Triazolated calix[4]semitubes: assembling strategies towards long multicalixarene architectures

Abstract

Cone and 1,3-alternate calix[4]arenes bearing pairs of 2-azidoethyl or propargyl groups, and 1,3-alternate calix[4]arenes having four 2-azidoethyl, four propargyl groups or pairs of 2-azidoethyl and silylated propargyl groups were explored...

Switchable silver-ion complexation by triazolated calix[4]semitubes

“…Bis(calix[4]arene) 1 6 and ditopic triscalixarene semitubes 2–4 7 having different mutual arrangements of bistriazole receptor units (head-to-head, tail-to-tail, and head-to-tail) were prepared according to recently developed procedures. Triazolated bis(calixarenes) 5–7 bearing one or two crown-5-ether loops as the additional receptor units were prepared from 1,3-alternate bis(alkynes) 11 6 and 13 5 e and bis(azides) 12 6 and 15 (Scheme 1).…”

“…Triscalixarene semitube 8 bearing a single crown-5-ether loop was prepared in 33% yield under the same CuAAC-conditions from crowned bis(azide) 15 and biscalixarene semitube 16 7 having two propargyl groups in the structure (Scheme 2). To synthesize isomeric tris(calixarene) 9 with the crownether loop located at the opposite ‘end’ of the semitube and to complete the series with triscalixarene 10 having two crownether loops, propargylated calix[4]crown-5-ether 13 was first reacted with calix[4]arene 17 7 bearing pairs of 2-azidoethyl groups and silylated propargyl groups at different sides of the 1,3-alternate calixarene core, and thus biscalixarene semitube 18 was obtained in 43% yield. Next, tert -butyldimethylsilyl protecting groups in compound 18 were removed using tetrabutylammonium fluoride in aqueous THF, and biscalixarene semitube 19 having a crownether loop and a pair of propargyl groups at the opposite ‘ends’ of the molecule was obtained in 81% yield.…”

“…We have recently reported on the synthetic availability of triazolated calix[4]semitubes assembled from two 6 or three 7 cone or 1,3-alternated calix[4]arene cores by using copper( i )-catalyzed azide–alkyne cycloaddition (CuAAC). 8 These linear-shaped molecules are inherent receptors targeted to transition cations due to bistriazole sites formed between each pair of adjacent calixarene cores during synthesis.…”

Synthesis and crystal structures of 5,17-dibromo-26,28-dihydroxy-25,27-dipropynyloxycalix[4]arene, 5,17-dibromo-26,28-dipropoxy-25,27-dipropynyloxycalix[4]arene and 25,27-bis(2-azidoethoxy)-5,17-dibromo-26,28-dihydroxycalix[4]arene

“…The modification of calixarene macrocycles by azide or alkyne functional groups makes them suitable for copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) (Song et al, 2014). Under the usual CuAAC conditions, biscalixarene (Gorbunov et al, 2021) or triscalixarene (Malakhova et al, 2022a) molecular semitubes were synthesized, and the processes of intramolecular oscillations of Ag + inside them were studied (Malakhova et al, 2022b). It is expected that grafting of additional substituents into the para-positions of phenolic fragments of the azide/alkynecontaining calix [4]arenes, on the one hand, should improve shielding of the internal cavity of the calixarene semitube and, on the other hand, may provide possibilities for further modifications of the multicalixarene assemblies.…”

Copper(I)-Catalyzed Alkyne–Azide Cycloaddition (CuAAC) “Click” Reaction: A Powerful Tool for Functionalizing Polyhydroxylated Platforms

“…Finally, Table − shows examples of the incorporation of other organic molecules, such as cationic, ionic, nonionic, allyl, benzyl, triphenylene, thiazole acetate, dimethyl acetylenedicarboxylate, and polyammonium, along with their required conditions. This comparative table allows us to show the great versatility that the copper-catalyzed cycloaddition reaction can have between an alkyne group and an azide group (CuAAC) in the generation of new calixarene/resorcinarene derivatives.…”