STRUCTURES OF THE SYMMETRIC CALIX[4]ARENES. Young Ja Park, Kwanghyun No, Jung Mi Shin, Department of Chemistry, Sook Myung Women's University, Seoul, Korea 140-742
We have determined two structures of calix[4]arenes having their own two-fold rotational symmetry.
l.Tetra-butanoyloxycalix[4]arene, monoclinic, C2/c, a=18.435(4), b=13.774(2), c=l6.94l(3)Å, [[beta]]=116.23(1)deg., Z=4, V= 3859(1) Å3, Dm=1.21 gcm-3, R=0.078 for 2605 observed reflections. The molecule is in the 1,2 alternate conformation. Two-fold symmetry axis is along the line connecting between two opposite methylene carbon atoms.
2.Tetra-tert-butyl-dipropionyloxydihydroxycalix[4]arene, monoclinic, C2/c, a=16.067(2), b=26.391(17), c=10.335(1)Å, [[beta]]=94.26(1)deg. , Z=4, V= 4370(3)Å3, Dm=1.16 gcm-3, R=0.070 for 2354 observed reflections. The molecule is in the 1,3 alternate conformation: two propionyloxyphenyls are up and two hydroxyphenyls are down. Two-fold symmetry axis is in the center of the molecule.
The molecular structures will be discussed with relation to NMR results and to molecular mechanics calculations.