Supramolecular systems based on poly(ethyleneimines) and calix[4]resorcinarenes with alkylphosphonate fragments. Aggregation and catalytic activity

Aggregation in poly(ethylenimine)-calix[4]resorcinarene-water-DMF systems was studied by the methods of conductometry and dynamic light scattering. The sizes (radii) of the aggregates formed and the critical micelle concentrations were determined. The catalytic activity for these systems in the hydrolisys of phosphorus acid esters was shown. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 924–931, May, 2007.     

Synthesis,Self-Association,and Solubilizing Ability of an Amphiphilic Derivative of Poly(ethylene glycol) Methyl Ether

A new amphiphilic derivative–methoxy(polyethoxy)ethyl stearate has been synthesized with the goal of creating therefrom systems for delivery and enhancement of bioavailability of piperine. The aggregation and solubilizing properties of ω-methylpoly(oxyethylene) stearate have been studied by means of a set of physicochemical methods.     

Aggregation and catalytic properties of polymer-calix[4]resorcinarene-water-dimethylformamide systems

The aggregation in poly(ethylene imine) (poly(ethylene glycol))-calix[4]resorcinarene-water-dimethylformamide (30 vol %) systems and the catalytic activity of these compositions in hydrolysis of 4-nitrophenylbis(chloromethyl)phosphinate are studied by conductometry, tensiometry, lightscattering, and viscometry. Critical association concentrations, hydrodynamic radii of polymer-colloid aggregates, and kinetic parameters of hydrolysis are determined.     

Supramolecular catalytic systems based on 1, 4-diazabicyclo[2.2.2]octane,its alkylated quaternary derivatives,and lanthanum nitrate

Spectrophotometry was used to study the catalytic effects of the systems composed of N-monoand N, N-dialkylated 1, 4-diazabicyclo[2.2.2]octanes and lanthanum nitrate on the hydrolysis rate of O-alkyl O-4-nitrophenyl chloromethylphosphonates (Alk = Et, Buⁿ, and n-hexyl). The mechanism of action and efficiency of the catalytic system depend on the structure of the heterocycle, its propensity to aggregation and complexation with the lanthanum cation, and the relative content of the components in solution. The maximum catalytic effect (a ～115-fold increase in the hydrolysis rate constant) was achieved in micellar solutions of the cationic monoalkylated derivative of 1, 4-diazabicyclo[2.2.2]octane and lanthanum nitrate.

     

Synthesis and aggregation properties of novel amino acetals with the calix[4]resorcinol platform

Reactions of calixarenes with methylaminoacetaldehyde dimethyl acetal and formalin gave Mannich bases with the calixarene platform. It was found by dielcometric titration that calix[4]resorcinols with acetal groups in the aminomethyl fragment form head-to-head supra-molecular aggregates in chloroform at low concentrations. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 888–891, May, 2006.     

Aggregation of amphiphilic aminomethylated calix[4]resorcinarenes and the nonionic surfactant Triton-X-100 in organic solvents

Aggregation and intermolecular interactions of amphiphilic calix[4]resorcinarene (1), aminomethylated calix[4]resorcinarenes (AMC 2—7) with different structures of the upper rim (including the oxazine structure in 6 and 7) and hydrophobic substituents on the lower (2—5), upper (6), or both rims (7) in the absence and in the presence of the nonionic surfactant Triton-X-100 (8) and p-nitrophenol (9) in chloroform and 1,4-dioxane were studied by permittivity measurements and 2D ROESY ¹H NMR technique. The tendency of amphiphilic derivatives 1—7 toward self-aggregation and mixed aggregation with surfactant 8 primarily depends on the nature of both the solvent and the polar groups on the upper rim of calixarenes. In chloroform, AMC—8 aggregates show interactions of the methyl and methylene groups of the hydrophobic substituents of AMC with the ethyleneoxy fragments of surfactant 8, while in stable intermolecular complexes of 5 and 6 with compound 9, the methylene groups of the long-chain radicals of the AMC strongly interact with the aromatic protons ortho to the hydroxy group of 9. In 1,4-dioxane, calix[4]resorcinarenes 1 and 5 are bound in stable solvates, which prevents them from forming aggregates and mixed micelles.     

Calix[4]resorcinolarenes with alkylphosphonic fragments: Protolytic properties and interaction with lanthanum(III)

The protolytic and complexing properties of phosphorylated derivatives of calix[4]resorcinolarenes were studied by pH-metric titration at 298 K in water-2-propanol (80 vol % 2-propanol). It was shown that calix[4]resorcinolarene containing the propylphosphonic acid fragment at the C atom linking the aryl groups exists in solution mainly as tetramer. At pH > 4, the anions of tetrameric, dimeric, and monomeric forms of this compound are formed. The neutral form of aminomethylated calix[4]resorcinolarene contaning, along with the propylphosphonic acid fragment, the CH₂NEt₂ group on the opposite side of the molecule is monomeric. It exists as a zwitterion and contains four betaine protons. Three dimeric species of this compound, one protonated and two deprotonated, were revealed. The dissociation constants of the phosphonate groups and two betaine protons were evaluated. The other two betaine protons and the protons of hydroxy groups do not dissociate. The equilibrium constants of the complex formation with lanthanum(III) and in some cases the stability constants of the complexes were calculated. Probable modes of coordination of calix[4]resorcinolarenes are discussed. Depending on the acidity of the medium, the competition between the phosphonic group and the phenolate ions takes place, and complexes with the coordination via phosphonic groups can rearrange into complexes with the coordination via phenolate groups.     

Supramolecular systems formed by calix[4]resorcinarenes and surfactants in chlorophorm

Capacity titration and ¹H NOESY 2D NMR were applied to investigation of intermolecular interactions and aggregation of amphiphilic calix[4]resorcinarenes (CRA 1, 2) modified with 1,2,4-triazine (1) and oxazine (2) functions in chloroform in the presence of cationic (3) and non-ionic (4) surfactants (SAA). Critical concentrations of micelle formation (CMC) indicate that the ability of CRA 1, 2 to form supramolecular aggregates like micelles or hybrid micelles with SAA 3, 4 only weakly depends on the constitution of CRA functional groups. In the case of the hybrid micelles, when CMC are defined by the nature of surfactants 3 or 4, the methyl and methylene groups of the hydrophobic fragments (CRA 1, 2) were found to interact with the hydroxy groups of SAA 3 and ethylene oxide moieties of SAA 4.     

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.     

Driving matrix liquid crystal displays

Liquid crystal displays had a humble beginning with wrist watches in the seventies. Continued research and development in this multi-disciplinary field have resulted in displays with increased size and complexity. After three decades of growth in performance, LCDs now offer a formidable challenge to the cathode ray tubes (CRT). A major contribution to the growth of LCD technology has come from the developments in addressing techniques used for driving matrix LCDs. There are several approaches like passive matrix addressing, active matrix addressing and plasma addressing to drive a matrix display. Passive matrix LCD has a simple construction and uses the intrinsic non-linear characteristic of the LCD for driving. Departure from conventional line by line addressing of a passive matrix has resulted in improved performance of the display. Orthogonal functions have played a crucial role in the development of passive matrix addressing. Simple orthogonal functions that are useful for driving a matrix LCD are introduced. The basics of driving several rows simultaneously (multi-line addressing) are discussed by drawing analogies from multiplexing in communication. The impact of multi-line addressing techniques on the performance of the passive matrix LCDs in comparison with the conventional technique will be discussed.