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Synthesis, Structure and Molecular Recognition of Functionalised Tetraoxacalix[2]arene[2]triazines
Author(s) -
Wang QiQiang,
Wang DeXian,
Yang HaiBo,
Huang ZhiTang,
Wang MeiXiang
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201000003
Subject(s) - chemistry , hydrogen bond , host–guest chemistry , dimer , lone pair , triazine , nuclear magnetic resonance spectroscopy , monomer , intermolecular force , crystallography , molecule , stereochemistry , supramolecular chemistry , polymer chemistry , crystal structure , organic chemistry , polymer
Functionalised dialkoxy‐substituted tetraoxacalix[2]arene[2]triazine macrocycles 6 have been readily synthesised by the fragment coupling approach using methyl 3,5‐dihydroxy‐4‐alkoxybenzoates and cyanuric chloride as the starting materials under very mild conditions. AlCl 3 ‐mediated deallylation and debenzylation reactions afforded the lower‐rim dihydroxy‐substituted tetraoxacalix[2]arene[2]triazine derivatives 11 and 13 in good yields. Although dialkoxy‐substituted tetraoxacalix[2]arene[2]triazine macrocycles are fluxional in solution on the NMR spectroscopy timescale, they adopt a symmetric or slightly distorted 1,3‐alternate conformation with the bridging oxygen atoms conjugated with the triazine rings. The dihydroxylated tetraoxacalix[2]arene[2]triazine 13 b , which gives a mixture of monomer and dimer in solution according to a diffusion NMR spectroscopy study, adopts a 1,3‐alternate conformation and forms a cyclic tetrameric assembly in the solid state due to the formation of intermolecular hydrogen‐bonding networks. This dihydroxylated macrocyclic host molecule, a hydrogen‐bond donor macrocycle with a V‐shaped cleft, interacts with 2,2′‐bipyridine, 4,4′‐bipyridine and 1,10‐phenanthroline guests. Although in solution they form the corresponding 1:1 complexes with binding constants ranging from 37.7 to 213 M −1 , 2:2 host–guest complexes were observed in the crystalline state. Hydrogen‐bonding interactions, along with other non‐covalent interactions, such as lone‐pair‐electron–π and CH⋅⋅⋅π interactions, were found to be the driving force for the formation of host–guest complexes.