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  1. Free, publicly-accessible full text available January 19, 2024
  2. Free, publicly-accessible full text available February 1, 2024
  3. Utilizing first-principles calculations combined with phonon Boltzmann transport theory up to fourth-order anharmonicity, we systematically investigate the thermal transport properties of the biphenylene network [BPN, recently synthesized experimentally by Fan et al. , Science , 2021, 372 , 852–856] and hydrogenated BPN (HBPN). The calculations show that four-phonon scattering significantly affects the lattice thermal conductivity ( κ ) of BPN. At room temperature, the κ of BPN is reduced from 582.32 (1257.07) W m −1 K −1 to 309.56 (539.88) W m −1 K −1 along the x ( y ) direction after considering the four-phonon scattering. Moreover, our results demonstrate that the thermal transport in BPN could also be greatly suppressed by hydrogenation, where the κ of HBPN along the x ( y ) direction is merely 16.62% (10.14%) of that of pristine BPN at 300 K. The mechanism causing such an obvious decrease of κ of HBPN is identified to be due to the enhanced phonon scattering rate and reduced group velocity, which is further revealed by the increased scattering phase space and weakened C–C bond. The results presented in this work shed light on the intrinsic thermal transport features of BPN and HBPN, which will help us to understand the phonon transport processes and pave the way for their future developments in the thermal field. 
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  4. We report a molecular switching ensemble whose states may be regulated in synergistic fashion by both protonation and photoirradiation. This allows hierarchical control in both a kinetic and thermodynamic sense. These pseudorotaxane-based molecular devices exploit the so-called Texas-sized molecular box (cyclo[2]-(2,6-di(1H-imidazol-1-yl)pyridine)[2](1,4-dimethylenebenzene); 14+, studied as its tetrakis-PF6salt) as the wheel component. Anions of azobenzene-4,4′-dicarboxylic acid (2H+•2) or 4,4′-stilbenedicarboxylic acid (2H+•3) serve as the threading rod elements. The various forms of 2 and 3 (neutral, monoprotonated, and diprotonated) interact differently with 14+, as do the photoinducedcisortransforms of these classic photoactive guests. The net result is a multimodal molecular switch that can be regulated in synergistic fashion through protonation/deprotonation and photoirradiation. The degree of guest protonation is the dominating control factor, with light acting as a secondary regulatory stimulus. The present dual input strategy provides a complement to more traditional orthogonal stimulus-based approaches to molecular switching and allows for the creation of nonbinary stimulus-responsive functional materials.

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