Modelagem e síntese de éteres-coroa contendoo grupo sulfóxido e seus complexos com íonslantanídeos

by Silva Júnior, Lourinaldo da

The synthesis of new crown ethers containing sulfoxide groups in their structurewas persuade in this work, aiming the application as ligands for coordination withlanthanide ions.The structures of crown ethers and their complexes with Eu3+ were obtained withthe SMLC/AM1 method. The results for the complexation were favorable for thefollowing ligands: 2,3,11,12-dibenzo-1,4,10,13-tetraoxa-7,16-dithia-cyclooctadeca-2,11-diene-7,16- dioxide (dibenzo-18-crown-4-7,16-(SO)2) and 1,4,10,13-tetraoxa-7,16-dithia-cyclooctadecane-7,16-dioxide (18-crown-4-7,16-(SO)2. The coordination ofa third ligand, 2,4,12,14-dibenzo-1,5,11,15-tetraoxa-8,18-dithia-cycloeico-2, 12-diene-8,18-dioxide (dibenzo-20-crown-4-8,18-(SO)2) with Eu3+ was not favorable due tosterical hindrance.The methodologies of synthesis for these ligands were adapted from aproachesdescribed in the literature for similar systems, but these reaction conditions did notfavored for the formation of the desired crown ethers with sulfoxide groups. Only theproduct 2,3-benzo-1,4-dioxa-7-thia-ciclonona-2-ene-7-oxide (benzo-9-crown-2-7-(SO)),D, was obtained in approximately 10% yield and the confirmation of its structure stillneeds aditional experiments.The development of more specific methodologies for the preparation of thesenew compounds is necessary since the crown ether?s cavity size can be controlled byreaction conditions.Molecular modeling for the synthesized crown ether suggests that it can form acoordenate with Eu3+ leading to an hexacoordinated [Eu(D)2]3+ complex indicating apotential application for this new class of ligands