Reactivity of aqua coordinated monoporphyrinate lanthanide complexes: Synthetic, structural and photoluminescent studies of lanthanide porphyrinate dimers

Dimerization of monoporphyrinate lanthanide complexes [Yb(Por)(H2O)3]Cl, (Por = TTP2-, TMPP2-and TPP2-) in the presence of sterically hindered tripodal ligand, zinc Schiff-base, dilute HCl, K2CO3solution, 4,4′-bipyridine (bipy), and basic 8-hydroxyquinaldine (HQ) solution was observed in CH2Cl2at room temperature. Six neutral dimeric lanthanide porphyrinate complexes, [Yb(TTP)(μ-OH)]2(μ-THF) (1), [Yb(TMPP)(μ-OH)(H2O)]2(2), [Yb(TPP)(μ-OH)(μ-H2O)]2(4), [Yb(TMPP)(μ-Cl) (H2O)]2(5), [Yb(TMPP)(μ-OH)]2(THF) (6) and [Yb(TPP)]2(μ-OH)(μ-Q) (7), were obtained. X-Ray diffraction studies showed that for the dimers, the two lanthanide ions were bridged by OH-, Cl-or H2O. Photoluminescent studies showed that the porphyrinate dianion acted as an antenna, transferred its absorbed visible energy to the lanthanide ion and enabled the latter emitting in the near-infrared (NIR) region. In general, the NIR emission is more intense for the dimers than for the monomers, and the NIR emission intensity decreases as the number of O-H oscillators present in the molecule increases.