Bismesitoylphosphinic Acid (BAPO-OH): A Ligand for Copper Complexes and Four-Electron Photoreductant for the Preparation of Copper Nanomaterials.

Bismesitoylphosphinic acid, (HO)PO(COMes)2 (BAPO-OH), is an efficient photoinitiator for free-radical polymerizations of olefins in aqueous phase. Described here are the structures of various copper(II) and copper(I) complexes with BAPO-OH as the ligand. The complex CuII (BAPO-O)2 (H2 O)2 is photoactive, and under irradiation with UV light in aqueous phase, it serves as a source of metallic copper in high purity and yield (>80 %). Simultaneously, the radical polymerization of acrylates can be initiated and allows the preparation of nanoparticle/polymer nanocomposites in which the metallic Cu nanoparticles are protected against oxidation. The determination of the stoichiometry of the photoreductions suggests an almost quantitative conversion from CuII into Cu0 with half an equivalent of BAPO-OH, which serves as a four-electron photoreductant.

Cell-penetrating and neurotargeting dendritic siRNA nanostructures.

We report the development of dendritic siRNA nanostructures that are able to penetrate even difficult to transfect cells such as neurons with the help of a special receptor ligand. The nanoparticles elicit strong siRNA responses, despite the dendritic structure. An siRNA dendrimer directed against the crucial rabies virus (RABV) nucleoprotein (N protein) and phosphoprotein (P protein) allowed the suppression of the virus titer in neurons below the detection limit. The cell-penetrating siRNA dendrimers, which were assembled using click chemistry, open up new avenues toward finding novel molecules able to cure this deadly disease.

Beyond absorption maxima: the impact of wavelength-resolved photochemistry on materials science.

Reflecting on Giacomo Ciamician's revolutionary vision of harnessing sunlight to drive photochemical transformations, the field of materials science has evolved significantly, yet it has been constrained by the misconception that the highest reactivity in photochemical systems is achieved at the absorption maxima. Here, we explore this notion further with evidence from photochemical action plots, demonstrating that reactivity can indeed be maximal at wavelengths significantly separated from the absorption peak. By examining the implications of the disparity between absorptivity and photochemical reactivitiy, we explore its impact for the enhanced penetration depth of light in photoresists, the reduction of energy requirements for photochemical reactions, and its transformative potential for volumetric 3D printing. Ultimately, we argue for a renewed appreciation of light's capability to facilitate photochemical reactions across the entire volume of a material.

Bisacylphosphane oxides as photo-latent cytotoxic agents and potential photo-latent anticancer drugs.

Bisacylphosphane oxides (BAPOs) are established as photoinitiators for industrial applications. Light irradiation leads to their photolysis, producing radicals. Radical species induce oxidative stress in cells and may cause cell death. Hence, BAPOs may be suitable as photolatent cytotoxic agents, but such applications have not been investigated yet. Herein, we describe for the first time a potential use of BAPOs as drugs for photolatent therapy. We show that treatment of the breast cancer cell lines MCF-7 and MDA-MB-231 and of breast epithelial cells MCF-10A with BAPOs and UV irradiation induces apoptosis. Cells just subjected to BAPOs or UV irradiation alone are not affected. The induction of apoptosis depend on the BAPO and the irradiation dose. We proved that radicals are the active species since cells are rescued by an antioxidant. Finally, an optimized BAPO-derivative was designed which enters the cells more efficiently and thus leads to stronger effects at lower doses.

From the parent phosphinidene-carbene adduct NHC = PH to cationic P4-rings and P2-cycloaddition products.

Reactions of the parent phosphinidene-carbene adduct (Dipp)NHC = PH with chlorophosphanes are reported herein. The obtained (Dipp)NHC-substituted chlorodiphosphanes, (Dipp)NHC = P-PClR, and the formation of their cationic derivatives, [(Dipp)NHC-P = PR](+), were also explored. Depending on the steric demand of their substituents, these cations were found to be monomeric [(Dipp)NHC-PP-N(i)Pr2][GaCl4] or to dimerise to cyclotetraphosphanes [(Dipp)NHC-PP-R]2[GaCl4]2 (R = Ph, NMe2). For R = NMe2, this dication is the first isolated example of a tetrasubstituted all-σ(3) cyclotetraphosphane. Finally, the hetero-Diels-Alder reactivity of these cations was studied with 2,3-dimethylbuta-1,3-diene and cyclopentadiene, resulting in the isolation of a number of cationic 1,2-diphosphinanes.

Atmospheric pressure chemical ionization of explosives induced by soft X-radiation in ion mobility spectrometry: mass spectrometric investigation of the ionization reactions of drift gasses, dopants and alkyl nitrates.

A promising replacement for the radioactive sources commonly encountered in ion mobility spectrometers is a miniaturized, energy-efficient photoionization source that produce the reactant ions via soft X-radiation (2.8 keV). In order to successfully apply the photoionization source, it is imperative to know the spectrum of reactant ions and the subsequent ionization reactions leading to the detection of analytes. To that end, an ionization chamber based on the photoionization source that reproduces the ionization processes in the ion mobility spectrometer and facilitates efficient transfer of the product ions into a mass spectrometer was developed. Photoionization of pure gasses and gas mixtures containing air, N2 , CO2 and N2 O and the dopant CH2 Cl2 is discussed. The main product ions of photoionization are identified and compared with the spectrum of reactant ions formed by radioactive and corona discharge sources on the basis of literature data. The results suggest that photoionization by soft X-radiation in the negative mode is more selective than the other sources. In air, adduct ions of O2- with H2 O and CO2 were exclusively detected. Traces of CO2 impact the formation of adduct ions of O2- and Cl- (upon addition of dopant) and are capable of suppressing them almost completely at high CO2 concentrations. Additionally, the ionization products of four alkyl nitrates (ethylene glycol dinitrate, nitroglycerin, erythritol tetranitrate and pentaerythritol tetranitrate) formed by atmospheric pressure chemical ionization induced by X-ray photoionization in different gasses (air, N2 and N2 O) and dopants (CH2 Cl2 , C2 H5 Br and CH3 I) are investigated. The experimental studies are complemented by density functional theory calculations of the most important adduct ions of the alkyl nitrates (M) used for their spectrometric identification. In addition to the adduct ions [M + NO3 ]- and [M + Cl]- , adduct ions such as [M + N2 O2 ]- , [M + Br]- and [M + I]- were detected, and their gas-phase structures and energetics are investigated by density functional theory calculations. Copyright © 2016 John Wiley & Sons, Ltd.