On the redox reactions of radicals with Al^III(phthalocyaninate) pendants covalently bonded to poly(ethyleneamide). Mechanistic alterations when radicals are formed inside pockets of micelle‐like polymer aggregates

Abstract

The mechanisms of the redox reactions between a polymer containing Al(III) sulfonated phthalocyanine pendants, (Al III ( b NHS(O 2 )trspc) 2À ) 2 , and radicals have been investigated in this work. Pulse radiolysis and photochemical methods were used for these studies. Oxidizing radicals, OH , HCO 3 , (CH 3 ) 2 COHCH 2 , and N 3 , as well as reducing radicals, e aq À , CO 2 À , and (CH 3 ) 2 C OH, respectively accept or donate one electron forming pendent phthalocyanine radicals, Al III ( b NH-S(O 2 )trspc ) À or 3À . The kinetics of the redox processes is consistent with a mechanism where the pendants react with radicals formed inside aggregates of five to six polymer strands. Electron donating radicals, that is, CO 2 À and (CH 3 ) 2 C OH, produce one-electron reduced phthalocyanine pendants that, even though they were stable under anaerobic conditions, donated charge to a Pt catalyst. While the polymer was regenerated in the Pt catalyzed processes, 2-propanol and CO 2 were respectively reduced to propane and CO. The reaction of SO 3 À radicals with the polymer stood in contrast with the reactions of the radicals mentioned above. A first step of the mechanism, the coordination of the SO 3 À radical to the Al(III), was subsequently followed by the formation of a SO 3 À phthalocyanine ligand adduct. The decay of the SO 3 À -phthalocyanine ligand adduct in a $10 2 ms time domain regenerates the polymer, and it was attributed to the dimerization/disproportionation of SO 3 À radicals escaping from the aggregates of polymer.

Photocatalytic reactions of a nickel(ii) annulene complex incorporated in polymeric structures

“…Formation of a water soluble polyelectrolyte where the annulene complexes are graed can impart upon the complex enhanced solubility in water. 2,[4][5][6] To this aim, two new compounds, poly(Ni II [tmdbzTAA]) n , formed when different proportions of the annulene complex, [Ni(tmdbzTAA)], tmdbTAA ¼ [5,7,12,14]-tetramethyldibenzo [2,3-b:2,3-b,i] [1, 4,8,11]tetraaza [14] annulenate 2À , were graed into a poly-(isobutylene-alt-maleic anhydride) backbone, Scheme 1 bottom. The large solubility in water of the nickel(II) complex, present now as pendants in the polycarboxylate backbone, allows to investigate previously inaccessible thermal, electrochemical and photochemical reactions of the graed nickel(II) complex in this medium.…”

Review: Properties and chemical reactivity of metallo phthalocyanine and tetramethylbenzoannulene complexes grafted into a polymer backbone

“…Pulse radiolytically generated SO 3 •-radicals react with either Al III (tspc) 3-and pendent Al III (└NHS(O 2 )trspc) 2-producing similar transient spectra [34]. In both cases, formation of the final product occurs in two steps with strikingly different reaction rates.…”

“…Because the stabilizing interactions are intrinsic to the pendent coordination complex so is the stability of the bundles. This is exemplified by the series of polymers poly(Mtspc) containing pendent phthalocyanines of the M = Al(III), Co(II), Ni(II) and Cu(II) ions [31,33,34] There are also examples where the morphology of the polymer (where complexes are to be grafted) remains in the final polymer containing the grafted complexes. The average structure of Rh III (pc) grafted into poly(acrylate) is shown in figure 1c [33].…”

“…Although the materials considered here are essentially cationic and anionic polyelectrolytes (figure 1) [31][32][33][34][35], a common phenomenon is the formation of bundles of multiple strands and diverse shapes in solution phase which stands against chemical intuition.…”

“…SO3 •-radicals that escape from the aggregate undergo disproportionation and/or dimerization with an overall rate constant 2k. The disappearance of the adduct will be kinetically of a second order with an integrated rate law, -d[ρ adduct ]/dt = (2k K /ρ pendant ) x [ρ adduct ] 2 , where ρ adduct and ρ pendant are, respectively, the molar densities of adducts and pendants in the aggregate[34].…”