Wide-rim functionalization of calix[4]arene: The di- and tetraisocyanocalix[4]arene assembling ligands and their silver(I) polymers and oligomers

The 5,11- and 5,17-diisocyano-25,26,27,28-tetra-n-propoxycalix[4]arene bridging ligands (calix(NC)(2)) have been prepared in four steps with 34 and 30% global yields, respectively. Their corresponding Ag(I) complexes have been prepared from the direct reaction of the ligand with AgBF4 and are characterized from various spectroscopic and physical techniques. The MALDI-TOF spectra indicate the presence of polymers or oligomers of the type {Ag(calix(NC)(2))(BF4)}(n). The compounds have been characterized further from TGA, DSC, and XRD and compared with the oligomeric species 5,11,17,23-tetraisocyano-25,26,27,28-tetra-n-propoxycalix[4]arene silver(I) (as a BF4- salt).