Alkane films on water: stability and wetting transitions

Types of surface forces determining the disjoining pressure isotherms of wetting films of low-molecular-weight alkanes on water surface are discussed. The van der Waals forces in alkane interlayers at different temperatures were calculated using a combination of exact equations of the Dzyaloshinsky—Lifshitz—Pitaevsky macroscopic theory and the multi-oscillator model for representation of the dielectric permittivity spectra of contacting bodies. Taking account of competitive action of the van der Waals and image forces allows one not only to reproduce specific features of wetting in the systems studied at different temperatures, but also to describe quantitatively the contact angles and the experimentally observed isotherms of polymolecular adsorption. The experimentally detected wetting transition in the water—pentane—vapor system was rationalized using the results of calculations mentioned above and the Derjaguin—Frumkin theory of wetting. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 256–266, February, 2008.     

Two new isomeric zinc(II) metal–organic frameworks based on 1,5‐bis(2‐methyl‐1H‐imidazol‐1‐yl)pentane and 5‐methylisophthalate ligands

Many factors, such as temperature, solvent, the central metal atom and the type of coligands, may affect the nature of metal–organic frameworks (MOFs) and the framework formation in the self‐assembly process, which results in the complexity of these compounds and the uncertainty of their structures. Two new isomeric Zn^II metal–organic frameworks (MOFs) based on mixed ligands, namely, poly[[μ‐1,5‐bis(2‐methyl‐1H‐imidazol‐1‐yl)pentane‐κ²N ³:N ^3′](μ‐5‐methylisophthalato‐κ²O ¹:O ³)zinc(II)], [Zn(C₉H₆O₄)(C₁₃H₂₀N₄)]_n , (I), and poly[[μ‐1,5‐bis(2‐methyl‐1H‐imidazol‐1‐yl)pentane‐κ²N ³:N ^3′](μ₃‐5‐methylisophthalato‐κ³O ¹:O ^1′:O ³)(μ₃‐5‐methylisophthalato‐κ⁴O ¹:O ^1′:O ³,O ^3′)dizinc(II)], [Zn₂(C₉H₆O₄)₂(C₁₃H₂₀N₄)]_n , (II), have been synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, elemental analysis and thermogravimetric analysis. Complex (I) displays a two‐dimensional layer net, while complex (II) exhibits a twofold interpenetrating three‐dimensional framework. Both complexes show high stability and good fluorescence in the solid state at room temperature.     

Synthesis and spectroscopic characterization of a new macrocyclic Schiff base formed by the reaction of 1,5- bis (2-formylphenyl)pentane and 2,6-diaminopyridine,and a study of its metal complexes

A new dialdehyde 1,5-bis(2-formylphenyl)pentane was synthesized from 1,5-dibromopentane with salicylaldehyde and K₂CO₃; macrocyclic ligand was synthesized by reaction of 2,6-diaminopyridine and 1,5-bis(2-formylphenyl)pentane. Cu(II), Ni(II), Pb(II), Zn(II), Cd(II) and La(III) complexes were synthesized by reaction of the ligand and Cu(ClO₄)₂ · 6H₂O, Ni(ClO₄)₂ · 6H₂O, Pb(ClO₄)₂ · 6H₂O, Zn(ClO₄)₂ · 6H₂O, Cd(ClO₄)₂ · 6H₂O and La(ClO₄)₃ · 6H₂O, respectively. The ligand and its metal complexes have been characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV–Vis spectra, magnetic susceptibility, conductivity measurements and mass spectra. All complexes are diamagnetic and Cu(II) complex is binuclear.     

双(二苯基膦戊烷)富勒烯合铂配合物的合成及光电性能

采用配体取代法合成了以双二苯基膦戊烷（dpppe）及C60为配体、Pt为中心金属的C60Pt(dpppe)新型富勒烯膦金属配合物。 运用质谱、元素分析、紫外-可见吸收光谱、红外吸收光谱和光电子能谱等测试技术对产物进行了表征,同时采用循环伏安法对目标产物进行氧化还原性能研究。 结果表明,C60与金属Pt配位后还原电位发生负移。 结合电子光谱数据确定了目标产物的能级结构,其最高占有轨道和最低非占轨道能级分别为5.635和3.815 eV。 还考察了目标产物在光化学电池中的光伏效应,测试结果表明,在 BQ/H2Q介质溶液中镀层厚度为 1~2 μm 时,具有较好的光电转换性能,光生电压值最高达358 mV。     

The effect of the conditions of the photocatalytic carbonylation of pentane catalyzed by the Rh2Cl2(CO)4-PMe3 system on the yield of C6-aldehyde

The yield of C₆-aldehyde in the photocatalytic system Rh₂Cl₂(CO)₄-PMe₃ passes through a maximum as the CO pressure and PMe₃ concentration increase. The increase in the yield of aldehydes with increasing CO pressure is related to the increase in the carbonylation rate and to the retardation of the photodecomposition of the aldehydes. The rate of the photocatalytic carbonylation of pentane in this system is 20 times higher than in the presence of RhCl(PMe₃)₂(CO).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1013–1015, June, 1994.     

Synthesis of some new dispiro[dipyrano-(2,4′:6,4″)bidithiolo(4,5-b:4′,5′-e)-4,8-benzoquinones]

Summary The one pot reaction of acetylacetone, CS₂, and tetrabromobenzoquinone in a 2:2:1 molar ratio affords 2,6-di-(1-acetyl-2-oxopropylidene)-bidithiolo-(4,5-b:45-e)-4,8-benzoquinone (3) which was allowed to react with some active methylene reagents in a 1:2 molar ratio to give the dispiro derivatives5–11. The reaction is assumed to proceedvia a hydrolysis of the two acetyl groups in compound3 followed by a nucleophilic addition of the active methylene reagents at the two ethylenic bonds and subsequent cyclization.

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Synthese einiger neuer Dispiro[dipyrano(2,4:6,4)bidithiolo(4,5-b:4,5-e)-4,8-benzochinone]

Zusammenfassung Die Eintopfreaktion von Acetylaceton, CS₂ und Tetrabrombenzochinon in einem molaren Verhältnis von 2:2:1 liefert 2,6-Di-(1-acetyl-2-oxopropyliden)-bidithiolo-(4,5-b:4,5-e)-4,8-benzochinon (3), das anschließend mit aktivierten Methylenverbindungen im Verhältnis 1:2 zu den Dispiroverbindungen5–11 umgesetzt wurde. Die Reaktion verläuft offenbar über eine Hydrolyse der beiden Acetylgruppen in Verbindung3, gefolgt von einer nucleophilen Addition der aktiven Methylengruppen an die ethylenischen Doppelbindungen und anschließender Cyclisierung.

     

磷钨杂多酸及其铯盐上的常温正戊烷异构化反应

制备了一系列用于正戊烷异构化的磷钨杂多酸及其铯盐催化剂,并对它们进行了详细的物性表征。实验结果表明, Cs含量对催化剂的比表面、孔结构、热稳定性和表面酸量有显著的影响。考察了所制备的催化剂上常温下正戊烷异构化反应的活性和选择性。利用催化剂表征结果讨论了活化温度和Cs含量等因素对催化性能的影响。磷钨杂多酸及其铯酸式盐属固体超强酸。根据35℃时正戊烷异构化反应速率常数估测H~3PW~1~2O~4~0和Cs~2~.~2~5H~0~.~7~5PW~1~2O~4~0的酸强度H~0约在-13～-12.4之间。     

Synthesis of Bicyclo[1.1.1]pentane (BCP)-Based Straight-Shaped Diphosphine Ligands**

[1.1.1]Propellane, which is structurally simple and compact, exhibits promising potential for the synthesis of disubstituted straight-shaped bicyclo[1.1.1]pentane (BCP) compounds by manipulation of its highly reactive internal C−C bond. BCPs are considered to be isosteres of 1,4-disubstituted benzenes, which have found broad applications in the areas of functional molecules and drug discovery. The internal C−C single bond of [1.1.1]propellane is regarded as a charge-shift bond, which can be readily cleaved by radical means to construct BCPs. We herein report a novel synthetic method for (un)symmetric diphosphines based on the BCP motif, which can be interpreted as isosteres of 1,4-bis(diphenylphosphino)benzenes. The obtained BCP-diphosphine derivatives were used to generate a straight-shaped Au complex and an Eu-based coordination polymer.