Erbium hydroxide ethanedisulfonate: a cationic layered material with organic anion exchange capability.

We describe a cationic erbium-based material [Er12(OH)29(H2O)5][O3SCH2CH2SO3]3.5·5H2O. As synthesized, the material is water stable and capable of complete organic anion exchange for a variety of α,ω-alkanedicarboxylates. We chose these anions as initial examples of exchange and as an analog for pharmaceutical waste, some of which have a carboxylate functionality at neutral pH range. Free-floating and partially anchored organosulfonate anions reside between the cationic corrugated layers and allow for exchange. The structure also displays a reversible hydration event above 100 °C. Both the as-synthesized and the exchanged materials are characterized by a variety of analytical techniques.

Revisiting N-to-O acyl shift for synthesis of natural product-like cyclic depsipeptides.

Despite the prevalence of head-to-side chain threonine linkages in natural products, their incorporation has been underexplored in synthetic cyclic peptides. Herein we investigate a cyclic peptide scaffold able to undergo an N-O acyl rearrangement. Upon acylation of the amine with diverse carboxylic acids, the resulting cyclic depsipeptides displayed favorable cellular permeability and a conformation similar to the parent peptide. The rearrangement was found to be scaffold and conformation dependent as evidenced by molecular dynamics experiments.

Intraparticle donor-acceptor dyads prepared using conjugated metal-ligand linkages.

Ruthenium nanoparticles were stabilized by the self-assembly of 1-decyne forming ruthenium-vinylidene interfacial bonds and further functionalized by metathesis reactions with 4-ethynyl-N,N-diphenylaniline (EDPA) and 9-vinylanthracene (VAN). Photoluminescence studies of the resulting bifunctionalized Ru(EDPA/VAN) nanoparticles showed that as both ligands were bound onto the nanoparticle surface, effective mixing of the π electrons occurred leading to the appearance of excitation and emission profiles that were completely different from those of ruthenium nanoparticles functionalized with only EDPA or VAN. Furthermore, in photoelectrochemical studies, the EDPA moieties exhibited a pair of well-defined voltammetric peaks in the dark, which were ascribed to the redox reaction involving the formation of cationic radicals; however under UV photoirradiation the voltammetric features diminished markedly. These results strongly suggest that the particle-bound EDPA and VAN moieties behaved analogously to those of conventional molecular dyads based on the same electron-donating and -accepting units, where the intraparticle charge transfer was facilitated by the conjugated metal-ligand interfacial bonds.

Solvothermal synthesis and characterization of two inorganic-organic hybrid materials based on barium.

Two metal-organic frameworks containing barium were synthesized hydrothermally and investigated for their catalytic properties. Ba(2)F(2)[O(3)SC(2)H(4)SO(3)] has barium fluoride layers linked by organic 1,2-ethanedisulfonate molecules. Ba[O(3)SC(2)H(4)SO(3)] has discrete barium centers arranged in layers and connected covalently by ethanedisulfonate bridges. Thermogravimetric analysis showed that Ba(2)F(2)[O(3)SC(2)H(4)SO(3)] is stable to ca. 325 °C and Ba[O(3)SC(2)H(4)SO(3)] to ca. 375 °C. These materials expand the metal-organic frameworks available for group II metals bound to organodisulfonate linkers and are potentially useful for a range of heterogeneous acid catalysis reactions.