TY - JOUR
T1 - Synthesis of potential receptor molecules by combination of upper-rim-functionalized calix[4]arenes and partly bridged resorcinarenes
AU - Timmerman, Peter
AU - Boerrigter, Harold
AU - Verboom, Willem
AU - Reinhoudt, David N.
PY - 1995
Y1 - 1995
N2 - Combination of upper‐rim‐1,3‐difunctionalized calix[4]arenes 14, 16, and 18 with tribridged resorcinarenes 4 and 6 and A,C‐di‐bridged resorcinarenes 10 and 13 yields both 1/1 calix‐resorcinarenes (22–24) and 2/1 calix‐resorcinarenes (25, 26). 1/1 Calix‐resorcinarene 22 mainly exists as one conformer (a), but at low temperatures (−60°C) very small amounts ( < 5%) of a second conformer (b) can be observed. Both conformers equilibrate via rotation about one of the C(arene)‐N bonds, with an activation free energy (Δ G≠) of 13 kcal/mol. 2/1 Calix‐resorcinarenes 25 and 26 are more flexible and exist as a mixture of conformers. In order to be able to rigidify the structure of 2/1 calix‐resorcinarenes via rigid spacers between the calix[4]arene fragments, 1,3‐diaminocalix[4]arene derivatives 31, 32, and 34 were synthesized carrying nitro, carboxylic ester, and cyano groups at the unsubstituted aromatic rings. With these calix[4]arene derivatives, three new, functionalized 2/1 calix‐resorcinarenes 35–37 have been synthesized.
AB - Combination of upper‐rim‐1,3‐difunctionalized calix[4]arenes 14, 16, and 18 with tribridged resorcinarenes 4 and 6 and A,C‐di‐bridged resorcinarenes 10 and 13 yields both 1/1 calix‐resorcinarenes (22–24) and 2/1 calix‐resorcinarenes (25, 26). 1/1 Calix‐resorcinarene 22 mainly exists as one conformer (a), but at low temperatures (−60°C) very small amounts ( < 5%) of a second conformer (b) can be observed. Both conformers equilibrate via rotation about one of the C(arene)‐N bonds, with an activation free energy (Δ G≠) of 13 kcal/mol. 2/1 Calix‐resorcinarenes 25 and 26 are more flexible and exist as a mixture of conformers. In order to be able to rigidify the structure of 2/1 calix‐resorcinarenes via rigid spacers between the calix[4]arene fragments, 1,3‐diaminocalix[4]arene derivatives 31, 32, and 34 were synthesized carrying nitro, carboxylic ester, and cyano groups at the unsubstituted aromatic rings. With these calix[4]arene derivatives, three new, functionalized 2/1 calix‐resorcinarenes 35–37 have been synthesized.
U2 - 10.1002/recl.19951140306
DO - 10.1002/recl.19951140306
M3 - Article
VL - 114
SP - 103
EP - 111
JO - Recueil des travaux chimiques des Pays-Bas
JF - Recueil des travaux chimiques des Pays-Bas
SN - 0165-0513
IS - 3
ER -