ISSN:
1573-1111
Keywords:
Azacalixarene
;
azacyclophane
;
chiral molecule
;
MM3 calculation
;
strong hydrogen bond
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Side arm modifications of hexahomotriazacalix[3]arene (1) were achieved by simple synthetic methods. Compound5 has picolyl side arms and liquid-liquid extraction experiments showed that the alkali cation affinity of5 is much stronger than that of1. A chiral group was also introduced into the azacalixarene structure. Calix[4]arene was converted into dihomoazacalix[4]arene (2) in 8% yield. Clathrate formation of2 with various solvents is described. MM3 calculations were carried out onp-substituted analogs of2. The ‘self-filled’ structure, in which the benzyl side arm is placed in its cavity, is the most stable structure when thep-positions of the aromatic rings carry small substituents. Strong hydrogen bonds between nitrogen and phenolic hydroxyl groups in dihomoazacalix[4]arene (2) were observed at low temperatures. The1H-NMR signals of phenolic hydroxyl groups appeared as six singlets in the range of 9.8∼17.1 ppm at −70°C.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00708982
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