Harnessing electron-rich framework in cyclophosphazene derived hybrid nanoporous materials for organocatalytic C C bond formation and gas sorption applications

A Carbazole-Functionalized Porous Aromatic Framework for Enhancing Volatile Iodine Capture via Lewis Electron Pairing

Nitrogen-rich porous networks with additional polarity and basicity may serve as effective adsorbents for the Lewis electron pairing of iodine molecules. Herein a carbazole-functionalized porous aromatic framework (PAF) was synthesized through a Sonogashira-Hagihara cross-coupling polymerization of 1,3,5-triethynylbenzene and 2,7-dibromocarbazole building monomers. The resulting solid with a high nitrogen content incorporated the Lewis electron pairing effect into a π-conjugated nano-cavity, leading to an ultrahigh binding capability for iodine molecules. The iodine uptake per specific surface area was ~8 mg m-2 which achieved the highest level among all reported I2 adsorbents, surpassing that of the pure biphenyl-based PAF sample by ca. 30 times. Our study illustrated a new possibility for introducing electron-rich building units into the design and synthesis of porous adsorbents for effective capture and removal of volatile iodine from nuclear waste and leakage.

A POSS-Phosphazene Based Porous Material for Adsorption of Metal Ions from Water

The development of adsorptive materials continues to be an important area of research for removal of heavy metal ions from waste water. The adsorption capacity can be modulated by both physical and chemical modification of the adsorbent. Herein, we combine the unique properties of polyhedral oligomeric silsesquioxane (POSS) and organocyclophosphazene as the building units to synthesize a hybrid porous material, abbreviated as PN-POSS. The synthetic method follows a Heck reaction between hexa(4-bromophenoxy)cyclotriphosphazene and octavinylsilsesquioxane (OVS). The Brunauer-Emmett-Teller (BET) analysis shows that the material possesses micro- and mesopores of 1.5 and 3.8 nm size and a surface area on the order of 500 m²  g^-1 . These attributes in combination with the donor ability of the phosphazene units qualify the material for high adsorption of Pb²⁺ , Hg²⁺ and Cu²⁺ ions with maximal adsorption capacities on the order of 1326, 1927 and 2654 mg g^-1 , respectively. The adsorbent exhibits a good regeneration performance and can be effectively used for water treatment.

Nitrogen Amelioration-Driven Carbon Dioxide Capture by Nanoporous Polytriazine

Nitrogen-enriched nanoporous polytriazines (NENPs) have been synthesized by ultrafast microwave-assisted condensation of melamine and cyanuric chloride. The experimental conditions have been optimized to tune the textural properties by synthesizing materials at different times, temperatures, microwave powers, and solvent contents. The maximum specific surface area (SA_BET) of 840 m² g^-1 was estimated in the sample (NENP-1) synthesized at 140 °C with a microwave power of 400 W and reaction time of 30 min. One of the major objectives of achieving a large nitrogen content as high as 52 wt % in the framework was realized. As predicted, the nitrogen amelioration has benefitted the application by capturing a very good amount of CO₂ of 22.9 wt % at 273 K and 1 bar. Moreover, the CO₂ storage capacity per unit specific surface area (per m² g^-1) is highest among the reported nanoporous organic frameworks. The interaction of the CO₂ molecules with the polytriazine framework was theoretically investigated by using density functional theory. The experimental CO₂ capture capacity was validated from the outcome of the theoretical calculations. The superior CO₂ capture capability along with the theoretical investigation not only makes the nanoporous NENPs superior adsorbents for the energy and environmental applications but also provides a significant insight into the fundamental understanding of the interaction of CO₂ molecules with the amine functionalities of the nanoporous frameworks.

A multifunctional triazine-based nanoporous polymer as a versatile organocatalyst for CO2utilization and C–C bond formation

Conversion of CO₂to cyclic carbonates, methanol and methane by using a nanoporous MNENP as a multifunctional metal-free organocatalyst.

Nitrogen enriched polytriazine as a metal-free heterogeneous catalyst for the Knoevenagel reaction under mild conditions

A nitrogen-enriched nanoporous polytriazine was used as a metal-free heterogeneous organocatalyst for high-yielding ultra-fast Knoevenagel reactions under ambient conditions.