[Cu32(H)20{S2P(OiPr)2}12]: The Largest Number of Hydrides Recorded in a Molecular Nanocluster by Neutron Diffraction

An air‐ and moisture‐stable nanoscale polyhydrido copper cluster [Cu₃₂(H)₂₀{S₂P(OiPr)₂}₁₂] ( 1_H ) was synthesized and structurally characterized. The molecular structure of 1_H exhibits a hexacapped pseudo‐rhombohedral core of 14 Cu atoms sandwiched between two nestlike triangular cupola fragments of (2×9) Cu atoms in an elongated triangular gyrobicupola polyhedron. The discrete Cu₃₂ cluster is stabilized by 12 dithiophosphate ligands and a record number of 20 hydride ligands, which were found by high‐resolution neutron diffraction to exhibit tri‐, tetra‐, and pentacoordinated hydrides in capping and interstitial modes. This result was further supported by a density functional theory investigation on the simplified model [Cu₃₂(H)₂₀(S₂PH₂)₁₂].     

Polyethyleneimine Immobilized on Silica Endcapped with Octadecyl Groups as a Stationary Phase for RP-LC

A new reversed stationary phase was prepared, based on thermal immobilization of trimethoxysilylpropyl modified polyethyleneimine onto silica particles endcapped with octadecyl molecules. The physicochemical and morphological properties of the stationary phase were characterized by solid state cross-polarization and magic angle spinning ²⁹Si nuclear magnetic resonance, infrared spectroscopy, porosimetry, and elemental analysis. For the studies on reversed phase high-performance liquid chromatography (HPLC) retention, separation of the established Tanaka and Engelhardt test mixtures was performed. The stationary phase showed a typical partition mechanism for the reversed phase; however, the low hydrophobicity required a low organic content solvent in the mobile phase for chromatographic separation of more hydrophobic compounds. The stationary phase also showed low residual silanol activity for the elution of basic compounds due to the protection offered by octadecyl endcapped molecules and the competition provided by the imine groups of the polymeric layer. The proposed stationary phase possesses interesting selectivity and is convenient for applications requiring the separation of more retentive compounds in conventional HPLC columns using more aqueous mobile phases.     

Helichrysum gymnocephalum essential oil: chemical composition and cytotoxic, antimalarial and antioxidant activities, attribution of the activity origin by correlations

Helichrysum gymnocephalum essential oil (EO) was prepared by hydrodistillation of its leaves and characterized by GC-MS and quantified by GC-FID. Twenty three compounds were identified. 1,8-Cineole (47.4%), bicyclosesquiphellandrene (5.6%), γ-curcumene (5.6%), α-amorphene (5.1%) and bicyclogermacrene (5%) were the main components. Our results confirmed the important chemical variability of H. gymnocephalum. The essential oil was tested in vitro for cytotoxic (on human breast cancer cells MCF-7), antimalarial (Plasmodium falciparum: FcB1-Columbia strain, chloroquine-resistant) and antioxidant (ABTS and DPPH assays) activities. H. gymnocephalum EO was found to be active against MCF-7 cells, with an IC(50) of 16 ± 2 mg/L. The essential oil was active against P. falciparum (IC(50) = 25 ± 1 mg/L). However, the essential oil exhibited a poor antioxidant activity in the DPPH (IC(50) value > 1,000 mg/L) and ABTS (IC(50) value = 1,487.67 ± 47.70 mg/L) assays. We have reviewed the existing results on the anticancer activity of essential oils on MCF-7 cell line and on their antiplasmodial activity against the P. falciparum. The aim was to establish correlations between the identified compounds and their biological activities (antiplasmodial and anticancer). β-Selinene (R2 = 0.76), α-terpinolene (R2 = 0.88) and aromadendrene (R2 = 0.90) presented a higher relationship with the anti-cancer activity. However, only calamenene (R2 = 0.70) showed a significant correlation for the antiplasmodial activity.     

Crystallization and characterization of an inflammatory lectin purified from the seeds of Dioclea wilsonii

DwL, a lectin extracted from the seeds of Dioclea wilsonii, is a metalloprotein with strong agglutinating activity against rabbit and ABO erythrocytes, inhibited by glucose and mannose. DwL was purified by affinity chromatography on a Sephadex G-50 column and ion exchange chromatography on a HiTrap SP XL column. SDS-PAGE revealed three electrophoretic bands corresponding to the α (25,634 ± 2 Da), β (12,873 ± 2 Da) and γ (12,779 ± 2 Da) chains. Protein sequencing was done by Tandem Mass Spectrometry. The primary sequence featured 237 amino acids and was highly homologous to other reported Diocleinae lectins. A complete X-ray dataset was collected at 2.0 ? for X-Man-complexed DWL crystals produced by the vapor diffusion method. The crystals were orthorhombic and belonged to the space group I222, with the unit-cell parameters a = 59.6, b = 67.9 and c = 109.0 ?. DWL differed in potency from other ConA-like lectins and was found to induce neutrophil migration in rats, making it particularly useful in structural/functional studies of this class of proteins.     

Synthesis of glyoxylyl peptides using a phosphine labile α,α′-diaminoacetic acid derivative

We describe in this letter the preparation of a novel protected α,α′-diaminoacetic acid derivative that acts as a masked glyoxylic acid equivalent. The reagent could easily be introduced on a peptide chain using standard Fmoc/tert-butyl solid-phase methods and resisted to the TFA treatment allowing the deprotection and cleavage of the peptide. Unmasking of the glyoxylyl group was performed in solution in the presence of a phosphine.     

Thermal behavior and X-ray study of the new double salt hydrate SrCd2Cl6 · 8H2O

The double salt hydrate SrCd₂Cl₆?·?8H₂O undergoes a phase transition at T?=?318?K (phase I?–?(T?=?318)?→phase II). The structural characteristics, Raman scattering and dielectric measurements have been investigated. Phase II exhibits monoclinic symmetry (a?=?17.102(6), b?=?21.716(9), c?=?8.582(5)?Å and β?=?91.58(13)°).     

Synthesis of Bimetallic Copper‐Rich Nanoclusters Encapsulating a Linear Palladium Dihydride Unit

The structurally precise Cu‐rich hydride nanoclusters [PdCu₁₄H₂(dtc/dtp)₆(C≡CPh)₆] (dtc: di‐butyldithiocarbamate ( 1 ); dtp: di‐isopropyl dithiophosphate ( 2 )) were synthesized from the reaction of polyhydrido copper clusters [Cu₂₈H₁₅(S₂CNⁿBu₂)₁₂]⁺ or [Cu₂₀H₁₁{S₂P(OⁱPr)₂}₉] with phenyl acetylene in the presence of Pd(PPh₃)₂Cl₂. Their structures and compositions were determined by single‐crystal X‐ray diffraction and the results supported by ESI‐mass spectrometry. Hydride positions in 1 were confirmed by single‐crystal neutron diffraction. Each hydride is connected to one Pd⁰ and four Cu^I atoms in slightly distorted trigonalbipyramidal geometry. The anatomies of clusters 1 and 2 are very similar and DFT calculations allow rationalizing the interactions between the encapsulated [PdH₂]^2? unit and its Cu₁₄ bicapped icosahedral cage. As a result, Pd has the highest coordination number (14) so far recorded.