We report two nonanuclear lanthanide complexes, [Ln9(μ4-O)(μ3-OH)8(LH)4(OAc)4(H2O)12]·5ClO4·24H2O (Ln = Gd, 1; Dy, 2), where LH2– is the doubly deprotonated chiral ligand Chromogen I (2-acetamido-2,3-dideoxy-D-erythro-hex-2-enofuranose), one of the many products from the dehydration of N-acetyl-D-glucosamine (GlcNAc). Mass spectroscopic studies established the solution stability of these clusters. Through hydrogen bonding, the cluster complex self-organizes into a nanostructured 54-metal cagelike assembly featuring six of its units occupying the vertices of an octahedron. Free Chromogen I can be obtained in pure form and high yield by a straightforward workup of the cluster complex. This is the first report of dehydrating GlcNAc without the need of a catalyst or forcing conditions.

Acetonitrile bound to and activated by the Lewis acidic [Re6(μ3-Se)8]2+ cluster core was transformed into acetamidine in quantitative yield using NH3 as the nucleophile at room temperature. The amidine ligand was removed by treating the cluster–acetamidine complexes with trifluoroacetic acid in CH3CN, affording amidinium trifluoroacetate and the starting acetonitrile complexes.

A lanthanide metal–organic framework (MOF) compound of the formulation [Eu2(CO3)(ox)2(H2O)2]·4H2O (1, ox = oxalate) was prepared by hydrothermal synthesis with its structure determined crystallographically. Temperature-dependent but humidity-independent high proton conduction was observed with a maximum of 2.08 × 10–3 S cm–1 achieved at 150 °C, well above the normal boiling point of water. Results from detailed structural analyses, comparative measurements of conductivities using regular and deuterated samples, anisotropic conductivity measurements using a single-crystal sample, and variable-temperature photoluminescence studies collectively establish that the protons furnished by the Eu(III)-bound and activated aqua ligands are the charge carriers and that the transport of proton is mediated along the crystallographic a-axis by ordered hydrogen-bonded arrays involving both aqua ligands and adjacent oxalate groups in the channels of the open framework. Proton conduction was enhanced with the increase of temperature from room temperature to about 150 °C, which can be rationalized in terms of thermal activation of the aqua ligands and the facilitated transport between aqua and adjacent oxalate ligands. A complete thermal loss of the aqua ligands occurred at about 160 °C, resulting in the disintegration of the hydrogen-bonded pathway for proton transport and a precipitous drop in conductivity. However, the structural integrity of the MOF was maintained up to 350 °C, and upon rehydration, the original structure with the hydrogen-bonded arrays was restored, and so was its high proton-conduction ability.

Isostructural lanthanide metal–organic frameworks (MOFs) are synthesized through the spontaneous self-assembly of H3BTPCA (1,1′,1″-(benzene-1,3,5-triyl)tripiperidine-4-carboxylic acid) ligands and lanthanide ions (we term these MOFs Ln-BTPCA, Ln = La3+, Tb3+, Sm3+, etc.). Prompted by the observation that the different lanthanide ions have identical coordination environment in these MOFs, we explored and succeeded in the preparation of mixed-lanthanide analogues of the single-lanthanide MOFs by way of in situ doping using a mixture of lanthanide salts. With careful adjustment of the relative concentration of the lanthanide ions, the color of the luminescence can be modulated, and white light-emission can indeed be achieved. The mechanisms possibly responsible for the observed photophysical properties of these mixed-lanthanide MOFs are also discussed.

A series of novel lanthanide metal–organic frameworks were synthesized using a ligand featuring three carboxylate groups stationed on a triazinyl central motif. The readily accessible multiple Lewis basic triazinyl N atoms allow for complexation of incoming metal ions. Such interactions have been established quantitatively.