Extensive recent progress has been made on the design and applications of organic photothermal agents for biomedical applications because of their excellent biocompatibility comparing with inorganic materials. One major hurdle for the further development and applications of organic photothermal agents is the rarity of high‐performance materials in the second near‐infrared (NIR‐II) window, which allows deep tissue penetration and causes minimized side effects. Up till now, there have been few reported NIR‐II‐active photothermal agents and their photothermal conversion efficiencies are relatively low. Herein, optical absorption of π‐conjugated small molecules from the first NIR window to the NIR‐II window is precisely regulated by molecular surgery of substituting an individual atom. With this technique, the first demonstration of a conjugated oligomer (IR‐SS) with an absorption peak beyond 1000 nm is presented, and its nanoparticle achieves a record‐high photothermal conversion efficiency of 77% under 1064 nm excitation. The nanoparticles show a good photoacoustic response, photothermal therapeutic efficacy, and biocompatibility in vitro and in vivo. This work develops a strategy to boost the light‐harvesting efficiency in the NIR‐II window for cancer theranostics, offering an important step forward in advancing the design and application of NIR‐II photothermal agents.

Here we show that it is possible to modulate the supramolecular assembly of designed H-bonding amphiphilic perylene-based materials through simple solvent interactions. These modulated supramolecular interactions have been translated to and observed in macroscopic properties, and provide new pathways to the preparation of switchable interfaces based on designed supramolecular interactions.

A new symmetrical sugar‐based perylenediimide derivative PTCDI‐BAG is synthesized and its aggregate morphologies and formation mechanisms are studied in detail in the mixed solvent system water/N,N‐dimethylformamide (H2O/DMF) with changing volume ratios. PTCDI‐BAG molecules self‐assemble into planar ribbons in 20/80 and 40/60 H2O/DMF (v/v), but their chiralities are opposite according to recorded circular dichroism (CD) spectra. With a further increase of the water content, only left‐handed helical nanowires are obtained in 60/40 and 80/20 H2O/DMF (v/v) mixtures. By combining density functional theory (DFT) calculations with the experimental investigations, it is proposed that kinetic and thermodynamic factors play key roles in tuning PTCDI‐BAG structures and helicity. The formation of the ribbon is thermodynamically controlled in the 20/80 H2O/DMF system, but kinetically controlled nucleation followed by thermodynamically controlled self‐assembly plays the governing roles for the formation of nanoribbons in 40/60 H2O/DMF. Devices based on single nanoribbons for hydrazine sensing exhibit better performance than nanofiber bundles obtained in this study and achiral nanostructures reported in previous study. This study not only provides an elaborated route to tuning the structures and helicity of PTCDI molecules, but also provides new possibilities for the construction of high‐performance nanodevices.

Dopant‐induced helical conformations of polyaniline (PANI) nanofibers are presented. Right‐ and left‐handed helical nanofibers of conducting PANI are produced using respectively D‐ and L‐camphorsulfonic acid as the dopant, it is reported, as proved by the mirror‐image chiral dichroism spectra (see figure). The authors suggest a mechanism for the formation of nanofibrillar bundles of helical nanofibers.