New poly(aryl ether ketone)s containing 2,6-diphenylpyridyl units and diphenylphosphinophenyl pendant groups

4-(4-Diphenylphosphino)phenyl-2,6-bis(4-hydroxyphenyl)pyridine, as a new bisphenol monomer, was prepared from 4-(diphenylphosphino)benzaldehyde and 4-hydroxyacetophenone and used in the preparation of several aromatic poly(ether ketone)s (PEKs) containing 2,6-diphenylpyridyl units and diphenylphosphinophenyl pendant groups via a nucleophilic aromatic substitution polycondensation with difluorinated aromatic ketones. The polycondensation proceeded quantitatively in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the polymers with high molecular weights. The resulting PEKs are amorphous and exhibit high glass transition temperatures of 209–255°C and 5% weight loss temperatures of 536–554°C with char yields of 57–62% at 800°C in nitrogen. Their high char yields and good limited oxygen index values ranging from 39 to 43 indicated these polymers exhibited good thermal stability and flame-retardant property. All new PEKs were soluble in common organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and chloroform and could form tough, flexible, and strong films with tensile strengths of 74.6–86.8 MPa, tensile moduli of 2.9–3.6 GPa, and elongations at break of 5–9%.

Synthesis, Optical and Electrochemical Properties of High-Quality Cross-Conjugated Aromatic Polyketones

This paper describes the synthesis and characterization of three new aromatic polyketones with repeating units based on 2,2'-(2,5-dihexyl-1,4-phenylene) dithiophene (PTK), 2,2'-(9,9-dihexyl-9H-fluorene-2,7-diyl)dithiophene (PFTK), and 4,7-bis(3-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (PBTK). These polymers were obtained with a one-pot Suzuki-Miyaura cross-coupling-promoted homopolymerization to afford high-quality, defect-free polymers. Experimental and theoretical studies were applied to investigate their optical and electrical properties. The cross-conjugated nature of aromatic polyketones imparts excellent thermal stability. Exposure to acid converts the cross-conjugation to linear-conjugation, enabling the dynamic tuning of optoelectronic properties.

Preparation of poly(ether ketone)s having phenyl, biphenyl, and terphenyl side groups and comparison of their properties

Three kinds of bis(aromatic fluoride) compounds, 3,5-bis(4-fluorobenzoyl)biphenyl (1), 3,5-bis(4-fluorobenzoyl)-1,1′:4′,1″-terphenyl (2), and 3,5-bis(4-fluorobenzoyl)-1,1′:4′,1″:4″,1′′′-quaterphenyl (3), were synthesized by cross-coupling of the corresponding triflates with phenylboronic acid. Linear poly(ether ketone)s (1x, 2x, and 3x) having phenyl, biphenyl, and terphenyl side groups, respectively, were prepared by the polycondensation of the bis(aromatic fluoride) compounds with bisphenol A (a) and 4,4′-dihydroxybiphenyl (b) in N-methyl-2-pyrrolidone. The obtained poly(ether ketone)s were characterized by X-ray diffraction, differential scanning calorimetry, and thermogravimetry. The structure–property relationships of these poly(ether ketone)s were examined and compared with those of poly(ether ketone)s (4x) having no side group, which were prepared from 3,5-bis(4-fluorobenzoyl)benzene (4). The properties of the poly(ether ketone)s, solubilities, and thermal properties were compared and discussed based on the length of the side groups.

Effect of chalcogens on CO insertion into the palladium-methyl bond of [(N^N^X)Pd(CH3)](+) (X = O, S, Se) and on CO/ethylene copolymerisation

Neutral chloromethylpalladium(II) complexes, [Pd(Cl)(CH3)(L)] (1a-5a) with ligands κ(2)-N^S-2-((3,5-di-tert-butyl-1H-pyrazol-1-yl)methyl)-6-(phenylthiomethyl)pyridine (L1), κ(2)-N^S-2-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-6-(phenylthiomethyl)pyridine (L2), κ(2)-N^Se-2-((3,5-di-tert-butyl-1H-pyrazol-1-yl)methyl)-6-(phenylselanylmethyl)pyridine (L3), κ(2)-N^Se-2-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-6-(phenylselanylmethyl)pyridine (L4), and κ(2)-N^N-2-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-6-(phenoxymethyl)pyridine (L5) have been synthesised and characterised by various spectroscopic techniques. Ligands L1-L4 exhibit Npy^S/Se bidentate coordination whereas L5 shows an Npy^Npz bidentate coordination mode in their corresponding neutral palladium complexes. Abstraction of chloride in neutral palladium complexes with NaBAr4 (BAr4 = tetrakis[3,5-bis(trifluoromethyl)-phenyl]borate) resulted in the formation of the cationic palladium complexes 1b-5b, in which L1-L4 adopt a tridentate Npz^Npy^X (X = S or Se) coordination mode in their respective cationic palladium complexes (1b-4b) whilst L5 in complex 5b adopts a Npy^Npz bidentate coordination mode and the palladium centre is stabilized by the weakly coordinating acetonitrile. Compounds 1b-5b readily undergo CO insertion into the Pd-CH3 bond to form Pd-acyl that determines their ability to catalyse CO/ethylene copolymerisation to polyketones.