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

Dimerization of monoporphyrinate lanthanide complexes [Yb(Por)(H ₂O)₃]Cl, (Por = TTP²-, TMPP^2- and TPP^2-) 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)(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.