Design and synthesis of manganese porphyrins with tailored lipophilicity: Investigation of redox properties and superoxide dismutase activity
摘要:
Thirteen new manganese porphyrins and two porphodimethenes bearing one to three different substituents at the meso positions in a variety of architectures have been synthesized. The substituents employed generally are (i) electron-withdrawing to time the reduction potential to the desirable range (near +0.3 V vs NHE), and/or (ii) lipophilic to target the interior of lipid bilayer membranes and/or the blood-brain barrier. The influence of the substituents on the Mn-II /Mn-II reduction potentials has been characterized. and the superoxide disimutase activity of the compounds has been examined. (C) 2007 Elsevier Ltd. All rights reserved.
Investigations on the directive effects of a single meso-substituent via nitration of 5,12,13,17,18-pentasubstituted porphyrins: syntheses of conjugated β-nitroporphyrins
摘要:
Vilsmeier formylation of 5-substituted 1,9-diunsubstituted dipyrromethanes afforded 1,9-diformyldipyrromethanes in good yields. Their MacDonald condensation with tetra-beta -alkyldipyrromethanes produced 5,12,13,17,18-pentasubstituted porphyrins. A mesoelectron-donating group, presumably acting by destabilizing the porphyrin at, ground state, directs the nitrations to the mese-carbons. beta -Nitration takes place on porphyrins bearing a meso-electron-withdrawing group. Unhindered beta -nitro groups are shown to exert stronger electronic effects relative to meso-nitro groups by conjugating effectively with the porphyrin macrocycle. (C) 2001 Elsevier Science Ltd. All rights reserved.