Mechanistic insights into the visible-light-driven -arylation of carboxylic acids catalyzed by xanthine-based nickel complexes.

We present a photocatalytic protocol for the -arylation of carboxylic acids using nickel complexes bearing C8-pyridyl xanthines. Our studies suggest that the underlying mechanism operates independently of external photosensitizers. Stoichiometric experiments and crystallographic studies characterize the catalytically relevant Ni complexes.

A dual experimental-theoretical perspective on ESPT photoacids and their challenges ahead.

Photoacids undergo an increase in acidity upon electronic excitation, enabling excited-state proton transfer (ESPT) reactions. A multitude of compounds that allow ESPT has been identified and integrated in numerous applications, as is outlined by reviewing the rich history of photoacid research reaching back more than 90 years. In particular, achievements together with ambitions and challenges are highlighted from a combined experimental and theoretical perspective.

Asymmetric Migratory Tsuji-Wacker Oxidation Enables the Enantioselective Synthesis of Hetero- and Isosteric Diarylmethanes.

Diarylmethanes play, in part, a pivotal role in the design of highly potent, chiral, nonracemic drugs whose bioactivity is typically affected by the substitution pattern of their arene units. In this context, certain arenes such as -substituted benzenes or unsubstituted heteroarenes cause particular synthetic challenges, since such isosteric residues at the central methane carbon atom are typically indistinguishable for a chiral catalyst. Hence, the stereoselective incorporation of isosteric (hetero)arenes into chiral methane scaffolds requires the use of stoichiometrically differentiated building blocks, which is typically realized through preceding redox-modifying operations such as metalation or halogenation and thus associated with disadvantageous step- and redox-economic traits.

Fluorescent probes for investigating the internalisation and action of bioorthogonal ruthenium catalysts within Gram-positive bacteria.

Bioorthogonal reactions are extremely useful for the chemical modification of biomolecules, and are already well studied in mammalian cells. In contrast, very little attention has been given to the feasibility of such reactions in bacteria. Herein we report modified coumarin dyes for monitoring the internalisation and activity of bioorthogonal catalysts in the Gram-positive bacterial species .

Tuning The Intracellular Distribution of [3+2+1] Iridium(III) Complexes In Bacterial And Mammalian Cells By iClick Reaction With Biomolecular Carriers Functionalized With Alkynone Groups.

Three iridium(III) triazolato complexes of the general formula [Ir(triazolato)(ppy)(terpy)]PF with ppy=2-phenylpyridine and terpy=2,2':6',2''-terpyridine were efficiently prepared by iClick reaction of [Ir(N)(ppy)(terpy)]PF, with alkynes and alkynones, which allowed facile introduction of biological carriers such as biotin and cholic acid. In contrast to the precursor azido complex, which decomposed upon photoexcitation on a very short time scale, the triazolato complexes were stable in solution for up to 48 h. They emit in the spectral region around 540 nm with a quantum yield of 15-35 % in aerated acetonitrile solution and exhibit low cytotoxicity with IC values >50 μM for most complexes in L929 and HeLa cells, demonstrating their high suitability as luminescent probes.