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Organic photothermal conversion materials hold immense promise for various applications owing to their structural flexibility. Recent research has focused on enhancing near‐infrared (NIR) absorption and mitigating radiative transition processes. In this study, we have developed a viable approach to the design of photothermal conversion materials through the construction of ternary organic cocrystals, by introducing a third component as a molecular blocker and motion unit into a binary donor–acceptor system. Superstructural and photophysical properties of the ternary cocrystals were characterized using various spectroscopic techniques. The role of the molecular blocker in radical stabilization and photothermal conversion was demonstrated. Intriguingly, the motions of the entire pyrene molecules in the cocrystal have been observed by the results of variable temperature single‐crystal X‐ray diffraction. The excellent performance of the ternary cocrystal as a photothermal material was validated through efficient NIR‐II photothermal and solar‐driven water evaporation experiments. The efficiency of water evaporation reached 88.7 %, with a corresponding evaporation rate of 1.29 kg m−2 h−1, representing excellent performance among pure organic small molecular photothermal conversion materials. Our research underscores the introduction of molecular blockers and motion units to stabilize radicals and produce outstanding photothermal conversion materials, offering new pathways for developing efficient and stable photothermal conversion materials. [ABSTRACT FROM AUTHOR]

The year 2022 marks the 30th anniversary of the first reports of polyrotaxanes in the scientific literature. During the past three decades, many combinations of molecular rings and polymer chains have been synthesised and characterised. Until recently, however, the permutations of polyrotaxanes available to researchers were limited by synthetic methods which typically relied on an innate affinity between the molecular rings and polymer chains. With the advent of oligorotaxane-forming molecular pumps in 2015, it has now become possible to pump multiple rings against their will onto oligomer and polymer chains which have little or no affinity for the rings. These molecular pumps, which can recruit rings actively from solution to form precise polyrotaxanes, represent a major breakthrough in the field. This Tutorial Review highlights key milestones in the synthesis and investigation of polyrotaxanes along with recent developments in the synthesis and theory relating to molecular pumps. Polyrotaxane properties, arising from their topologies, have allowed them to steal a march on traditional polymers in a wide range of applications in materials, electronic and biological science, from slide-ring gels to robust coatings on cell phones, from molecular wires to flexible binders for battery anodes, from efficient multivalent protein binders to bio-cleavable polyplexes for cellular DNA delivery. Molecular pumps have the potential to blaze a contemporary trail for the synthesis of precise mechanically interlocked materials, especially those dependent on non-equilibrium chemistry and those related to energy storage and nanomedicine. [ABSTRACT FROM AUTHOR]

Complexation between a viologen radical cation (V.+) and cyclobis(paraquat‐p‐phenylene) diradical dication (CBPQT2(.+)) has been investigated and utilized extensively in the construction of mechanically interlocked molecules (MIMs) and artificial molecular machines (AMMs). The selective recognition of a pair of V.+ using radical‐pairing interactions, however, remains a formidable challenge. Herein, we report the efficient encapsulation of two methyl viologen radical cations (MV.+) in a size‐matched bisradical dicationic host — namely, cyclobis(paraquat‐2,6‐naphthalene)2(.+), i.e. CBPQN2(.+). Central to this dual recognition process was the choice of 2,6‐bismethylenenaphthalene linkers for incorporation into the bisradical dicationic host. They provide the space between the two bipyridinium radical cations in CBPQN2(.+) suitable for binding two MV.+ with relatively short (3.05–3.25 Å) radical‐pairing distances. The size‐matched bisradical dicationic host was found to exhibit highly selective and cooperative association with the two MV.+ in MeCN at room temperature. The formation of the tetrakisradical tetracationic inclusion complex — namely, [(MV)2⊂CBPQN]4(.+) – in MeCN was confirmed by VT 1H NMR, as well as by EPR spectroscopy. The solid‐state superstructure of [(MV)2⊂CBPQN]4(.+) reveals an uneven distribution of the binding distances (3.05, 3.24, 3.05 Å) between the three different V.+, suggesting that localization of the radical‐pairing interactions has a strong influence on the packing of the two MV.+ inside the bisradical dicationic host. Our findings constitute a rare example of binding two radical guests with high affinity and cooperativity using host‐guest radical‐pairing interactions. Moreover, they open up possibilities of harnessing the tetrakisradical tetracationic inclusion complex as a new, orthogonal and redox‐switchable recognition motif for the construction of MIMs and AMMs. [ABSTRACT FROM AUTHOR]

Keywords: binding stoichiometry; host-guest systems; molecular recognition; radical-pairing interactions EN binding stoichiometry host-guest systems molecular recognition radical-pairing interactions 25787 25787 1 11/17/21 20211122 NES 211122 B Die selektive Erkennung b von zwei gestapelten Viologen-Radikalkationen in Lösung unter Verwendung eines größenangepassten radikalischen Wirts wird von J. Fraser Stoddart et al. in der Zuschrift auf S. 25658 beschrieben. Binding stoichiometry, host-guest systems, molecular recognition, radical-pairing interactions Durch die Verwendung von 2,6-Bismethylennaphthalin als Linker ist der bisradikalische dikationische Wirt in der Lage, zwei Methylviologen-Radikalkationen als Gäste mit starker und kooperativer Bindung aufzunehmen. [Extracted from the article]

Binding stoichiometry, host-guest systems, molecular recognition, radical-pairing interactions Keywords: binding stoichiometry; host-guest systems; molecular recognition; radical-pairing interactions EN binding stoichiometry host-guest systems molecular recognition radical-pairing interactions 25583 25583 1 11/17/21 20211122 NES 211122 B Selective recognition b of two stacked viologen radical cations in solution using a size-matched radical host is reported by J. Fraser Stoddart and co-workers in their Research Article on page 25454. By employing 2,6-bismethylenenaphthalene as the linker, the bisradical dicationic host is able to accommodate two methyl viologen radical cation guests with strong and cooperative binding. [Extracted from the article]