L. A. Bulavin

On the Origin of C60 Fullerene Solubility in Aqueous Solution

In this work, we report that the surface hydroxylation of C60 molecules is the most likely mechanism for pristine C60 fullerenes/C60 fullerene aggregate stabilization in water, being independent of the method of C60 fullerene aqueous solution preparation.

How flexible are DNA constituents? The quantum-mechanical study.

Abstract Relaxed force constants (RFCs) and vibrational root-mean-square deviations have been evaluated by the original calculation method for conformational parameters of the DNA structural units and their constituents: nucleic acid bases (uracile, thymine, cytosine, adenine and guanine) and their ‘building blocks’ (benzene, pyrimidine, imidazole and purine molecules), as well as the DNA backbone structural units: tetrahydrofuran, 1,2-dideoxyribose, methanol and orthophosphoric acid. It has been found that the RFCs for nomenclature torsions β, γ, ε and sugar pseudorotation angle P in 1,2-dideoxyribose are sensible to the molecule conformation and their values are in the range of 1–25 kcal/(mole-rad2) obeying the inequality K γ > K ε > KP > K β. The RFCs values for endocyclic torsions of nucleic acid bases six-member rings lie within 15–45 kcal/(mole·rad2) in pyrimidines and within 20–60 kcal/(mole·rad2) in purines. It is shown that the quantum zero-point motion effectively neglects the amino group non-planarity in cytosine, adenine and partially in guanine.

Structure and Thermophysical Properties of Fullerene C60 Aqueous Solutions

The structure and thermophysical properties of fullerene C60aqueous solutions were investigated both experimentally and theoretically. The aggregation kinetics results indicated that the structure of fullerene C60aggregates in water could be described as a fractal system. The IR and electronic absorption spectra obtained confirm the presence of the crystalline phase in aqueous solution. The numerical values of thermodynamic coefficientsαP,βT,βS,cP, andcV, and sound velocity were determined from the measured (P–V–T) data. The vibrational spectrum of the crystalline structure (Thsymmetry group) formed from the hydrated single fullerene C60molecules in aqueous solutions was calculated using the molecular dynamics approach.

Structure of fullerene C60 in aqueous solution

The structure of fullerene C60 in aqueous solution was investigated both experimentally and theoretically. The fullerene C60 was found to aggregate rapidly at room temperature. The aggregation kinetics results indicated that the structure of C60 aggregates in water could be described as a fractal system. The optical absorption spectra obtained testify to the crystalline character of absorption. The formation in water of fractal structures and a crystalline phase from highly stable hydrated fullerene (C60)13 clusters (Ih symmetry group) was predicted using the molecular dynamics approach.

Self-organization C60 nanoparticles in toluene solution

The structure of fullerene C60 in toluene solution was investigated both experimentally and theoretically in detail. C60 was found to aggregate slowly even in fairly dilute solution concentrations ranging from 0.18 to 0.78 g/l at room temperature. The electronic absorption spectra obtained testify to the mainly molecular character of absorption. The aggregation kinetics results indicated that the structure of C60 aggregates could be described as a fractal system. The numerical calculations predicted the formation of stable fullerene (C60)N clusters in toluene solution with sizes >1.2 nm and aggregation number N≥3.

Study of Structure of Colloidal Particles of Fullerenes in Water Solution

Abstract The formation in water of highly stable cluster/crystallite structures from fullerene C60 is theoretically predicted and experimentally confirmed.

Analysis of the structure of aqueous ferrofluids by the small-angle neutron scattering method

The structures of several aqueous magnetic fluids stabilized by different combinations of surfactants have been compared using small-angle neutron scattering. The size distribution functions of colloidal particles in water have been determined. The degree of clustering of magnetic nanoparticles has been obtained from comparison with electron microscopy data. The combinations of surfactants that lead to a minimum clustering have been revealed.

Structure of water-based ferrofluids with sodium oleate and polyethylene glycol stabilization by small-angle neutron scattering: contrast-variation experiments

Contrast variation in small-angle neutron scattering (SANS) experiments is used to compare the structures of a water-based ferrofluid, where magnetite nanoparticles are stabilized by sodium oleate, and its mixture with biocompatible polyethylene glycol, PEG. The basic functions approach is applied, which takes into account the effects of polydispersity and magnetic scattering. Different types of stable aggregates of colloidal particles are revealed in both fluids. The addition of PEG results in a reorganization of the structure of the aggregates: the initial comparatively small and compact aggregates (about 40 nm in size) are replaced by large (more than 120 nm in size) fractal-type structures. It is postulated that these large structures are composed of single magnetite particles coated with PEG, which replaces sodium oleate. Micelle formation involving free sodium oleate is observed in both fluids. The structures of the fluids remain unchanged with increasing temperature up to 343 K. New and specific possibilities of SANS contrast variation with respect to multicomponent systems with different aggregates are considered.

Solvatochromism and Fullerene Cluster Formation in C60/N-methyl-2-pyrrolidone

UV-Vis spectroscopy and small-angle neutron scattering experiments are performed on the cluster solution of fullerene C60 in N-methyl-2-pyrrolidone before and after dilution of the system with pure solvent. Some changes in the UV-Vis spectra showing solvatochromism at dilution are observed, while the neutron scattering signal does not change. The effect is discussed with respect to the relation between solvatochromism and cluster formation for fullerene solutions in nitrogen-containing solvents.

Unified Picture for the Classical Laws of Batschinski and the Rectilinear Diameter for Molecular Fluids

The explicit relations between the thermodynamic functions of the lattice gas model and the fluid within the framework of an approach proposed earlier [ Kulinskii , V. L. J. Phys. Chem. B 2010 , 114 , 2852 ] are derived. It is shown that the Widom line serves as the natural border between the gas-like and the liquid-like states of the fluid. The explanation of the global cubic form of the binodal for the molecular liquids is proposed, and the estimate for the amplitude of the binodal opening is obtained.