13958-90-2Relevant articles and documents
Aggregation?induced emissions in columnar wedge?shaped pyridinium?based ionic liquid crystals
Wang, Ren-Tzong,Jane Tsai, Suh-Jen,Lee, Gene-Hsiang,Lai, Chung K.
, (2020)
Two series of ILCs derived from wedge?shaped N-phenylpyridiniums 1–2 were prepared and their mesomorphic properties were investigated. The X?ray crystal structure analyses of two single crystals 2-PF6 (n = 12) and 2-NTf2 (n = 12) revealed that bilayer structures induced by H?bonds in the solid state were observed. A complementary dimeric structure induced by H?bonds in such type of wedge?shaped cation (or anion) moiety was attributed to the formation of columnar phases. The type of counter anions has a significant influence on the formation of the mesophase; five counter anions (i.e. X = PF6￣, BF4￣, OTf￣, SCN￣, RSO3￣) induced columnar mesophase. In contrast, anion X = Tf2N￣ as a bulky moiety and less H?bond active sites formed crystal phase. The powder XRD data appeared that the diameter of the hard columnar part increased with the effective ionic radius for different counter ion. A linear correlation plot (R2 = 0.9203) was obtained. All ethanol solutions of compounds 1–2 were detected without any observable signals on photoluminescence. But compounds 2-X will aggregate in the aqueous mixture with high water fractions (?w) needed to turn on their light emission process. Weak PL signals are recorded at ?w w > 50% till it reached to the maximum intensity at ?w ~70%.
Baumgarten
, p. 1637,1642 (1932)
Dual-Cavity Basket Promotes Encapsulation in Water in an Allosteric Fashion
Chen, Shigui,Yamasaki, Makoto,Polen, Shane,Gallucci, Judith,Hadad, Christopher M.,Badji?, Jovica D.
, p. 12276 - 12281 (2015)
We prepared dual-cavity basket 1 to carry six (S)-alanine residues at the entrance of its two juxtaposed cavities (289 ?3). With the assistance of 1H NMR spectroscopy and calorimetry, we found that 1 could trap a single molecule of 4 (K1 = 1.45 ± 0.40 × 104 M-1, ITC), akin in size (241 ?3) and polar characteristics to nerve agent VX (289 ?3). The results of density functional theory calculations (DFT, M06-2X/6-31G?) and experiments (1H NMR spectroscopy) suggest that the negative homotropic allosterism arises from the guest forming C-H···π contacts with all three of the aromatic walls of the occupied basket's cavity. In response, the other cavity increases its size and turns rigid to prevent the formation of the ternary complex. A smaller guest 6 (180 ?3), akin in size and polar characteristics to soman (186 ?3), was also found to bind to dual-cavity 1, although giving both binary [16] and ternary [1-62] complexes (K1 = 7910 M-1 and K2 = 2374 M-1, 1H NMR spectroscopy). In this case, the computational and experimental (1H NMR spectroscopy) results suggest that only two aromatic walls of the occupied basket's cavity form C-H···π contacts with the guest to render the singly occupied host flexible enough to undergo additional structural changes necessary for receiving another guest molecule. The structural adaptivity of dual-cavity baskets of type 1 is unique and important for designing multivalent hosts capable of effectively sequestering targeted guests in an allosteric manner to give stable supramolecular polymers.
An efficient ultrasonic-assisted synthesis of imidazolium and pyridinium salts based on the Zincke reaction
Zhao, Sanhu,Xu, Xiaoming,Zheng, Lu,Liu, Hai
experimental part, p. 685 - 689 (2011/02/23)
A mild and efficient method has been developed using ultrasound irradiation for the synthesis of imidazolium and pyridinium salts based on the Zincke reaction. Tertiary nitrogen nucleophiles such as pyridines and imidazoles can be alkylated with primary amine by simply using their ammonium form Zincke salts. In almost all cases, a clear yield increase results and a dramatic reduction of the reaction time accompanied by an improved quality of the products occurs.
