Supramolecular systems based on the melamine salt of bis(hydroxymethyl)phosphinic acid (melafen) dihydrate and surfactants

Abstract

Bis(hydroxymethyl)phosphinic acid and melamine were shown by FTIR and UV spectroscopy to form the salt (melafen), whose cations and anions involving water molecules can be joined into supramolecular structures due to electrostatic interactions and hydrogen bonds. The conductometry, dielcometric titration, and dynamic light scattering methods showed that melafen in water and chloroform in a concentration range of 10 -10 -10 -4 mol L -1 involving the solvent structures exist as supramolecular polymeric nanostructures, whose size and properties change nonlinearly depending on the melafen concentration.The melamine salt of bis(hydroxymethyl)phosphinic acid dihydrate (melafen, 1) is an efficient regulator of plant growth and development, which is of considerable interest for practical use in agriculture and biotech nology. 1,2a The studies of the influence of compound 1 on the growth and energy processes in the living cell 3 and on the physicochemical state of biological membranes of various origin, 4 as well as the investigation of the mecha nism of action of the compound on the regulation of the plant cell metabolism 2b revealed that melafen is highly physiologically active at low concentrations, which are classified as low and superlow doses of biologically active substances. 5,6 The existing hypotheses for the mechanism of action of the superlow doses cannot completely explain the nature of this widespread phenomenon. 5,6 Therefore, the broad study of the effect of biologically active sub stances of the melafen type on systems of different levels of complexity and organization, namely, from supramo lecular systems modeling functions of biomolecules to complicated biological objects, seems especially urgent.Our first report is devoted to the study of the structure of melafen and its self association in aqueous and organic (chloroform) media. The interaction of melafen with surfactants of different nature and their micellar aggre gates modeling the components and surface layer of bio logical membranes will be discussed elsewhere. ExperimentalMelafen (1) was synthesized according to an earlier described procedure. 1 The association of compound 1, bis(hydroxymethyl) phosphinic acid (BPA), and melamine (M) in chloroform was studied by dielcometric titration, during which the concentration dependences of the dielectric permittivity (ε) were obtained and analyzed. 7-10 The dielectric permittivities of a series of solutions were determined on a setup consisting of an E12 I instrument operating in the beat mode and a measuring cell, being a tempera ture controlled condenser. Chloroform was purified using a stan dard method. 11 The estimation of the residual water content carried out by FTIR spectroscopy showed that the chloroform samples used contained ~0.1 wt.% water. The association of compound 1, BPA, and M in water was studied by the conductometric method, measur ing the change in the electric conductivity (χ) of the solutions at 25 °С (inoLab Cond Level 1 conductometer, relative measurement error 0.5%). Water and solu...

Nanosized mixed aggregates of alkylated p-sulfonatocalix[n]arenes and cetyltrimethylammonium bromide: self-organization and catalytic activity

“…22 As for nanoparticles with a size of an order of hundreds of nanometers, it is most probable that they are similar in nature to supramolecular structures (giant clusters) de scribed recently 23,24 and to nanoassociates, which have been found for the first time in solutions of low concentra tions. [25][26][27] The authors of these works assume that or dered structures of water along with molecules or ions of the solute participate in the formation of such associates. The plot of the nanoassociate sizes vs CTAB concentra tion in the interval below 10 -5 mol L -1 is shown in Fig.…”

Self-Organization and Physicochemical Properties of Aqueous Solutions of the Sodium Salt of Azosulphonate Calix[4]arene

“…Previously, when studying self-organization and UV spectra of aqueous systems of melaphen in the concentration range 1•10 -6 -1•10 -4 M, a nonlinear change in the molar absorption coefficient (ε) with a decrease in substance concentration due to the formation of molecular-water domains of hundreds of nm in size was shown for the first time. [21] In order to further study this interesting phenomenon, and to establish the relationship between the rearrangement of molecular-water domains and changes in the spectral properties of the dispersed system, solutions of 1 were jointly studied by the methods of DLS and UV spectroscopy in the range of 1•10 -6 -1.5•10 -5 M, which is characterized by the transition from bi-to monomodal size distribution of domains, nonmonotonic change in their size (Figure 4, curve 1) and the absence of the ζ-potential.…”

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“…Down to ultra low concentrations (C) -about 10 -20 M -serial diluted vigorously shaken polar liquids (SDVSPL) may affect bio-systems (Palmina et al, 1994;Konovalov et al, 2008Konovalov et al, , 2014aKonovalov and Ryzhkina 2014b).…”

“…In ultra low concentrated (ULC) SDVSPL at ambient conditions, part of the solvent molecules form groupings, as initially revealed with calorimetric, electric conductivity and pH data; serial diluted solutions, which at each dilution step are not vigorously shaken, do not contain groupings for C below a solute type dependent critical concentration (C crit ); typically ~10 -8 M < C crit <~10 -6 M (Elia and Niccoli, 1999, 2000, 2004a, 2004b. The groupings comprising 10 -7 -10 -5 m sized molecular associates, their electrokinetic potential and their impact on the liquid's dielectric permittivity were first uncovered with dynamic light scattering, electrophoresis and dielcometric titrations, respectively (Konovalov et al, 2008;Ryzhkina et al, 2009). Stabilization of the groupings occurs during the period of about 1-18 hours after the SD-VSPL's preparation.…”