Unveiling the Mechanism of Water‐Triggered Diplex Transformation and Correlating the Changes in Structures and Separation Properties

Abstract

Recently, great attention has been devoted to the initial and final structures of single‐crystal to single‐crystal (SCSC) transformations and dissolution‐recrystallization structural transformations (DRSTs), whereas the isolation and characterization of crucial intermediates and the unequivocal mechanism of the dynamic conversion process receive comparatively little consideration. Herein, a CuII‐based porous coordination polymer (PCP), which possesses a Kagomé lattice, is solvothermally synthesized. Triggered by water, the 2D Kagomé lattice (PCP‐1) primarily undergoes a reversible SCSC transformation to a distorted Kagomé intermediate (PCP‐2), which is followed by a DRST process to form a 3D NbO framework (PCP‐3) in situ. To the best of our knowledge, this is the first demonstration of a mixed SCSC and DRST transformation process. Notably, the sequential transformations result in the formation of the intermediate and the final product, which could not be obtained by direct synthesis. Regarding the intermediate, we have characterized the transformation separately and propose a plausible mechanism. More interestingly, the adsorption isotherms of water, methanol, and ethanol for the activated materials are distinctly different from one another. PCP‐2′ can uptake all three vapors with different adsorption capacities; however, the 3D transformed material PCP‐3′ only significantly absorbs water, which is concomitant with an amorphous‐to‐crystalline transformation, leading to the selective extraction of water from alcohol.

Polymorph transformation in a mixed-stacking nickel-dithiolene complex with the derivative of 4,4′-bipyridinium

“…These subsets involve solvent or adsorbent-induced solid-to-solid transformations and dissolved-recrystallization. 14 Such forms are frequently observed in metal–organic frameworks (MOFs) or porous coordination polymers (PCPs). Typically, solvent or adsorbent molecules coordinate with the metal ions in the framework, resulting in alterations in the coordination geometry.…”

“…This was succeeded by an in situ dissolved-recrystallized process, resulting in the formation of a three-dimensional NbO framework (PCP-3). 14 Typically, a polymorph possessing higher solubility tends to undergo solvent-mediated transformation, wherein it dissolves and subsequently recrystallizes into another polymorph characterized by lower solubility, while the differences in solubility between polymorphs stem from differences in lattice energy. 7 The microcrystals of 1 -g show a limited solubility in MeOH, suggesting that the transformation from 1 -g to 1 -r involves a dissolution-recrystallization process and 1 -g shows lower lattice energy in comparison to 1 -r. Scanning electron microscopy (SEM) images depicted in Fig.…”

LiSc(SeO3)2·xH2O (0 ≤ x ≤ 1): New Selenites Revealing Water Molecule-Driven Extremely High Temperature Single-Crystal-to-Single-Crystal Transformations

“…One successful approach exploited in crystal engineering to tailor interesting solid state materials is single-crystal-to-single-crystal (SCSC) transformations. Several extremely interesting dynamic behaviors found at the molecular level without disorganizing periodicity in single crystals include sensing, − thermal response, , catalysis, − separation, − and gas storage. − Most of these interesting SCSC transformations, however, have been observed from metal–organic hybrid compounds at rather lower temperatures under mild conditions thus far. − With oxides, only a few examples of SCSC transformations have been reported perhaps due to their rigid structural characteristics. − Herein, we report a series of novel mixed metal selenites revealing SCSC transformations up to 450 °C, which were driven by water molecules. The phase-pure synthesis, crystal structures, characterization, and temperature-dependent SCSC transformation will be presented.…”

Improved quantum yield in geometrically constrained tetraphenylethylene-based metal–organic frameworks

“…MOFs have been reported previously as solvatochromic materials, 7,8 in which the color of the material is dependent on guest molecules in the MOF's pores. This change in emission is useful to detect gases such as hydrogen sulfide, ammonia, sulfur dioxide, or nitrous oxides.…”

“…4,5 The potential for synergistic effects between the metal and linker, as well as the diversity of potential structures, make them a particularly attractive class of materials for tuneable sensors. 6 MOFs have been reported previously as solvatochromic materials, 7,8 in which the color of the material is dependent on guest molecules in the MOF's pores. This change in emission is useful to detect gases such as hydrogen sulfide, ammonia, sulfur dioxide, or nitrous oxides.…”