Syntheses and Crystal Structures of Dinuclear Complexes Containing d-Block and f-Block Luminophores. Sensitization of NIR Luminescence from Yb(III), Nd(III), and Er(III) Centers by Energy Transfer from Re(I)− and Pt(II)−Bipyrimidine Metal Centers

Abstract

Mononuclear complexes [Re(bpym)(CO)(3)Cl] and [Pt(bpym)(CC-C(6)H(4)CF(3))(2)] (bpym = 2,2'-bipyrimidine), in which one of the bipyrimidine sites is vacant, have been used as "complex ligands" to prepare heterodinuclear d-f complexes in which a lanthanide tris(1,3-diketonate) unit is attached to the secondary bipyrimidine site to evaluate the ability of d-block chromophores to act as antennae for causing sensitized near-infrared (NIR) luminescence from adjacent lanthanide(III) centers. The two sets of complexes so prepared are [Re(CO)(3)Cl(mu-bpym)Ln(fod)(3)] (abbreviated as Re-Ln; where Ln = Yb, Nd, Er) and [(F(3)C-C(6)H(4)-CC)(2)Pt(mu-bpym)Ln(hfac)(3)] (abbreviated as Pt-Ln; where Ln = Nd, Gd). Members of both series have been structurally characterized; the metal-metal separation across the bipyrimidine bridge is approximately 6.3 A in each case. In these complexes, the (3)MLCT (MLCT = metal to ligand charge-transfer) luminescences of the mononuclear [Re(bpym)(CO)(3)Cl] and [Pt(bpym)(CC-C(6)H(4)CF(3))(2)] complexes are quenched by energy transfer to those lanthanides (Ln = Yb, Nd, Er) that have low-lying f-f states capable of NIR luminescence; as a result, sensitized NIR luminescence is seen from the lanthanide center following excitation of the d-block unit. In the solid state, quenching of the luminescence from the d-block chromophore is complete, indicating efficient d --> f energy transfer, as a result of the short metal-metal separation across the bipyrimidine bridge. In a CH(2)Cl(2) solution, partial dissociation of the dinuclear complexes into the mononuclear units occurs, with the result that some (3)MLCT luminescence is observed from mononuclear [Re(bpym)(CO)(3)Cl] or [Pt(bpym)(CC-C(6)H(4)CF(3))(2)] present in the equilibrium mixture. Solution UV-vis and luminescence titrations, carried out by the addition of portions of Ln(fod)(3)(H(2)O)(2) or Ln(hfac)(3)(H(2)O)(2) to the d-block complex ligands, indicate that binding of the lanthanide tris(1,3-diketonate) unit at the secondary bipyrimidine site to give the d-f dinuclear complexes occurs with an association constant of ca. 10(5) M(-)(1).

Syntheses, Structures and Photophysical Properties of New Heterodinuclear Cd–Ln Coordination Complexes (Ln = Sm, Eu, Tb, Nd, Ho, Er)

“…So both of the two observed emissions at 1378 and 1513 nm are assigned to the 5 F 5 Ǟ 5 I 6 transition ( Figure 10). In some papers, Er III complexes usually only exhibit one emission band at about 1535 nm corresponding to the 4 I 13/2 Ǟ 4 I 15/2 transition, [1,41] whereas complex 6 exhibits two emission bands at 1343 and 1515 nm (λ Ex. = 985 nm) (Figure 11).…”

“…[1][2][3] Lanthanide ions can show linelike emission spectra with a narrow wavelength range and high color purity. In addition, the emission properties of this family of complexes are notable, and the emissions cover an exceptionally wide spectral range: near-infrared (Nd III .…”

Heterometallic CoIII–LnIII (Ln = Gd, Tb, Dy) Complexes on a p‐Sulfonatothiacalix[4]arene Platform Exhibiting Redox‐Switchable Metal‐to‐Metal Energy Transfer

“…Lanthanides with their well-defined energy levels provide high sensitivity to chemical environments due to the variety of energy exchange processes, [1] and d-f complexes are of particular importance from this point of view, as they can provide both efficient sensitizing [2][3][4][5] and quenching [6,7] of f luminescence. The main advantage of the use of d chromophores as an antenna or quencher for f luminescence is their kinetic and photochemical inertness.…”

“…The main advantage of the use of d chromophores as an antenna or quencher for f luminescence is their kinetic and photochemical inertness. [3] The redox properties of the d block of d-f complexes provide a prerequisite condition of redox switching of f luminescence. The redox switchable luminescence is of particular importance in the development of logic gates and signaling systems.…”

“…[8,9] Thus, it is interesting to use both the chromophore and redox properties of the d block to develop redox-switchable luminescent bimetallic d-f complexes on a p-sulfonatothiaca-TCAS favors binding of the inner-sphere lanthanide ions through the lower rim of TCAS, whereas noninclusive binding of Co III bis(histidinate) provides no effect on the binding of lanthanide ions. The emission properties of [Co(dipy) 3 lix [4]arene (TCAS) platform. The choice of TCAS as a platform for a heterometallic complex is conditioned by its versatile complexability, which has earned considerable attention during the last decades.…”