A calixarene dendron with surface congestion at the first generation

The X-ray structure of a dendrimeric receptor based on calixarenes showed a packed periphery in the first generation. The presence of urea groups as linkers between the calix[4]arene core and the calix[6]arene dendrons makes it a good model as an endo-receptor which is able to coordinate squarate dianions with a high association constant.