A nature-inspired hydrogen-bonded supramolecular complex for selective copper ion removal from water

Self-Assembly of Nitrogen-Rich Heterocyclic Compounds with Oxidants for the Development of High-Energy Materials

The development of energetic materials with high energy and low sensitivity has attracted immense interests due to their widespread applications in aerospace technology and national defense. In this work, a promising self-assembly strategy was developed to prepare three high-energy materials (1-3) through the introduction of oxidant molecules into the crystal voids of the parent materials. The structures of these new materials were comprehensively examined by infrared spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and single-crystal X-ray diffraction. In these materials, three unique layer structures with hcb, sql, and interrupted sql topologies were observed, which were formed by the fused-ring-based energetic components. Windows with hexagonal, square, and rectangular structures were observed within these layer structures, which were occupied by H₂O₂, NO₃^-, and ClO₄^-, respectively. Oxidant molecules interacted with parent molecules via hydrogen bonds to form crystal structures of these materials. Moreover, the energetic property of these materials was estimated by computing methods. The calculation results revealed that these self-assembly materials exhibit excellent energetic properties. The highest energetic performance was observed for compound 3. The detonation velocity, detonation pressure, and specific impulse values were up to 9339 m·s^-1, 42.5 GPa, and 308 s, respectively, which were greater than those of HMX. Furthermore, these materials exhibited good sensitivity, which was closely related to their unique crystal structures. The high performance of these materials indicated that the self-assembly strategy should be a promising method for the development of novel energetic materials.

Equilibrium and thermodynamic investigation of biosorption of nickel from water by activated carbon made from palm kernel chaff

Novel biosorbents were derived from a waste product of palm kernel oil extraction known as palm kernel chaff (PKC). One portion of the PKC was carbonized in a furnace and then activated chemically, while the other half was activated without carbonization. Both were designated as CPKC and UPKC, respectively. The two biosorbents so produced were then used to conduct batch equilibrium and kinetic sorption studies at 30 °C, 35 °C and 40 °C and pH 3.0 and 9.0 for an agitation period of 5, 10, 20, 40, 60, 90, and 120 min. The Koble-Corrigan, Dubinin-Radushkevich, and the Freundlich isotherms fitted the experimental data very well with R² values of 0.97 to 1.0, 0.95 to 1.0, and 0.96 to 1.0, respectively. The linear type II Langmuir isotherm performed much better (0.96 ≤ R² ≤ 1.0) than the nonlinear isotherm. The maximum sorption capacity was obtained as 120.6 mg/g using CPKC at pH 9.0 and 35 °C. The Langmuir separation coefficient values (0.022 ≤ R_L ≤ 0.926) show that the sorption of nickel to PKC is favorable. The most favorable sorption condition was found for CPKC at pH 9 and temperature of 40 °C. The values of sorption energy (8.21 ≤ E ≤ 14.27) and the isosteric heat of sorption (-133.09 ≤ ∆H_x ≤ -17.92) indicate that the mode of sorption is mostly ion exchange. Thermodynamic parameters also show that the process is exothermic and entropy-driven. The pseudo-second-order kinetic model shows the best correlation compared to the other kinetic models. The coefficient of correlation for the pseudo-second-order model was mostly within the range of 0.999-1.000 for 90% of all kinetic studies carried out.

Reduction of structural hierarchy translates into variable influence on the performance of boron nitride aerogel

The rise of ceramic aerogel offers traditional ceramics a new window. Alongside the emerging prospects, what is open to explore includes the elegant design of a ceramic aerogel with tailorable inner organizations, what would occur when complex hierarchy exists in such an already intricate system, and how the properties get influenced as the complexity fades. Borrowing the wisdom from supramolecular world, we exquisitely transform BN aerogel from a complex hierarchy to a flatten microstructure based on solvent-induced morphology switch of its supramolecular precursor gel. Such reduction in structural hierarchy has insignificant effect on the thermal conductivity (∼0.027 W/(m·K)) but shifts the wettability from hydrophobicity to hydrophilicity and occasions nearly 3-fold difference in ion adsorption rate, as exemplified by lead ions. This work may promote the understanding of special hierarchy existing in delicate systems and inspire other attempts to harness the functionality of aerogels by manipulating structural hierarchy.

Fe-Mn Oxides Based Multifunctional Adsorptive/Electrosensing Nanoplatforms: Dynamic Site Rearrangement for Metal Ion Selectivity

Achieving structural requirements for the exclusive selectivity of adsorbent to a specific metal remains challenging, as certain metal ions show similar adsorptive behaviors and preference toward a given site. We reported the morphology and oxidation state-dependent selectivity manipulating of layered oxides by controlling the dynamic evolution of different adsorptive sites. The computational investigation predicted the site-specific partitioning trends of metal ions at two sites of manganese oxide (MnO₂) layers: the lateral edge sites (LESs) and octahedral vacancy sites (OVSs). In contrast to the predominant occupation of the OVSs for other metal ions, the binding of lead (Pb) ions was energetically favored at both the sites. We assembled ultrathin MnO₂ nanosheets on the magnetic iron oxides to first enhance the accessibility of the LESs. A sequential ligand-promoted partial reduction of the atomic MnO₂ layers induced the edge-to-interlayer migration of Mn atoms to block the nonspecific OVSs and activate the LESs, enabling a superior selectivity to Pb. In addition, the iron oxides helped construct a multifunctional adsorptive/electrosensing platform for Pb regarding their facile magnetic separation and electrochemical activity. Simultaneous selective adsorption and on-site monitoring of Pb(II) were achieved on this nanoplatform, owing to its satisfactory stability and sensitivity without an obvious matrix effect.

Acceleration of Nitric Oxide Release in Multilayer Nanofilms through Cu(II) Ion Intercalation for Antibacterial Applications

Implant-derived bacterial infection is a prevalent cause of diseases, and no antibacterial coating currently exists that is biocompatible and that does not induce multidrug resistance. To this end, nitric oxide (NO) has been emerging as an effective antimicrobial agent that acts on a broad range of bacteria and elicits no known resistance. Here, a method for accelerating NO release from multilayered nanofilms has been developed for facilitating antibacterial activity. A previously reported multilayered nanofilm (nbi film) was fabricated by alternative deposition of branched polyethyleneimine (BPEI) and alginate via the layer-by-layer assembly method. N-Diazeniumdiolate, a chemical NO donor, was synthesized at the secondary amine moiety of BPEI within the film (nbi/NO film). Cu(II) ions can be incorporated into the film by forming chelating compounds with unreacted amines that have not been converted to NO donors. The increase of the amine protonation state in the chelate caused destabilization of the NO donor by reducing hydrogen bonding between the deprotonated amine and the NO donor. Thus, the Cu(II) ion-embedding film presented accelerated NO release and was further subjected to antibacterial testing to demonstrate the correlation between the NO release rate and the antibacterial activity. This study aimed to establish a novel paradigm for NO-releasing material design based on multilayered nanofilms by presenting the correlation between the NO release rate and the antibacterial effect.