LANTHANIDE PICRATE COMPLEXES AND PICRIC ACID ADDUCT OF A CALIX[4]ARENE DIAMIDE - SYNTHESES AND STRUCTURES OF [TM(LH(-2))A], [CE(LH(-2))(MEOH)(2)A]CENTER-DOT-HA, [PRLA(3)] AND L-CENTER-DOT-2HA (L=5,11,17,23-TETRA-TERT-BUTYL-25,27-BIS(DIETHYLCARBAMOYLMETHOXY)-26,28-DIHYDROXYCALIX[4]ARENE, HA=PICRIC ACID)

Reactions of 5,11,17,23-tetra-tert-butyl-25,27-bis(diethylcarbamoylmethoxy)-26,28-dihydroxycalix-[4]arene (L) with lanthanide picrates produced 1:1 metal-calixarene complexes incorporating one, two or three picrate moieties, depending on the reaction conditions and the lanthanide used. Dichloromethane solutions of L have been found to extract picric acid (HA) from aqueous solution, resulting in the formation of an L . 2HA adduct. Single crystal structure determinations have been carried out on [Tm(LH(-2))A]. 2.5CH(2)Cl(2), [Ce(LH(-2))(MeOH)(2)A]. HA . H2O, [PrLA(3)]. 2CH(2)Cl(2) . 1.5H(2)O and L . 2HA . EtOH. The possible variations of these formulae, depending on the charge distribution within the complexes. are discussed. The calixarene is found in a distorted cone conformation in each case. The intense colour of some of these complexes appears to correlate with the disposition of a picrate moiety close to a calixarene phenyl ring, consistent with calixarene-->picrate charge-transfer absorption. The UV/VIS spectroscopic studies suggest that at least some aspects of the solid-state structures are maintained in solution.