Mercaptothiazolinyl Functionalized Hexapodal and Tripodal Receptors on Benzene Platform: Formation of Silver Ion Assisted Hexanuclear Metallocage vs Metal–Organic Polymer

Mercaptothiazolinyl functionalized hexapodal (L1) and tripodal (L2) receptors on the benzene platform have been synthesized easily in good yields and structurally characterized by a single-crystal X-ray crystallographic study. In the solid state, L1 shows an orientation of six arms in 1,3,5 vs 2,4,6 facial steric gearing fashion, whereas L2 adopted C2v symmetry where two of its thiazolinyl arms are oriented in one direction and the third arm in the another direction. Two silver complexes of L1, 1 ([2(L1)·6(AgClO4)·2(CHCl3)·HClO4]) and 2 ([2(L1)·6(AgClO4)]), that are suitable for single-crystal X-ray studies are isolated upon the slow diffusion of a dimethylformamide solution of AgClO4 to the solution of L1 in chloroform and dichloromethane, respectively. Similarly, upon the slow diffusion of an acetonitrile solution of AgClO4 to the chloroform solution of L2, colorless crystals of the silver complex of L2, 3, are successfully isolated. The structural analyses of 1 and 2 show the formation of a silver ion assisted hexanuclear metallocage Ag6(L1)2 via dimeric assembly of L1 with multiple clefts and pockets toward guests binding. In 1, two chloroform molecules sit in top and bottom pockets, whereas six perchlorate counteranions are bound in six clefts between the silver ion pillared side arms of the metallocage. Though complex 2 shows the formation of a metallocage like 1, the single crystal structural analysis depicts perchlorate counteranions bonded to the silver atoms of the metallocage. On the contrary, the silver complex of tripodal receptor L2, 3, shows the formation of a metallo-organic polymeric network of L2 and Ag+. To the best of our knowledge, this work represents the first report on the formation of an M6L2 type metallosupramolecular cage topology with multiple clefts for guest binding by a semirigid hexapodal receptor.