A study of nerve agent model organophosphonate binding with manganese-A(2)B-corrole and -A(2)B(2)-porphyrin systems

Abstract

Herein the synthesis and binding studies of novel trans-A(2)B-corrole and trans-A(2)B(2)-porphyrin derivatives are presented in comparing manganese(III)-organophosphonate (OP) binding (e.g., Mn+ <- O=PR(OR)(2)) capabilities. H-3(PFP-VC) [PFP-VC = 5,15-di(pentafluorophenyl)-10-(3-vinylphenyl)corrolate] was synthesized by way of literature procedures and was characterized by a variety of 2-D NMR spectroscopic techniques and single-crystal X-ray diffraction. These compounds represent the first example of 3-vinyl-phenyl-containing meso-substituted corroles or porphyrins. Mn(PFP-VC) (3) was treated separately with (CH3CH2O)(2)P=O(C3H6NMe2), (C4H9O)(2)P=O(Me), (C2H5O)(2)P=O(CH2COCH3), (CH3CH2O)(2)P=O(Me), to give 1:1 adducts, as determined by UV-Vis spectroscopy (Job Plot), giving a red shift: Ph3P=O, was also found to bind, but very weakly. The trans-A(2)B(2)-porphyrin analogue Mn(PFP-VP) (4) was also prepared by way of a literature procedure: related binding studies gave 1: 1 organophosphonate-Mn(PFP-VP) adducts (Job Plot). A clean blue shift occurred for the Mn-porphyrins at higher organophosphonate loadings (K-a values: 6.7 (0.9)-11.9 (0.4) M-1). DFT geometry optimizations of O=P(OMe)(2)Me binding and formal Mn-O or P-O cleavage products in the unsubstituted neutral Mn-corrolato and -porphyrinato systems with a range of metal-based spin states revealed greatest stability in formal phosphoryl oxygen binding (energies: 11-13 kcal/mol) for the Mn-corrole (singlet); the Mn-porphyrin (sextet) was also quite stable. (C) 2009 Elsevier Ltd. All rights reserved.