Trifluoroacetylated Amino Alcohols Research Articles

Hierarchy of Times for Forming the System of Chiral Phases in Solutions of Trifluoroacetylated Amino Alcohols

It has been experimentally established that the chiroptical characteristics of freshly prepared solutions of trifluoroacetylated amino alcohols (TFAAAs) evolve before reaching equilibrium. The evolution can be monotone or quasi-oscillatory. The latter reflects the formation of successive levels of the hierarchy of chiral phases with an alternating sign of chirality in the solution. The fast (the characteristic time τ from ~30 s to ~30 min) and slow (τ ~ 1–3 h) stages of evolution have been experimentally revealed. It is shown via calculation that the fast stage corresponds to the early stages of the formation of the supramolecular structure of the solutions of TFAAAs, namely, the growth of strings with diameters from several nanometers to tenths of a micrometer, while the slow stage corresponds to the late stages in the formation of the structure of the solutions, namely, the growth of strings with diameters from tenths of a micrometer up to several micrometers.

The Properties of Strings Formed in the Homochiral Solutions of Trifluoroacetylated Amino Alcohols in Cyclohexane

The strings formed in the solutions of trifluoroacetylated amino alcohols in cyclohexane were studied. It was found that microscopic strings with the diameter d ∼ 1 μm were woven from tightly coupled rigid submicroscopic strings with the diameter d ∼ 0.1 μm in increments of >100 μm. Therefore, the compound strings are transparent, and they usually look like an unstructured cylinder. Microscopic strings can be tightly combined in strings to 60 μm in diameter. Submicroscopic strings are arranged almost parallel to the axis of a microscopic string. The microscopic string acts as a polarizer: it transmits light polarized across its axis and absorbs light polarized along the axis. The majority of these properties can be explained based on the assumption that a connection between the strings of all hierarchical levels in cyclohexane is stronger than that in solvents with different string morphology.

Physicochemical modeling of the main stages of formation of a chirally pure prebiotic world

The formation of a chirally pure prebiotic environment was modeled using solutions of chiral trifluoroacetylated amino alcohols (TFAAA). We have previously shown that, homochiral TFAAA solutions, molecularly thin strings are formed. In TFAAA-1 and TFAAA-5 solutions in heptane, the physicochemical annihilation of antipodes occurs, whereby isometric granules or a viscous liquid are formed from a racemic solution. In a heterochiral solution, the chiral polarization grows spontaneously, so that its chiral purity becomes high enough to produce TFAAA homochiral strings. A racemic solution of TFAAA-6 in CCl4 forms TFAAA homochiral strings of two opposite chiralities; i.e., the separation of the isomers takes place. It demonstrated two possible scenarios for the formation of a chirally pure system.

Specific features of molecular mobility of paramagnetic probe in chiral biomimetic solutions

Molecular mobility of a nitroxyl radical (as a paramagnetic probe) in methylcyclohexane (MCH) solutions of chiral biomimetic gelators—trifluoroacetylated amino alcohols (synthetic analogues of biological molecules)—has been studied by monitoring thermally induced changes in EPR spectra. The phase state of the systems has been examined by the low-temperature scanning calorimetry method. There has been found an unusual concentration and temperature dependence of probe species mobility in diluted solutions (10–2–10–3 M) of trifluoroacetylated amino alcohols with a molecular weight of no more than 200. From the temperature-induced changes in EPR spectra of the paramagnetic probe in the temperature range 170–290 K, the rotation activation energies of probe species in biomimetic solutions and in the neat solvent. The minimum radical rotation activation energy (2.1 kcal/mol) is observed in the most concentrated gelator solution, whereas in neat MCH, this energy is 3.7 kcal/mol.

Elementary supramolecular strings in solutions of chiral trifluoroacetylated amino alcohols

IR spectroscopy is applied to studying the effect of nonpolar and low-polar solvents on the molecular structure of solid-state quasi-one-dimensional strings formed through the chiral self-assembly from solutions of trifluoroacetylated homochiral amino alcohols (TFAAA). It is experimentally confirmed that in stable two-phase string/solvent gels and respective xerogels, solid-phase strings contain no solvent molecules as a structural element, experiencing, however, a weak disturbing influence of solvent molecules. It is shown that the process of spontaneous self-assembly of chiral strings in solutions is accompanied by the formation of a complex system of hydrogen bonds involving the C=O, N–H, and O–H functional groups of dissolved TFAAA molecules and by the displacement of solvent molecules to the periphery of the resulting quasi-one-dimensional strings. The results of the present work, together with data obtained by other experimental methods, indicate that TFAAA-based elementary strings have diameters of 1–2 nm, being crystalline, molecularly thin, quasi-one-dimensional objects. The amplitude of the thermally activated bending vibrations (transverse phonons) of elementary strings is sufficient to cause the entanglement of elementary strings, which leads to the formation of larger diameter supercoiled strings.

Modeling of dimers of chiral trifluoroacetylated aminoalcohols

The formation of nanodroplets in solutions of gelating trifluoroacetylated amino alcohols (TFAAA), constituting one of the fractions of the dispersed phase, is simulated by the molecular dynamics method. It is shown that the main contribution to the energy of formation of nanodroplets comes from dispersion forces (~14 kJ/mol), which constitutes 3/4 of the total energy of interaction of a pair of molecules. The dipole–dipole component of the interaction energy for the molecules with anticollinear dipole moments is ~kT. It is shown that there are differences in the topology of pairs of bound homochiral TFAAA molecules, associated with their nonhomeomorphicity. In the first case, the chiral tetrahedrons of the molecules are nested into each other. During condensation, due to the formation of stacks, such pairs are capable of anisotropic growth. In the second case, the tetrahedrons join via their bases, creating isometric nuclei for isotropic condensation.

Fluorescence of the low-concentration solutions of homochiral trifluoroacetylated amino alcohols

The bimodal fluorescence spectra of the low-concentration (10−3 M) solutions of homochiral trifluoroacetylated amino alcohols (TFAAAs) were experimentally measured at the fluorescence excitation wavelength λ = 247 nm. A hysteresis of the fluorescence spectra, which corresponds to a gel-sol transition, was detected.

Self assembly of supramolecular homochiral structures in solutions of chiral biomimetics

The phenomenon of the formation of homochiral sets of supramolecular vortices in xerogels with a low concentration of chiral biomimetics of trifluoroacetylated amino alcohols that are metrically similar to certain macromolecular and macroscopic helical biological structures was discovered and described. Each vortex, with a characteristic scale of ∼ 1 mm, corresponds approximately to the rotational symmetry S n groups depending on the number of strings that have a common anchorage or are formed from a single nucleation and experience a mutual agreed deviation. It is essential that the direction of deviation is changed to the opposite one with the change of the chirality of the enantiomer and does not depend on the solvent type. Both weakening and strengthening of this trend were observed in the mixtures of various chiral compounds. The result is an important confirmation of the synergetic rule that was proposed by authors. According to this rule, the sign of the chirality of a supramolecular helix is changed to the opposite with a change in the chirality sign of the basic monomers from which it is formed. This regularity has a fundamental character and is executed as a trend in the hierarchies of DNA, protein, and polysaccharide macromolecular structures.

Phenomenon of the interaction of strings formed in homochiral solutions with the surface of solids

A phenomenon of the interaction of elastic supramolecular strings forming in homochiral solu� tions with the surface of solids was described. It was established that, in the interaction with a conducting surface, strings do not form; with a dielectric surface, strings efficiently form; and with a weakly or nonuni� formly conducting surface, strings form, but their for� mation is either less intense or nonuniform. A long� range mechanism of decomposition, pulling, and rup� ture of a string while interacting with a conducting sur� face was proposed. We previously described a phenomenon of the spontaneous formation of strings in lowconcentra� tion chiral solutions (1-4). In this work, we detected and studied a phenome� non of the interaction of the forming strings with the surface of a solid at the solution interface. Longrange physicochemical mechanisms were considered that lead to the vanishing and rupture of a string in a surface solution layer to 300 µm in thickness and to the forma� tion of domain structures. In the experiments, we used homochiral solutions of trifluoroacetylated amino alcohols (TFAAA) in heptane and cyclohexane (99.9%, Khimmed), and also xerogels formed upon evaporation of the solvent from these solutions. TFAAA were synthesized according to a published procedure (5). The study was performed with a MIKMED�6 opti� cal microscope and a Solver HV atomicforce micro� scope (NDMDT, Zelenograd, Russia). The xerogels were produced by applying a solution drop to various microscopically smooth solid surfaces (mica, glass, graphite, metal mirror) and, after drying, were exam� ined with the optical and atomicforce microscopes. The atomicforce microscopy was carried out in two standard complementary modes: tapping and phase contrast. Hermetically sealed solutions were examined with the optical microscope under normal conditions. Let us consider specific features of the typology of

Metric Similarity of Dynamic Commutation Processes In Situ and In Vitro

The dynamics of string growth was studied in model homochiral solutions of biomimetics, trifluoroacetylated amino alcohols (TFAAA) in heptane, water, and inverted heptane-water emulsion. In heptane and water, a thick (~1 μ in diameter) string had a crown of thin strings on its growing terminal and these thin strings effectively adsorbed dissolved TFAAA. In emulsion, the strings grew inside the water droplets, in which this TFAAA cannot be solved, presumably due to transport of TFAAA molecules from heptane into water in the surface layer surrounding the string. Applications of these phenomena to in vivo cell commutation were discussed.

Experimental investigation of anisometric chiral phase xerogel

The microstructure of a cured state (xerogel) of homochiral and achiral compounds belonging to a series of trifluoro acetylated amino alcohols has been investigated. It is shown that the substance of the cured homochiral compound consists of anisometric structures with an observed rigidity (strings) which are crystalline monophase. The xerogel of an achiral compound is represented by isometric microstructures. It is suggested that intermolecular hydrogen bonds comprising the molecular strings are apparently packed within the phase.

On the supramolecular mechanism of cell-cell commutation

Processes of cell commutation via anisometric supramolecular structures (strings) are considered in vitro and using physicochemical models of lipids and trifluoroacetylated amino alcohols. The biological effectiveness of commutation via strings is demonstrated to be higher compared to the diffusion mechanism of transfer of biologically active molecules over distances between objects typical of populations of microorganisms. A kinetic model of strings is developed, and the rate of signal transmission in such systems is estimated. It is shown that the condition of the chirality of lipids forming the biomembranes of cells follows from the experimentally observed cell commutation by means of supramolecular anisometric structures.

Chirality and Homochirality of Lipids is Necessary to Form LD-Supramolecular Structures of Cell-Cell Communications

The processes of cell-cell commutations via anisometric supramolecular structures (strings) in vitro and in physicochemical models of lipids (trifluoroacetylated amino alcohols) were studied. It was shown that biological commutation through strings is more efficient than the diffusion mechanism of transfer of bioactive molecules at distances typical of populations. Strings kinetics was constructed and the signal turnover rate in these systems was evaluated. It was demonstrated that the condition of chirality of lipids forming the cell biomembrane stems from experimentally observed cell commutation through anisometric supramolecular structures.