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Investigating electrochemical features of proton-conducting organic crystalline materials is relevant in developing efficient energy storage and conversion devices. However, the poor structural flexibility of the crystalline materials at the molecular level often impedes hydrogen bond reorganization of the proton carriers during proton migration, ultimately leading to low ionic conductivity. Here, we report crystals of azobenzene, functionalized with dipicolylamine at both ends (Azo-DPA), which contain an extended hydrogen-bonding network with water molecules in its structure. Interestingly, the crystals display remarkable mechanical flexibility explicitly probed by the nanoindentation technique. The mechanically flexible neutral organic crystals devoid of any acidic moieties (–COOH, –PO3H2, etc.) within the system, exhibit promising proton conductivity (1.63 × 10−4 S cm−1 at 30 °C under 95% relative humidity) which is almost 100 times better compared to the neutral organic systems reported to date. Mechanically flexible redox-active crystalline organic material (Azo-DPA) capable of impressive proton conduction was employed as an electrode material for the first time in an aqueous battery containing Zn2+ ions. The experimental and theoretical studies on the charge storage mechanism revealed the redox activity of the azo (–N＝N–) centers involving reversible insertion/extraction of protons and Zn2+ ions. Ultimately, the electrode displayed a specific capacity ∼49 mA h g−1 with almost 100% retention after 1400 cycles, encouraging the scope of redox-active organic crystalline materials for energy storage applications. [ABSTRACT FROM AUTHOR]

Fluorescent plastically bendable crystals are a promising alternative to silicon‐based materials for fabricating photonic integrated circuits, owing to their optical attributes and mechanical compliance. Mechanically bendable plastic organic crystals are rare. Their formation requires anisotropic intermolecular interactions and slip planes in the crystal lattice. This work presents three fluorescent plastically bendable crystalline materials namely, 2‐((E)‐(6‐methylpyridin‐2‐ylimino)methyl)‐4‐chlorophenol (SB1), 2‐((E)‐(6‐methylpyridin‐2‐ylimino)methyl)‐4‐bromophenol (SB2), and 2‐((E)‐(6‐Bromopyridin‐2‐ylimino)methyl)‐4‐bromophenol (SB3) molecules. The crystal plasticity in response to mechanical stress facilitates the fabrication of various monolithic and hybrid (with a tip‐to‐tip coupling) photonic circuits using mechanical micromanipulation with an atomic force microscope cantilever tip. These plastically bendable crystals act as active (self‐guiding of fluorescence) and passive waveguides both in straight and extremely bent (U‐, J‐, and O‐shaped) geometries. These microcircuits use active and passive waveguiding principles and reabsorbance and energy‐transfer mechanisms for their operation, allowing input‐selective and direction‐specific signal transduction. [ABSTRACT FROM AUTHOR]

Understanding the molecular packing is pivotal to understand the process of crystal growth and the establishment of the structure–property relationship. We report a two-component organic crystal 1, with extraordinarily high Z = 64, Z′′ = 32 and Z′ = 16. Low Z′ polymorphs of the reported structure remain elusive and crystallization and recrystallization from numerous solvent systems under different conditions yielded crystals with the same cell values. DSC and variable temperature powder-X-ray diffraction studies of the salt indicate the absence of any phase transition in the crystal prior to its melting point. The crystal exhibits unusually high thermal stability and does not undergo any phase transformation before melting, as validated by variable temperature powder X-ray diffraction and thermal studies. Quantification of the nanomechanical properties provides further structural insights. Interestingly, 1 exhibits rare dual stimuli-responsive behavior on grinding and exposure to base fumes. [ABSTRACT FROM AUTHOR]

The cocrystallisation of carbamazepine (CBZ) with 3,4-/3,5-dihydroxybenzoic acids (34/35DHBA) with different stoichiometries formed molecular alloys, exchanging a water molecule, in their isostructural CBZ dihydrate form. Furthermore, we show a correlation between the mechanical properties of the CBZ–DHBA cocrystals with the amount of coformer present. [ABSTRACT FROM AUTHOR]

Although, dynamic crystals are attractive for use in many technologies, molecular level mechanisms of various solid‐state dynamic processes and their interdependence, remain poorly understood. Here, we report a rare example of a dynamic crystal (1), involving a heavy transition metal, rhenium, with an initial two‐face elasticity (within ≈1 % strain), followed by elasto‐plastic deformation, at room temperature. Further, these crystals transform to a rotator (plastic) crystal phase at ≈105 °C, displaying exceptional malleability. Qualitative and quantitative mechanical tests, X‐ray diffraction, μ‐Raman and polarized light microscopy experiments reveal that the elasto‐plastic deformation involves both partial molecular rotations and slip, while malleability in the rotator phase is facilitated by reorientational motions and increased symmetry (slip planes). Our work, connecting the plastically bendable (1D or 2D) crystals with the rotator phases (3D), is important for designing multi‐functional dynamic crystals. [ABSTRACT FROM AUTHOR]