Appearance of induced chiral nematic phase in solutions of 4-n-alkyloxy-4′-cyanobyphenyles with symmetric camphorsubstituted hemiporphyrazines

Chiral Macroheterocycles as Inducers of Helical Liquid Crystals: Molecular Design, Specialty of Functioning

“…Thus, if doping with MHC racemate leads to a gradual decrease in the anisotropy of the dielectric constant Δɛ = ɛ k À ɛ⊥, which is due to the interaction of the dopant with highly polar LC molecules, then the introduction of a chiral additive is accompanied by a strong and nonmonotonic drop in Δɛ (Figure 5a). [24] In the temperature dependences of the CB-6 system with optically active (+)HPA at a concentration of the latter of 0.92 % and 1.80 %, a jump-like change is in ɛ k and ɛ ⊥ in the mesophase (Figure 5a), which is associated with the formation of a chiral nematic in the spiral-order system. In this case, one should expect effective compensation of mesogen dipoles in the volume of the sample due to the director shift in the quasinematic layers and a decrease in the anisotropy of the dielectric constant to zero.…”

“…The subjects of study included nematic LCs and chiral MHCs of various structures: nickel complex of octa-substituted tetraphenylporphine (Ni-(+)TPP), [23] symmetric camphor-substituted hemiporphyrazine ((+)HPA), [24] nickel complex of tetracamphoropyrazinoporphyrazine (Ni(À )TPPA), chlorin e6 13(N)-methylamide-15,17-dimethyl ether (MADMECl) and its metal complexes (M-MADMECl), [25,26] the structure of which is presented in Scheme 1.…”

Push‐Pull Effect at Formation of Sitting‐Atop Metal‐Porphyrin Complex in Solvating Media: H‐Bonding and Electrostatic Repulsion

“…Metal complexes of synthetic macroheterocycles are widely used as pigments [8,9] and catalysts [10–12] . Recently, new promising directions for the use of macroheterocyclic metal complexes in supramolecular chemistry, [13,14] for the induction of spiral liquid‐crystalline phases [15,16] and as stationary phases for chromatography [17–19] have appeared. All this determines the special relevance of studying the processes of porphyrins metallation.…”

Microwave-Assisted Synthesis and Characterization of Carba- and Triazolehemiporphyrazines with Camphorapyrazine Fragments

“…[16,17] Optically active compounds based on tetrapyrazinoporphyrinoids have been obtained by introduction of camphor fragments in their structure. [18][19][20][21] Recently [22] we briefly reported on the synthesis of racemic and R-(+)-camphor substituted cHps, the last one being used as optically active dopant of a nematic mixture of cucurbit [6]uril (CB6). However, to the best of our knowledge, tHp having camphorapyrazines subunits have not been reported in literature so far.…”