Three Isomeric Zn(II)–Sn(IV)–Zn(II) Porphyrin-Triad-Based Supramolecular Nanoarchitectures for the Morphology-Dependent Photocatalytic Degradation of Methyl Orange

Abstract

Three isomeric Zn(II)–Sn(IV)–Zn(II) porphyrin-based triads ( T2 , T3 , and T4 ) were synthesized by the reaction of common Zn(II) porphyrins (ZnL) with different Sn(IV) porphyrins ( SnP n ). The Sn(IV) porphyrin precursors differ with respect to the position of the pyridyl- N atoms. All compounds were characterized by 1 H NMR, UV–vis, fluorescence spectroscopy, electrospray ionization–mass spectrometry, and field-emission scanning electron microscopy measurements. In these structures, the intramolecular cooperative metal–ligand coordination of the 3-pyridyl nitrogen in SnP 3 with axial ZnL and the π–π interactions between the adjacent porphyrin triad are the determining factors affecting the nanostructures of T3 . Owing to the geometrical constraints of the SnP 2 center, this type of interaction is not possible for T2 . Therefore, only the π–π interactions affect the self-assembly process. In the case of SnP 4 , intermolecular coordinative interactions and then π–π interactions are responsible for the nanostructure of T4 . The morphology-dependent photocatalytic degradation of methyl orange (MO) dye in aqueous solution under visible light irradiation was observed for these photocatalysts, and the degradation ratio of MO varied from 76 to 94% within 100 min. Nanorod-shaped T3 exhibited higher performance compared to nanosphere T2 and nanoflake T4 .

Sn(IV) Porphyrin-Based Ionic Self-Assembled Nanostructures and Their Application in Visible Light Photo-Degradation of Malachite Green

“…Several possible mechanisms for the photodegradation of pollutant dyes in aqueous solutions using porphyrin-based photocatalysts have been reported [11,[15][16][17]. The mechanism consists of five steps for porphyrin-based nanomaterials (P).…”

“…From Figure S16, the degradation rate was affected by the presence of t BuOH as well as BQ, suggesting that hydroxyl radicals and superoxide radicals are the major reactive species that contribute to the catalytic oxidation of the MG dye. For further details on the detection of all intermediate species involved in the dye degradation process (all oxygen species, such as 1 O 2 and 3 O 2 , • OH, or O 2 −• ), readers can refer to our previous reports [11,[15][16][17].…”

“…However, the use of porphyrinoids in homogeneous catalysis has drawbacks, which include the aggregation of porphyrin in solution, low reusability, and poor recovery from the reaction mixture. To overcome these challenges, porphyrin-based nano-or microstructured materials have been proposed and have received significant attention from the basic and applied chemistry research community over the last two decades [14][15][16][17]. These nanomaterials display unique features, including large surface areas and high physicochemical stability, compared to their parent compounds.…”

Photocatalytic Hydrogen Production by the Sensitization of Sn(IV)-Porphyrin Embedded in a Nafion Matrix Coated on TiO2

“…Sn(IV)-porphyrin has an intrinsically strong oxidation ability owing to the high charge of the Sn(IV) center; consequently, the excited state of SnP has a high affinity for electrons that initiate photooxidative reactions. The excited Sn(IV)-porphyrin exhibits a high photochemical activity for the oxidative degradation of organic pollutants under visible light [14][15][16][17][18][19]. Sn(IV)-porphyrin complex-based nanoparticles have been also used in photochemical hydrogen production [20].…”

“…Molecules 2022, 27, x 2 of 10 [14][15][16][17][18][19]. Sn(IV)-porphyrin complex-based nanoparticles have been also used in photochemical hydrogen production [20].…”