Four new symmetrical Schiff bases derived from 2,2′-diamino-6,6′-dibromo-4,4′-dimethyl-1,1′-biphenyl or 2,2′-diamino-4,4′-dimethyl-1,1′-biphenyl, and 3,5-dichloro- or 5-nitro-salicylaldehyde, were synthesized and reacted with copper-, iron- and zinc-acetate, producing the corresponding complexes. The Schiff bases and their metal complexes were characterized by ¹H-, ¹³C-NMR, IR and UV-Vis spectroscopy and elemental analysis. The structures of one Schiff base and the two zinc complexes were resolved by X-ray structure determination. Density functional theory (DFT) calculations at the B3LYP/6-31G(d) level of the latter compounds were carried out to optimize and examine their molecular geometries. The biomedical applications of the Schiff bases and their complexes were investigated as anticancer or antimicrobial agents.

A new open-chain ether-linked polymer has been prepared via nucleophilic aromatic substitution reaction on a C-F bond of 1,4-dibromo-2,5-difluorobenzene by using 2,2-bis(4-hydroxyphenyl) hexafluoropropane (bisphenol AF or BAF). The new polymer (PE-AF) has shown a good solubility in non-polar solvents, good thermal stability (up to 300 °C) and random surface morphology. Tailoring these properties has been achieved by utilizing the post-modification synthetic methodology on the bromo-sites of the polymer backbone via the application of an Ullmann coupling reaction with aniline to form the polymer (PE-Sec-NHPh). The successful synthesis of the polymers has been confirmed by elemental analysis, infrared spectroscopy (IR), ¹H- and ¹³C-NMR and ¹³C CP-MAS solid state. Upon incorporation of the aniline linker, the nitrogen content increased when compared with the parent polymer chain, and thus PE-Sec-NHPh revealed a higher thermal stability up to 350 °C and a more uniformly aggregated morphology (spherical particles ca. 0.3–0.1 µm). A further evaluation has been conducted on the polymers by measuring their surface tendency toward carbon dioxide capture. Interestingly, despite their non-porous nature, the polymers demonstrated a reasonable amount of gas capture that reached 90.0 and 41.0 mg/g for PE-Sec-NHPh and PE-AF, respectively. Furthermore, the calculated CO₂ binding affinities of the polymers are consistent with data reported previously in the literature.

This study reports on the synthesis and characterization of novel perfluorinated organic polymers with azo- and azomethine-based linkers using nucleophilic aromatic substitution. The polymers were synthesized via the incorporation of decafluorobiphenyl and hexafluorobenzene linkers with diphenols in the basic medium. The variation in the linkers allowed the synthesis of polymers with different fluorine and nitrogen contents. The rich fluorine polymers were slightly soluble in THF and have shown molecular weights ranging from 4886 to 11,948 g/mol. All polymers exhibit thermal stability in the range of 350–500 °C, which can be attributed to their structural geometry, elemental contents, branching, and cross-linking. For instance, the cross-linked polymers with high nitrogen content, DAB-Z-1h and DAB-Z-1O, are more stable than azomethine-based polymers. The cross-linking was characterized by porosity measurements. The azo-based polymer exhibited the highest surface area of 770 m²/g with a pore volume of 0.35 cm³/g, while the open-chain azomethine-based polymer revealed the lowest surface area of 285 m²/g with a pore volume of 0.0872 cm³/g. Porous structures with varied hydrophobicities were investigated as adsorbents for separating water-benzene and water-phenol mixtures and selectively binding methane/carbon dioxide gases from the air. The most hydrophobic polymers containing the decafluorbiphenyl linker were suitable for benzene separation, while the best methane uptake values were 6.14 and 3.46 mg/g for DAB-Z-1O and DAB-A-1O, respectively. On the other hand, DAB-Z-1h, with the highest surface area and being rich in nitrogen sites, has recorded the highest CO₂ uptake at 298 K (17.25 mg/g).

In this report, an open-chain ether-linked polymer (PE-AF) has been prepared via one-step co-condensation polymerization of 1,4-dibromo-2,5-difluorobenzene with bisphenol AF. The new polymer has shown a good solubility in non-polar solvents, good thermal stability (up to 300 °C), high char residue with a limiting oxygen index (LOI) of 33.5, surface morphology with random fluffy-like texture, and a non-porosity nature with a surface area (SA) of 35 m²g⁻¹. Tailoring these properties has been achieved by considering post-modification on the Bromo-sites of the polymer backbone. The post-modification was attained by applying Ullmann-coupling reaction of the Bromo-sites of PE-AF and aromatic diamines in presence of a catalytic amount of copper iodide. Upon inclusion of the aromatic diamines within the polymer’s backbone, the new polymers have depicted aggregated surface morphology (e.g. spherical particles ca. 0.3–0.1 µm), pronounced porosity nature (SA up to 354 m²g⁻¹), varied range of pore size distribution, and higher thermal stability with lower char residue contents when compared with PE-AF. The successful production of the polymers was confirmed by (C, H, O, and N) elemental analysis, solid-state ¹³C-NMR, and infrared (IR) spectroscopy. The application of Ullmann-coupling raises the opportunity to create cavities and pores within the polymer’s framework. Though this modification lowered the LOI of the polymers and their flame-retardant tendency, it enhanced their opportunity for gas capture and separation applications.