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Interfacial solar water evaporation (ISWE), a new water treatment technology, exhibits promising applications in the fields of fresh water and sustainable energy. Preventing surface salt accumulation while maintaining high solar-thermal conversion performance is a critical issue in ISWE-based desalination. Herein, we report a new strategy to design a salt-resistant solar evaporator, namely construction of a hydrophilic solar-thermal evaporator featuring capillary action enabled by loading organic photothermal materials onto a biomass substrate. Using diradicaloid boron-doped molecular carbons as photothermal materials, the as-prepared solar evaporators exhibit a temperature rise to 74 °C under 1 kW m−2 simulated solar irradiation. The solar-to-vapor efficiency is up to 93%, and the rate of water evaporation reaches 1.36 kg m−2 h−1. Importantly, this evaporator can sustain long periods of evaporating water without surface salt accumulation from the outdoor evaporation of seawater for 14 days. Moreover, the waste heat may be used to generate electricity and collect minerals at the end of the device in the evaporation process. Therefore, the efficient and persistent water evaporation without salt accumulation is achieved for this salt-resistant solar evaporator, which will promote the development of the ISWE technology for solar desalination and other applications. [ABSTRACT FROM AUTHOR]

Single-molecule diode was the first proposed device in molecular electronics. Despite the great efforts and advances over 50 years, the reported rectification ratios, the most critical parameter of a diode, remain moderate for the single-molecule diode. Herein, we report an approach to achieve a larger rectification ratio by adopting the combined strategies of p-type boron doping, the single-layer graphene nodes, and the van der Waals layer-by-layer architecture. Measured current-voltage curves showed one of the as-fabricated single-molecule diodes hit an unprecedented large rectification ratio of 457 at ±1 V. Break junction operations and spectroscopic measurements revealed the three-atom-thick configuration of the single-molecule diodes. With the experimental and theoretical calculation results, we demonstrated the doped boron atoms induced holes to redistribute the electron density, making the asymmetric coupling at positive and negative biases, and the van der Waals interaction promoted asymmetric coupling and significantly boosted diode performance., (© 2024 Wiley‐VCH GmbH.)

Helicenes, featuring unique helical structures, have a long history as three-dimensional polycyclic aromatic hydrocarbons (PAHs). Incorporation of heteroatoms into helicenes may alter their electronic structures and achieve unexpected physical properties. Here, we disclose fusion of boron-doped π-systems onto helicenes as an efficient strategy to design boron-doped carbohelicenes. Two boron-doped double [6]carbohelicenes were synthesized, which possess the C 58 B 2 and C 86 B 2 polycyclic π-skeletons containing two [6]helicene subunits, respectively. The C 86 B 2 molecule thus represents the largest-size helicene-based boron-doped PAH. A thorough investigation reveals that the helicene moieties and boron atoms endow the polycyclic π-systems with delocalized electronic structures, and well-tunable ground-state and excited-state photophysical properties. It is notable that the C 58 B 2 molecule displays excited-state stimulated emission behavior and amplified spontaneous emission (ASE) properties in not only the blend films with various doped concentrations but also the pure film. To our knowledge, it is the first example of ASE-active [ n ]helicene ( n ≥ 6), and moreover, such robust ASE performance has rarely been observed in PAHs, demonstrating the promising utility of boron-doped carbohelicenes for laser materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Doping heteroatoms into polycyclic aromatic hydrocarbons (PAHs) may alter their structures and thereby physical properties. This study reports the construction of B/N-codoped PAHs via combining the B- and N-doped π-systems. Two π-extended B/N-codoped PAHs were synthesized through the Mallory photoreaction. Both feature a C 48 BN 2 π-skeleton, which is assembled by linearly fusing three substructures including B-doped and sp 2 -hybridized N-doped π-moieties and one pyrene unit. In comparison to the pristine B-doped analog, their intramolecular charge transfer (ICT) states are distinctly modulated by the fused N-doped π-system and the further incorporated cyano group, leading to their tunable optical properties, as revealed by detailed theoretical and experimental analysis. Furthermore, these three molecules have sufficient Lewis acidity and can coordinate with Lewis base to form Lewis acid-base adducts, and notably, such intermolecular complexation can further dynamically modulate their ICT transitions and thereby photophysical properties, such as producing blue, green and red fluorescence., (© 2023 Wiley-VCH GmbH.)

Heterocyclic diradicaloids with atom-precise control over open-shell nature are promising materials for organic electronics and spintronics. Herein, we disclose quinoidal π-extension of a B/N-heterocycle for generating B/N-type organic diradicaloids. Two quinoidal π-extended B/N-doped polycyclic hydrocarbons that feature fusion of the B/N-heterocycle motif with the antiaromatic s-indacene or dicyclopenta[b,g]naphthalene core were synthesized. This quinoidal π-extension and B/N-heterocycle leads to their open-shell electronic nature, which stands in contrast to the multiple-resonance effect of conventional B/N-type emitters. These B/N-type diradicaloids have modulated (anti)aromaticity and enhanced diradical characters comparing with the all-carbon analogues, as well as intriguing properties, such as magnetic activities, narrow energy gaps and highly red-shifted absorptions. This study thus opens the new space for both of B/N-doped polycyclic π-systems and heterocyclic diradicaloids., (© 2023 Wiley-VCH GmbH.)

Tuning diradical character is an important topic for organic diradicaloids. Herein, we report the precise borylation enabling structural isomerism as an effective strategy to modulate diradical character and thereby properties of organic diradicaloids. We synthesized a new B-containing polycyclic hydrocarbon that has the indeno[1,2-b]fluorene π-skeleton with the β-carbons bonding to two boron atoms. Detailed theoretical and experimental results show that this bonding pattern leads to its distinctive electronic structures and properties in comparison to that of its isomeric molecule. This molecule has the efficient conjugation between boron atoms and π-skeleton, resulting in downshifted LUMO and HOMO levels. Moreover, it exhibits smaller diradical character and thereby inhibited diradical properties, such as significantly blue-shifted light absorption, larger energy bandgap and weak para-magnetic resonance. Notably, this B-containing polycyclic hydrocarbon possesses much stronger Lewis acidity and its Lewis acid-base adducts display enhanced diradical character, demonstrating the positive effects of Lewis coordination on modulating diradical performance., (© 2022 Wiley-VCH GmbH.)