L. I. Vagapova

Complex Formation of d-Metal Ions at the Interface of TbIII-Doped Silica Nanoparticles as a Basis of Substrate-Responsive TbIII-Centered Luminescence

The complex formation of d-metal ions at the interface of Tb(III)-doped silica nanoparticles modified by amino groups is introduced as a route to sensing d-metal ions and some organic molecules. Diverse modes of surface modification (covalent and noncovalent) are used to fix amino groups onto the silica surface. The interfacial binding of d-metal ions and complexes is the reason for the Tb(III)-centered luminescence quenching. The regularities and mechanisms of quenching are estimated for the series of d-metal ions and their complexes with chelating ligands. The obtained results reveal the interfacial binding of Cu(II) ions as the basis of their quantitative determination in the concentration range 0.1-2.5 μM by means of steady-state and time-resolved fluorescence measurements. The variation of chelating ligands results in a significant effect on the quenching regularities due to diverse binding modes (inner or outer sphere) between amino groups at the interface of nanoparticles and Fe(III) ions. The applicability of the steady-state and time-resolved fluorescence measurements to sense both Fe(III) ions and catechols in aqueous solution by means of Tb(III)-doped silica nanoparticles is also introduced.

Synthesis of novel 2-arylpyrrolidines by the reaction of 1-(4,4-diethoxybutyl)urea with resorcinols

Reaction of 1-(4,4-diethoxybutyl)urea with resorcinol, 2-methylresorcinol and pyrogallol in chloroform in the presence of trifluoroacetic acid affords new 2,2′-(1,3-phenylene)-bis(pyrrolidine-1-carboxamides).

Aggregation behavior and catalytic properties of systems based on aminomethylated calix[4]resorcinarenes and poly(ethylene) imines

Self-assembling in systems poly(ethylene) imine-aminomethylated calix[4]resorcinarene-water-DMF (30 vol%) and catalytic properties of these compositions in hydrolysis of 4-nitrophenylbis (chloromethyl)phosphinate are studied. Critical concentrations of association, aggregates radii, and kinetic parameters of the reaction are established.

Mannich reaction involving calix[4]resorcinarenes and aminoacetals

The Mannich reaction involving calyx[4]resorcinarenes, aminoacetals, and formaldehyde in the molar ratio 1:4:4 yields calixarenes containing aminoacetal fragments on the upper molecule rim. Four oxazinyl rings formed with the retention of acetal groups as the formaldehyde amount was twofold increased.

Aminoacetal Derivative of Calix(4)resorcinarene. Acid-Base Properties and Reactions with Copper(II) and Lanthanum(III) in Various Media

Studies were carried out by means of pH-metry, spectrophotometry, and mathematic simulation of equilibria (program CPESSP) on the state, acid-base properties and complexing ability [with respect to copper(II) and lanthanum(III)] of calix[4]resorcinol with acetal groups in the aminomethyl substituent [H8L: R1 = C7H15, R2 = CH2N(CH3)CH2CH2CH(OCH3)2] in water-alcohol solution [80 vol % of i-PrOH] and in solutions of nonionogenic and ionic surfactants [Triton X-100, Brij-35, sodium dodecyl sulfate]. In all environments protonated and deprotonated tetrameric, dimeric, and monomeric species were found (pH range 3–10.6). In the presence of sodium dodecyl sulfate dimer (H8L)2 did not form that was the main speciation form in the other solvents. The sodium dodecyl sulfate like also Brij-35 favors formation of a hexadecamer (H8L)16 (pH about 6.3–6.5) in relatively small maximum accumulation fractions, 20 and 16% respectively. The solubility of H8L in acid medium in the presence of cetyltrimethylammonium bromide, and in the presence of sodium dodecyl sulfate in alkaline medium, originated from the formation of mixed cationic and mixed anionic aggregates respectively. In a water-alcohol solution six complexes of copper(II) were detected: four mononuclear, one binuclear, and one tetranuclear complex with neutral and deprotonated forms of the ligand. Lanthanum(III) formed nine mononuclear complexes and in general coordinated more ligands than copper(II) favoring association (aggregation) of the compound under study.

Calix[4]resorcinols containing acetal fragments

Recently the chemistry of calixarenes attracted considerable interest of chemists. Compounds of this type are easily obtained through condensation of phenols with aldehydes. They readily undergo functionalization and are of obvious interest as basic compounds for the synthesis of the spatially organized structures of new type [1–3]. Specifically, calixarenes having acetal fragments on the upper rim of the molecule are very promising substances since they can provide a basis for design of container and tubular structures by reaction with polyphenols molecules. Recently we reported the first example of calix[4]resorcinols derivatives aminomethylated on the upper rim and containing acetal fragments [4]. In this study functionalized secondary amine III, in which acetal and amino groups were separated by two carbon atoms, was involved into the Mannich reaction with calixarenes. Compound III was obtained as a result of successive interaction of isobutanal I with ethylamine hydrochloride and methanol without intermediate isolation of aldehyde II. By the reaction of aminoacetal III with paraformaldehyde and calixarenes IVa–IVc in the ratio 4 : 4 : 1 target products Va–Vc were obtained containing four acetal fragments in the calixarene matrix (Scheme 1).

Reaction of 9-[2-(1,3-dioxolan-2-yl)ethyl]-9H-purin-6-amine with phenols. Synthesis of diarylpropanes

New 1,1-diarylpropanes containing an adenine fragment on C3 have been synthesized by reaction of 9-[2-(1,3-dioxolan-2-yl)ethyl]-9H-purin-6-amine with phenols in aqueous HCl.

Synthesis and structure of new phosphorylated β- and γ-amino acetals containing a sterically hindered phenol group

Abstractα-Phosphorylated 3,5-di-tert-butyl-4-methylidenecyclohexa-2,5-dien-1-ones reacted with 3,3-diethoxypropan- 1-amine and 4,4-diethoxybutan-1-amine to afford new α-amino phosphonates containing sterically hindered phenol and acetal groups.

Synthesis and Structure of Aminophosphonates Containing 3,5-Di-Tert-Butyl-4-Hydroxyphenyl and Acetal Groups

GRAPHICAL ABSTRACT Abstract The reactions of dialkyl [(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadienyl)methyl]phosphonates with N-nucleophiles (aminoacetaldehyde dimethyl acetal and diethyl [(2,2-dimethoxyethyl)aminomethyl]phosphonate give new aminophosphonates containing the 3,5-di-tert-butyl-4-hydroxyphenyl substituent, in addition to the acetal group. The crystal structure of diethyl {(3,5-di-tert-butyl-4-hydroxyphenyl)[(2,2-dimethoxyethyl)amino]methyl}phosphonate is elucidated. The presence of a chiral carbon atom and prochiral phosphorus atom in the aminophosphonate products is responsible for the complicated pattern in the 1H NMR spectra, the features of which are discussed.

Synthesis and structure of phosphorylated acetals

The Kabachnik-Fields reaction in a triple system (aminoacetal-paraform-diethyphosphite) resulted in the formation of the previously unknown aminophosphonates that contained the acetyl group and also their monoesters. Structures of the products were confirmed by 1H NMR, IR spectra and X-ray diffraction analysis. The MALDI mass spectra indicated that the presence of N-hydroxyethoxyphosphorylmethylaminomethyl groups underlies the ability of these compounds to self-assembly with the formation of n-dimensional H-bonded associations.