More Like this

1. Ortho ‐Alkoxy‐benzamide Directed Formation of a Single Crystalline Hydrogen‐bonded Crosslinked Organic Framework and Its Boron Trifluoride Uptake and Catalysis

   https://doi.org/10.1002/anie.202311601  

   Li, Fangzhou; Li, Errui; Samanta, Krishanu; Zheng, Zhaoxi; Wu, Lianqian; Chen, Albert D.; Farha, Omar K.; Staples, Richard J.; Niu, Jia; Schmidt‐Rohr, Klaus; et al (November 2023, Angewandte Chemie International Edition)

   Abstract Boron trifluoride (BF₃) is a highly corrosive gas widely used in industry. Confining BF₃in porous materials ensures safe and convenient handling and prevents its degradation. Hence, it is highly desired to develop porous materials with high adsorption capacity, high stability, and resistance to BF₃corrosion. Herein, we designed and synthesized a Lewis basic single‐crystalline hydrogen‐bond crosslinked organic framework (H_COF‐50) for BF₃storage and its application in catalysis. Specifically, we introduced self‐complementaryortho‐alkoxy‐benzamide hydrogen‐bonding moieties to direct the formation of highly organized hydrogen‐bonded networks, which were subsequently photo‐crosslinked to generate H_COFs. The H_COF‐50 features Lewis basic thioether linkages and electron‐rich pore surfaces for BF₃uptake. As a result, H_COF‐50 shows a record‐high 14.2 mmol/g BF₃uptake capacity. The BF₃uptake in H_COF‐50 is reversible, leading to the slow release of BF₃. We leveraged this property to reduce the undesirable chain transfer and termination in the cationic polymerization of vinyl ethers. Polymers with higher molecular weights and lower polydispersity were generated compared to those synthesized using BF₃ ⋅ Et₂O. The elucidation of the structure–property relationship, as provided by the single‐crystal X‐ray structures, combined with the high BF₃uptake capacity and controlled sorption, highlights the molecular understanding of framework‐guest interactions in addressing contemporary challenges. 

   more » « less
2. A Heteromeric Carboxylic Acid Based Single‐Crystalline Crosslinked Organic Framework

   https://doi.org/10.1002/anie.202109987  

   Liang, Rongran; Samanta, Jayanta; Shao, Baihao; Zhang, Mingshi; Staples, Richard J.; Chen, Albert D.; Tang, Miao; Wu, Yuyang; Aprahamian, Ivan; Ke, Chenfeng (September 2021, Angewandte Chemie International Edition)

   Abstract The development of large pore single‐crystalline covalently linked organic frameworks is critical in revealing the detailed structure‐property relationship with substrates. One emergent approach is to photo‐crosslink hydrogen‐bonded molecular crystals. Introducing complementary hydrogen‐bonded carboxylic acid building blocks is promising to construct large pore networks, but these molecules often form interpenetrated networks or non‐porous solids. Herein, we introduced heteromeric carboxylic acid dimers to construct a non‐interpenetrated molecular crystal. Crosslinking this crystal precursor with dithiols afforded a large pore single‐crystalline hydrogen‐bonded crosslinked organic framework H_COF‐101. X‐ray diffraction analysis revealed H_COF‐101 as an interlayer connected hexagonal network, which possesses flexible linkages and large porous channels to host a hydrazone photoswitch. Multicycle Z/E‐isomerization of the hydrazone took place reversibly within H_COF‐101, showcasing the potential use of H_COF‐101 for optical information storage. 

   more » « less
3. A Crosslinked Ionic Organic Framework for Efficient Iodine and Iodide Remediation in Water

   https://doi.org/10.1002/anie.202214189  

   Zhang, Mingshi; Samanta, Jayanta; Atterberry, Benjamin A.; Staples, Richard; Rossini, Aaron J.; Ke, Chenfeng (November 2022, Angewandte Chemie International Edition)

   Abstract Iodine is widely used as an antimicrobial reagent for water disinfection in the wilderness and outer space, but residual iodine and iodide need to be removed for health reasons. Currently, it is challenging to remove low concentrations of iodine and iodide in water (≈5 ppm). Furthermore, the remediation of iodine and iodide across a broad temperature range (up to 90 °C) has not previously been investigated. In this work, we report a nitrate dimer‐directed synthesis of a single‐crystalline ionic hydrogen‐bonded crosslinked organic framework (H_COF‐7). H_COF‐7 removes iodine and iodide species in water efficiently through halogen bonding and anion exchange, reducing the total iodine concentration to 0.22 ppm at room temperature. Packed H_COF‐7 columns were employed for iodine/iodide breakthrough experiments between 23 and 90 °C, and large breakthrough volumes were recorded (≥18.3 L g⁻¹). The high iodine/iodide removal benchmarks recorded under practical conditions make H_COF‐7 a promising adsorbent for water treatment. 

   more » « less
4. Influence of water activity on hydration of tricalcium aluminate‐calcium sulfate systems

   https://doi.org/10.1111/jace.17046  

   Lapeyre, Jonathan; Ma, Hongyan; Okoronkwo, Monday; Sant, Gaurav; Kumar, Aditya (February 2020, Journal of the American Ceramic Society)

   Abstract The hydration of tricalcium silicate (C₃S)—the major phase in cement—is effectively arrested when the activity of water (a_H) decreases below the critical value of 0.70. While it is implicitly understood that the reduction ina_Hsuppresses the hydration of tricalcium aluminate (C₃A: the most reactive phase in cement), the dependence of kinetics of C₃A hydration ona_Hand the criticala_Hat which hydration of C₃A is arrested are not known. This study employs isothermal microcalorimetry and complementary material characterization techniques to elucidate the influence ofa_Hon the hydration of C₃A in [C₃A + calcium sulfate (C$) + water] pastes. Reductions in water activity are achieved by partially replacing the water in the pastes with isopropanol. The results show that with decreasinga_H, the kinetics of all reactions associated with C₃A (eg, with C$, resulting in ettringite formation; and with ettringite, resulting in monosulfoaluminate formation) are proportionately suppressed. Whena_H ≤0.45, the hydration of C₃A and the precipitation of all resultant hydrates are arrested; even in liquid saturated systems. In addition to—and separate from—the experiments, a thermodynamic analysis also indicates that the hydration of C₃A does not commence or advance whena_H ≤0.45. On the basis of this criticala_H, the solubility product of C₃A (K_C3A) was estimated as 10^−20.65. The outcomes of this work articulate the dependency of C₃A hydration and its kinetics on water activity, and establish—for the first time—significant thermodynamic parameters (ie, criticala_HandK_C3A) that are prerequisites for numerical modeling of C₃A hydration. 

   more » « less
5. Intra- and intermolecular C—H...F hydrogen bonds in the crystal structure of 1,2-bis[2-(2,3,4,5-tetrafluorophenyl)ethynyl]benzene

   https://doi.org/10.1107/S2056989024010995  

   Bosch, Eric; Bowling, Nathan P (December 2024, Acta Crystallographica Section E Crystallographic Communications)

   The title molecule, C₂₂H₆F₈, crystallizes in the monoclinic space groupP2₁/cwith two unique molecules in the asymmetric unit andZ= 8. Each molecule features a short intramolecularsp²-C—H...F hydrogen bond with H...F separations at 2.363 (14) and 2.270 (14) Å, corresponding to 91 and 87.5% of the sum of the van der Waals radii, and C—H...F angles of 158.3 (14) and 166.8 (14)°, respectively. Each molecule also forms an intermolecular bifurcated CH...(F)₂interaction with H...F distances ranging from 2.500 (16) to 2.597 (17) Å. 

   more » « less