Cyclometalated Iridium(III) Complexes Incorporating Aromatic Phosphonate Ligands: Syntheses, Structures, and Tunable Optical Properties.

The incorporation of phosphonate ligands into the cyclometalated iridium(III) complexes can not only tune their electronic and optical properties but also provide the possibility of anchoring these molecules on the semiconductor surfaces for further applications. Herein, we report the first examples of mononuclear cyclometallated iridium(III) complexes incorporating phosphonate ligands, namely, [Ir(ppy)2(HL1)]·0.5H2O (1), [Ir(ppy)2(HL2)]·0.5H2O (2), [Ir(dfppy)2(HL1)] (3), and [Ir(dfppy)2(HL2)]·3.5H2O (4) (ppy = 2-phenylpyridine, dfppy = 2-(2,4-difluorophenyl)pyridine, H2L1 = 2-pyridylphosphonic acid, H2L2 = 2-quinolinephosphonic acid). Luminescent spectra are studied both in solution and in the solid state, and significantly red-shifted broad emission bands are observed in complexes 2 and 4. The experimental and density functional theory (DFT) time-dependent-DFT calculation results indicate that the expansion of the aromatic conjugation length in the ancillary phosphonate ligands decreases the lowest unoccupied molecular orbital energy levels of the systems, originating from the triplet state associated with the ancillary ligand such as 3MLCT, 3LC, and 3LLCT charge-transfer transitions.

Polymorphic layered copper phosphonates: exfoliation and proton conductivity studies.

Three polymorphic copper carboxylate-phosphonates are reported, namely, α-Cu(4-cnappH)(H2O) (α-Cu-1), α-Cu(4-cnappH)(H2O)·0.5H2O (α-Cu-2) and ß-Cu(4-cnappH)(H2O) (ß-Cu), where 4-cnappH3 is (4-carboxynaphthalen-1-yl)phosphonic acid. All show layer structures but with different layer topologies. The layer topologies of the α-phases are similar, where the distorted {CuO4} planes and {PO3C} tetrahedra are corner-shared forming an inorganic layer containing 8- and 16-member rings. In ß-Cu, double chains made up of corner-sharing {CuO5} and {PO3C} are crossed-linked through edge-sharing of the {CuO5} square pyramids to form an inorganic layer containing 4- and 8-member rings. The uncoordinated carboxylate groups are protonated and are involved in the interlayer hydrogen bonds in all cases. Antiferromagnetic interactions are dominant in all cases. Compounds α-Cu-1, α-Cu-2 and ß-Cu can be exfoliated in THF resulting in 2D nanosheets of mainly two-layer thickness. Proton conductivity measurements reveal that the proton conduction is more favorable in α-Cu-2 than in α-Cu-1, but exfoliation into nanosheets decreases the conductivity.

Lanthanide anthracene complexes: slow magnetic relaxation and luminescence in DyIII, ErIII and YbIII based materials.

Four mononuclear lanthanide complexes, [Ln(depma)2(H2O)6]Cl3·xH2O·yCH3OH [Ln = Dy (1Dy), x = 6, y = 0; Gd (2Gd), x = 3, y = 1; Er (3Er), x = 6, y = 0; Yb (4Yb), x = 3, y = 1; depma = 9-diethylphosphono-methylanthracene], are reported and structurally characterized. The octa-coordinated environment of LnIII is composed of two oxygen atoms from two different depma ligands and six oxygen atoms from each bound water molecule. All four complexes show photoluminescence in the solid state at room temperature, originating from the ligand-centered emissions of depma. Furthermore, slow magnetization relaxation is found in 1Dy, 3Er and 4Yb with the energy barriers (Ueff) of 40.5 K (1 kOe), 9.8 K (1 kOe) and 28.9 K (0.75 kOe), respectively.