Mixed-magnesium/zinc calix[4]arene complexes: structure, and ring opening polymerisation studies

Different combinations of organomagnesium reagents and zinc bromide react with either 1,3-dimethoxy-4-tert-butylcalix[4]areneH2 (L(OMe)2H2) or trialkoxycalix[4]arenes (L(OR)3H) (R = n-Pr, n-pentyl) to afford mixed-metal calix[4]arene systems. Intriguing molecular structures are formed and the systems are capable of the ring opening polymerisation of epsilon-caprolactone under N2, air, or as melts. Molecular structures of mixed magnesium/zinc calix[4]arene complexes are reported. Such systems are capable of the ring opening polymerization of epsilon-caprolactone affording mixtures of low and high molecular weight products with differing end groups.