1,10-Dimethyl-1,4,7,10,13,16-hexaazacyclooctadecane L and 1,4,7- Trimethyl-1,4,7,10,13,16,19-heptaazacyclohenicosane L1: Two New Macrocyclic Receptors for ATP Biding. Synthesis, Solution Equilibria and the Crystal Structure of (H4L)(C