Lower Rim−Upper Rim Hydrogen-Bonded Adducts of Calix[4]arenes

Abstract

An upper-rim-substituted calix[4]arene tetracarboxylic acid forms hydrogen-bonded duplexes with lower-rim-substituted tetra(4-pyridyl)- and tetra(3-pyridyl)calix[4]arenes in chloroform. The formation of these adducts was studied by extraction experiments. The association constants determined via (1)H NMR dilution experiments in CDCl(3) are 7.6 x 10(3) and 1.3 x 10(3) M(-1) for the 4-pyridyl and the 3-pyridyl derivative, respectively. IR studies in the solid state and in solution indicate that the interaction is based on hydrogen bonding and that the degree of proton transfer is negligible. VPO measurements support the formation of 1:1 adducts.

Giant regular polyhedra from calixarene carboxylates and uranyl

“…by formylation of calix[4]arene 3 , although use of microwave heating produced quantitative yields in shorter reaction times. Although O -alkyl calix[4]arenes 9 and 10 were easily prepared by oxidation of the corresponding aldehydes by well-established procedures2728, oxidation of 5 to the OH-free calix[4]arene 7 was only achieved by sodium chlorite29 in a dimethylsulphoxide (DMSO)/water mixture that prevents precipitation of both the reagents and the partially oxidised intermediates. Compound 7 was isolated in good yield by simple precipitation upon addition of hydrochloric acid.…”

“…All chemicals were used without further purification. Compounds 3 43, 4 44, 9 27 and 10 28 were obtained according to literature procedures. Compound 5 was prepared using a modified literature procedure26 in a microwave reactor at 110 °C for 3 h. Compound 7 was obtained by a different procedure from the one reported in the literature45.…”

Self-Assembling Cavities: Present and Future

“…The fruitful combination of pyridine and carboxylic acid functionalities has been exploited for the assembly of two calix [4]arenes in either lower-rim/upper-rim [5] or in upper-rim/ upper-rim [6] modes, although encapsulation of substrates has not been reported for such systems. More recently, dimerization of the larger calix [6]arenes bearing three carboxylic acids in alternate positions at the upper rim has been observed.…”

Hydrogen bond-directed aggregation of diazadibenzoperylene dyes in low-polarity solvents and the solid state

“…For most examples, this interaction relies on hydrogen-bonding, which is a directionalreversible interaction with adjustable binding strength (4,5). Within the family of hydrogen-bonded systems, the association of carboxylic acids and pyridines has received special attention and includes work on defined molecular assemblies (6)(7)(8)(9), supramolecular polymers and networks (4,5,(10)(11)(12)(13)(14), and hydrogen-bonded liquid crystals (15)(16)(17)(18). However, the lowbinding constant between pyridines and carboxylic acids precludes high degrees of polymerization in solution between dicarboxylic acid and dipyridine building blocks, which, up to now, limited this supramolecular synthon to applications in solid-state materials.…”