Hamigerols A and B, Unprecedented Polysulfate Sterol Dimers from the Mediterranean Sponge <i>Hamigera hamigera</i>

Two novel polysulfate sterol dimers, hamigerols A (1) and B (2), have been isolated from the Mediterranean sponge Hamigera hamigera. Their structures and stereochemistry have been assigned from the analysis of spectroscopic data

Hamigerols A and B, Unprecedented Polysulfate Sterol Dimers from the Mediterranean Sponge <i>Hamigera hamigera</i>

Two novel polysulfate sterol dimers, hamigerols A (1) and B (2), have been isolated from the Mediterranean sponge Hamigera hamigera. Their structures and stereochemistry have been assigned from the analysis of spectroscopic data

Seven New Microcystins Possessing Two l-Glutamic Acid Units, Isolated from <i>Anabaena</i> sp. Strain 186

Electrospray ionization mass spectrometry has been applied to the structure assignment of seven new microcystins (1−7), obtained from cultured Anabaena sp. strain 186. The seven new microcystins contain the dehydroalanine (Dha) or l-Ser unit instead of the N-methyldehydroalanine unit and the l-Glu and/or its δ-methyl ester [E(OMe)] units at the two variable l-amino acid units, and the structures were assigned as [Dha7]microcystin-E(OMe)E(OMe) (1), [d-Asp3,Dha7]microcystin-E(OMe)E(OMe) (2), [l-Ser7]microcystin-E(OMe)E(OMe) (3), [d-Asp3,l-Ser7]microcystin-E(OMe)E(OMe) (4), [Dha7]microcystin-EE(OMe) (5), [d-Asp3,Dha7]microcystin-EE(OMe) (6), and [l-Ser7]microcystin-EE(OMe) (7). These microcystins are the first examples containing dicarboxylic amino acids at the two variable l-amino acid units in microcystins

Local Li⁺ Framework Regulation of a Garnet-Type Solid-State Electrolyte

Garnet-type solid-state electrolytes Li7La3Zr2O12 (LLZO) for high-energy-density batteries have attracted extensive attention. However, stabilizing the high-conductive cubic phase and improving its ionic conductivity remain challenges of current research. Here, a Ca–W dual-substitution strategy has been designed, and the effect of doping on cubic phase formation and Li+ mobility has been investigated thoroughly. The results indicated that the partial substitution of Ca2+ at the La3+ site and W6+ at the Zr4+ site can effectively stabilize the cubic phase while reducing the endothermic enthalpy during the synthesis. Moreover, Ca–W dual substitution regulates the local Li+ framework by increasing Li+ occupancy at the 96h site, which can significantly lower the Li+ migration barrier and thus improve the ionic conductivity by two orders of magnitude. This work addresses the challenge of stabilizing a highly conductive cubic phase with low-energy consumption and represents a major breakthrough in understanding how to improve the ionic conductivity by regulating local structures

Synthesis and Characterization of the Platinum-Substituted Keggin Anion α‑H₂SiPt­W₁₁O₄₀^4–

Acidification of an aqueous solution of K₈SiW₁₁O₃₉ and K₂Pt­(OH)₆ to pH 4 followed by addition of excess tetramethylammonium (TMA) chloride yielded a solid mixture of TMA salts of H₂SiPt­W₁₁O₄₀^4– (<b>1</b>) and SiW₁₂O₄₀^4– (<b>2</b>). The former was separated from the latter by extraction into an aqueous solution and converted into tetra-<i>n</i>-butylammonium (TBA) and potassium salts <b>TBA-1</b> and <b>K-1</b>. The α-H₂SiPtW₁₁O₄₀^4– was identified as a monosubstituted Keggin anion using elemental analysis, IR spectroscopy, X-ray crystallography, electrospray ionization mass spectrometry, ¹⁹⁵Pt NMR spectroscopy, ¹⁸³W NMR spectroscopy, and ¹⁸³W–¹⁸³W 2D INADEQUATE NMR spectroscopy. Both <b>TBA-1</b> and <b>K-1</b> readily cocrystallized with their unsubstituted Keggin anion salts, <b>TBA-2</b> and <b>K-2</b>, respectively, providing an explanation for the historical difficulty of isolating certain platinum-substituted heteropolyanions in pure form