Triazine-Based Porous Organic Polymers: Synthesis and Application in Dye Adsorption and Catalysis

Abstract

The scientific community has been developing promising materials to increase the sustainability and efficiency of production processes and pollutant environmental remediation strategies. Porous organic polymers (POPs) are of special interest, as they are insoluble custom-built materials at the molecular level, endowed with low densities and high stability, surface areas, and porosity. This paper describes the synthesis, characterization, and performance of three triazine-based POPs (T-POPs) in dye adsorption and Henry reaction catalysis. T-POPs were prepared by a polycondensation reaction between melamine and a dialdehyde (terephthalaldehyde (T-POP1) or isophthalaldehyde derivatives with a hydroxyl group (T-POP2) or both a hydroxyl and a carboxyl group (T-POP3)). The crosslinked and mesoporous polyaminal structures, with surface areas between 139.2 and 287.4 m2 g−1, positive charge, and high thermal stability, proved to be excellent methyl orange adsorbents, removing the anionic dye with an efficiency >99% in just 15–20 min. The POPs were also effective for methylene blue cationic dye removal from water, reaching efficiencies up to ca. 99.4%, possibly due to favorable interactions via deprotonation of T-POP3 carboxyl groups. The modification of the most basic polymers, T-POP1 and T-POP2, with copper(II) allowed the best efficiencies in Henry reactions catalysis, leading to excellent conversions (97%) and selectivities (99.9%).

Synthesis and Characterization of Bromine- and Hydroxyl-Functionalized Polyaminals for CO₂ Capture

“…The characteristic peaks of C−N exist at 1329 and 1348 cm -1 for PAN-BrNA and PAN-HNA, respectively. PAN-BrNA and PAN-HNA have C-H stretching vibrations at 2929 and 2969 cm -1 , respectively [12]. For PAN-BrNA, The aminal linkage stretching vibration occurs at 3440 and 1197 cm -1 , and the band at 1046 cm -1 is due to the stretching vibrations of the C-Br bond [13].…”

“…For PAN-BrNA, The aminal linkage stretching vibration occurs at 3440 and 1197 cm -1 , and the band at 1046 cm -1 is due to the stretching vibrations of the C-Br bond [13]. The O-H characteristic peaks are energetically overlapped with N-H, resulting in one broad peak of 3414 cm -1 in PAN-HNA spectra [12]. In order to further verify the PAN-BrNA and PAN-HNA network structure, the solid-state 13 C NMR spectrums were recorded, as shown in Figure 2 (a, b), respectively.…”

Triazene-Linked Porous Organic Polymers for Heterogeneous Catalysis and Pollutant Adsorption

“…Porous organic polymers (POPs) are an emerging class of reticulated organic macromolecules that combine rigid, covalent structures and intrinsic, permanent porosity with low density, high specific surface area, and thermal and chemical stabilities. − POPs encompass several different families of polymerssuch as porous aromatic frameworks (PAFs), covalent organic frameworks (COFs), covalent triazine frameworks (CTFs), conjugated microporous polymers (CMPs), hyper-cross-linked polymers (HCPs), or polymers with intrinsic microporosity (PIMs), among otherswith differing physical and chemical characteristics, depending on the type of building blocks used and reaction conditions employed. ,− Precisely due to their high synthetic diversity and pore customizability, POPs are regarded as highly potential materials for a wide array of applications in different scientific fields, thus constituting one of the most currently researched topics in materials chemistry. Over the years, POP materials have been successfully used in the most varied applications, such as molecular biosensing, drug delivery systems and related biomedical applications, − gas capture and storage, , optoelectronics and energy storage, − adsorption of pollutants from aqueous solution, − and heterogeneous catalysisincluding conventional, − electrocatalytic, and photocatalytic , variantsamong others.…”