We report the deletion of nitrogen atoms from multiple template sites in rotaxanes, catenanes, and a molecular knot. Nitrogen extrusion from secondary amines in the backbone of the interlocked structures is achieved using O-diphenylphosphinylhydroxylamine (DPPH), forming carbon–carbon bonds while largely maintaining the integrity of the original mechanical bonding. We find that DPPH gives improved yields (up to 51%) for nitrogen atom deletions from template sites in rotaxanes compared to an anomeric amide nitrogen-deletion reagent and overcomes a major substrate limitation in that, using DPPH, only one of the substituents of the secondary amine in the rotaxane axle needs to be radical-stabilizing. Multiple template site nitrogen atom deletions were accomplished from a range of mechanically interlocked architectures, despite the potential for dethreading, unlinking, and/or strand uncrossing during each successive deletion event. Highlights include the deletion of two template sites from a doubly threaded [3]rotaxane (37% yield) and [3]catenane (45%), quadruple N-deletion of amines from both rings of a [2]catenane (33%), and six N-deletions from the six amine groups in a molecular trefoil knot (7%). The combination of skeletal editing with template synthesis provides a general strategy for synthesis that significantly increases the structural diversity of interlocked molecules that are potentially accessible.

An abiotic information ratchet mechanism increases selectivity for the correct DNA duplex from 2:1 at equilibrium to 6:1 under energy-dissipating conditions.

We report the in situ quantification of directional rotation of a new type of catalysis-driven rotary motor featuring a phenyl carboxylic acid rotor attached to a 7-azaindole-N-oxide stator through a biaryl C–N bond. Continuous directional rotation of the rotor about the stator is driven by the achiral motor’s rotary catalysis of carbodiimide hydration in the presence of a chiral pyrrolidinylpyridine-N-oxide. The catalytic cycle features an intermediate O-acyl-azaindole-N-oxide ester tether formed between the carboxylic acid of the rotor and the N-oxide of the stator. Face-selective cleavage of the tether by the chiral pyrrolidinylpyridine-N-oxide additive generates relatively long-lived diastereomeric pyridine-N-oxide esters of the phenyl carboxylic acid. These are hydrolyzed during the catalytic cycle to reform the carboxylic acid resting state of the motor, completing net directional 360° rotation. In contrast to previous catalysis-driven motor-molecules, the motor’s directionality could be determined directly from the transient concentrations of the diastereomeric intermediates formed during rotary catalysis. This avoids reliance on restricted rotation models to assess motor directionality and provides direct access to other key performance indicators such as motor speed and catalytic, coupling and fuel efficiency. The in situ-determined directionality of the motor was found to be in excellent agreement with the directionality determined from a restricted rotation model, supporting both the efficacy of the new approach and the validity of using appropriately designed restricted rotation models. The results establish a straightforward method for the in situ quantification of various aspects of motor behavior, aiding the design and optimization of artificial molecular motors.

L'histoire des Hospices Civils de Beaune a commencé en 1443 par la volonté de Nicolas Rolin et Guigone de Salins de construire un hôpital : l'Hôtel-Dieu.