Dimerization of monoporphyrinate lanthanide complexes [Yb(Por)(H(2)O)(3)]Cl, (Por = TTP(2-), TMPP(2-) and TPP(2-)) in the presence of sterically hindered tripodal ligand, zinc Schiff-base, dilute HCl, K(2)CO(3) solution, 4,4'-bipyridine (bipy), and basic 8-hydroxyquinaldine (HQ) solution was observed in CH(2)Cl(2) at room temperature. Six neutral dimeric lanthanide porphyrinate complexes, [Yb(TTP)(mu-OH)](2)(mu-THF) (1), [Yb(TMPP)(mu-OH)(H(2)O)](2) (2), [Yb(TPP)(mu-OH)(mu-H(2)O)](2) (4), [Yb(TMPP)(mu-Cl)(H(2)O)](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 H(2)O. 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.

The interaction of cationic lanthanide complexes [Ln(porp)(H 2 O) 3 ] ϩ (Ln = Er or Yb; porp = porphyrinate) with sodium (cyclopentadienyl)tris(diethylphosphito)cobaltate (NaL OEt ) gives the neutral 3d-4f bi-metallic porphyrinate complexes, [(L OEt )Ln(porp)]. X-Ray structural analyses reveal that these complexes are seven-coordinate with the three oxygen atoms of the O 3 -tripodal ligand, L OEt , coordinated to the lanthanide metal behaving as a 6-electron donor. Photophysical measurements show that the porphyrinate ligand behaves as a sensitizer by absorbing visible light to excite the Ln() metal ions, producing near-infrared emission.

N¢-bis-(3-methoxysalicylidene)ethylene-1,2-diamine). The structures of 2a,b and 3b-e have been determined by single-crystal X-ray diffraction studies. Structural differences between the complexes affect the photophysical properties, which have been studied in acetonitrile solutions.

The antibacterial effect of Yb3+, the free porphyrin base 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin (H2TMP; 1), and the corresponding Yb3+ porphyrinato complex [Yb(III)(TMP)(H2O)3]+ Cl- (Yb(TMP); 2) towards Staphylococcus aureus was investigated by stop-flow microcalorimetry. By analyzing the obtained metabolic thermogenic curves, crucial parameters such as rate constant of bacterial growth (k), half inhibitory concentration (IC50), and generation time (t(G)) were determined. The antibacterial activities of the three compounds tested was 2>1>Yb3+, with an IC50 value of 273 mg/l for complex 2. The Yb3+ porphyrinato complex is proposed to benefit from synergetic effects of Yb3+ and the free porphyrin 1.

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