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, K2CO3 solution, 4,4'-bipyridine (bipy), and basic 8-hydroxyquinaldine (HQ) solution was observed in CH2Cl2 at room temperature. Six neutral dimeric lanthanide porphyrinate complexes, [Yb(TTP)(mu-OH)](2)(mu-THF) (1), [Yb(TMPP) (mu-OH) (H2O)](2) (2), [Yb(TPP) (mu-OH) (mu-H2O)](2) (4), [Yb(TMPP) (mu-Cl) (H2O)](2) (5), [Yb(TMPP) (mu-OH)](2)(THF) (6) and [Yb(TPP)](2)(mu-OH) (mu-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.