Synthesis and structure of bis(tetraphenyl-λ5-stibanyl)-1,7-carborane-1,7-dicarboxylate

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Chiral recognition capabilities of melamine and cyanuric acid supramolecular structures

Currently, there are numerous papers that discuss local chiral domains in supramolecular structures of achiral molecules established using the STM method, and by using DFT calculations. However, there are no data regarding the obtainment of macroscopically chiral 2D-supramolecular structures from achiral molecules. In this study, melamine and cyanuric acid supramolecular structures were self-assembled on a graphitized carbon black surface, which had a surface structure that was identical to HOPG, and also on the surface of an inert solid support for chromatography. Chirality induction according to the Kondepudi effect was used. For the supramolecular structures, MD calculations showed the possibility of obtaining a chiral structure. To establish macroscopic chirality, we proposed the use of the difference in enantiomer adsorption on the modified adsorbents. For this, two indirect methods were used: static adsorption with a polarimetric control and gas chromatography. Both methods indicated the chiral recognition ability of the adsorbents used.     

Aminoalkylated Calix[4]resorcinarenes as pH Sensitive “hosts” for Charged Metallocomplexes

On the basis of RCA, pH-potentiometry and EPR-spectroscopy data aminoalkylated derivatives were proved to bind metal ion complexes both in alkaline and in acidic media. Outer-sphere coordination is the only interaction mode in these host-guest complexes.     

Synthesis and crystal structures of the first germanium-containing alkylidene complexes of molybdenum R3Ge-CHMo(NAr)(OR′)2 (R = Me, Ph) with direct germanium-carbene carbon bond

The novel germanium-containing alkylidene complexes of molybdenum R₃Ge-CHMo(NAr)(OCMe₂CF₃)₂ (Ar = 2,6-i-Pr₂C₆H₃; R = Me, Ph) have been prepared by the reaction of organogermanium vinyl reagents R₃ GeCHCH₂ with known alkylidene compounds Alkyl-CHMo(NAr)(OCMe₂CF₃)₂ (Alkyl = Bu^t, PhMe₂C). The titled compounds were isolated as crystalline solids and characterized by elemental analysis, ¹H NMR, ¹³C NMR spectroscopy and X-ray diffraction studies. The geometry of the Mo atoms in the compounds can be described as a distorted tetrahedron.     

Cationic amphiphilic polyelectrolytes and oppositely charged surfactants at the silica-aqueous interface

The influence of sodium dodecyl sulfate (SDS) on the interfacial behavior of two amphiphilic polyelectrolytes, which are copolymers of the cationic monomers triethyl(vinylbenzyl)ammonium chloride and dimethyldodecyl(vinylbenzyl)ammonium chloride, at the silica-aqueous interface was studied. The fraction of amphiphilic monomers was varied, where 0DT, 40DT, and 80DT contained 0, 40, and 80 mol % monomers with dodecyl side chains, respectively. We used in situ ellipsometry to follow the kinetics of adsorption, in terms of adsorbed amount and adsorbed layer thickness, as well as the response of the adsorbed layers to changes in ionic strength and surfactant concentration. Different results were obtained when surfactant was added to the preadsorbed layers compared to the cases when complexes were preformed in the solution prior to the adsorption. In the whole range of concentrations studied, SDS interacts with 40DT and 80DT noncooperatively, whereas for 0DT cooperativity of binding is observed. The amount adsorbed increased significantly as the SDS concentration was close to the cmc. At high SDS concentrations, a lowering of the layer density was observed. For the amphiphilic polyelectrolytes, 40 DT and 80DT, no desorption from the interface was detected for the range of SDS concentrations studied, while 0DT features a maximum in adsorbed amount at concentrations close to the cmc of SDS. Adsorption of 40DT and 80DT from their mixtures with SDS is found to be path dependent with respect to the variation in SDS concentration, where the reversibility decreases with increasing SDS concentration above the expected charge neutralization point. The coadsorption of 80DT and SDS is highly irreversible with respect to changes in the ionic strength within the time scale of the experiment. In this study, we attempt to illustrate both general mechanisms and specific effects. With regard to the general behavior, it is important to note the charge regulation of both the silica surfaces and the polyion/surfactant complexes; an interplay between the two charge-regulating effects is the key to understanding our observations.     

Efficient scrambling-free synthesis of heteroleptic terbium triple-decker (porphyrinato)(crown-phthalocyaninates)

New heteroleptic triple-decker terbium complexes of general structure [Br(4)TPP]Tb[(15C5)(4)Pc]Tb[Br(4)TPP] (Tb-TD) and [Br(4)TPP]Tb[(15C5)(4)Pc]Tb[(15C5)(4)Pc] (Tb-TD*) (Br(4)TPP = tetrakis-meso-(4-bromophenyl)-porphyrin, (15C5)(4)Pc = tetra-(15-crown-5)-phthalocyanine) are synthesized with 48% and 57% yields, respectively. The triple-decker complexes were prepared by interaction of generated in situ terbium monoporphyrinate [Br(4)TPP]Tb(acac) and corresponding double-decker precursors. The heteroleptic double-decker precursor [Br(4)TPP]Tb[(15C5)(4)Pc] was prepared for the first time in a two step one-pot synthesis. No ligand scrambling was observed in the synthesis of Tb-TD, while 4% scrambling was determined in the case of Tb-TD*. High yields of target triple-decker complexes were achieved despite the presence of electron-donating crown-ether fragments with low thermal stability at the phthalocyanine deck. Analysis of lanthanide-induced paramagnetic shifts of protons of Tb-TD together with data of previously reported La, Pr, Nd and Eu analogues allowed precise separation of contributions of contact and dipolar lanthanide terms as well as verification of isostructurality of complexes within the series.     

Novel 4-chloro-or-4-bromoresorcinol-based bicyclic phosphonates

Abstract

The reaction of 4-chloro- and 4-bromoresorcinol with 2-ethoxyvinylphosphonic acid dichloroanhydride has been investigated for the first time. It has been determined that the product of the reaction is the mixture of structural isomers of bicyclic phosphonates at the ratio of 9:1. The structure and composition of the compounds have been elucidated from ¹H, ³¹P, and ¹³C NMR spectroscopy, mass-spectrometry (MALDI-TOF), as well as elemental and X-ray analysis.     

Phosphorylation of oxyethylated resorcinol and calix[4]resorcinarene with P(III) acid amides

Abstract

Phosphorylation of 1,3-bis(2-hydroxyethoxy)benzene and octa(2-hydroxyethyl) calix[4]-resorcinarenes with P(III) acid amides and chloramides has been studied. It has been determined that the nature of phosphorous acid amides affects significantly the synthetic result of the reaction.