Double Heterohelicenes Composed of Benzo[b]- and Dibenzo[b,i]phenoxazine: A Comprehensive Comparison of Their Electronic and Chiroptical Properties

Heterohelicenes are potential materials in molecular electronics and optics because of their inherent chirality and various electronic properties originating from the introduced heteroatoms. In this work, we comprehensively investigated two kinds of double NO-hetero[5]helicenes composed of 12H-benzo[b]phenoxazine (BPO) and 13H-dibenzo[b,i]phenoxazine (DBPO). These helicenes exhibit good electron donor property reflecting the electron-rich character of their monomers and were demonstrated to work as p-type semiconductors. The enantiomers of these helicenes show the largest class of dissymmetry factors for circularly polarized luminescence (CPL) (|gCPL| > 10−2) among the previously reported helicenes. Interestingly, the signs of CPL are opposite between BPO- and DBPO-double helicenes of the same helicity. The origin of the large gCPL values and the inversion of the CPL signs was addressed by analysis of the transition electronic dipole moments (TEDM) and transition magnetic dipole moments (TMDM) based on the TD-DFT calculations.

Electrochemical reversibility of Me6Fc/Me6Fc+PF6- and Me8Fc/Me8Fc+PF6- redox systems in acetonitrile

Two new redox systems, sym. 1,2,4,1¢,2¢,4¢-hexamethylferrocene/cation sym. 1,2,4,1¢,2¢,4¢-hexamethyl ferricinium and sym. octamethylferrocene/cation sym. Octamethyl­ferricinium (MenFc/MenFc+, n = 6, 8) were studied by the cyclic voltammetry method. The observed dif­ference between potentials of anodic and cathodic peaks of 0.063 to 0.075 V, and its inde­pendence on the potential scan rate, the straight-line depen­dence of the current value of anodic (and cathodic) peak on square root of the potential scan rate, as well as shapes of the recorded cyclic voltammograms indicate that both redox systems in acetonitrile meet the most important requirement of IUPAC regarding internal reference redox systems (IRRS) - electrochemical reversibility of electron transfer reaction. The same method under identical conditions was used to study the effect of the number of methyl groups on the redox potential of MenFc/MenFc+ systems, n = 0, 6, 8, 10. It was shown that the successive displacement of half-wave potential in the series of Fc/Fc+ - Me6Fc/Me6Fc+ - Me8Fc/Me8Fc+ -Me10Fc/Me10Fc+ towards negative potentials is attributed to the electron-donor property of methyl groups. The location of the redox potentials values of new systems [n=6 (111 mV), n=8 (23 mV)] between redox potentials of systems of n = 0 (431 mV) and n = 10 (-77 mV) means that the redox potential of the systems of MenFc/MenFc+(n = 6, 8) has an optimal position on the electrode potential scale, i.e. meets another of the IUPAC criteria for IRRS.

Water-oriented magnetic anisotropy transition

Water reorientation is essential in a wide range of chemical and biological processes. However, the effects of such reorientation through rotation around the metal–oxygen bond on the chemical and physical properties of the resulting complex are usually ignored. Most studies focus on the donor property of water as a recognized σ donor-type ligand rather than a participant in the π interaction. Although a theoretical approach to study water-rotation effects on the functionality of a complex has recently been conducted, it has not been experimentally demonstrated. In this study, we determine that the magnetic anisotropy of a Co(II) complex can be effectively controlled by the slight rotation of coordinating water ligands, which is achieved by a two-step structural phase transition. When the water molecule is rotated by 21.2 ± 0.2° around the Co–O bond, the directional magnetic susceptibility of the single crystal changes by approximately 30% along the a-axis due to the rotation of the magnetic anisotropy axis through the modification of the π interaction between cobalt(II) and the water ligand. The theoretical calculations further support the hypothesis that the reorientation of water molecules is a key factor contributing to the magnetic anisotropy transition of this complex.

Ionic Charge-Transfer Liquid Crystals Formed by Alternating Supramolecular Copolymerization of Liquid π-Donors and TCNQ

A new family of liquid π-donors, lipophilic dihydrophenazine (DHP) derivatives, show remarkably high π-electron-donor property which exhibit supramolecular alternating copolymerization with 7,7,8,8-tetracyanoquinodimethane (TCNQ), giving ionic charge-transfer (ICT) complexes. The ICT complexes form distinct columnar liquid crystalline (LC) mesophases with well-defined alternating molecular alignment as demonstrated by UV-Vis-NIR spectra, IR spectra, and X-ray diffraction (XRD) patterns. These liquid crystalline ICT complexes display unique phase transitions in response to mechanical stress: the columnar ICT phase is converted to macroscopically oriented smectic-like mesophases upon applying shear force. Although there exist reports on the formation of ICT in the crystalline state, this study provides the first rational identification of ICT mesophases based on the spectroscopic and structural data. The liquid crystalline ICT phases are generated by strong electronic interactions between the liquid π-donors and solid acceptors. It clearly shows the significance of simultaneous fulfillment of strong π-donating ability and ordered self-assembly of the stable ICT pairs. The flexible, stimuli-responsive structural transformation of the ICT complexes offer a new perspective for designing processable CT systems with controlled hierarchical self-assembly and electronic structures.

ON THE THEORY OF THE PROCESS OF BORONATION OF IRON-CARBON ALLOYS IN A MAGNETIC FIELD

The article offers an analysis of the results of the processes of formation of iron borides from the point of view of quantum theory. The object of study is the phase composition, physicomechanical and electrophysical properties of boride, borosilicidal and aluminum-boride coatings on iron and steel. The research method is x-ray and metallographic analysis. Based on the analysis of the results of the formation of iron borides on boron diffusion from the point of view of quantum theory, it was found that a significant increase in the physicomechanical properties of partially microhardness and wear resistance occurs by establishing stable electronic configurations of chemical compounds. So, when creating FeB compounds, boron atoms (2s22p1) form sp3 configurations due to electrons of iron atoms (3d64s2), which have the donor property to form stable d5 configurations. Experimental studies of the properties of chemical compounds that form during diffusion saturation confirm a correlation with their electronic structure, and iron atoms tend to form a strong covalent bond with boron atoms. KEY WORDS: BORING, BOROSILICATION, ATOMS, ENERGY LEVELS, QUANTUM NUMBERS, ELECTRON CONFIGURATION.

Solvent effect on the aggregation of amphiphilic phthalocyanines substituted by polyethyleneoxide

Metal-free and copper(II) tetra-β-polyethyleneoxide-substituted phthalocyanine derivatives, TDEO6-MPc, where polyethylene oxide derivative is hexaethyleneglycolmonododecylether (DEO6), were synthesized. Those compounds are soluble in both lipophilic and hydrophilic solvents. By taking advantage of this amphiphilic property, solvent effect on the aggregation of the phthalocyanine was studied by means of UV-vis absorption and fluorescence spectroscopies. Dimerization constants of TDEO6-MPc in non-coordinating solvents were determined by the concentration dependence of absorption spectra. Aggregation is suppressed by the increase in the E T (30) value (acceptor property) of solvents in non-coordinating solvents, whereas it is promoted by the increase in Donor Number (donor property) of solvent in coordinating solvents.