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

Abstract

Sub 5 micrometer sized polystyrenic microspheres bearing theophylline residues were synthesized and used as adsorbent and catalytic support for palladium ions.

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

“…It needs to note here that the microflowers with nanopetals of theophylline–Pd complexes once formed are not soluble in any solvents. For comparison, we examined two kinds of catalysts (one is a water-soluble polymers bearing theophylline–Pd complex (not published) and other one is heterogeneous theophylline–Pd( ii ) catalyst supported by polystyrenic spheres 41 ) in C–C coupling reaction between BB and PBA in the same conditions, but no predominance in the yields of biphenyl appeared than the case of microflowers. It is conceivable that the nanopetals on microflowers, which have a lot of Pd species in their surface, might be helpful in concentration and diffusion of the substances and thus promote the reaction.…”

“…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.…”

“…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. In this work, we found that complexation-driven self-assemblies between bis-theophylline alkane and PdCl 2 in aqueous media results in microowers packed densely by nanopetals.…”

Photoluminescent polymer micelles with thermo-/pH-/metal responsibility and their features in selective optical sensing of Pd(ii) cations

“…Recently, we developed a strategy to fabricate nano/micro polymeric materials using theophylline-Pd complexation as a driving force. 54,56 In contrast to imidazole, theophylline (T) can chelate with Pd(II) even in strong acidic conditions to form a stable complex consisting of T 2 Pd. Thus, the moiety of theophylline features selective adsorption of palladium in mixed metal ions.…”

“…53 Very recently, we revealed that theophylline, an imidazolecondensed xanthine derivative, is a strong receptor of Pd(II) ions due to the formation of an extraordinary stable complex with Pd(II), and we found that polymers bearing residues of the theophylline coordinated-Pd(II) complex could function as good catalysts in C-C coupling reactions. 54,55 Herein, we focused our attention on multiple stimuli-responsive issues in the design of an amphiphilic block copolymer comprising a pH/photoresponsive non-conjugated hydrophobic polystyrenic block with pendant rings of a xanthine derivative (theophylline) and imidazole and a thermo-responsive hydrophilic block of PNIPAM. We rstly synthesized a block copolymer that consisted of a poly(vinylbenzyl chloride) (PVBC) block and PNIPAM block via RAFT polymerization, and then we introduced theophylline (xanthine derivative) and/or imidazole pendants into the PVBC block.…”