A chiral "Siamese-Twin" calix[4]pyrrole tetramer. Issue 9 (7th June 2016)

• Record Type: Journal Article
• Authors: Galán, Albano; Aragay, Gemma; Ballester, Pablo
• Is Part Of: Chemical science. Volume 7:Issue 9(2016:Sep.)
• Page Start: 5976
• Page End: 5982
• Publication Date: 2016-06-07
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6sc01843b
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : We describe our results in the attempted template syntheses of oligomacrocycle calix[4]pyrrole dimer4, using Hay coupling reaction conditions, tetraalkynyl calix[4]pyrrole5 as starting material and two bipyridyl N -oxides of different length as templates. Abstract : We describe our results in the attempted template syntheses of oligomacrocycle calix[4]pyrrole dimer4, using Hay coupling reaction conditions, tetraalkynyl calix[4]pyrrole5 as starting material and two bipyridyl N -oxides of different length as templates. We found that the short bis- N -oxide3 was not an efficient template for the macrocyclization reaction producing an insoluble crude reaction mixture containing exclusively oligomerization and polycondensation products. On the other hand, when we used the long bis- N -oxide6 as template we obtained a soluble crude reaction mixture in which we did not detect the expected calix[4]pyrrole dimer4 . Instead, we isolated, in low yield, an encapsulation complex of the bis- N -oxide6 in a partially reacted calix[4]pyrrole dimer. The major isolated species was an unprecedented calix[4]pyrrole tetramer encapsulating two molecules of6 . The complex adopted a chiral helical-like conformation in the solid state resembling the previously described so-called "Siamese-Twin porphyrins".