Antonín Lyčka

13C and 119Sn NMR spectra of Di-n-butyltin(IV) compounds

Abstract The 13C and 119Sn NMR spectra of a set of di-n-butyltin(IV) compounds and their complexes in coordinating and non-coordinating solvents have been studied. The results have shown that it is possible to describe semiquantitatively the shape of coordination polyhedra of these compounds from analysis of their δ(119Sn) and 1J(119Sn-13C) parameters. The values of δ(119Sn) define the regions with different coordination numbers of the central tin atom, so that four-coordinate compounds have δ(119Sn) ranging from about + 200 to −60 ppm, five-coordinate compounds, −90 to −190 ppm, and six-coordinate compounds, −210 to −400 ppm. The values of 1J(119Sn-13C) were used for the calculation of the CSnC angle in the coordination polyhedron of individual compounds.

13C and 119Sn NMR Study of some four- and five-coordinate triphenyltin(IV) compounds

Abstract The 13C and 119Sn NMR spectra of four- and five-coordinate triphenyltin(IV) compounds have been examined. The chemical shifts δ(119Sn) and the coupling constants 1J(119Sn-13C) depend markedly on the coordination number of the tin atom and on the geometry of the coordination sphere. The chemical shifts and the coupling constants 1J(119Sn-13C) for four-coordinate compounds are in the range −40 to −120 ppm and 550–660 Hz, respectively. The δ(119Sn) values for five-coordinate compounds (trigonal bipyramid arrangement) are in the range −180 to −260 ppm. The 1J(119Sn-13C) values for the compounds with three phenyl groups in the equatorial plane and the other ligands in axial positions (trans) are in the range 750–850 Hz. The chelate compound with two phenyl groups in the equatorial plane and the third in the axial position and the two donor atoms of chelating ligand in equatorial and axial positions, respectively, have the coupling constants in the range 600–660 Hz. The NMR spectra are discussed in terms of a three-centre molecular orbital model.

The 13C and 119Sn NMR spectra of some four- and five-coordinate tri-n-butyltin(IV) compounds

The 13C and 119Sn NMR spectra of a set of tri-n-butyltin(IV) compounds and their complexes in coordinating and non-coordinating solvents have been studied. The chemical shifts δ(119Sn) and δ(13C) and the coupling constants 1J(119Sn13C) depend significantly on the coordination number of the tin atom and on the geometry of its coordination sphere. Approximate ranges of these characteristic NMR parameters for various types and configurations of tri-n-butyltin(IV) compounds have been defined. The data for these compounds are discussed in comparison with those for triphenyltin(IV) compounds.

Nontargeted quantitation of lipid classes using hydrophilic interaction liquid chromatography-electrospray ionization mass spectrometry with single internal standard and response factor approach.

The identification and quantitation of a wide range of lipids in complex biological samples is an essential requirement for the lipidomic studies. High-performance liquid chromatography-mass spectrometry (HPLC/MS) has the highest potential to obtain detailed information on the whole lipidome, but the reliable quantitation of multiple lipid classes is still a challenging task. In this work, we describe a new method for the nontargeted quantitation of polar lipid classes separated by hydrophilic interaction liquid chromatography (HILIC) followed by positive-ion electrospray ionization mass spectrometry (ESI-MS) using a single internal lipid standard to which all class specific response factors (RFs) are related to. The developed method enables the nontargeted quantitation of lipid classes and molecules inside these classes in contrast to the conventional targeted quantitation, which is based on predefined selected reaction monitoring (SRM) transitions for selected lipids only. In the nontargeted quantitation method described here, concentrations of lipid classes are obtained by the peak integration in HILIC chromatograms multiplied by their RFs related to the single internal standard (i.e., sphingosyl PE, d17:1/12:0) used as common reference for all polar lipid classes. The accuracy, reproducibility and robustness of the method have been checked by various means: (1) the comparison with conventional lipidomic quantitation using SRM scans on a triple quadrupole (QqQ) mass analyzer, (2) (31)P nuclear magnetic resonance (NMR) quantitation of the total lipid extract, (3) method robustness test using subsequent measurements by three different persons, (4) method transfer to different HPLC/MS systems using different chromatographic conditions, and (5) comparison with previously published results for identical samples, especially human reference plasma from the National Institute of Standards and Technology (NIST human plasma). Results on human plasma, egg yolk and porcine liver extracts are presented and discussed.

13C, 15N and 119Sn NMR spectral evidence for tin five-coordination in triorganotin(IV) oxinates

The 13C and 119Sn NMR spectra of tri(1-butyl)tin(IV) and triphenyltin(IV) oxinates and 1-naphthoxides in neat liquid and deuteriochloroform, pentadeuteriopyridine and hexamethylphosphortriamide solutions, and the 15N NMR spectra of both the oxinates and 8-methoxyquinoline in deuteriochloroform have been recorded. From the comparison of chemical shifts δ(13C), δ(15N) and δ(119Sn) and coupling constants nJ(119Sn13C) of the compounds it is concluded that the triorganotin(IV) oxinates, both as the neat liquid and in solution, form complexes containing five-coordinate tin atoms. In the neat liquid and in deuteriochloroform (a non-coordinating solvent) oxinates form chelate complexes with a cis-trigonal bipyramid arrangement. In coordinating solvents (pentadeuteriopyridine, hexamethylphosphortriamide) these are equilibria involving the formation of small amounts of oxinate complexes with one solvent molecule. These complexes have trans-trigonal bipyramid geometry with butyl or phenyl groups in equatorial plane and the monodentate oxinate group and a solvent molecule in axial positions.

13C and 15N-NMR studies of the azo-hydrazone tautomerism of some azo dyes

Abstract The 13 C and 15 N-NMR spectra of compounds prepared by coupling benzenediazonium ions with 9-hydroxyanthracene, acetylcyclopentadiene, 8-hydroxy quino line, 3-cyano-1,4-dimethylpyridine-2,6-dione and 1-naphthol have been measured. Using δ( 13 C), δ( 15 N), 1 J( 15 NH) and 1 J( 15 N 15 N) it has been found that the products exist, in deuterio-chloroform or in hexadeuteriodimethyl sulfoxide solutions, as 9,10-anthraquinone 9-phenylhydrazone ( I ), 2-acetyl-2,4-cyclopentadienone 1-phenylhydrazone ( II ), 5-phenylazo-8-hydroxyquinoline ( III ), 3-cyano-1,4-dimethylpyridine-2,5,6-trione 5-phenylhydrazone ( IV ) and 4-phenyl-azo-1-naphthol ( V ). The compounds VI and VII have been found to be equilibrium mixtures of the azo and hydrazone tautomers, with prevailing 1,2-naphthoquinone 2-phenylhydrazone ( VI ) and 4-phenylazo-1,2-naphthoquinone 2-phenylhydrazone ( VII ) configurations.

Five-membered [C,N] and [N,O] metallocyclic complexes of palladium(II) with monoalkyl [α-(4-benzeneazoanilino)-N-benzyl]phosphonates: synthesis, characterization and antitumour activity

Abstract The synthesis, spectroscopic and biological properties of the novel palladium(II) complexes with monoethyl (HL1) and monobutyl (HL2) esters of [α-(4-benzeneazoanilino)- N -benzyl]phosphonic acid, have been prepared and studied. These potential polydentate ligands form two types of metallocyclic compounds, those with [C,N] and [N,O] five-membered chelate rings. The former are cyclopalladated chloro-bridged binuclear complexes, [PdL(μ-Cl)] 2 , in which the deprotonated ligand undergoes palladation at the azo nitrogen and the ortho -carbon, while the latter mononuclear complexes, PdL 2 , contain the organophosphorus ligand bonded through the aniline nitrogen and the deprotonated phosphonic acid oxygen. The complexes were identified and characterized by elemental analysis, magnetic and conductance measurements as well as by IR, 1 H, 13 C and 31 P nuclear magnetic resonance and ESI-mass spectroscopic studies. The in vitro antitumour activity of all the complexes was evaluated against the human KB cell line as a preliminary screening for their biological activity. The coordination behaviour of monoalkyl benzeneazophosphonates as well as the spectral and biological properties of their complexes were compared with the results reported for the corresponding dialkyl phosphonates and their palladium(II) complexes.

Organostannate derivatives of dicyclohexylammonium hydrogen 2,6-pyridinedicarboxylate: solution/solid-state 13C,119Sn NMR and in vitro antitumour activity of bis(dicyclohexylammonium) bis(2,6-pyridinedicarboxylato)dibutylstannate, and the crystal structure of its monohydrate

Bis(dicyclohexylammonium) bis(2,6-pyridine-dicarboxylato)dibutylstannate is assigned seven-fold coordination at tin on the basis of its ll9 Sn CP/MAS NMR chemical shift (δ=-424.9 ppm). The assignment has been corroborated by a crystal structure determination of its monohydrate, whose tin atom has the trans-C 2 SnNO 4 pentagonal bipyramidal [Sn-C=2.040(9), 2.067(8) A; C-Sn-C =168.9(5)°] geometry. One 2,6-pyridine-dicarboxylato group chelates to the tin atom (Sn-O=2.234(4), 2.260(4); Sn-N = 2.279(5) A) whereas the other binds through only one carboxyl -C0 2 end (Sn-O=2.416(5), 2.441(5)A). Hydrogen bonds link the cation and the stannate into a linear chain parallel to the b-axis. The lattice water molecule is hydrogen-bonded to the free carboxyl end. The anhydrous compound showed higher in vitro antitumor activity than those of carboplatin and cisplatin when screened against breast (MCF-7, EVSAT), colonic (WiDr), ovarian (IGROV) and renal (A498) carcinoma, and melanoma (M19 MEL) cell lines.

15N, 13C and 1H NMR spectra and azo-hydrazone tautomerism of some dyes prepared by coupling of 1-naphthalenediazonium salt

Abstract 2-(1-Naphthyl)azo-5-tert.butylphenol ( 1 ), 3-methyl-1-phenylpyrazole-4,5-dione 4-(1-naphthyl)hydrazone ( 2 ), 1-(1-naphthyl)azo-2-naphthol ( 3 ), and 4-(1-naphthyl)azo-1-naphthol ( 4 ) were prepared by coupling naphthalene-diazonium chloride with the appropriate passive components and their 1 H, 13 C and 15 N NMR spectra were measured and analysed. Two-dimensional NMR experiments were used to assign 1 H and 13 C chemical shifts unambiguously. The values of 1 J( 15 N, 1 H) and 15 N chemical shifts show that compounds 1 and 4 exist almost completely in azo tautomeric forms, whilst compound 2 exists completely in the hydrazone form and compound 3 predominantly in the hydrazone form. The increase of hydrazone content in compound 3 compared with the hydrazone content in 1-phenylazo-2-naphthol is in the range 1–2.7%, calculated from δ ( 15 N a ) and δ ( 15 N b ) chemical shifts and 1.2–1.6% using 1 J( 15 N, 1 H), i.e. the annelation of the benzene ring in the active component has, contrary to the annelation of the benzene ring in the passive component, practically negligible influence on the azo-hydrazone equilibrium in compounds studied.

Unprecedented reactivity of 3-amino-1H,3H-quinoline-2,4-diones with urea: an efficient synthesis of 2,6-dihydro-imidazo(1,5-c)quinazoline-3,5-diones

Abstract Substituted 3-amino-1H,3H-quinoline-2,4-diones react with urea in acetic acid to give novel 2,6-dihydro-imidazo[1,5-c]quinazoline-3,5-diones in high yields. The same compounds were obtained, albeit with small yields, from 3-chloro-1H,3H-quinoline-2,4-diones and urea. In the proposed reaction mechanism, a molecular rearrangement of the primarily formed mono-substituted urea takes place. The prepared 2,6-dihydro-imidazo[1,5-c]quinazoline-3,5-diones were characterized by their 1H, 13C, 15N NMR and IR spectra and atmospheric pressure chemical ionisation mass spectra.