Molecular cleft or tweezer compounds derived from trioxabicyclo[3.3.1]nonadiene diisocyanate and diacid dichloride

The structures of two derivatives of the bisdioxine Ski de fond - Enfant - Skis - Skate diisocyanate 1, the bisurea 4 and the biscarbamate 5, are established by X-ray crystallography and DFT calculations.These compounds possess endo,endo structures, in the case of the bisurea 4 with two nearly parallel pendant chains.The X-ray structures are reproduced very well by DFT calculations.Similar endo,endo conformations are calculated for the bisamide crown ether derivatives 7, where two proximate and nearly parallel crown ether units endow the molecules CIDER VIN with a claw-like molecular cleft or tweezer structure as evidenced by an enhanced ability to extract some alkali, alkaline earth and rare earth metal ions.