Synthesis of an efficient photocatalyst by incorporation of phthalocyanine into KIT-6

Mesoporous magnetic supported Cu complex for one-pot synthesis of 5-substituted 1H-tetrazoles in green media and the oxidation of sulfides

We used the copper Phthalocyanine (Pc) on magnetic mesoporous silica nanoparticles. Therefore, several coordination sites became available which enhance chelating potency to load appropriate amounts of Gadolinium (Gd). This improves the catalytic activity in converting nitrile to tetrazole and selective oxidation of sulfides. Gadolinium (Gd) with incompletely occupied 4f and empty 5d orbitals can be used as the active component or as the promoter of the catalyst. Here, we outline the synthesis, characterization, and catalytic activity of a novel Gd(III) copper Phthalocyanine (Pc) coordination on the CoFe2O4/SBA-15 (CoFe2O4/SBA-15/CuPc@Gd). The prepared material was characterized using powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, elemental mapping, vibrating-sample magnetometer (VSM), Inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption isotherm. The CoFe2O4/SBA-15/CuPc@Gd composite consists of a mesoporous structure with a surface area by BET and t-plot of 122.2 m2/g and 86.28 m2/g respectively, with a mean pore size of 5.37 nm, and pore volume of 0.164 cm3/g. The CoFe2O4/SBA-15/CuPc@Gd was successfully applied as a powerful catalyst for green synthesis of 5-substituted 1H-tetrazoles in water and selective oxidation of sulfides at room temperature. This catalyst was recovered and reused several times without a significant decrease in efficiency and stability. The catalyst could be fully recovered by an external magnetic field and showed good reusability.

Degradation of Rhodamine B dye using the mesoporous material KIT-6/TiO2 photocatalyst obtained by in situ anchoring method

In this study, a novel synthesis approach was employed to create the KIT-6/TiO2 photocatalyst with different ratios of Si/Ti. The results of the X-ray diffraction revealed that incorporating TiO2 with the anatase phase maintained the mesoporous structure of KIT-6 (Korean Institute of Technology 6). The scanning electron microscope and transmission electron microscope images exhibited unobstructed mesopores, validating their anchoring within the internal structure of the support. Furthermore, nitrogen adsorption-desorption studies confirmed the presence of TiO2 within the pores. X-ray photoelectron spectroscopy (XPS) analysis corroborated the successful incorporation of TiO2, showing the presence of Ti4+ and Ti3+ species, with Ti3+ indicating the presence of oxygen vacancies that enhance photocatalytic performance. Photodegradation efficiency was assessed for Rhodamine B, achieving 95% and 86.5% for KIT-6/TiO2 (Si/Ti = 25) and KIT-6/TiO2 (Si/Ti = 75), respectively. The molar ratio Si/Ti = 25 exhibited higher activity, which can be attributed to a better distribution of active sites, as confirmed by the measurement of turnover frequency (TOF = 2.0 × 10-2 min-1). The stability of the KIT-6/TiO2 (Si/Ti = 25) has also been investigated, and stable performance in recycling photocatalytic reactions was obtained after four cycles of use. The scavengers used indicated that the superoxide anion radical (•O2-) and electron (e-) were the major active species. This study successfully demonstrated the incorporation of TiO2 into the walls of mesoporous materials using the ISA method, achieving high photocatalytic efficiency. Moreover, this method enabled superior performance with a reduced amount of photocatalyst compared to a pure TiO2 sample.

A versatile heterogeneous photocatalyst: nanoporous gold powder modified with a zinc(II) phthalocyanine derivative for singlet oxygen [4 + 2] cycloadditions

Nanoporous gold was functionalized with a photosensitizer, a zinc(II) phthalocyanine derivative. Such systems are active for the generation of reactive singlet oxygen which can be used for photocatalytic oxidation reactions. This study aims to demonstrate the versatility of such an approach, in terms of substrates and the employed solvent, only possible for a truly heterogeneous catalytic system. The activity of the hybrid system was studied for [4 + 2] cycloadditions of three different types of dienes and a total of eight substrates in two organic solvents and once in water. The highest activity was measured for 1,3-diphenylisobenzofuran, which is also highest in terms of sensitivity for the reaction with ¹O₂. Trends in conversion could be anticipated based on reported values for the rate constant for the reaction of ¹O₂. In almost all cases, an amplification of the conversion by immobilization of the sensitizer onto nanoporous gold was observed. The limiting case was ergosterol, which was the largest of all substrates with a van-der-Waals radius of about 2.1 nm. Additional factors such as the limited lifetime of ¹O₂ in different solvents as well as the hampered diffusion of the substrates were identified.