Electrochemistry of Sc3N@C78 embedded in didodecyldimethylammonium bromide films in aqueous solution

The electrochemical behavior of trimetallic nitride clusterfullerene (Sc₃N@C₇₈) embedded in films of the cationic surfactant didodecyldimethylammonium bromide (DDAB) on glassy carbon (GC) electrodes in aqueous solution was investigated. Four pairs of reversible redox peaks were observed in the potential range between +0.6 and ?0.9 V vs. SCE. Different to the electrochemistry of pristine Sc₃N@C₇₈ in organic solution, the first reduction is a one-electron rather than simultaneous two-electron process because of the strong binding between DDA⁺ and the monoanion of Sc₃N@C₇₈. The generated radial monoanion, dianion and trianion of Sc₃N@C₇₈ are stable during continuous potential cycling, while some chemical reactions take place when the third anion is further reduced in the films. The cyclic voltammograms of Sc₃N@C₇₈/DDAB films checked at different temperatures pointed to strong temperature dependence. The electrochemical processes were also measured in different electrolytes, which showed pronounced anionic dependence and no cathodic dependence on either the cation or anions present. A possible electron-transfer mechanism of a Sc₃N@C₇₈/DDAB film was presented.     

Effect of isomeric pyridine moieties in ethynylstyrene derivatives on their anionic polymerization

The anionic polymerization behaviors of ethynylstyrene derivatives containing isomeric pyridine moieties, 2‐(2‐(4‐vinylphenyl)ethynyl)pyridine ( A ), 3‐(2‐(4‐vinylphenyl)ethynyl)pyridine ( B ), and 4‐(2‐(4‐vinylphenyl)ethynyl)pyridine ( C ), were investigated in the identical conditions. The anionic polymerization of A – C was performed with (diphenylmethyl)potassium (Ph₂CHK) in tetrahydrofuran (THF) at ?78 °C. The polymerization of A proceeded quantitatively at –78 °C for 4 h, and the resulting poly( A ) possessed predictable molecular weights (M_n = 3300–68,500) and narrow molecular weight distributions (MWDs) (M_w/M_n = 1.04–1.11). In contrast, the anionic polymerization of B was not performed at –78 °C for 4 h due to the occurrence of side reactions. The monomer B was quantitatively recovered after the reaction. In the polymerization of C performed at –78 °C for 6 h, observed M_n values of the resulting poly( C ) were in good agreement with calculated molecular weights based on monomer to initiator ratios, but the MWDs were somewhat broad (M_w/M_n = 1.23–1.31). To estimate the reactivity of A and to characterize its living nature, the block copolymerization of A with 2‐vinylpyridine (2VP) and methyl methacrylate (MMA) was performed. The well‐defined block copolymers, poly(2VP)‐b‐poly( A ) and poly( A )‐b‐poly(MMA), were successfully synthesized without any additives. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Generation of highly stable amidate anion in anionic polymerization of 3‐(triethylsilyl)propyl isocyanate

To study living anionic polymerization, 3‐(triethylsilyl)propyl isocyanate (TEtSPI) monomer was synthesized by hydrosilylation of allylamine with triethylsilane and treatment of the resulting amine with triphosgene. The polymerization of TEtSPI was performed with sodium naphthalenide (Na‐Naph) as an initiator and in the absence and presence of sodium tetraphenylborate (NaBPh₄) as an additive in tetrahydrofuran (THF) at ?78 and at ?98 °C. A highly stabilized amidate anion for living polymerization of isocyanates was generated for the first time with the combined effect of the bulky substituent and the shielding action of the additive NaBPh₄, extending the living character at least up to 120 min at ?98 °C. Even the anion could exist at ?78 °C for 10 min. A block copolymer, poly(n‐hexyl isocyanate)‐b‐poly[(3‐triethylsilyl)propyl isocyanate]‐b‐poly(n‐hexyl isocyanate), was synthesized with quantitative yields and controlled molecular weights via living anionic polymerization in THF at ?78 °C for TEtSPI and ?98 °C for n‐hexyl isocyanate, respectively, with Na‐Naph with three times of NaBPh₄ as a common ion salt. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 933–940, 2004     

Removal of cadmium and copper ions by <Emphasis Type="Italic">Trichosporon cutaneum</Emphasis> R57 cells immobilized onto polyvinyl alcohol/tetraethoxysilane hybrid matrices

Polyvinyl alcohol (PVA) and tetraethoxysilane (TEOS) hybrid materials were prepared by sol-gel methods and tested as matrices for immobilization of Trichosporon cutaneum R57, capable of removing cadmium and copper ions from aqueous solutions. A kinetic model was applied and the effects of matrix TEOS content on the copper and cadmium uptake equilibria and rate constants were investigated.      

Phase identification in Ti/TiN diffusion couples with the Kossel technique

A Ti/TiN diffusion couple, which had been prepared by isothermal annealing of a Ti sheet in nitrogen atmosphere at 1091 °C and quenched in water, was investigated by Kossel microdiffraction. Kossel patterns were obtained from all phases present in the diffusion couple (-Ti(N), -Ti₃N_2–x, -Ti₄N_3–x and -TiN_1-x)It could be shown that the Kossel technique has a superior lateral resolution (10 m) compared to commercially used X-ray microdiffraction methods, especially in the case of weak X-ray radiation.     

Studies of equilibrium geometries and electronic spectra for C78O4

Equilibrium geometries and relative stabilities of 24 possible isomers for C₇₈O₄ based on C₇₈ (C_2v) were studied by intermediate neglect of differential overlap (INDO) calculations. It was indicated that the most stable geometry is 28,29,30,31,52,53,73,78‐C₇₈O₄, where three oxygen atoms are added to the same hexagon, through which the longest axis of C₇₈ (C_2v) goes, and the forth oxygen atom is added to the C(73)? C(78) bond intersected by the shortest axis of C₇₈ (C_2v), and epoxide structures are formed. Electronic spectra of C₇₈O₄ isomers were investigated based on the optimized geometries. The blue shift of the first absorption for 28,29,30,31,52,53,73,78‐C₇₈O₄ compared with that of C₇₈ (C_2v) was rationalized and nature of transition for the peaks discussed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Cyclopolymerization. VI. Polymerization mechanism of N-methyl-N-allylmethacrylamide at lower temperature

Mechanistic investigations on the polymerization of N-methyl-N-allylmethacrylamide (MAMA) at lower temperature were carried out based upon the ESR studies of MAMA and its monofunctional counterparts irradiated with ⁶⁰Co γ rays. Cyclopolymerizability of MAMA was also studied in connection with the hindered rotation about its amide C? N bond. The propagating radical observed is only related to the methacryl group but not to the allyl group both in MAMA and its monofunctional counterparts. Polymerization at ?78°C yielded a polymer with a lower degree of cyclization(88.8%) as compared with that of polymers formed at higher temperatures (93.5% above 0°C). A structural study revealed that the increment of the unsaturation in the poly-MAMA obtained at ?78°C is due to the allyl group and the content of pendant methacryl group is almost unchanged over the temperature range from ?78 to 120°C. These results led to the conclusion that the polymerization of MAMA at ?78°C proceeds mainly through the methacryl group, the rate-determining step is the cyclization reaction, and, in addition, cyclization reaction scarcely occurs when it polymerizes through the allyl group. Since MAMA is frozen into a glassy state, the effect of glass transition temperature (T_g) has been studied and it was suggested that the polymerization of MAMA proceeds only above T_g.     

Three-Dimensional Cubic and Dice-Like Microstructures of Higher Fullerene C78 with Enhanced Photoelectrochemical and Photoluminescence Properties

The single-crystal micro/nanostructures of fullerene species, namely C₆₀ and C₇₀, have been previously studied, but studies on the morphology and properties of higher fullerenes have rarely been reported due to the limited amount of samples and their ellipsoidal isomeric structures. Herein, we report the formation of three-dimensional (3D) micro-cubes and micro-dice of a higher fullerene (C₇₈) via a facile liquid–liquid interfacial precipitation (LLIP) method. The micro-cubes were prepared by regulating the concentration of C₇₈ in trimethylbenzene (TMB) and the volume ratio of TMB and isopropanol. Interestingly, the micro-cubes are transformed into micro-dice with an open-hole on each crystal face by simply shaking the solution. X-ray diffraction and Fourier-transform infrared spectroscopic studies revealed a simple cubic unit cell with a lattice constant of 10.6 Å and intercalated TMB molecules in both crystals. The C₇₈ cubic and dice-like microstructures exhibited enhanced photoelectrochemical and photoluminescence properties compared with pristine C₇₈ powder, indicating their potential applications as photodetectors and photoelectric devices.     

Isolation and Crystallographic Characterization of Two,Nonisolated Pentagon Endohedral Fullerenes: Ho3N@C2(22010)-C78 and Tb3N@C2(22010)-C78

Purified samples of Ho₃N@C₂(22010)-C₇₈ and Tb₃N@C₂(22010)-C₇₈ have been isolated by two distinct processes from the rich array of fullerenes and endohedral fullerenes present in carbon soot from graphite rods doped with Ho₂O₃ or Tb₄O₇. Crystallographic analysis of the endohedral fullerenes as cocrystals with Ni(OEP) (in which OEP is the dianion of octaethylporphyrin) shows that both molecules contain the chiral C₂(22010)-C₇₈ cage. This cage does not obey the isolated pentagon rule (IPR) but has two sites where two pentagons share a common C−C bond. These pentalene units bind two of the metal ions, whereas the third metal resides near a hexagon of the cage. Inside the cages, the Ho₃N or Tb₃N unit is planar. Ho₃N@C₂(22010)-C₇₈ and Tb₃N@C₂(22010)-C₇₈ use the same cage previously found for Gd₃N@C₂(22010)-C₇₈ rather than the IPR-obeying cage found in Sc₃N@D_3h-C₇₈.     

Phytoecdysteroids ofRhaponticum carthamoides

From the roots with rhizomes of the plantRhaponticum carthamoides Willd) Iljin Compositae), in addition to integristerone A, ecdysterone, polypodin B, 2-deoxyecdysterone, and 24(28)-dehydromakisterone A, we have isolated the new compounds ecdysteron3–2,3-monoacetonide (I), ecdysterone 20,22-monoacetonide (II)) and rhapisterone (III): I — C₃₀H₄₈O₇, mp 232–233° (ethyl acetate-methanol) [] _D ²⁰ +56.4±2° (c 0.0; methanol); II — C₃₀H₄₈O₇, mp 227–229° (ethyl acetate-methanol), [] _D ²⁰ +60.1±2° (c 1.3; methanol); III — C₂₉H₄₈O₇, mp, 241–242° (ethyl acetate-methanol), [] _D ²⁰ +30±2° (c 0.1; dioxane). The structure of (III) was established on the basis of spectral characteristics as 2, 3, 14, 20R, 22R, 23-5-stigmast-7-en-6-one. Details of the PMR, mass, and IR spectra of all the compounds and of the CD of rhapisterone are given.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 681–684, September–October, 1987.     

Conductivity and interfacial behaviour of bis-1,4-dioxapentyl sulfate (IV) and 1,4,7-trioxaoctyl sulfate (IV) based electrolyte for lithium batteries

The electrolytic conductivity and viscosity of lithium perchlorate in bis-1,4-dioxapentyl sulfate (IV) [OS22] and 1,4,7-trioxaoctyl sulfate (IV) [OS32] were determined as a function of salt concentration (0.00005–2 M) and temperature (286–318 K). At 298 K, the highest conductivity (=2.77×10^{–3 –1} cm^–1) was achieved for OS22 based solutions containing 1–2 M LiClO₄. Formation of electrically neutral ion pairs appeared to be the main reason for a continuous decline in the molar conductivity () observed in dilute solutions with increasing salt concentration. Additionally, an increase in the dynamic viscosity () accounted for a decrease in the mobility of charge carriers with increasing length of the oxaalkyl chain in the podand molecules. The temperature dependence of the conductivity and viscosity was found to be of the Arrhenius type for both systems investigated, while the activation energies, E ^# and E ^#, varied in parallel with the degree of interionic aggregation. CVs obtained on a polycrystalline Pt electrode indicated the electrochemical stability of OS22 in the potential range between –0.8 V and 4.7 V versus Li⁺/Li. A linear current density–potential dependence, with the same slope for the anodic and cathodic branches proved the reversibility of lithium electrodeposition and re-dissolution at the Pt/1 M LiClO₄+OS22 interface.     

The Exohedral Diels–Alder Reactivity of the Titanium Carbide Endohedral Metallofullerene Ti2C2@D3h‐C78: Comparison with D3h‐C78 and M3N@D3h‐C78 (M=Sc and Y) Reactivity

The chemical functionalization of endohedral (metallo)fullerenes has become a main focus of research in the last few years. It has been found that the reactivity of endohedral (metallo)fullerenes may be quite different from that of the empty fullerenes. Encapsulated species have an enormous influence on the thermodynamics, kinetics, and regiochemistry of the exohedral addition reactions undergone by these species. A detailed understanding of the changes in chemical reactivity due to incarceration of atoms or clusters of atoms is essential to assist the synthesis of new functionalized endohedral fullerenes with specific properties. Herein, we report the study of the Diels–Alder cycloaddition between 1,3‐butadiene and all nonequivalent bonds of the Ti₂C₂@D_3h‐C₇₈ metallic carbide endohedral metallofullerene (EMF) at the BP86/TZP//BP86/DZP level of theory. The results obtained are compared with those found by some of us at the same level of theory for the D_3h‐C₇₈ free cage and the M₃N@D_3h‐C₇₈ (M=Sc and Y) metallic nitride EMFs. It is found that the free cage is more reactive than the Ti₂C₂@D_3h‐C₇₈ EMF and this, in turn, has a higher reactivity than M₃N@D_3h‐C₇₈. The results indicate that, for Ti₂C₂@D_3h‐C₇₈, the corannulene‐type [5, 6] bonds c and f , and the type B [6, 6] bond 3 are those thermodynamically and kinetically preferred. In contrast, the D_3h‐C₇₈ free cage has a preference for addition to the [6, 6] 1 and 6 bonds and the [5, 6] b bond, whereas M₃N@D_3h‐C₇₈ favors additions to the [6, 6] 6 (M=Sc) and [5, 6] d (M=Y) bonds. The reasons for the regioselectivity found in Ti₂C₂@D_3h‐C₇₈ are discussed.     

均相稀土配位催化剂及其活性体结构的研究——Ⅰ.丁二烯在(CF_3COO)_2NdCl·EtOH-AlEt_3体系中的聚合

合成了新的釹络合物。分析结果表明这一络合物为(CF_3COO)_2NdCl·EtOH。这一络合物与三乙基铝可组成均相催化体系使丁二烯聚合得到顺式1,4-含量为78—98％的聚丁二烯。     

Monometallic cyanide cluster fullerene YCN@C78: A theoretical prediction

Stimulated by the recent experimental success in production and characterization of YCN@C_s(6)‐C₈₂, the possibility of encapsulating YCN cluster in the C₇₈ fullerene has been performed using density functional theory. Six isomers of YCN@C₇₈ are considered based on six lowest energy C₇₈^2? isomers. The results reveal that YCN@D_3h(24109)‐C₇₈ and YCN@C_2v(24107)‐C₇₈, both of which satisfy the isolated‐pentagon rule, present excellent thermodynamic stability with very small energy differences. Moreover, the large HOMO‐LUMO gaps (1.55 and 1.47 eV for YCN@D_3h(24109)‐C₇₈ and YCN@C_2v(24107)‐C₇₈, respectively) indicate their high kinetic stabilities. Significantly, in both the structures, the encapsulated YCN cluster is triangular, similar to the cases of YCN@C_s(6)‐C₈₂ and TbCN@C₂(5)‐C₈₂. In addition, electronic absorption spectra, infrared spectra, and ¹³C nuclear magnetic resonance spectra of two stable structures have also been explored to further disclose the molecular structures and properties. © 2015 Wiley Periodicals, Inc.     

Paths for the formation of dioxin-type xenobiotics: Quantum-chemical treatment 1. Formation of polychlorobiphenylenes from polychlorobenzenes

The heats of formation of polychloroarynes (PCA's) from polychlorobenzenes (PCB's) have been calculated by the AMI method as a function of the composition and structure of the PCB's according to a two-step scheme including deprotonation with the formation of carbanions (PCCA's, H₁) and dechlorination to PCA's (H₂). The influence of the solvent on H₁ and H₂ has been evaluated in the framework of the solvaton model. It has been shown that the value of H₁ decreases as the number of C1 atoms in the PCB is increased, while H₂ increases along the same series due to the increase in the relative stability of the PCCA as the number of C1 atoms is increased. Although the dimerization of PCA's with the formation of polychlorobiphenylenes (PCBP's) is forbidden by orbital symmetry rules, calculations of fragments of the potential-energy surface have shown that this reaction takes place with an energy barrier amounting to about 1 kcal/mole.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Institute of Organic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 350–355, February, 1992.     

Spektralphotometrische Bestimmung von Eisen(II) mit α-Benzildioxim und 4-Methylpyridin

Zusammenfassung Eine hochempfindliche extraktionsphotometrische Methode zur Bestimmung von Eisen(II) wurde angegeben. Der mit -Benzildioxim und 4-Methylpyridin gebildete Komplex wird mit Chloroform extrahiert und bei 559 nm gemessen. Der Einfluß verschiedener Fremdionen wird angegeben und auf die Möglichkeit hingewiesen, das Eisen von störenden Elementen abzutrennen.

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Spectrophotometric determination of iron(II)with -benzildioxime and 4-methylpyridine

Summary A high sensitive method was developed for extraction and photometric determination of iron(II). The method is composed of extraction of iron(II) with -benzildioxime and 4-methylpyridine into chloroform followed by absorption measurements at 559 nm. Influence of coexisting ions were studied and a method was suggested for the isolation of iron from other interfering elements.

     

The structures of macrocyclic heterocyclophane inclusion complexes

Crystal and molecular structures of (1:1) molecular complexes of N,N,N,N-tetramethyl-2, 11, 20, 29-tetraaza [3.3.3.3] paracyclophane (1) with CHCl₃, CH₂Cl₂, CH₃CN and CO₂ are reported. The macrocycle has square-box structure, giving hydrophobic cavity surrounded by four benzene rings. The guest molecules are included in the cavity. The uncomplexed1 was found to have a rectangular form, indicating large conformational flexibility of1. In solution,1 is achiral because rapid RS interconversion, but in solid, the macrocyclic conformation is frozen as R-conformer or S-conformer. The macrocycles with the same chirality are stacked alongb-axis to form chiral molecular columns, R-colums or S-columns. Complexes of1 crystallize differently depending on the guest molecules. R-columns (S-columns) packed alonga-axis produce R-layers (S-layers), which are further packed alongc-axis using R-layer to R-layer contact (RR) or SS and RS or SR. The crystals of1·CHCl₃ are formulated as--RRR--=[R]_n (Type I, chiral) and those of1·CH₃CN or1·CO₂ and1·CH₂Cl₂ are represented by [RS]_n (Type IIA, racemic) and [RRSS]_n (Type IIB, racemic), respectively.     

Nonlinear optical study of the five IPR isomers of C78 generated by capping C72 through C6

An excellent connection exists between pyramidalized angles (〈Θ_p〉) and the static third‐order polarizability (γ) for the five C₇₈ isolated pentagon rule (IPR) isomers. On the other hand, the C₇₂ isomers generated on the way to constructing C₇₈ through the circumscribe algorithm are found to have a poor correlation between γ and 〈Θ_p〉. However, the change in the γ values from C₇₂ to C₇₈ could well be correlated with a more involved local parameter like the capped angles. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 574–579, 2000     

Steroids of the spirostan and furostan series from plants of the genus Allium. XXVI. Structure of anzurogenin and anzuroside from the collective fruits of Allium suvorovii and Allium stipitatum

A new steroid glycoside of the spirostan series, anzuroside, has been isolated from the collective fruits of the cocultivatedAllium suvorovii Rgl. andA. stipitatum Rgl. (family Liliaceae, local name anzur). Enzymatic cleavage of the glycoside has given the previously undescribed steroid sapogenin anzurogenic C, which has the structure of (24S, 25S)-2,3,5,24-tetrahydroxy-5-spirostan-6-one. Anzuroside is the 24-O--D-glucopyranoside of anzurogenin C.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 505–510, July–August, 1989.     

Reaction of 2,2-bis(4′-hydroxy-3′-N,N-diethylaminomethylphenyl) propane with triethyl phosphite

Conclusions The reaction of 2,2-bis(4-hydroxy-3-N,N-diethylaminomethylphenyl)propane with triethyl phosphite gave 2,2-bis(4-ethoxy-3-diethylphosphonomethylphenyl)propane via the intermediate formation of a compound with a pentacovalent phosphorus atom. In the presence of acetic acid the reaction leads to 2,2-bis(4-hydroxy-3-diethylphosphonomethylphenyl)propane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1621–1624, July, 1978.