Quantum-chemical study of the molecular forms of vanillin

Equilibrium structural parameters, dipole moments, relative energies, vibration spectra, and ionization potentials of various conformers of benzoid (B), p- and o-quinoid (Q), and deprotonated anionic forms of vanillin in a vacuum and in a polarizable medium with dielectric properties of water were calculated by the quantum-chemical method (U)B3LYP/cc-pVTZ. The intramolecular hydrogen bond in free vanillin benzoid molecule B1 is characterized by the energy of 4 kcal mol⁻¹ and by the barrier of cleavage 8 kcal mol⁻¹ that correspond to the conformational transition B1 → B2. The energy of the optimal p-quinoid conformer (Q1) is 22 kcal mol⁻¹ larger than the energy of B1 in a vacuum and 15 kcal mol⁻¹ in water. The p-quinoid forms greatly exceeds the benzoid forms by dipole moment, electrophilicity, and nucleophilicity. The structure calculated for the anion is intermediate between benzoid and p-quinoid forms, and the calculated energy of polarization stabilization in water is 57 kcal mol⁻¹.     

3,6-Di-tert-butyl-o-benzosemiquinone complexes of copper(1) with bidentate bis(diphenylphosphine) ligands. Synthesis, structures, and properties

New mononuclear 3,6-di-tert-butyl-o-benzosemiquinone complexes of copper(1) with bis(diphenylphosphine) ligands were synthesized: (DBSQ)Cu(dppe) (1) (DBSQ=3,6-di-tert-butyl-o-benzosemiquinone and dppe=1,2-bis(diphenylphosphino)ethane), (DBSQ)Cu(dppp) (2) (dppp=1,3-bis(diphenylphosphino)propane), (DBSQ)Cu(dppn) (3) (dppn=2,2′-bis(diphenylphosphino)-1,1′-binaphthyl), and (DBSQ)Cu(dppfc) (4) (dppfc=1,1′-bis(diphenylphosphino)ferrocene). The compositions and structures of complexes1–4 were characterized by elemental analysis and electronic absorption, IR, and ESR spectroscopy. The molecular structures of complexes3 and4 were established by X-ray diffraction analysis. The reactions of elimination and replacement of neutral ligands in the coordination sphere of the complexes were studied by ESR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2333–2340, November, 1998.     

Reaction of 2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-carbaldehyde with naphthalen-1-amine,quinolin-8-amine,and 1,3-diketones

Condensation of 2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-carbaldehyde with naphthalen-1-amine and cyclohexane-1,3-dione, methyl 2,2-dimethyl-4,6-dioxocyclohexane-1-carboxylate, or dimedone gave the corresponding 7-(2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-yl)-7,8,9,10,11,12-hexahydro-12H-benzo[c]acridin-8-ones. The reaction of 2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-carbaldehyde with naphthalen-1-amine and indan-1,3-dione produced 7-(2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-yl)-8H-benzo[h]indeno[1,2-b]quinolin-8-one. 7-(2′-Hydroxy-1,1′: 3′,1″-terphenyl-5′-yl)-7,8,9,10,11,12-hexahydrobenzo[b][1,10]phenanthrolin-8-ones were obtained by three-component condensation of 2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-carbaldehyde with quinolin-8-amine and cyclohexane-1,3-dione, methyl 2,2-dimethyl-4,6-dioxocyclohexane-1-carboxylate, or dimedone.     

A convenient synthetic route from isatin N-Mannich bases to nitrogen-containing derivatives of isoindigo

Abstract  

The reaction of aminomethylisatins (isatin N-Mannich bases) with hexaethylphosphorous triamide leads to the formation of 1,1′-bis(dialkylaminomethyl)-3,3′-bis(indolin-3-ylidene)-2,2′-diones and 1,1′-bis(1,3-dioxo-1,3-dihydroisoindol-2-ylmethyl)-1H,1′H-[3,3′]bisindolylidene-2,2′-dione.     

The Structure of New Host Molecules that form Channel Inclusion Compounds

1,3-Benzenediamine,N,N′-bis(4,6-dichloro-1,3,5-triazine-2-yl) and 1,3,5-Triazine,2,2′-[2-methyl-1,3-phenylenebis(oxy)] bis(4,6-dichloro) were synthesized as host molecules. The inclusion compound of 1,3-Benzenediamine,N,N′-bis(4,6-dichloro-1,3,5-triazine-2-yl) crystallizes in the monoclinic crystal system in space group C2/c. The host molecule occupies the space group 2-fold special position and packed in the crystal lattice in such a manner as to leave channels running along the c axis of a rectangular cross-section. It crystallizes with two molecules of acetone that are hydrogen bonded to the amino nitrogen atoms. Molecules of 1,3,5-Triazine,2,2′-[2-methyl-1,3-phenylene bis(oxy)]bis(4,6-dichloro) are packed in the crystal in such a manner as to leave channels of a trapezoid cross-section that are running along the a axis. Guest molecules such as metanol, ethanol, and ethyl acetate can be used to fill the channels. The crystal structures of two inclusion compounds are described.     

Synthesis and structure of an arylpyran normal, pseudodiacid showing recognition

Abstract  

Oxidation of 1,4-bis(4′-oxo-2′,2′-dimethylpent-2-yl)benzene with hypochlorite produces 1,4-bis(3′-carboxy-2′-methylbut-2-yl)benzene and 3-(4′-carboxyphenyl)-3,3-dimethylpropanoic acid. Cyclization of this mixture forms 3,3,7,7-tetramethyl-1,2,3,5,6,7-hexahydro-s-indacen-1,5-dione, 3,3,7,7-tetramethyl-1,2,3,5,6,7-hexahydro-as-indacen-1,5-dione (5) and 6-carboxy-3,3-dimethyl-1-indanone (6). Ketoacid (6) is converted to the arylpyran pseudoacid 7-carboxy-3-hydroxy-4,4-dimethylisobenzopyran-1-one (7). In the crystal structure of (7), carboxylic acid and the pseudoacid groups each form complementary dimer hydrogen bonds linking the molecules in chains. Contact O···O distances reflect their differing energetics, with pseudoacyl O···O at 2.78(1)Å and carboxylic O···O at 2.62(1)Å.     

Polyfused nitrogen-containing heterocycles 18. 2′-Amino-5-methyl-1,2,3,4,4′,5′-hexahydrospiro[quinoxaline-2,4′-thiazol]-3-ones. Synthesis,structure, and recyclization

Bis-3-(α-bromoethyl)quinoxalin-2-ones with 3-oxapentane or 3,6-dioxaoctane spacer binding two heterocyclic fragments react with thiourea to give the corresponding bis-spirothiazoloquinoxalines, which upon treatment with acetic anhydride can be converted to podands with terminal thiazoloannulated quinoxaline fragments. X-Ray data for 2′-amino-4-ethyl-5-methyl-1,2,3,4,4′,5′-hexahydrospiro[quinoxaline-2,4′-thiazol]-3-one indicate for this compound a potentiality to form clathrate structures with various solvate molecules. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2386–2393, December, 2007.     

Enhanced photovoltaic performance of quasi-solid-state dye-sensitized solar cells via incorporating quaternized ammonium iodide-containing conjugated polymer into PEO gel electrolytes

In this study, a series of gel electrolytes prepared from blends of alternating conjugated polymer electrolytes (CPEs)/poly(ethylene oxide) (PEO) were developed for use in quasi-solid-state dye-sensitized solar cells (DSSCs). The alternating CPEs poly[(N-(3′-((N,N-dimethyl)-N-ethylammonium)propyl)-3,6-carbazole)-alt-(9,9-dioctyl-2,7-fluorene)]diiodide, poly[(N-(3′-((N,N-dimethyl)-N-ethylammonium)propyl)-3,6-carbazole)-alt-(9,9-bis(2-(2-methoxyethoxy)ethyl)-2,7-fluorene)]diiodide (MPCFO-E), and poly[(N-(3′-((N,N-dimethyl)-N-ethylammonium)propyl)-3,6-carbazole)-alt-(siloxane substituted-2,7-fluorene)]diiodide (MPCFS-E) were synthesized through copolymerization of carbazole units (featuring quaternized ammonium iodide groups) and fluorene units featuring flexible side chains (9,9-dioctylfluorene, ethylene oxide-substituted fluorene, and siloxane-substituted fluorene, respectively). The MPCFO-E/PEO-based and MPCFS-E/PEO-based DSSCs exhibited lower electrochemical resistances, superior photovoltaic (PV) properties, and improved PV stabilities relative to those of the corresponding PEO-based DSSC. Among the studied systems, the DSSC based on the MPCFO-E (0.5 wt.%)/PEO blend electrolyte exhibited the best PV performance, with a short current density of 4.97 mA cm⁻² and a photoenergy conversion efficiency of 1.17%.     

Synthesis of α,α′-bis(R-benzylidene)cycloalkanones catalyzed by potassium hydrogen sulfate under solvent-free conditions

Cyclopentanone or cyclohexanone were condensed with aromatic aldehydes to give corresponding α,α′-bis(R-benzylidene)cyclopentanones or α,α′-bis(R-benzylidene)cyclohexanones. The reaction was catalyzed by potassium hydrogen sulfate with a yield of 84–95% under solvent-free conditions.     

Investigation on the thermal decomposition some heterodinuclear NiII-MII complexes prepared from ONNO type reduced Schiff base compounds ( M II=ZnII, CdII)

N,N′-bis(salicylidene)-1,3-propanediamine (LH₂), N,N′-bis(salicylidene)-2,2′-dimethyl-1,3-propanediamine (LDMH₂), N,N′-bis(salicylidene)-2-hydroxy-1,3-propanediamine (LOH₃), N,N′-bis(2-hydroxyacetophenylidene)-1,3-propanediamine (LACH₂) and N,N′-bis(2-hydroxyacetophenone)-2,2′-dimethyl-1,3-propanediamine (LACDMH₂) were synthesized and reduced to their phenol-amine form in alcoholic media using NaBH₄ (L^HH₂, LDM^HH₂, LOH^HH₂, LAC^HH₂ and LACDM^HH₂). Heterodinuclear complexes were synthesized using Ni(II), Zn(II) and Cd(II) salts, according to the template method in DMF media. The complex structures were analyzed using elemental analysis, IR spectroscopy, and thermogravimetry. Suitable crystals of only one complex were obtained and its structure determined using X-ray diffraction, NiLAC^H·CdBr₂·DMF₂, space group orthorhombic, Pbca, a=20.249, b=14.881, c=20.565 ? and Z=8. The heterodinuclear complexes were seen to be of [Ni·ligand·MX₂·DMF₂] structure (ligand=L^H2−, LDM^H2−, LOH^H2−, LAC^H2−, LACDM^H2−, M=Zn^II, Cd^II, X=Br⁻, I⁻). Thermogravimetric analysis showed irreversible bond breakage of the coordinatively bonded DMF molecules followed by decomposition at this temperature.     

Solid-phase oxidation of 2,4-Di-tert-butylphenol and 3,6-Di-tert-butylpyrocatechol in the presence of alkali and alkaline earth metal halides under elastic deformation

Solid-phase oxidation of 2,4-di-tert-butylphenol to give 2,2′,4,4′-tert-butyl-6,6′-bisphenol and of 3,6-di-tert-butylpyrocatechol to afford 3,6-di-tert-butyl-l,2-benzoquinone was performed in the presence of alkali and alkaline earth metals halides under conditions of modified extrusion. The formation of the corresponding metal 3,6-di-tert-butylsemiquinolates was registered by ESR method. The different behavior of chlorides, bromides, and iodides was observed and rationalized basing on the dissimilar complexing ability of halogens. The mechanism of activated oxidation was assumed. The study was carried out under financial support of the Russian Foundation for Basic Research (grant no. 96-03-33253a). Deceased.     

Reactions of 2-phenyl-4,4-bis(trifluoromethyl)-4,5-dihydro-1,3,2-benzodioxaphosphepin-5-one with phenanthrenequinone and dibenzoyl

Reactions of 2-phenyl-4,4-bis(trifluoromethyl)-4,5-dihydro-1,3,2-benzodioxaphosphepin-5-one with 9,10-phenanthrenequinone and dibenzoyl gave hydrolytically unstable spirophosphoranes with five- and seven-membered rings, 2-phenyl-4,4-bis(trifluoromethyl)-4,5-dihydrospiro[[1,3,2]benzodioxaphosphepine-2,2′-phenanthro[9,10-d][1,3,2]dioxaphosphol]-5-one and 2,4′,5′-triphenyl-4,4-bis(trifluoromethyl)-4,5-dihydrospiro[[1,3,2]benzodioxaphosphepine-2,2′-[1,3,2]dioxaphosphol]-5-one. The structure of the first of these was proved by X-ray analysis.     

Synthesis,characterization and catalytic properties of heterogeneous iron(III) tetradentate Schiff base complexes for the aerobic epoxidation of styrene

A series of hybrid mesoporous SBA-15 materials containing four iron(III) Schiff base complexes of the type [FeL ^x (NO₃)] (x = 4–7, L = N,N′-bis(salicylidene)ethylenediamine, N,N′-bis(salicylidene)diethylenetriamine, N,N′-bis(salicylidene)o-phenylenediamine, N,N′-bis(3-nitro-salicylidene)ethylenediamine) was synthesized by a post-grafting route. The XRD, N₂ adsorption/desorption and TEM measurements confirmed the structural integrity of the mesoporous hosts, and the spectroscopic characterization techniques (FT-IR, UV–vis spectroscopy, ¹H NMR) confirmed the ligands and the successful anchoring of iron(III) Schiff base complexes over the modified mesoporous support. Quantification of the supported ligand and metal was carried out by TG/DSC and ICP-AES techniques. The catalyst FeL⁷-SBA resulting from N,N′-bis(3-nitro-salicylidene)ethylenediamine) ligand was considerably active for the aerobic epoxidation of styrene, in which the highest conversion of styrene reached 83.6%, and the selectivity to styrene oxide was 83.0%. Moreover, it was also found that the catalytic activity increases with the decrease in the electron-donating ability of the Schiff bases, and the selectivity varies according to the types of substituents in the ligands.     

1,2,3-Oxadiazole rings in the aromatic compounds: A quantum-chemical investigation

Quantum chemical method PBE0/cc-pVTZ in conjunction with the polarizable continuum model (PCM) was applied to the calculation of the equilibrium structural parameters of the benzene and naphthalene 1,2,3-oxadiazole derivatives, as well as relevant diazocarbonyl compounds both in the free state and dissolved in dichloromethane. The calculated ionization potentials of benzo-1,2,3-oxadiazole (9.49 eV), 6-diazocyclohexa-2,4-dien-1-one (8.16 eV) and (6-oxocyclohexa-2,4-dien-1-ylidene)carbonyl (8.34 eV) differ from the experimental values no more than by 0.09 eV. The calculations indicate the possible existence of naphtho [2,3-d:6,7-d′]bis(1,2,3-oxadiazole) in the gas phase and in aprotic solvents.     

Reactivity of diazoazoles and azolediazonium salts in <Emphasis Type="Italic">C</Emphasis>-azo coupling reactions

The comparative reactivity of heterocyclic diazo compounds and the corresponding diazonium salts in C-azo coupling reactions was studied using imidazole, pyrazole, and triazole derivatives as examples.The reactivities of pyrazole- and imidazole-derived diazonium salts are much lower than those of thiadiazole- and 1,2,4-triazole-derived diazonium salts but higher than those of pyrrole and indole diazo compounds.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 348–358, February, 2005.     

Effects of initiators and photo-acid generators on nitroxide-mediated photo-living radical polymerization of methyl methacrylate

The effects of the structure of initiators and photo-acid generators on the nitroxide-mediated photo-living radical polymerization of methyl methacrylate were explored. The bulk polymerization was performed at room temperature using nine different initiators in the presence of (4-tert-butylphenyl)diphenylsulfonium triflate as the photo-acid generator. 2,2′-Azobisisobutyronitrile, 2,2′-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis(2-methylpropionate), and 2,2′-azobis(N-butyl-2-methylpropionamide) produced the polymers with a molecular weight distribution (MWD) around 1.6, while the racemic- and meso-(2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) provided a 1.4 MWD. 2,2′-Azobis(2-methylbutyronitrile), 1,1′-azobis(cyclohexane-1-carbonitrile), and 1-(cyano-1-methylethoxy)-4-methoxy-2,2,6,6-tetramethylpiperidine produced a broad MWD over 4.0. The structure of the photo-acid generator also had an influence on the molecular weight control. The photo-acid generator of sulfonium salts supporting the alkyl, methoxy, phenoxy, methylthio, and tert-butoxycarbonylmethoxy groups, coupled with halogens with the exception of the iodide had no effect on the MWD. On the other hand, the salts containing the iodide, phenylthio, and naphthyl groups produced polymers with broad MWDs and with uncontrolled high molecular weights.     

α,ω-Bis(3,6-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)alkanes and products of their cyclization, pyrimidinophanes: intra- and intermolecular interaction in crystals and in solutions

Reaction of α,ω-bis(3,6-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)alkanes with paraformaldehyde leads to pyrimidinophanes, which contain four 3,6-dimethyluracil fragments, connected to each other by the methylene chains. A comparative study of intra- and intermolecular interactions of “open” and macrocyclic uracil derivatives in the crystal state and in solution was performed. According to the NMR spectroscopy data, there is no self-association of “open” and macrocyclic compounds in chloroform solutions, whereas the X-ray data revealed the intermolecular π-π contacts between the 3,6-dimethyluracil fragments in the crystals of these compounds. Conclusions on the presence of intramolecular interactions in chloroform solutions of α,ω-bis(3,6-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)alkanes and pyrimidinophanes were made based on the UV spectra, which were interpreted in terms of hypo- and hyperchromic effects relatively to the model uracil derivative. These conclusions correlate with the X-ray data: there are no intramolecular π-π contacts between the 3,6-dimethyluracil fragments both in the crystals and in solutions of “open” compounds, positions of these fragments relatively to each other in the molecules of pyrimidinophanes are defined by the lengths of the polymethylene bridges. The intramolecular stacking effect between the opposite uracil rings is observed for the macrocycles with trimethylene and hexamethylene chains, whereas there is no such interactions in pyrimidinophanes with tetramethylene chains. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 119–131, January, 2008.     

Reaction of <Emphasis Type="Italic">N,N</Emphasis>′-bis(trimethylsilyl)dicyandiamide with bis(η<Superscript>5</Superscript>-cyclopentadienylvanadium) dichloride

1,3,5-Tris[bis(η⁵-cyclopentadienyl)chlorovanadium]melamin is prepared in high yield by the reaction of N,N′-bis(trimethylsilyl)dicyandiamide with bis(η⁵-cyclopentadienylvanadium) dichloride in tetrahydrofuran. As side products, trimethylchlorosilane and cyclopentadiene formed. Reaction of N,N′-bis(trimethylsilyl) dicyandiamide with benzoyl chloride results in the formation of tris(benzoyl)melamin.     

Conformational analysis and interpretation of ν(OH) band in the IR spectrum of o-vinylphenol: a DFT study

Two-dimensional cyclic potential energy surface for internal rotation of vinyl and hydroxyl substituents in o-vinylphenol molecule was constructed by the B3LYP/6-311G(d) method. It was shown that o-vinylphenol molecule exists in the gas phase as a mixture of seven rotamers denoted as A (A′), B (B′), C (C′) and D. The B3LYP/cc-pVTZ calculated percentage of the rotamers A and A′ in which OH…π intramolecular interaction occurs, is at most 24%. The height of barriers t interconversions between o-vinylphenol rotamers varies from 0.1 to 5.2 kcal mol⁻¹. According to B3LYP/cc-pVTZ calculations, the inclusion of solvent effect in the framework of the polarizable continuum model for a solution of o-vinylphenol in CCl₄ leads to a decrease in theoretical values of ν(OH) frequencies by about 4–9 cm⁻¹ and to an increase in the percentage of the rotamers without intramolecular hydrogen bond by about 4.3% compared to the corresponding gas-phase values. The simulated IR spectral contours of ν(OH) bands are in good agreement with experimental one Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 499–508, March, 2008.     

peri-Naphthylenediamines

The reaction of 1,8-bis(dimethylamino)naphthalene (“proton sponge”) with trifluoroacetic anhydride afforded new derivatives of naphtho[1,8-c,d]pyran,viz., trans-) (4) andcis-1,3-dihydroxy-6,7-bis(dimethylamino)-1,3-bis(trifluoromethyl)-1H,3H-naphthol[1,8-c,d]pyran (5) and symmetrical 3,4,10,11-tetrakis(dimethylamino)-7,14-bis(trifluoromethyl)-7,14-epoxydinaphtho[1,8-a,b;1′, 8′-ef]cyclooctane (3), which belongs to a new type of double “proton sponges,” along with the expected 1,8-bis(dimethylamino)-4-trifluoroacetylnaphthalene. The structures of compounds3 and4 were established by spectral studies and X-ray diffraction analysis.