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

ESTIU, GUILLERMINA; FERRAUDI, GUILLERMO; LAPPIN, A GRAHAM; RUIZ, GUSTAVO T.; VERICAT, CAROLINA; COSTAMAGNA, JUAN; VILLAGRÁN, MANUEL

RSC Advances

Royal Society of Chemistry

Año: 2014 vol. 4 p. 53157 - 53171

2046-2069

The photochemical reactions of the Ni(II) annulene complex, [NiII([5,7,12,14]-tetra methyl dibenzo[2,3-b:2,3-b,i][1,4,8,11]tetraaza[14]annulenate)], grafted into a poly(isobutylene-alt-maleate) backbone wereinvestigated in aqueous media. The grafted Ni(II) complex becomes soluble in aqueous and organicsolvents where the strands form aggregates with medium-dependent shapes. Irradiation of the polymerat 532 or 351 nm produce charge-separated macrocyclic pendants, CS, with a lifetime s
30 ns. CSreacts with electron donors and acceptors before it decays with a lifetime s
1 ms. In parallel to thedecay of CS, an excited state-excited state annihilation process gives rise to luminescence whosespectrum spans wavelengths shorter than the wavelength of the irradiation, lex > 500 nm. Theoreticalcalculations were carried out with the aim of understanding the morphology and structures of strandaggregates, to confirm the nature of reaction products and to account for the spectroscopic andphotochemical properties of the Ni(II) pendants. The endothermic reduction of CO2 to CO by S(IV)species was used as a test of the Ni(II) complex´s ability to photocatalyze the reaction. In thephotoprocess, the Ni(II) complex fulfills the double role of antenna and catalyst.