The identification of psychoactive substances, in particular of designer drugs, on the site of their discovery is crucial to contrast the diffusion of drugs of abuse. We report here the first example of a nanoscale colorimetric probe, based on the nanoconfinement of a tricyclic dye and the target analytes in the cavity of cucurbit[8]uril. The probe selectively responds to N-(2methoxybenzyl)phenethylamines, with a limit of detection of 3 μM. The sensing system can be deposited on paper, thus obtaining a colorimetric strip test capable of discriminating illegal drugs from other substances of common use.

Herein, we report our study on the design and development of a novel photocarboxylation method. We have used an organic photoredox catalyst (PC, 4CzIPN) and differently substituted dihydropyridines (DHPs) in combination with an organic base (1,5,7-triazabicyclodec-5-ene, TBD) to access a proton-coupled electron transfer (PCET) based manifold. In depth mechanistic investigations merging experimental analysis (NMR, IR, cyclic voltammetry) and density-functional theory (DFT) calculations reveal the key activity of a H-bonding complex between the DHP and the base. The thermodynamic and kinetic benefits of the PCET mechanism allowed the implementation of a redox-neutral fixation process leading to synthetically relevant carboxylic acids (18 examples with isolated yields up to 75%) under very mild reaction conditions. Finally, diverse product manipulations were performed to demonstrate the synthetic versatility of the obtained products.