Molecular machine properties such as speed, efficiency, power, and torque depend upon particular features of structure, mechanism, and chemistry. The graphical abstract shows a Top Trumps-style representation of key performance indicators, illustrating how the first generation of synthetic catalysis-driven small-molecule machines compare with their biomolecular analogs. The understanding of how molecular machine design affects properties should aid technological advancements and a deeper understanding of the fundamental principles that link physics, chemistry, and biology.

Nature Nanotechnology, Published online: 19 September 2025; doi:10.1038/s41565-025-01997-yIn a non-equilibrium environment, molecular machines can undergo a directed flow through configurational changes, a feature that is widely exploited in processes characteristic of life. The use of such a flow to enhance the specificity of molecular recognition beyond equilibrium conditions has now been demonstrated in a minimal, synthetic, DNA-based system.

Triptycylhelicenes 1 and 2 were examined as molecular rachets (see picture) in which the triptycene serves as the rachet wheel (a) and the helicenes as pawl (b) and spring (c). The ease of rotation o...

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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.

This paper examines the temperature-mortality relationship over the course of the 20th century US both for its own interest and to identify potentially useful a

Le ministre de la recherche a dit sa « préoccupation », mercredi, après cette décision des autorités américaines. Le chercheur du CNRS aurait subi un contrôle aléatoire à son arrivée, avant que son or...

Some things are changing rather fundamentally and the way we think should perhaps change too

Continuous directionally biased 360° rotation about a covalent single bond was recently realized in the form of a chemically fueled 1-phenylpyrrole 2,2′-dicarboxylic acid rotary molecular motor. However, the original fueling system and reaction conditions resulted in a motor directionality of only ∼3:1 (i.e., on average a backward rotation for every three forward rotations), along with a catalytic efficiency for the motor operation of 97% and a fuel efficiency of 14%. Here, we report on the efficacy of a series of chiral carbodiimide fuels and chiral hydrolysis promoters (pyridine and pyridine N-oxide derivatives) in driving improved directional rotation of this motor-molecule. We outline the complete reaction network for motor operation, composed of directional, futile, and slip cycles. Using derivatives of the motor where the final conformational step in the 360° rotation is either very slow or completely blocked, the phenylpyrrole diacid becomes enantiomerically enriched, allowing the kinetic gating of the individual steps in the catalytic cycle to be measured. The chiral carbodiimide fuel that produces the highest directionality gives 13% enantiomeric excess (e.e.) for the anhydride-forming kinetically gated step, while the most effective chiral hydrolysis promoter generates 90% e.e. for the kinetically gated hydrolysis step. Combining the best-performing fuel and hydrolysis promoter into a single fueling system results in a 92% e.e.. Under a dilute chemostated fueling regime (to avoid N-acyl urea formation at high carbodiimide concentrations with pyridine N-oxide hydrolysis promoters), the motor continuously rotates with a directionality of ∼24:1 (i.e., a backward rotation for every 24 forward rotations) with a catalytic efficiency of >99% and a fuel efficiency of 51%.

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