Triazole-Containing Dendrimer-like Core Cross-Linked Micelles that Stabilize Pd Nanoparticles as Heterogenized Homogeneous Catalysts for Room-Temperature Suzuki-Miyaura Reactions in Water

The influence of ferrocene anchoring method on the reactivity and stability of SBA-15-based catalysts in the degradation of ciprofloxacin via photo-Fenton process

The study is aimed at evaluation of the impact of ferrocene (Fc) anchoring method on the efficiency of its incorporation on the surface of mesoporous silica SBA-15, as well as the reactivity and stability of these hybrid organic-inorganic materials in degradation of ciprofloxacin (CIP) via photocatalytic, Fenton and photo-Fenton processes. For this purpose, Fc was anchored on SBA-15 supports via three different methods: (i) Schiff base formation, (ii) Friedel-Crafts alkylation, and (iii) click reaction (azide-alkyne cycloaddition). The as-prepared materials were characterized by powder X-ray diffraction, nitrogen physisorption, infrared spectroscopy and inductively coupled plasma optical emission spectrometry, as well as UV-visible and X-ray photoelectron spectroscopies. The highest efficiency of Fc anchoring was obtained when applying the Friedel-Crafts alkylation, while the least effective was the Schiff base formation. As concerns the catalysts activity, all materials exhibited negligible reactivity in the photocatalytic process, but were capable of degrading CIP in the presence of H₂O₂ (Fenton process). For all materials, the highest efficiency of CIP removal was observed for the photo-Fenton reaction. When expressed as the activity of a single Fc site, the most reactive were Fc species from the catalyst prepared by the click reaction. All materials, irrespectively of the ferrocene anchoring method, were deactivating over the reaction time because of Fc leaching. The highest stability in three subsequent reaction cycles was observed for the catalyst prepared by the azide-alkyne cycloaddition. Thus, the click reaction was found to be the best method for the preparation of Fc-containing catalysts for CIP degradation.

Construction and morphology of non-covalently double-crosslinked supramolecular polymer networks

A straightforward synthesis of α-Ba, ω-TAP functionalized polymers, Ba-PnBuA-TAP, is reported, leading to the formation of double-crosslinked supramolecular networks driven via the sequential hydrogen-bonding association and metal-coordination.

Scope and limitation of propylene carbonate as a sustainable solvent in the Suzuki–Miyaura reaction

The Suzuki–Miyaura reaction is one of the most used transformations in drug research. Thus making this reaction more sustainable is of considerable current interest. Here we show that propylene carbonate (PC) can be used as a solvent for the Suzuki–Miyaura reaction. PC is one of the greenest solvents since it is synthesized under green conditions by the use of carbon dioxide in the air. All reactions proceeded well and good or excellent yields were observed for the biaryl products. Nonetheless in the case of pyridazinones, 2-hydroxypropyl- chain containing side-products were observed. Importantly, this fact allowed the isolation of several novel compounds which were generated under prominently green conditions.

The Suzuki–Miyaura reaction was carried out in propylene carbonate yielding an interesting side-product besides the biphenyl derivative.

Poly(tetrafluoroethylene)-Stabilized Metal Nanoparticles: Preparation and Evaluation of Catalytic Activity for Suzuki, Heck, and Arene Hydrogenation in Water

Poly(tetrafluoroethylene)-stabilized Pd nanoparticles (PTFE-PdNPs) were prepared in water with 4-methylphenylboronic acid as a reductant and characterized using powder X-ray diffraction, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Small PdNPs with a fairly uniform size were obtained in the presence of PTFE, whereas aggregation of palladium was observed in the absence of PTFE. PTFE-PdNPs showed high catalytic activity for the Suzuki coupling reaction in water and were reused without any loss of activity. No palladium species were observed by ICP-AES analysis in the reaction solution after the reaction, nor was any change in particle size observed after the recycle experiment. PTFE-PdNPs also exhibited excellent catalytic activity and reusability for the Heck reaction in water. Although palladium species were not detected in the reaction solution after the reaction, aggregates and smaller sizes of PdNPs were observed in the TEM image of the recovered catalyst. PTFE was also useful as the stabilizer of rhodium nanoparticles (RhNPs) prepared by reduction with NaBH4. PTFE-RhNPs showed high catalytic activity and reusability toward arene hydrogenation under mild conditions.

Latent Naphthalimide Bearing Water-Soluble Nanoprobes with Catechol-Fe(III) Cores for in Vivo Fluorescence Imaging of Intracellular Thiols

Here, a novel latent naphthalimide bearing water-soluble nanoprobes with catechol-Fe(III) cores (Fe@LNNPs) was designed, synthesized, and evaluated for in vivo fluorescence imaging of intracellular thiols, as various diseases are associated with overexpression of cellular biothiols. The Fe@LNNPs are mainly composed of three components. The inner part constitutes pyrocatechol groups, which can coordinate with Fe(III) to form a cross-linked core for improving the stability in the complex biological environment. The naphthalimide group is linked by disulfide with the core to quench the probe fluorescence. The outer part is designed to be a hydrophilic glycol corona for prolonging blood circulation. Also, a biotin group can be easily introduced into the nanoprobe for actively targeting the HepG2 cells. The fluorescence spectra reveals that the Fe@LNNPs can be reduced explicitly by glutathione to trigger the fluorescence emission. Confocal microscopic imagings and animal experiments manifest that the Fe@LNNPs, especially with biotin groups, have much better fluorescence signal imaging compared to the reported small-molecule probe 1' both in vitro and in vivo (up to 24 h). The Fe@LNNPs thus feature great advantages such as specificity, stability, biocompatibility, and long retention time for thiol-recognition imaging and hold potential applications in clinical cancer diagnosis.

Magnetic dendritic polymer nanocomposites as supports for palladium: a highly efficient and reusable catalyst for Mizoroki–Heck and Suzuki–Miyaura coupling reactions

A novel catalyst Fe₃O₄@SiO₂-Dendrimer-Pd based on palladium immobilized on magnetic dendritic polymer nanocomposites was successfully synthesized and characterized by FT-IR, EA, XRD, TEM, EDX, VSM and XPS.

Tetraphenylethylene-Induced Cross-Linked Vesicles with Tunable Luminescence and Controllable Stability

Luminescence-tunable vesicles (LTVs) are becoming increasingly attractive for their potential application in optics, electronics, and biomedical technology. However, for real applications, luminous efficiency and durability are two urgent constraints to be overcome. Combining the advantages of aggregation-induced emission in luminous enhancement and cross-linking in stability, we herein fabricated tetraphenylethylene-induced cross-linked vesicles with an entrapped acceptor of RhB (TPE-CVs@RhB), which achieved a high-efficiency multicolor emission of the visible spectrum, including white, by altering the amount of entrapped acceptor. Stability tests show that the luminescence of TPE-CVs@RhB has excellent environmental tolerance toward heating, dilution, doping of organic solvent, and storage in serum. Further outstanding performance in the application of fluorescent inks suggests that the new LTVs hold high potential in industrialization. More attractively, although the TPE-CVs@RhB can tolerate various harsh conditions, their stability can actually be controlled through the cross-linker adopted. For example, the employment of dithiothreitol in the present work produces an acid-labile β-thiopropionate linker. The cellular uptake by HepG2 cells shows that the acid-labile TPE-CVs@RhB can effectively respond to the acidic environment of cancer cells and release the entrapped RhB molecules, indicative of promising applications of this new type of LTVs in bioimaging and drug delivery.