Igor P. Chuikov

Thermolytic reactions of polyfluoroorganic compounds. Part XXVII. Interaction of 1,1- dichloropolyfluoroindanes with haloforms

Abstract A number of polyfiuoro-1-methyieneindanes have been obtained by copyrolysis of 1,1-dichloropolyfluoroindanes with CF2= CF2, CHClF2, CHCl2F and CHCl3. A possibility is shown for the reaction of 1,1-dichloroctafluoroindan with CHClF2 to proceed by way of difluorocarbene insertion into the CCl bond of the benzylic position of This indan, with subsequent dechlorination of the insertion product.

Synthesis and molecular and crystalline structure of polyfluoro-1,3-diazafluorenes

Reactions of 2-amino-3-(1-imino-2,2,2-trifluoroethyl)hexafluoro-1H-indene with carboxylic acid anhydrides and chlorides afforded 2-alkyl(aryl)-4-trifluoromethyl-5,6,7,8,9,9-hexafluoro-1,3-diazafluorenes. The molecular and crystalline structure of the products was studied by NMR spectroscopy and X-ray diffraction. 5,6,7,8,9,9-Hexafluoro-2-phenyl-4-trifluoromethyl-1,3-diazafluorene in crystal gives rise to infinite ladder chains via π-stacking interaction between the benzene ring of one molecule and tetrafluorobenzene fragment of the other.

Non-empirical and DFT calculations of 19 F and 13 C chemical shifts in the NMR spectra of substituted pentafluorobenzenes

Chemical shifts in 19F and 13C NMR spectra of substituted pentafluorobenzenes are calculated by Hartree-Fock and density functional theory methods. The calculated values are compared with the experimental data known from the literature. It is shown that chemical shifts in non-polar solvents can be predicted sufficiently accurately by the GIAO-DFT(PBE/L22) method. This method is used to predict the 19F and 13C chemical shifts of a heptafluorobenzyl cation in the SbF5 medium. The best agreement between the calculated and experimental values is achieved when the counterion effect is taken into account.

Detection of anilines by luminescence spectroscopy using dissolved and adsorbed pyrylocyanine dyes

Reactions of three pyrylocyanine dyes (derived from 2,4,6-trimethylpyrylium perchlorate) with p-toluidine and 2,4-diaminotoluene were studied to develop methods for detection of aromatic amines. The emission spectrum characteristics of the starting dyes and the final products obtained in solution and on silica gel were examined. The presence of open forms of the pyridocyanine dye in acetonitrile was suggested after analyzing the excitation and emission spectra of reaction intermediates. The formation of luminescent pyridocyanine in solution took several days, while its synthesis from the starting dye adsorbed on silica gel was completed within a few seconds.

Synthesis and Structure of N-(4-Dialkylaminophenyl)hexafluoro- 1,4-naphthoquinone 4-Imines

The reaction of heptafluoro-1-naphthol with N,N-dialkyl-p-nitrosoanilines or N,N-dialkyl-p-phenylenediamines in the presence of HIO3 gave the corresponding polyfluorinated N-aryl-1,4-naphthoquinone 4-imine derivatives which exist in solution as equilibrium mixtures of Z and E isomers. 2,3,5,6,7,8-Hexafluoro-N-(4-dimethylaminophenyl)-1,4-naphthoquinone 4-imine in crystal has exclusively the Z-isomer structure.

Generation of perfluoro- and 1-chloropolyfluorobenzocycloalken-1-yl cations and their relative stability

Treatment of perfluorinated benzocyclobutene, indan, and tetralin with SbF5-SO2Cl2, as well as of their 1,1-dichloro analogs with SbF5, gave 1-chloropolyfluorobenzocycloalken-1-yl cations whose structure was studied by 19F and 13C NMR and confirmed by their transformations into perfluorinated ketones upon hydrolysis. Dissolution of perfluorinated benzocyclobutene, indan, and tetralin in excess SbF5 generated perfluorobenzocycloalken-1-yl cations in equilibrium with their precursors. The relative stability of perfluoro- and 1-chloropolyfluorobenzocycloalken-1-yl cations decreases as the size of the alicyclic fragment increases.

Formation of Fluoroderivatives of 1,2,3,4-Tetrahydro-1,3-diazafluorene from 2-Dialkylamino- 3-(1-imino-2,2,2-trifluoroethyl)hexafluoroindenes

Abstract2-Dimethylamino-3-(1-imino-2,2,2-trifluoroethyl)hexafluoroindene in the presence of DMSO or NEt3 undergoes isomerization into 1-methyl-4-trifluoromethyl-5,6,7,8,9,9-hexafluoro-1,2,3,4-tetrahydro-1,3-diazafluorene, and from 1-(1-amino-2,2,2-trifluoroethylidene)octafluoroindane by the treatment with water solution of NHEt2 2-methyl-4-trifluoromethyl-1-ethyl-5,6,7,8,9,9-hexafluoro-1,2,3,4-tetrahydro-1,3-diazafluorene was obtained.

Fluoro-indenes. Part 14. Interaction of perfluorinated 3-methyl-indene and 1-methylene-indan with nitrating agents in anhydrous HF

Abstract The reaction of perfluorinated 3-methyl-indene and 1-methylene-indan with nitrating agents in anhydrous HF leads to the formation of perfluoro-indan containing an oxygen function together with nitrofluorination products. From an analysis of the experimental data and the results of MNDO calculations of the starting compounds (including perfluorinated indene and 2-methyl-indene), their radical cations and polyfluorinated nitro-indanyl cations, a scheme for the process has been suggested including both a classical electrophilic route and a route involving radical cations of the substrates. The latter are assumed to be generated together with NO 2 · from the intermediate nitro-indanyl cations.

Controlled self-assembly of π-stacked/H-bonded 1D crystal structures from polyfluorinated arylamines and 18-crown-6 (2:1). Associates vs co-formers fluorescence properties

Supramolecular 1D assemblies supported by N–H⋯Ocr and π-stacking interactions were designed and synthesized using polyfluorinated arylamines, differing in the nature of the aromatic ring (benzene, naphthalene, pyridine) and para-substituents (H, F, CN, CF3), and 18-crown-6 ether. Co-crystal structures and intermolecular interactions were studied in detail using X-ray analysis and compared with those in individual arylamine crystals. In the co-crystals, all relatively weak H-bonds N–H⋯X (X = F, Nhet, Ncyano) are replaced by the stronger bond N–H⋯Ocrown and π-stacking in pairs of the arylamine molecules is realized. Depending on the arylamine structure, a parallel displaced, rotated, or slipped stack geometry occurs. Using DSC, phase transitions in the co-crystals were determined and the thermal characteristics were found to be reproduced in the melting-crystallization cycles, which indicates the regeneration of the crystal structure. For a number of compounds, there are significant changes in the fluorescence characteristics, in terms of both intensity and wavelength, due to the formation of associates with 18-crown-6: aggregation-induced emission in the pentafluoroaniline associate, a large shift of λem in the 4-cyanotetrafluoroaniline associate, and aggregation-caused quenching in the 4-aminotetrafluoropyridine associate. Crystal structure analysis reveals that π-stacking interactions between arylamines play a key role in the modulation of the solid-state fluorescence properties. The revealed effect of fluorescence build-up/quenching shows these types of supramolecular associates to be promising solid-state chemosensors.

Synthesis and E-Z isomerism of 4-(4-dimethylaminophenylimine) derivatives of 3-dialkylamino-2,5,6,7,8-pentafluoro-1,4-naphthoquinones

Amination of 2,3,5,6,7,8-hexafluoro-1,4-naphthoquinone 4-(4-dimethylaminophenylimine) with secondary amines gives the corresponding 3-amino derivatives existing in solutions as a mixture of E and Z isomers about the C=N imine bond.