Synthesis and Characterization of Bulky Substituted Hemihexaphyrazines Bearing 2,6-Diisopropylphenoxy Groups

New substituted [30]trithiadodecaazahexaphyrines (hemihexaphyrazines) were synthesized by a crossover condensation of 2,5-diamino-1,3,4-thiadiazole with 4-chloro-5-(2,6-diisopropylphenoxy)- or 4,5-bis-(2,6-diisopropylphenoxy)phthalonitriles. The compounds were characterized by 1H-, 13C-NMR, including COSY, HMBC, and HSQC spectroscopy, MALDI TOF spectrometry, elemental analysis, IR and UV-Vis absorbance and fluorescence techniques.

Conformational and Supramolecular Aspects in Chirality of Flexible Camphor-Containing Schiff Base as an Inducer of Helical Liquid Crystals

The experimental and theoretical study of influence of the conformational state and association on the chirality of the stereochemically nonrigid biologically active bis-camphorolidenpropylenediamine (CPDA) and its ability to induce the helical mesophase of alkoxycyanobiphenyls liquid-crystalline binary mixture was carried out. On the basis of quantum-chemical simulation of the CPDA structure, four relatively stable conformers were detected. A comparison of the calculated and experimental electronic circular dichroism (ECD) and ¹H, ¹³C, ¹⁵N NMR spectra, as well as specific optical rotation and dipole moments, allowed to establish the most probable trans-gauche conformational state (tg) of dicamphorodiimine and CPDA dimer with a predominantly mutually parallel arrangement of molecular dipoles. The induction of helical phases in LC mixtures based on cyanobiphenyls and bis-camphorolidenpropylenediamine was studied by polarization microscopy. The clearance temperatures and the helix pitch of the mesophases were measured. The helical twisting power (HTP) was calculated. The decrease in HTP with increasing dopant concentration was shown to be connected with the CPDA association process in the LC phase. The effect of camphor-containing chiral dopants of various structures on nematic LCs was compared. The values of the permittivity and birefringence components of the CPDA solutions in CB-2 were measured experimentally. A strong effect of this dopant on the anisotropic physical properties of the induced chiral nematic was established. A significant decrease in the dielectric anisotropy was associated with the 3D compensation of the LC dipoles during the formation of the helix.

Synthesis of unsymmetrically substituted expanded hemiporphyrazines: A monoiodo functionalized hemihexaphyrazine

A monoiododi(tert-butyl)substituted macroheterocyclic compound of ABAB′AB′-type 4 was obtained, as a mixture of regioisomers, by statistical condensation of 4-iodophthalonitrile, 4-tert-butylphthalonitrile and 2,5-diamino-1,3,4-thiadiazole in a molar ratio 1:2:3 respectively. The structure of the functionalized hemihexaphyrazine was confirmed by MALDI-TOF mass spectrometry, IR and UV-vis spectroscopy.

Bornane[2,3-b]pyrazino-fused [30]trithiadodecaazahexaphyrin. Synthesis, acid-base behavior and nickel(II) coordination ability

Polydentate ligand-bornane[2,3-b]pyrazino-fused [30]trithiadodecaazahexaphyrin has been synthesized by crossover condensation of the racemic mixture of (R/S)-bornane[2[Formula: see text],3[Formula: see text]-b]-2,3-dicyanopyrazine and 2,5-diamino-1,3,4-thiadiazole. Its coordination ability, acid-base behavior and stability were studied by chemical kinetics/thermodynamics, UV-vis spectrophotometry and quantum chemical DFT/B3LYP/6-31G(d,p) methods. The fourth-order kinetic equation with the kinetic constant of 3.38 × 108 s[Formula: see text].mol3.L[Formula: see text] and the association mechanism according to the Langford−Gray classification were established for the fused [30]trithiadodecaazahexaphyrin–nickel diacetate–DMF system. The stepwise protonation of macrocyclic ligand with p[Formula: see text] of -1.41 in CH2Cl2-CF3COOH mixtures at the Hammett acidity functions ([Formula: see text] changed from -2.0 to 2.0 and quantitative parameters of ligand stability in AcOH–H2SO4 mixtures was obtained. The chemical structure of protonated forms and ligand destruction mechanism have been proposed. The obtained results are of interest for development of technological regulations of complex formation and for the transition to the hetero nuclear complexes.

Optically Active Porphyrin and Phthalocyanine Systems

This review highlights and summarizes various optically active porphyrin and phthalocyanine molecules prepared using a wide range of structural modification methods to improve the design of novel structures and their applications. The induced chirality of some illustrative achiral bis-porphyrins with a chiral guest molecule is introduced because these systems are ideal for the identification and separation of chiral biologically active substrates. In addition, the relationship between CD signal and the absolute configuration of the molecule is analyzed through an analysis of the results of molecular modeling calculations. Possible future research directions are also discussed.