Inorganics

Anilido-oxazoline iron(II) chloride complexes were synthesized and evaluated for their catalytic performance in the ring-opening polymerization (ROP) of cyclic esters. Complexes 1–5 were obtained via transmetalation of FeCl₂(THF)_1.5 and pyridine derivatives with in situ generated anilido-oxazoline lithium. They exhibited excellent controllability and high initiating efficiency in the ROP of ε-caprolactone (CL). In the presence of benzyl alcohol as the initiator, these iron complexes efficiently catalyzed the ROP of CL, reaching a TOF of 3.2 × 10³ h⁻¹. High molecular weight polycaprolactone was obtained with a number-average molecular weight of 161.38 kg/mol. The chain initiation and propagation processes were investigated using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and kinetic analyses. Kinetic studies confirmed a pseudo-first-order dependence of the polymerization rate on catalyst concentration. Furthermore, the iron(II) complexes were also found to be efficient catalysts for the ROP of δ-valerolactone.

Methane (CH₄) is the second-largest contributor to climate change after carbon dioxide (CO₂) and has a global warming potential about 72 times greater than CO₂ over a 20-year timescale. A possible solution to mitigate CH₄ emissions from diluted sources is direct removal of CH₄ through tailored sorbents. In this work, ion-exchanged zeolites have been investigated, owing to their low cost, excellent chemical stability, and ease of production. The impact of barium, lithium, and nickel exchange was investigated, along with one, three, and five ion-exchange sequences. XRD analysis confirmed that the structure remained intact after ion exchange. However, nitrogen physisorption revealed that nickel- and barium-exchanged zeolites had reduced pore volume and surface area compared to the parent zeolite, possibly due to mesopore formation from lattice strain relaxation. ICP-OES and SEM-EDX confirmed the successful incorporation of metals into the zeolite. Finally, breakthrough experiments were carried out to assess the saturation capacity of the synthesized sample. The results demonstrated that the lithium-exchanged samples provided the highest saturation capacity, namely 1.58 ± 0.05 mmol g⁻¹ for the Li-13X-3 and 1.76 ± 0.07 mmol g⁻¹ for the Li-SAPO34-5 over 10 adsorption cycles. Furthermore, the stability of the Li-SAPO34-5 was confirmed over 100 adsorption cycles.

Electrodeposition of copper on the surface of the high-carbon steel (HCS) cathode was carried out in situ during the electrolysis of an aqueous KOH solution with a copper anode. A mechanism was proposed for the transfer of the copper from the anode to the cathode, followed by the formation of a copper film on the HCS. The surface roughness of the substrate and the copper coating was studied using AFM and profilographic data. There is a discrepancy between the roughness values of the substrate and coating obtained using different techniques. The surface morphology of the substrate was found to affect the copper film quality. The roughness of the copper coating calculated using AFM data replicated the roughness of the substrate surface. It was found that, despite some difference in the roughness calculated by profilographic and AFM data, the overall roughness trend remains unchanged.