Selective Extraction of Palladium(II) with Theophylline Derivatives

Microflowers formed by complexation-driven self-assembly between palladium(ii) and bis-theophyllines: immortal catalyst for C–C cross-coupling reactions

“…The decomplexation occurs in the limited conditions such as in the high concentrations of ammonia and/or thiourea solutions. [39][40][41] Therefore, we believe that Pd(II)-theophyllines microowers produced via complexation-driven self-assembly have great potential for developing generation-updated heterogeneous catalyst for the C-C cross coupling. Further related study using Pd(II)-theophylline-based heterogeneous catalysts is in progress.…”

“…In our early study, we elucidated that xanthine derivatives, such as theophylline and theobromine, are strong ligands for selectively capturing palladium chloride even in the hydrochloric acid media to form complex comprised of two molecules of xanthine derivatives and a palladium chloride by chelate bond. 39,40 Focusing on the feature of strong coordination of theophylline to palladium(II), we have developed an excellent adsorbent of porous polystyrenic sub-5 micrometer spheres bearing theophylline residues and found that the adsorbent with trapping Pd(II) ions plays well as a catalyst in the Suzuki-Miyaura C-C coupling reaction in aqueous media. 41 This promoted us to explore theophylline-mediated heterogeneous palladium catalyst system.…”

Theophylline-bearing microspheres with dual features as a coordinative adsorbent and catalytic support for palladium ions

“…The FT-IR spectra were recorded on a Jasco FT/IR-4600 spectrometer by diffusing the samples in KBr pellets. 13 C cross polarization magic angle spinning (CP/MAS) NMR spectra were obtained using a JEOL ECA-400 spectrometer operated at 100.53 MHz. The amount of theophylline residues in the microspheres…”

“…In an early report, it was shown that xanthine derivatives, such as theophylline and theobromine, are effective ligands for selectively capturing palladium ions and using them in a liquid-liquid extraction process for the selective recovery of palladium in mixed metal ions. 13,14 Unfortunately, this is not an attractive recycling approach because the theophylline-palladium complex is very soluble and thus consumes a lot of organic solvents in the extraction process. An effective method for solving this problem is to x theophylline residues onto a solid surface that has hydrophilic features.…”