A New Type of Double Calix[4]arenes by Linkage via the Phenolic Hydroxy Groups

Abstract

tion limit. In this respect, the performance of the a-methyl substituted catalysts approaches that of heterogeneous Ziegler catalysts, in which these regio-irregularities are not observed .The molecular weights of the polymers obtained with the catalysts 1-4 show a surprising correlation with the respective stereo-and regio-regularities of the catalysts: Complex 3 produces by far the longest and most isotactic, complex 1 the shortest and least isotactic polymer chains. This unexpected observation can be explained based on structural models for the reactive zirconocene alkyl olefin ~a t i o n [ "~: The P-agostic binding required for chain termination by P-H transfer places the polymer chain (Pl) of a stereoregular unit into that ligand sector (Fig. la) which is occupied by the ring substituent R'. If R' is sufficiently large, chain termination will therefore be largely suppressed except in those cases where the positions of the polymer and CH, substituents at the P-carbon are inverted, i.e. in a stereo-irregular unit, or where the P-carbon carries two H atoms, as in a regio-irregular unit.

Calix[4]arene daisychains

“…9 Subsequently, McKervey and Bo¨hmer described the first lower-rim, monolinked double calixarenes, which were straightforwardly obtained from the acid chloride 4. 10 Thus, 4 was reacted with 1,2-diaminoethane to yield the amido linked biscalixarene 5. Similarly, the double calixarene 6 with a diester bridge was formed upon reaction of 4 with ethylene glycol.…”

The Modular Approach in Supramolecular Chemistry

“…The 1 H-NMR ties, several groups synthesized double calix [4]arenes with spectra show a 1Ϫ4 ppm upfield shift for the signals of enforced cavities [1b] [22] . In hemicarcerboth lower rims, tail-to-tail (10) [24] , or via connecting the ands and hemicarceplexes there are only two [12] or three upper rim of one with the lower rim of another, head-tolinkages between the two parts or the four linkages are long tail (11) [25] . In hemicarcerboth lower rims, tail-to-tail (10) [24] , or via connecting the ands and hemicarceplexes there are only two [12] or three upper rim of one with the lower rim of another, head-tolinkages between the two parts or the four linkages are long tail (11) [25] .…”

An Efficient Synthesis of Bis(calix[4]arenes), Bis(crown ether)-Substituted Calix[4]arenes, Aza-Crown Calix[4]arenes, and Thiaza-Crown Calix[4]arenes

“…Double and triple calix [4]arenes connected through the oxygen atoms have been described, [23] produced by reactions between calix [4]arenes 1,3-difunctionalized at the smaller (lower) rim and difunctional reagents such as diacid dichlorides or diamines. [23,24] Double calixarenes linked through one bridge at the smaller (lower) rim and bearing urea groups on the larger (upper) rims have also been reported. [25,26] Recently, Rebek et al have described [27] the synthesis and the encapsulation behaviour of bis(calix [4]arenes) linked by one bridge at the larger (upper) rims and bearing urea groups in the same rims.…”