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Methylene blue (MB) is a well-established and extensively studied photosensitizer for photodynamic therapy (PDT), since it can generate singlet oxygen with a high quantum yield upon irradiation within the phototherapeutic (600–950 nm) window. However, its activity can decrease due to the formation of dimers or higher aggregates, which can take place in an aqueous solution at relatively high concentrations. The incorporation of this molecule into a matrix can avoid this aggregation and increase its activity relative to PDT. Silica porous nanoparticles are chosen here as a matrix to host MB. The size and pore geometry are tuned in order to decrease MB leaching while maintaining good singlet oxygen generation and colloidal stability for further applications in nanomedicine. In addition, phenyl functions are grafted on the pores of the silica matrix in order to avoid MB aggregation, thereby increasing the activity of the photosensitizer in the singlet oxygen generation. DFT calculations give insight in the structure of the aggregation of the MB units, and the roles of water and organic environments are investigated through time-dependent calculations on UV-vis spectra. [ABSTRACT FROM AUTHOR]

Beyond previously described carbo‐naphthalene and carbo‐biphenyl, a novel type of bis‐carbo‐benzenic molecules is envisaged from the stilbene parent. The synthesis, structure, spectroscopic and electrochemical properties of two such carbo‐stilbenes are described at complementary experimental and computational DFT levels. In the selected targets, the bare skeletal carbo‐mer of carbo‐stilbene is decorated by 8 or 10 phenyl groups, 0 or 2 tert‐butyl groups, and 2 n‐octyl chains, the later substituents being introduced to compensate anticipated solubility issues. As in the parent stilbene series, isomers of the phenylated carbo‐stilbenes are characterized. The cis‐ and trans‐isomers are, however, formed in almost equal amounts and could not be separated by either chromatography or crystallization. Nevertheless, due to a slow interconversion at the NMR time scale (up to 55 °C) the 1H NMR signals of both isomers of the two carbo‐stilbenes could be tentatively assigned. The calculated structure of the cis‐isomer exhibits a helical shape, consistent with the observed magnetic shielding of phenyl p‐CH nuclei residing inside the shielding cone of the facing C18 ring. The presence of the two isomers in solution also gives rise to quite broad UV‐vis absorption spectra with main bands at ca 460, 560 and 710 nm, and a significant bathochromic shift for the decaphenylated carbo‐stilbene vs the di‐tert‐butyl‐octaphenylated counterpart. Square wave voltammograms do not show any resolution of the two isomers, giving a reversible reduction wave at −0.65 or −0.58 V/SCE, and an irreversible oxidation peak at 1.11 V/SCE, those values being classical for most carbo‐benzene derivatives. Calculated NICS values (NICS(1)=−12.5±0.2 ppm) also indicate that the aromatic nature of the C18 rings is not markedly affected by the dialkynylbutatriene (DAB) connector between them. [ABSTRACT FROM AUTHOR]

A visible‐light‐induced iron‐catalyzed α‐alkylation of ketones with allylic and propargylic alcohols as pro‐electrophiles is reported. The diaminocyclopentadienone iron tricarbonyl complex plays a dual role by harvesting light and facilitating dehydrogenation and reduction steps without the help of any exogenous photosensitizer. γ,δ‐Unsaturated ketones can now be accessed through this borrowing hydrogen methodology at room temperature. Mechanistic investigations revealed that the steric hindrance on the δ‐position of either the dienone or ene‐ynone intermediate is the key feature to prevent or decrease the competitive 1,6‐reduction (and consequently the formation of the saturated ketone) and to favor the synthesis of a set of non‐conjugated enones and ynones. [ABSTRACT FROM AUTHOR]

We report herein an N‐alkylation reaction of amines with alcohols through a hydrogen autotransfer reaction. Unlike other catalytic systems containing transition metals or additives, potassium tertiary butoxide was found to be a unique and effective catalyst for synthesizing secondary amines. The role of the K+ ion and the reaction intermediates were studied under control experiments and by theoretical calculations. The reaction was found to be general and tolerates a series of functional groups, providing a convenient method to synthesize N‐alkylated compounds. [ABSTRACT FROM AUTHOR]

Herein we report an atom‐economical, transition metal‐free method for synthesizing 2‐aryl quinazolinones through a cascade annulation of 2‐amino benzamide and benzyl alcohol. The reaction proceeds via KOtBu‐mediated acceptorless alcohol dehydrogenation pathways. The procedure tolerates a wide variety of functional groups and provides a convenient method for the synthesis of 2‐aryl quinazolinones. Mechanistic insights by experiments and DFT calculations lead to unveil the reaction mechanism. [ABSTRACT FROM AUTHOR]