Design and synthesis of new cryptophanes with intermediate cavity sizes

The development of molecular imaging using hyperpolarized xenon MRI needs highly optimized biosensors. Cryptophane-111 and cryptophane-222 are promising candidates that show complementary encapsulation properties although they only differ by the length of the three alkane linkers joining two cyclotriphenolene units. Cryptophanes containing both methoxy and ethoxy linkers have never been synthesized. Here we synthesize two new cages with intermediate internal volumes, in two steps from cyclotriphenolene.