Theoretical Consideration of the Grafting of Polymer Chains onto Fullerene C60

Summary: For the first time, the kinetics and statistics of the formation of polymer stars by grafting linear macromolecules onto the fullerene C₆₀ are considered. Two kinetic models are put forward providing an explanation for some important experimentally observed peculiarities of these macromolecular reactions. The comparison of the results found from the solution of the kinetic equations and those obtained by Monte Carlo simulations demonstrates their good agreement. Due to the minimal number of the parameters involved, the theoretical approach proposed is rather convenient for the treatment of experimental data.

     

Re(I) Complexes as Backbone Substituents and Cross-Linking Agents for Hybrid Luminescent Polysiloxanes and Silicone Rubbers

This study focuses on the synthesis of hybrid luminescent polysiloxanes and silicone rubbers grafted by organometallic rhenium(I) complexes using Cu(I)-catalyzed azido-alkyne cycloaddition (CuAAC). The design of the rhenium(I) complexes includes using a diimine ligand to create an MLCT luminescent center and the introduction of a triple C≡C bond on the periphery of the ligand environment to provide click-reaction capability. Poly(3-azidopropylmethylsiloxane-co-dimethylsiloxane) (N₃-PDMS) was synthesized for incorporation of azide function in polysiloxane chain. [Re(CO)₃(MeCN)(5-(4-ethynylphenyl)-2,2′-bipyridine)]OTf (Re1) luminescent complex was used to prepare a luminescent copolymer with N₃-PDMS (Re1-PDMS), while [Re(CO)₃Cl(5,5′-diethynyl-2,2′-bipyridine)] (Re2) was used as a luminescent cross-linking agent of N₃-PDMS to obtain luminescent silicone rubber (Re2-PDMS). The examination of photophysical properties of the hybrid polymer materials obtained show that emission profile of Re(I) moiety remains unchanged and metallocenter allows to control the creation of polysiloxane-based materials with specified properties.     

A Series of Novel Pentagonal-Bipyramidal Erbium(III) Complexes with Acyclic Chelating N3O2 Schiff-Base Ligands: Synthesis,Structure, and Magnetism

A series of six seven-coordinate pentagonal-bipyramidal (PBP) erbium complexes, with acyclic pentadentate [N₃O₂] Schiff-base ligands, 2,6-diacetylpyridine bis-(4-methoxybenzoylhydrazone) [H₂DAPMBH], or 2,6-diacethylpyridine bis(salicylhydrazone) [H₄DAPS], and various apical ligands in different charge states were synthesized: [Er(DAPMBH)(C₂H₅OH)Cl] (1); [Er(DAPMBH)(H₂O)Cl]·2C₂H₅OH (2); [Er(DAPMBH)(CH₃OH)Cl] (3); [Er(DAPMBH)(CH₃OH)(N₃)] (4); [(Et₃H)N]⁺[Er(H₂DAPS)Cl₂]⁻ (5); and [(Et₃H)N]⁺[Y₀.₉₅Er₀.₀₅(H₂DAPS)Cl₂]⁻ (6). The physicochemical properties, crystal structures, and the DC and AC magnetic properties of 1–6 were studied. The AC magnetic measurements revealed that most of Compounds 1–6 are field-induced single-molecule magnets, with estimated magnetization energy barriers, U_eff ≈ 16–28 K. The experimental study of the magnetic properties was complemented by theoretical analysis based on ab initio and crystal field calculations. An experimental and theoretical study of the magnetism of 1–6 shows the subtle impact of the type and charge state of the axial ligands on the SMM properties of these complexes.     

Modification of the texture of a polymer material surface in dust plasma

We have analyzed the modification of the texture of polymer particle surface in a dust plasma. Monodisperse spherical melamine formaldehyde particles were injected into the glow discharge plasma in neon. At a certain discharge current and gas pressure in the discharge tube, the particles were suspended in dust-plasma traps and experienced the action of the plasma of 5–25 min. Then, the particles were extracted and the collected material was studied using the scanning electron microscope. Among the results, a change in the diameter and roughness of the surface depending on the residence time of particles in the dust plasma was established. It was found that the absolute deviation of all points of the surface profile averaged over the evaluation length were in the nanometer range. The time of complete degradation of particles in the experimental conditions has been established.

     

C100 is Converted into C94Cl22 by Three Chlorination‐Promoted C2 Losses under Formation and Elimination of Cage Heptagons

Chlorination of the C₁₀₀(18) fullerene with a mixture of VCl₄ and SbCl₅ gives rise to branched skeletal transformations affording non‐classical (NC) C₉₄(NC1)Cl₂₂ with one heptagon in the carbon cage together with the previously reported C₉₆(NC3)Cl₂₀ with three heptagons. The three‐step pathway to C₉₄(NC1)Cl₂₂ starts with two successive C₂ losses of 5:6 C?C bonds to give two cage heptagons, whereas the third C₂ loss of the 5:5 C?C bond from a pentalene fragment eliminates one of the heptagons. Quantum‐chemical calculations demonstrate that the two unusual skeletal transformations—creation of a heptagon in C₉₆(NC3)Cl₂₀ through a Stone–Wales rearrangement and the presently reported elimination of a heptagon through C₂ loss—are both characterized by relatively low activation energy.