The thermal and physicochemical properties of protic ionic liquids (PILs) are reported. It is highly evident that there has been an extensive range of alkylammonium, imidazolium, and heterocyclic cations paired with many organic and inorganic anions that have been employed to prepare PILs. There has been strong interest in modifying the properties of PILs through the addition of water or other molecular solvents. For many applications, the presence of some water in the PILs is not detrimental, and instead leads to enhanced solvent properties such as lower viscosity, higher conductivities, and lower melting points. It remains an issue of definition though of how to refer to these resulting protic solutions. There is also an ongoing difficulty surrounding how to describe the proton activity in the PILs, analogous to pH in aqueous systems. For a broad range of applications, it has been reported that the acidity/basicity of the PIL or PIL-solvent system is crucial for their beneficial properties. It is expected that the fundamental properties of PILs will continue to be explored, along with continued interest in many existing and new applications, such as in electrochemistry, organic and inorganic synthesis, and biological applications. In particular, there has been a significant interest in a broad- range of PILs for use as electrolytes and incorporation in polymer electrolytes for fuel cells, and other energy storage devices.

Protic Ionic Liquids: Evolving Structure–Property Relationships and Expanding Applications

In this manuscript, four common transition-metal derived metal–organic frameworks have been extensively investigated as heterogeneous catalyst supports for Knoevenagel condensation reactions. A simple post-synthetic modification strategy was employed for the rapid and facile introduction of a primary alkyl amino group. The resulting novel MOF–RNH2 catalysts showed greatly enhanced Knoevenagel condensation reactivities towards a variety of aldehyde electrophiles. IRMOF-3 proved to be an unsuitable heterogeneous catalyst support due to its fragile nature upon treatment with bases. The novel zirconium based UiO-66–NH–RNH2 and chromium based Cr-MIL-101–NH–RNH2 materials showed excellent catalytic reactivities, while being highly convenient to synthesize. The basic catalytic activity was further extended to the Henry reaction, and excellent catalytic reactivity was achieved. The size-selectivity was also studied to show that the Knoevenagel condensation occurred inside of the porous structure of the MOF catalyst. The recycling properties of zirconium, aluminum and chromium derived MOFs were evaluated and zirconium based UiO-66 and chromium based Cr-MIL-101 showed excellent catalytic efficiency after five reaction cycles.

A general post-synthetic modification approach of amino-tagged metal–organic frameworks to access efficient catalysts for the Knoevenagel condensation reaction

A multifunctional carbazole-based conjugated microporous polymer MFCMP-1 is successfully prepared by oxidative coupling polymerization using a single monomer and structurally characterized. A new three-dimensional π-conjugated polymer framework can be combined with permanent microporous, highly luminescent properties and abundant nitrogen activated sites in the skeleton. It possesses a large BET surface area of over 840 m2 g−1 with a pore volume of 0.52 cm3 g−1, and displays a high carbon dioxide uptake capacity (up to 3.69 mmol g−1) at 273 K and 1 bar, with good selectivity towards CO2 over N2 and CH4. MFCMP-1 exhibits also strong fluorescent emission at 529 nm after excitation at 380 nm in THF solution and works as a luminescent chemosensor towards hazardous and explosive molecules, such as nitrobenzene, 2-nitrotoluene, and 2,4-dinitrotoluene. In addition, MFCMP-1 features a high concentration of Lewis base nitrogen sites on its internal surfaces; it thus acts as a highly efficient recyclable heterogeneous organocatalyst towards Knoevenagel reaction of malononitrile with aromatics, heterocyclic aldehydes, and cyclic ketones. Furthermore, we further highlight that the ease of synthesis and low cost, coupled with multifunctional properties, make MFCMP-1 an attractive functional material in practical applications.

Gas uptake, molecular sensing and organocatalytic performances of a multifunctional carbazole-based conjugated microporous polymer

Ionic liquids, as reaction media, and sonochemistry are two recently developing fields of chemistry that present some similarities. Firstly, they constitute separately unconventional approaches to reaction chemistry that, in many cases, generate improvements in yield, rate and selectivity compared to classical chemistry, or even change the mechanisms or products expected. In addition, both are often associated with green chemistry concepts as a result of their properties and their possible eco-friendly uses. A recent trend has been to combine these two technologies in a range of different applications and the results demonstrate very significant and occasionally surprising synergetic effects. Here we critically review the advantages and limitations of the ionic liquid/ultrasound combination in different applications in chemistry, to understand how, and in which respects, it could become an essential tool of sustainable chemistry in the future. Many practical and theoretical aspects associated with this combination of techniques are not understood or resolved and we discus where fundamental studies might further advance this field.

Ionic liquids and ultrasound in combination: synergies and challenges

Carthamus tinctorius L. is a multifunctional cash crop. Its flowers and seeds are extensively used in traditional herbal medicine in China, Korea, Japan, and other Asian countries, for treating various ailments such as gynecological, cardiovascular, and cerebrovascular diseases as well as blood stasis and osteoporosis. More than 100 compounds have been isolated and identified from C. tinctorius. Flavonoids and alkaloids, especially the quinochalcone c-glycoside hydroxysafflor yellow A, N-(p-Coumaroyl)serotonin, and N-feruloylserotonin, are responsible for most of the pharmacological activities of C. tinctorius. In this paper, comprehensive and up-to-date information on the phytochemistry and pharmacology of C. tinctorius is presented. This information will be helpful for further explorations of the therapeutic potential of C. tinctorius and may provide future research opportunities.

Phytochemistry and Pharmacology of Carthamus tinctorius L.

An efficient and reusable protic-ionic-liquid solvent–catalyst system, HMTA–AcOH–H2O, has been developed and used in the Knoevenagel condensation reaction of aromatic aldehydes with ethyl 2-cyanoacetate. Under ultrasonic irradiation, the Knoevenagel condensation promoted by the protic-ionic-liquid solvent–catalyst system proceeds smoothly and cleanly. Moreover, the HMTA–AcOH–H2O solvent–catalyst system could be recycled for at least 6 times and no significant loss of activity was observed. This protocol has notable advantages, such as being eco-friendly, the ease of the work-up and reuse of the ionic liquid conveniently, which could help reduce disposal costs and contribute to the development of new catalysts for use in green and continuous chemical processes.

Rapid and efficient Knoevenagel condensation catalyzed by a novel protic ionic liquid under ultrasonic irradiation

A series of amide anthraquinone derivatives, an important component of some traditional Chinese medicines, were structurally modified and the resulting antitumor activities were evaluated. The compounds showed potent anti-proliferative activities against eight human cancer cell lines, with no noticeable cytotoxicity towards normal cells. Among the candidate compounds, 1-nitro-2-acyl anthraquinone-leucine (8a) showed the greatest inhibition of HCT116 cell activity with an IC50 of 17.80 μg/mL. In addition, a correlation model was established in a three-dimensional quantitative structure-activity relationship (3D-QSAR) study using Comparative Molecular Field Analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA). Moreover, compound 8a effectively killed tumor cells by reactive oxygen species (ROS)-JNK activation, causing an increase in ROS levels, JNK phosphorylation, and mitochondrial stress. Cytochrome c was then released into cytoplasm, which, in turn activated the cysteine protease pathway and ultimately induced tumor cell apoptosis, suggesting a potential use of this compound for colon cancer treatment.

https://www.mdpi.com/1420-3049/25/7/1672/pdf

Novel Anthraquinone Compounds Inhibit Colon Cancer Cell Proliferation via the Reactive Oxygen Species/JNK Pathway.

An efficient and versatile solvent–catalyst system, [HyEtPy]Cl–H2O-DABCO, has been developed and used in the Morita–Baylis–Hillman reaction. Under the mild reaction conditions, Morita–Baylis–Hillman proceeds very quickly and efficiently. This protocol has notable advantages such as eco-friendliness, ease of work-up and reuse of ionic liquid conveniently, which could help reduce disposal costs and contribute to the development of a new solvent–catalyst system for use in green and continuous chemical processes.

[HyEtPy]Cl–H2O: an efficient and versatile solvent system for the DABCO-catalyzed Morita–Baylis–Hillman reaction

Polyethylene Glycol (PEG-400) as an Efficient and Recyclable Reaction Medium for the Synthesis of 2-Aroylbenzofurans

The molecular mechanisms and the possible effects of hydroxysafflor yellow A (HSYA) on the induction of apoptosis in the human breast cancer MCF-7 cells were investigated. The MTT assay showed that HSYA could specifically inhibit the growth of several solid tumor cells in a dose-dependent manner, especially in the MCF-7 cells. Analysis by flow cytometry indicated that the apoptosis of the MCF-7 cells increased after treatment with HSYA. Moreover, the ROS level increased, and the cell cycle was blocked when the MCF-7 cells were treated with HSYA. The HSYA-induced apoptosis involved Bax and p53 up-regulation, Bcl-2 and cyclin D1 down-regulation, release of cytochrome c from the mitochondria to the cytosol, activation of caspase-3, and disruption of the mitochondrial transmembrane potential (Δψm). In addition, HSYA could inhibit the NFκB/p65 pathway by blocking the NFκB/p65 nuclear translocation. We concluded that HSYA could induce apoptosis in MCF-7 cells and promote it through the mitochondrial apoptotic pathway.

Liwei Zhang

Papers

Rapid and efficient Knoevenagel condensation catalyzed by a novel protic ionic liquid under ultrasonic irradiation

Novel Anthraquinone Compounds Inhibit Colon Cancer Cell Proliferation via the Reactive Oxygen Species/JNK Pathway.

[HyEtPy]Cl–H2O: an efficient and versatile solvent system for the DABCO-catalyzed Morita–Baylis–Hillman reaction

Polyethylene Glycol (PEG-400) as an Efficient and Recyclable Reaction Medium for the Synthesis of 2-Aroylbenzofurans

Hydroxysafflor yellow A induces apoptosis in MCF-7 cells by blocking NFκB/p65 pathway and disrupting mitochondrial transmembrane potential