In this study, the ability of the chiral tetracamphor derivative of tetrapyrazinoporphyrazine (Ni(−)TСPyzPz) to induce a helical liquid crystalline phase in a nematic mixture of alkoxycyanobiphenyls is investigated. Based on quantum chemistry and UV/Vis CD spectroscopy, it was shown that the chirality of (Ni(−)TCPyzPz) in chloroform solutions depends significantly on its association, leading to the appearance of a noticeable dipole moment. The H-dimer («face-to-face») is the most stable. Using polarisation microscopy, the formation of the fingerprint texture and Newton interference rings was recorded after the introduction of (Ni(−)TСPyzPz) into the nematic mixture of alkoxycyanobiphenyls CB-2. Clearing temperatures, helical pitch, and helical twisting power (HTP) were measured. The high efficiency of helix induction under the action of (Ni(−)TСPyzPz) (maximum HTP value 87.7 μm−1) was found, decreasing with increasing dopant concentration due to its association. The dichroic ratio of Q-band absorption and the order parameter of (Ni(−)TСPyzPz) were measured by polarisation spectroscopy. The CD spectra of the dopant in the CB-2 mixture were obtained, the values of the molar circular dichroism coefficient and the g-factor of the Q-band dissymmetry were calculated. The g value in LC was shown to be 147 times greater than in the chloroform solution as a result of the amplification of chirality in the anisotropic medium. An increase in circular dichroism with a rise in the number of nematic LC molecules in the solvation shell was shown by the quantum chemistry method.
扫码关注我们
求助内容:
应助结果提醒方式:
