class of bicyclic organic compounds. An example of these compounds are the 4-quinolinones, considered to be very useful building blocks, since they can adapt their molecular structures with different ligands for applications in various fields such as pharmacy, medicine, physics and engineering. The compounds (E)-3-(benzylidene)-2-(3-nitrophenyl)-2,3-dihydro-1-(phenylsulfonyl)-quinolin-4-(1H)-one (NFQ) and (E)-3-(benzylidene)-2-(4-bromophenyl)-2,3-dihydro-1-(phenylsulfonyl) quinolin-4-(1H)-one (BFQ) were synthesized and characterized by infrared spectroscopy, 1 H and 13 C NMR, and melting point. NFQ crystallized in the orthorhombic Pbca space group while BFQ appears in the monoclinic P2 1 /n space group. X-ray diffraction was used to evaluate their crystallographic structures, and Hirshfeld surface evaluates the intermolecular interactions, supramolecular arrangement and packaging. Theoretical vibrational assignments and calculated electronic properties also demonstrate acceptable agreement between experimental and theoretical results.
Three quinolone compounds featuring O...I halogen bonding
Acta Crystallographica Section C Crystal Structure Communications, 2009
Ethyl 1-ethyl-6-iodo-4-oxo-1,4-dihydroquinoline-3-carboxylate, C14H14INO3, (I), and ethyl 1-cyclopropyl-6-iodo-4-oxo-1,4-dihydroquinoline-3-carboxylate, C15H14INO3, (II), have isomorphous crystal structures, while ethyl 1-dimethylamino-6-iodo-4-oxo-1,4-dihydroquinoline-3-carboxylate, C14H15IN2O3, (III), possesses a different solid-state supramolecular architecture. In all three structures, O...I halogen-bonding interactions connect the quinolone molecules into infinite chains parallel to the unique crystallographic b axis. In (I) and (II), these molecular chains are arranged in (101) layers, via pi-pi stacking and C-H...pi interactions, and these layers are then interlinked by C-H...O interactions. The structural fragments involved in the C-H...O interactions differ between (I) and (II), accounting for the observed difference in planarity of the quinolone moieties in the two isomorphous structures. In (III), C-H...O and C-H...pi interactions form (100) molecular layers, which are crosslinked by O...I and C-H...I interactions.
Open Journal of Synthesis Theory and Applications, 2013
We have prepared the (5-chloro-quinolin-8-yloxy) acetic acid and characterized it by using infrared, Raman and multidimensional nuclear magnetic resonance spectroscopies. The density functional theory (DFT) together with the 6-31G* and 6-311++G** basis sets were used to study its structure and vibrational properties. Three stable conformations of the compound were theoretically determined in gas phase and probably these conformations are present in the solid phase. The harmonic vibrational wavenumbers for the optimized geometries were calculated at the same theory levels. For a complete assignment of the observed bands in the vibrational spectra, the DFT calculations were combined with Pulay's scaled quantum mechanical force field (SQMFF) methodology in order to fit the theoretical wavenumber values to the experimental ones. Besides, the force constants of the three conformers of (5-chloro-quinolin-8-yloxy) acetic acid were calculated and compared with those obtained by us for the 2-(quinolin-8-yloxy) acetic acid. In addition, the characteristics of the electronic delocalization of those structures were performed by using natural bond orbital (NBO), while the corresponding topological properties of electronic charge density are analysed by employing Bader's atoms in molecules theory (AIM). E. ROMANO ET AL. 9 acetic acid [6] numerous changes in the structural, topological and vibrational properties attributed to the chloro atom were observed. Additionaly, the nature of the different rings and bonds of the three studied structures of (5-chloro-quinolin-8-yloxy) acetic acid were analyzed by means of the NBO studies [10-12] while the topological properties of electronic charge density were determined employing the Bader's atoms in molecules theory (AIM) [13].