Nonprotecting Group Synthesis of a Phospholipase C Activatable Probe with an Azo-Free Quencher

The near-infrared fluorescent activatable smart probe Pyro-phosphatidylethanolamine (PtdEtn)-QSY was synthesized and observed to selectively fluoresce in the presence of phosphatidylcholine-specific phospholipase C (PC-PLC). PC-PLC is an important biological target as it is known to be upregulated in a variety of cancers, including triple negative breast cancer. Pyro-PtdEtn-QSY features a QSY21 quenching moiety instead of the Black Hole Quencher-3 (BHQ-3) used previously because the latter contains an azo bond, which could lead to biological instability

Formation and Characterization of Homoleptic Thorium Isocyanide Complexes

Homoleptic thorium isocyanide complexes have been prepared via the reactions of laser-ablated thorium atoms and (CN)₂ in a cryogenic matrix, and the structures of the products were characterized by infrared spectroscopy and theoretical calculations. Thorium atoms reacted with (CN)₂ under UV irradiation to form the oxidative addition product Th­(NC)₂, which was calculated to have closed-shell singlet ground state with a bent geometry. Further reaction of Th­(NC)₂ and (CN)₂ resulted in the formation of Th­(NC)₄, a molecule with a tetrahedral geometry. Minor products such as ThNC and Th­(NC)₃ were produced upon association reactions of CN with Th and Th­(NC)₂. Homoleptic thorium cyanide isomers Th­(CN)_<i>x</i> (<i>x</i> = 1–4) are predicted to be less stable than the corresponding isocyanides. The C–N stretches of thorium cyanides were calculated to be between 2170 and 2230 cm^–1 at the B3LYP level, more than 120 cm^–1 higher than the N–C stretches of isocyanides and with much weaker intensities. No experimental absorptions appeared where Th­(CN)_<i>x</i> should be observed

Tungsten-Mediated Selective Ring Opening of Vinylcyclopropanes

The complexes TpW­(NO)­(PMe₃)­(L), where L = 2<i>H</i>-phenol, 2<i>H</i>-<i>p</i>-cresol, 2<i>H</i>-5,6,7,8-tetrahydro-2-naphthol, 2<i>H</i>-<i><i>N,N</i>-</i>dimethylanilinium were cyclopropanated using Simmons–Smith conditions. Cyclopropanated derivatives of 2<i>H</i>-<i>N,N</i>-dimethylanilinium were selectively ring-opened with HOTf/MeCN to form allylic species, which could be coupled with various nucleophiles. The nucleophilic addition occurs <i>anti</i> to the metal fragment, as determined by X-ray crystallography. Moreover, the cyclopropane ring opening occurs regioselectively, owing to the stabilization of the allylic cation by the metal fragment. The resulting ligands can, in some cases, be removed from the metal by oxidative decomplexation using ceric ammonium nitrate (CAN)

Tungsten-Mediated Selective Ring Opening of Vinylcyclopropanes

The complexes TpW­(NO)­(PMe₃)­(L), where L = 2<i>H</i>-phenol, 2<i>H</i>-<i>p</i>-cresol, 2<i>H</i>-5,6,7,8-tetrahydro-2-naphthol, 2<i>H</i>-<i><i>N,N</i>-</i>dimethylanilinium were cyclopropanated using Simmons–Smith conditions. Cyclopropanated derivatives of 2<i>H</i>-<i>N,N</i>-dimethylanilinium were selectively ring-opened with HOTf/MeCN to form allylic species, which could be coupled with various nucleophiles. The nucleophilic addition occurs <i>anti</i> to the metal fragment, as determined by X-ray crystallography. Moreover, the cyclopropane ring opening occurs regioselectively, owing to the stabilization of the allylic cation by the metal fragment. The resulting ligands can, in some cases, be removed from the metal by oxidative decomplexation using ceric ammonium nitrate (CAN)