Synthesis and characterization of thianthrene-containing poly(benzoxazole)s

New thioether- and thianthrene-containing poly(benzoxazole)s (PBOs) were synthesized from 4,4′-thiobis[3-chlorobenzoic acid] and thianthrene-2,7- and -2,8-dicarbonyl chlorides with commercially available bis-o-aminophenols. Polymers were prepared via solution polycondensation in poly(phosphoric acid) at 90–200°C. Transparent PBO films were cast directly from polymerization mixtures or m-cresol. The films were flexible and tough. Non-fluorinated PBOs were soluble only in strong acids and AlCl₃/NO₂R systems by forming complexes with the benzoxazole heterocycle Glass transition temperatures ranged from 298–450°C, and thermogravimetric analysis showed good thermal stabilities in both air and nitrogen atmospheres. © 1995 John Wiley & Sons, Inc.     

Synthesis of thianthrene‐5,5,10,10‐tetraoxide‐containing polyimides via Yamazaki–Higashi phosphorylation method and their pervaporation properties to aromatic/nonaromatic hydrocarbon mixtures

High molecular weight polyimide was successfully prepared from thianthrene‐2,3,7,8‐tetracarboxylic acid‐5,5,10,10‐tetraoxide (TADATO‐4A) and 3,7‐diamino‐2,8(6)‐dimethyldibenzothiophene sulfone (DDBT) via the Yamazaki–Higashi phosphorylation method in the presence of triphenyl phosphite (TPP) and pyridine (Py). The obtained polyimide showed about 3–4 times larger inherent viscosity than that prepared by the conventional two‐step method in which the anhydride form (TADATO) of TADATO‐4A was used. The combination of the conventional two‐step method and Yamazaki–Higashi phosphorylation method, in which a dianhydride monomer [3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA)] was allowed to react with excessive DDBT to form an amine end‐capped polyamic acid oligomer and subsequently the oligomer was further polymerized with TADATO‐4A in the presence of TPP and Py, succeeded in giving the high molecular weight copolyimide, TADATO/DSDA(1/1)‐DDBT. However, both TADATO‐DDBT and TADATO/DSDA(1/1)‐DDBT showed fairly poor thermal stability due to the highly rigid structures. The pervaporation (PV) properties of the prepared polyimide membranes for benzene/cyclohexane (Bz/Cx) and benzene/n‐hexane (Bz/n‐Hx) mixtures were investigated. TADATO‐DDBT showed similar PV performance to DSDA‐DDBT at 60 °C. The sorption measurement revealed that these two kinds of polyimide membranes had a similar sorption amount, solubility selectivity, and diffusivity selectivity. The PV performance of TADATO/DSDA(1/1)‐DDBT was also found similar to DSDA‐DDBT for Bz/Cx mixture. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 895–906, 2000     

Structural Characterization,Antimicrobial Activity and BSA/DNA Binding Affinity of New Silver(I) Complexes with Thianthrene and 1,8-Naphthyridine

Three new silver(I) complexes [Ag(NO₃)(tia)(H₂O)]_n (Ag1), [Ag(CF₃SO₃)(1,8-naph)]_n (Ag2) and [Ag₂(1,8-naph)₂(H₂O)_1.2](PF₆)₂ (Ag3), where tia is thianthrene and 1,8-naph is 1,8-naphthyridine, were synthesized and structurally characterized by different spectroscopic and electrochemical methods and their crystal structures were determined by single-crystal X-ray diffraction analysis. Their antimicrobial potential was evaluated against four bacterial and three Candida species, and the obtained results revealed that these complexes showed significant activity toward the Gram-positive Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa and the investigated Candida species with minimal inhibitory concentration (MIC) values in the range 1.56–7.81 μg/mL. On the other hand, tia and 1,8-naph ligands were not active against the investigated strains, suggesting that their complexation with Ag(I) ion results in the formation of antimicrobial compounds. Moreover, low toxicity of the complexes was detected by in vivo model Caenorhabditis elegans. The interaction of the complexes with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) was studied to evaluate their binding affinity towards these biomolecules for possible insights into the mode of antimicrobial activity. The binding affinity of Ag1–3 to BSA was higher than that for DNA, indicating that proteins could be more favorable binding sites for these complexes in comparison to the nucleic acids.