Photochromism of indoline spiropyrans of the coumarin series in polymeric matrices

The photochromic properties and aggregation processes of merocyanine forms of indoline spiropyrans of the coumarin series in the block and film poly(methyl methacrylate) (PMMA) were studied and compared by spectral and kinetic methods. Photochromism of the synthesized compounds depends on their structure. The efficient formation of J-aggregates was observed for indoline spiropyrans of the coumarin series based on 8-formyl-7-hydroxy-4-methylcoumarin and 3-formyl-4-hydroxycoumarin. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 870–875, May, 2007.     

Controllable alignment of nematics by nanostructured polymeric layers

A method for a continuous control of the pretilt angle of the easy axis in the range 0–90° degrees and of the anchoring strength by using nanostructured polymers as alignment layers is described. The nanostructured polymers are blends of two different side-chain polymers each of them promoting planar and homeotropic alignment, respectively. A model to interpret the alignment of a nematic liquid crystal induced by such polymer layers is proposed. We show that in this case the anisotropic part of the surface tension can be approximated by a simple extension of the Rapini–Papoular expression. The predicted trend of the pretilt of the easy axis versus the concentration of the side-chain polymer promoting the planar alignment, for instance, is in good agreement with the experimental data. We also show that the effective anchoring strength of the system depends on the concentration of the side-chain polymer promoting planar alignment, and exhibits a minimum for a well-defined value of this quantity. The results obtained in this work seems to be of importance for liquid crystal displays technology since the control of the pretilt and the anchoring strength strongly affect the performance of liquid crystal displays.     

Biscyclopentadienyl compounds of zirconium and hafnium that contain chelate ligands

Conclusions The members of some new types of chelate compounds of zirconium and hafnium were obtained, in whose molecules, together with two cyclopentadienyl ligands, are present either one or two-diketone (either dibenzoylmethane or benzoylacetone) moieties.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1118–1121, May, 1973.     

Photochromic and thermochromic spiropyrans. 11. Calculation of the stabilities of the valence tautomers of spiropyrans

A method was developed for the estimation of the relative stabilities of spirocyclic and merocyanine structures of spiropyrans on the basis of the Pariser-Farr-Pople method in , parametrization with a corresponding estimate of the energy of formation of the spiro node. The results of the calculations are in satisfactory agreement with the experimental data and the results of calculation by the MINDO/3 method.See [1] for communication 10.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 177–184, February, 1980.     

Dithio- and monothiophosphates that contain mercaptoacetic and mercaptosuccinic acid moieties

Conclusions Some 0,0-diethyl dithio- and monothiophosphates, containing either mercaptoacetic or mercaptosuccinic acid moieties in the alkthiol radical, were synthesized by the alkylation of the salts of either 0,0-diethyldithiophosphoric or 0,0-diethylmonothiophosphoric acid with halo derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 699–705, March, 1977.     

Structures and reactivities of compounds that contain a phenanthridone grouping

The structures of 4H-cyclopenta[k,1,m]phenanthridine-5,9-dione, phenanthridone, and 5,10-dioxo-4,5,9,10-tetrahydro-5-aza-9-oxapyrene were refined by IR and electronic spectroscopy and quantum-chemical calculations, and the order of aromatic substitution of the lactam form of the first compound was evaluated. It is shown that all three compounds exist primarily in the form of lactam tautomers. The long-wave transition in their absorption spectra was interpreted.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1388–1392, October, 1982.     

Conversion of rhenium alkylidyne complexes that contain unsupported metal-metal double bonds into relatives that contain μ-alkylidyne ligands

Photolysis of compounds of the type [Re(CCMe₂R)(OR′)₂] (R = Me or Ph; OR′ = O′Bu, OCMe₂(CF₃), or OCMe(CF₃)₂) in benzene with a medium pressure mercury lamp yields compounds of the type [Re(OR′)₂]₂(μ-CCMe₂R)₂ in an intramolecular and irreversible manner. [Re(CCMe₂R)(OR′)₂]₂ and [Re(OR′)₂]₂(μ-CCMe₂R)₂ (OR′ = O′Bu or OCMe₂(CF₃)₂) both react with excess carbon monoxide in several solvents to afford the dimers [Re(OR′)₂(CO)]₂(μ-CCMe₂R)₂ quantitatively. An X-ray study of [Re(O^tBu)₂(CO)]₂ (μ-C^tBu)₂ shows it to consist of two distorted trigonal bipyramids connected by two symmetrically bridging neopentylidyne ligands. The unbridged dimers of general formula [Re(CCMe₂R)(OR′)₂]₂ do not react readily with simple substrates such as phosphines, olefins, or acetylenes, although [Re(CCMe₂R)(O^tBu)₂]₂ can be oxidized by iodine to yield Re(CCMe₂R)(O^tBu)₂I₂ in good yield. In contrast, {Re[OCMe(CF₃)₂]₂}₂(μ-C^tBu)₂ reacts with one equivalent of phenylacetylene to give a species in which one of the two bridging alkylidyne ligands is retained.     

Synthesis and properties of spiropyrans that are capable of reversible opening of the pyran ring (review)

The review is devoted to spiropyrans in which the pyran ring can be opened reversibly to give a completely conjugated colored isomer. Methods for the preparation of spiropyrans from various heterocyclic systems, their chemical properties, and the effects of various factors on the relative stabilities of the spiropyrans and the isomeric merocyanines are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 435–459, April, 1979.     

Determination of thorium in magnesium alloys that contain zirconium

Summary An indirect polarographic method for the determination of thorium in magnesium alloys that contain zirconium, zinc, and rare-earth elements is described. The method depends on the precipitation of thorium as the tetra (m-nitrobenzoate) and the polarographic determination of the m-nitrobenzoic acid that is equivalent to the amount of thorium that was so precipitated. The only interference, that of zirconium, is forestalled by the prior removal of the zirconium on an anion-exchange resin. The zirconium can easily be eluted quantitatively from the resin, for subsequent determination.The method avoids tedious separational procedures, and yields accurate and precise values for thorium in the alloys for which it was devised. It is also applicable to simpler substances.The authors gratefully acknowledge the grant from the Defence Research Board of Canada that made possible this investigation (Project D44-75-10-04).     

Bidentate ligands that contain pyrrole in place of pyridine

A series of ligands are prepared that are analogues of benzo-fused derivatives of 2,2'-bipyridine (bpy), in which pyrrole has been substituted for a pyridine ring. These ligands include 2-(2'-pyridyl)-indole, 2-(2'-pyrrolyl)-quinoline, and pyrrolo[3,2-h]quinoline. A novel reductive cyclization approach to the latter species is presented. All these ligands react with [Ru(bpy-d8)2Cl2], undergoing cyclometalation with concurrent deprotonation, to form complexes of the type [Ru(L)(bpy-d8)2]+ where L binds as a monoanionic ligand. The complexes are readily characterized by their 1H NMR spectra. Changes in the redox potentials and the electronic absorption spectra of both the ligands and the complexes are interpreted in terms of charge delocalization on the ligand.     

Synthesis and study of polydentate ligands that contain a pyrimidine ring

The corresponding hydrazones, azo compounds, and 2,4-bis(1H-pyrazol-1-yl)pyrimidines were synthesized by the reaction of 5-ethyl-2-hydrazino-6-methyl-4(3H)-pyrimidinone, 2-(N-p-butylanilino)-4-hydrazino-6-methylpyrimidine, and 4-hydrazino-2-(1H-pyrazol-1-yl)pyrimidines with salicylaldehyde, isatin, -naphthoquinone, phenanthrenequinone, and acetylacetone. The structures of the synthesized compounds are discussed on the basis of a study of their electronic, IR, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1682–1687, December, 1980.     

Synthesis and properties of 1,2,3-triazoles that contain a ferrocenyl ring

Ferrocenesulfonyl azide reacts with a number of aroylmethylenetriphenylphosphinomethylenes in dry methylene chloride to give 1,4,5-trisubstituted 1,2,3-triazoles (61–77% yields), which are readily converted to 4,5-disubstituted 1,2,3-triazoles and ethyl ferrocenesulfonate when they are refluxed in ethanol. The known tri-phenylphosphazo ferrocenyl sulfone and ethyl diazoacetate are formed in the case of the reaction of ferrocenesulfonyl azide with carbethoxymethylenetriphenylphosphinomethylene. The structures of the synthesized compounds were proved by the results of elementary analysis and IR, UV, and mass spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 701–704, May, 1980.