Adsorption of 1,2-diaminoethane on ZnO thin films from p-xylene

The interaction of 1,2-diaminoethane (DAE) with ZnO thin films prepared by electrodeposition and magnetron sputtering was investigated by X-ray photoelectron spectroscopy (XPS). The samples were exposed to organic solution of 0.5 M DAE-p-xylene in an Ar atmosphere glove box (O₂ and H₂O <5 ppm), directly connected to the XPS analysis chamber by an anaerobic and anhydrous transfer system. A clear interaction of DAE with the ZnO surface is evidenced by the presence of a high intensity N1s peak at BE = 399.5 ± 0.2 eV and C1s at BE = 286.3 ± 0.2 eV which are attributed to C-N bonding. The atomic ratio C:N was very close to 1:1 consistent with the molecular, non-dissociative adsorption of DAE on the ZnO layer. No significant difference in adsorption of DAE was observed for three different ZnO surfaces despite slight differences in their acid/base properties as evidenced by the O/OH ratio. The results are interpreted in terms of adsorption on Brönsted acid sites. A uniform layer model was used to approximate the DAE film thickness, which was found to be around 10 Å on three studied samples. The N1s and C1s_B signals were observed to decrease on sample exposure to vacuum and/or X-ray irradiation and additional N1s_B peak appeared at lower binding energy at around 398.5 ± 0.2 eV. This is interpreted by the desorption and modification of DAE, indicating low stability of the adsorbed state on ZnO. The exposure to water of the sample with adsorbed DAE causes a significant decrease of the N1s_A and C1s_B peak intensities attributed to the adsorbed DAE molecule, demonstrating the instability of the DAE-ZnO interface in water.     

Confocal micro-Raman investigation of multilayer systems

The modern technologies use many multilayer composites comprising, the connection of different classes substrates: ceramics, metals, polymers, etc. In this work we focused our attention on an application of confocal micro-Raman spectroscopy to study the multilayer composites. Different multilayer model systems were used to check the role of the confocal mode. The problem of the transparency of layer, and their thickness were discussed. The procedure of determination of interfaces from so-called depth profiles and their first derivatives was also presented.     

Die Reaktionen von tBu2P–P=P(Me)tBu2 und (Me3Si)tBuP–P=P(Me)tBu2 mit PR3

The Reactions of ^tBu₂P–P=P(Me)^tBu₂ and (Me₃Si)^tBuP–P=P(Me)^tBu₂ with PR₃ ^tBu₂P–P=P(Me)^tBu₂ ( 1 ) reacts at 20 °C with PMe₃, PEt₃, P(c‐Hex)₃, P(p‐Tol)₃, PPh₂Me, PPh₂Et, PPhEt₂, PPh₂ⁱPr, PPh₃ and P(NEt₂)₃ yielding ^tBu₂P–P=PR₃ and ^tBu₂PMe; however, P^tBu₃, P^tBu₂(SiMe₃) and ^tBu₂PCl don't. ^tBu₂PH and 1 form ^tBu₂P–PH–P^tBu₂ which yields ^tBu₂P–P=PEt₃ when treated with PEt₃. Ph₂PH, ^tBuPH₂, PH₃, Ph₂PCl and EtOH don't substitute the ^tBu₂PMe group in 1 , instead, the molecule is decomposed. With PEt₃, (Me₃Si)^tBuP–P=P(Me)^tBu₂ forms (Me₃Si)^tBuP–P=PEt₃. The compounds ^tBu₂P–P=PR₃ decompose at 20 °C to different degrees giving P‐rich consecutive products of the phosphinophosphinidene.     

Bildung und Struktur von [μ‐(1,2 : 2‐η‐tBu2P–P){Mo(CO)2cp′}2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXIV. Formation and Structure of [μ‐(1,2 : 2‐η‐^tBu₂P–P){Mo(CO)₂cp′}₂] [cp′Mo(CO)₂]₂ (cp′ = C₅H₄^tBu) reacts with ^tBu₂P–P=P(Me)^tBu₂ to yield the compound [μ‐(1,2 : 2‐η‐^tBu₂P–P){Mo(CO)₂cp′}₂], which crystallizes in the space group P2₁2₁2₁ with a = 1202.42(7), b = 1552.48(8), and c = 1765.3(1) pm.     

Die Reaktion von tBu2P‐P=P(Me)tBu2 mit [Fe2(CO)9] und [(η2‐C8H14)2Fe(CO)3]

^tBu₂P‐P=P(Me)^tBu₂ reacts with [Fe₂(CO)₉] to give [μ‐(1, 2, 3:4‐η‐^tBu₂P¹‐P²‐P³‐P^4tBu₂){Fe(CO)₃}{Fe(CO)₄}] ( 1 ) and [trans‐(^tBu₂MeP)₂Fe(CO)₃]( 2 ). With [(η²‐C₈H₁₄)₂Fe(CO)₃] in addition to [μ‐(1, 2, 3:4‐η‐^tBu₂P¹‐P²‐P³‐P^4tBu₂){Fe(CO)₂PMe^tBu₂}‐{Fe(CO)₄}] ( 10 ) and 2 also [(μ‐P^tBu₂){μ‐P‐Fe(CO)₃‐PMe^tBu₂}‐{Fe(CO)₃}₂(Fe‐Fe)]( 9 ) is formed. 1 crystallizes in the monoclinic space group P2₁/c with a = 875.0(2), b = 1073.2(2), c = 3162.6(6) pm and β = 94.64(3)?. 2 crystallizes in the monoclinic space group P2₁/c with a = 1643.4(7), b = 1240.29(6), c = 2667.0(5) pm and β = 97.42(2)?. 9 crystallizes in the monoclinic space group P2₁/n with a = 1407.5(5), b = 1649.7(5), c = 1557.9(16) pm and β = 112.87(2)?.     

Condensation and Polycondensation of Terephthaldehyde with Methyl D‐Hexopyranosides

The condensation and polycondensations of terephthaldehyde ( 1 ) and methyl D ‐hexopyranosides (gluco‐, galacto‐ and mannopyranoside) are described. Methyl α‐D ‐glucopyranoside and methyl α‐D ‐galactopyranoside react with 1 to give mono‐ 5 a and 6 a and diacetals 5 b and 6 b . Their structures were confirmed by NMR and IR spectroscopy. The polycondensation of methyl α‐D ‐mannopyranoside ( 4 ) with 1 was studied in various solvents within the temperature range of 80–140°C. Regardless of the conversion or the initial comonomer feed ratios the composition of polycondensates depended on the reaction conditions leading to the formation of materials with diverse solubilities, molecular weights and optical properties. The regioselective polycondensation of 1 and 4 was examined by the ¹H NMR spectroscopy of polymer 7 . In the case of five‐membered cyclic acetal units, mixtures of the endo‐H and exo‐H dioxolan‐2‐yl system diastereomers are formed. Experimental examples of functionalization via ester units in polymer molecules 8 are described and the efficiency of the reaction routes and procedures are evaluated. The molecular weight was estimated by size‐exclusion chromatography (SEC) measurements before and after the functionalization.     

Mild Copper-Catalyzed,l-Proline-Promoted Cross-Coupling of Methyl 3-Amino-1-benzothiophene-2-carboxylate

Cu-catalyzed N-arylation is a useful tool for the chemical modification of aromatic heterocycles. Herein, an efficient carbon–nitrogen cross-coupling of methyl 3-amino-1-benzothiophene-2-carboxylate with a range of (hetero)aryl iodides using CuI, l-proline and Cs₂CO₃ in dioxane at moderate temperature is described. The procedure is an extremely general, relatively cheap, and experimentally simple way to afford the N-substituted products in moderate to high yields. The structures of the new heterocyclic compounds were confirmed by NMR spectroscopy and HRMS investigation.     

Intermolecular chain transfer to polymer with chain scission: general treatment and determination of kp/ktr in L,L-lactide polymerization

A general kinetic treatment of the system with intermolecular chain transfer followed by fast reinitiation is given. It leads to the broadening of the molecular weight distribution (MWD), the number of growing chains being invariable. Thus, this system can be considered as a special case of living polymerization. A general method has been elaborated allowing the determination of the ratio of the rate constant of propagation (k_p) to the rate constant of the bimolecular transfer (k⁽²⁾_tr) from the dependence of the MWD on monomer conversion. Numerical values of k_p/k⁽²⁾_tr equal to ≈ 10² and 25 were thus determined for the polymerization of L , L -lactide (L , L -dilactide) initiated with aluminium tris(isopropoxide) trimer ({Al(OⁱPr)₃}₃) and tributyltin ethoxide (ⁿBu₃SnOEt), respectively.     

Synthesis of functional polymers with acetal-monosaccharide moieties

The polycondensation of methyl α-D-mannopyranoside ( 1 ) with 1,n-bis(formylphenoxy)alkanes ( 2 ), using acidic catalysts, leads to the formation of linear polymers and macrocyclic compounds. The structure of the polymer and macrocycles was determined by ¹H, ¹³C NMR spectroscopy and ESI-MS analysis.