Liquid-crystalline mesogens based on cyclo[6]aramides: distinctive phase transitions in response to macrocyclic host-guest interactions.
Producing macrocyclic mesogens that are responsive to guest encapsulation presents a significant challenge. Cyclo[6]aramides, a type of macrocycle with a hydrogen-bond-constrained backbone, exhibit thermotropic lamellar, discotic nematic, hexagonal, and rectangular columnar mesophases over a considerably wide temperature range, including at room temperature. Additionally, cyclo[6]aramides show unusual mesophase transitions from lamellar to hexagonal columnar phase mediated by macrocyclic host-guest (H-G) interactions between the macrocycles and alkylammonium salts. The phase transition, triggered by an organic guest engaging in H-G interactions with a macrocyclic cavity, provides a novel strategy for manipulating the properties of liquid-crystalline materials. The crystal structure of a homologous cyclo[6]aramide reveals a disk-shaped, near-planar molecular backbone that facilitates intermolecular π-π stacking and leads to columnar assembly.
College of Chemistry, Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China).
Xiaowei
X
Li
State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China).
Bao
B
Li
College of Chemistry, Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China).
Long
L
Chen
College of Chemistry, Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China).
Jinchuan
J
Hu
College of Chemistry, Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China).
Chengdanyang
C
Wen
State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China).
Qingdong
Q
Zheng
State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China).
Lixin
L
Wu
Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669 (Singapore).
Huaqiang
H
Zeng
Department of Chemistry, The State University of New York, Buffalo, NY 14260 (USA). bgong@buffalo.edu.
Bing
B
Gong
College of Chemistry, Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China). lhyuan@scu.edu.cn.
Lihua
L
Yuan
D000577:Amides / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D003500:Cyclization; D047028:Macrocyclic Compounds / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D000577:Amides; D047028:Macrocyclic Compounds
host-guest systems; liquid crystals; macrocycles; mesogens; mesophase transitions