More than expected: Overall initiation efficiencies of mono-, bis-, and tetraacylgermane radical initiators

We introduce a quantitative comparison of the overall initiation efficiency for a library of eight mono-, bis-, and tetraacylgermane visible light photoinitiators with p-methoxy and fluorine substitution patterns. Specifically, cocktail experiments were carried out, fusing pulsed laser polymerization (PLP) of methyl methacrylate (MMA) with subsequent high-resolution electrospray mass spectrometry (ESI-MS) analysis. The overall initiation efficiency reflects all critical events leading to macromolecular growth, i.e., from light absorption and cleavage of the initiator to radical initiation. Importantly, we show that the obtained overall initiation efficiencies are self-consistent when going from lower to higher substituted systems, evidencing the validity of the derived overall initiation efficiencies within the error margins of the experiment. Remarkably, the comparison of mono-, bis-, and tetraacylgermanes reveals a nonstoichiometric increase of 40-90% in the overall initiation efficiency with increasing number of benzoyl moieties per initiator (size dependence), e.g., a maximum value of 7.6 ± 1.8 for tetrabenzoylgermane versus benzoyltrimethylgermane. In addition, the size dependence observed for acylgermanes scales with the nπ∗ extinction coefficients with the number of benzoyl moieties of the respective photoinitiator. Finally, with increasing system size of the acylgermanes, a more complex channel branching - as suggested from time-dependent density functional theory (TDDFT) calculations - results in substitution-dependent intersystem crossing (ISC) and cleavage quantum yields

Installing lactone chain termini during photoinduced polymerization

We exploit the Thorpe–Ingold effect as a spontaneous end group transformation method during photo-induced polymerization of methacrylates using the functional (2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone) species as radical photoinitiator. Herein, the isopropyl hydroxyl function endows the polymer with geminal methyl groups inducing an angular compression, enabling through close proximity a ring-closing reaction between the hydroxyl group and the ester motif

Cuerpo y blasfemia en Cataluña (siglos XV-XVIII)

The profanity was a social practice which enjoyed a strong vitality from a vast number of people in the cultural framework of the Old Regime Catalonia. Anthropomorphic profanity –verbal and gestural- focused to vilify God bodily organs, and so the rest of the christian pantheon of celestial figures, occupy a privileged position within the transgressive people’s vocabulary. Living expressions of popular religious sacredness that openly violates christian orthodoxy and that institutional catholic Church will proceed to devaluate until its complete disappearance in its strategic program of catholic moral discipline started in the late Middle Ages.<br><br>El lenguaje blasfemo era una práctica social que gozaba de una vigorosa vitalidad entre una ingente cantidad de personas en el marco cultural de la Cataluña del Antiguo Régimen. Las blasfemias antropomórficas —verbales y gestuales— dirigidas a vilipendiar los órganos corporales de Dios y del resto de las figuras celestiales del panteón cristiano ocupan un lugar privilegiado dentro del vocabulario transgresor del pueblo. Expresiones vivas de una sacralidad religiosa popular que vulnera abiertamente la ortodoxia cristiana y que la Iglesia institucional procederá a desvalorizar hasta llegar a su completa desaparición en su estratégico programa de disciplinamiento moral católico empezado a fines de la Edad Media