Demetallatation of electrochemically polymerised Mn porphyrin anion / PEDOT composites under light-illumination

- Demetallation studies of electropolymerized PEDOT with low levels of an anionic Mn porphyrin monomer or Mn porphyrin polymer
- Demetallation under ambient light also occurs in these systems but to a lesser degree than with cationic dopants
- Demetallation appears to be an inherent feature of PEDOT with low levels of Mn porphyrins when illuminated with light

This work reports photo-demetallation studies of thin-layer, electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) loaded with low levels of: (i) an anionic Mn porphyrin monomer (5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato manganese(III) chloride (MnTPPS)), and (ii) an anionic Mn porphyrin polymer (poly(5-(4-vinylphenyl)-10,15,20-tris(4-sulfonatophenyl)) porphyrinato manganese(III) chloride (MnPVTPPS)). UV-vis and other measurements confirm that, like previously-studied cationic Mn(III) porphyrins embedded within vapour-phase polymerized PEDOT in low loadings, de-metallation under light illumination also occurs in these systems. However, it occurs to a significantly lesser degree. It can be concluded that demetallation appears to be an inherent feature of PEDOT coatings containing low levels of Mn porphyrins when they are illuminated with light. The demetallation process does not depend on the mode of polymerisation or the nature of the Mn porphyrin dopant. These findings have potentially important implications in water-splitting photocatalysis by Mn porphyrin-doped conducting polymers.