Co-Production of Dimethyl Carbonate, Dimethoxymethane and Dimethyl Ether from Methanol: Process Design and Exergy Analysis.

Dimethyl carbonate is an important green chemical that has been widely used in the chemical industry. In the production of dimethyl carbonate, methanol oxidative carbonylation has been studied, but the conversion ratio of dimethyl carbonate using this method is too low, and the subsequent separation requires a large amount of energy due to methanol and dimethyl carbonate being azeotrope. In this paper, the strategy of "reaction instead of separation" is proposed. Based on this strategy, a novel process is developed to combine the production of DMC with that of dimethoxymethane (DMM) and dimethyl ether (DME). The co-production process was simulated using Aspen Plus software, and the product purity was up to 99.9%. The exergy analysis of the co-production process and the existing process was carried out. The exergy destruction and exergy efficiency were compared with those of the existing production processes. The results show that the exergy destruction of the co-production process is about 276% less than that of the single-production processes, and the exergy efficiencies in the developed co-production process are significantly improved. The utility loads of the co-production process are significantly lower than that of the single-production process. The developed co-production process increases the methanol conversion ratio to 95%, with a reduced energy requirement. It is proved that the developed co-production process can provide an advantageous option over the existing processes with improved energy efficiency and material savings. The strategy of "reaction instead of separation" is feasible. A new strategy is proposed for azeotrope separation.

Theoretical analysis and evaluation of reaction routes by "three-parameter difference".

How to choose a high-efficiency, green and inherent safety synthetic route is an important issue for the development of the chemical industry. "Three-parameter difference" is a complex parameter with the calculation of Gibbs free energy, atom utilization and inherent safety index, and can be used to comprehensively evaluate the thermodynamic feasibility, greenness and safety of chemical reactions. This parameter has been proposed and established, but the reliability has not been determined. In this study, the parameter has been corrected to make it more universal. It was calculated and studied in the synthesis of dimethyl carbonate and toluene diisocyanate, separately. The results showed that the reaction pathways for synthesizing dimethyl carbonate from the gas-phase oxidative carbonylation of methanol by a one-step process, and toluene diisocyanate from dimethyl carbonate-ionic liquid hydroxylamine have obvious advantages and future research prospects. They are consistent with the existing actual research, which can prove the reliability of the "three-parameter difference". More importantly, the parameter provides a theoretical basis and has an adequate practical guidance significance to design and evaluate a new synthesis route.

Metal-Organic Frameworks for Photodynamic Therapy: Emerging Synergistic Cancer Therapy.

Photodynamic therapy (PDT) conducted by photosensitizers producing cytotoxic reactive oxygen species (ROS) under light irradiation is widely used in cancer treatment. A great number of photoactive nanoscale metal-organic frameworks (NMOFs) have been prepared for PDT. With the development of biomedicine and nanotechnology, many synergistic cancer therapies have emerged. In this mini-review, an overview on the latest progress in the application of NMOFs in PDT is provided, with emphasis on the recent emergence of some synergistic therapies.

Metal-Organic Sheets for Efficient Drug Delivery and Bioimaging.

Metal-organic frameworks (MOFs) formed by coordination between metal ions or clusters and organic bridging ligands possess great potential for biomedicine applications, given their high biocompatibility and biodegradability. Compared with the traditional three-dimensional (3D) MOFs, two-dimensional (2D) MOFs with sheet-like morphologies exhibit unique properties. In this study, a nanoscale 2D leaf-shaped MOF (NZIF-L) was synthesized via coordination self-assembly between 2-methylimidazole (Hmim) and Zn2+ with subsequent morphology and size control. The fabricated NZIF-L is cytocompatible and can be quickly endocytosed, which makes it an excellent cargo carrier. Subsequent to loading with either doxorubicin (DOX) or 4,4'-(1,2-diphenylvinyl)-1,2-di-(phenylcarboxylic acid) (TCPE), the respectively obtained DOX@NZIF-L and TCPE@NZIF-L showed promise for killing and imaging cancer cells.

Enhancing the antivirus activity of chimeric canine interferon with ricin subunit B by using nanoparticle formulations.

Despite interferon alpha having a broad spectrum of antiviral activity and strong antiproliferative activity, its applications are severely limited due to the intrinsic properties of proteins, such as poor stability and short serum half-life. In our study, canine interferon alpha (CaIFNα) gene was fused with the ricin toxin B chain (RTB) to form rCaIFNα/RTB, which encodes a 463-amino acid protein containing a 15-amino acid encoded (G4S)3 flexible linker. After expression in prokaryote, purification and renaturation, the cytotoxicity and antiviral activity of rCaIFNα/RTB were investigated in Madin-Darby canine kidney (MDCK) cells. rCaIFNα/RTB exerted a superior anti-vesicular stomatitis virus (VSV) activity on MDCK cells. Furthermore, we have developed a nanoparticle formulation of rCaIFNα/RTB by using polyethylenimine (PEI) through electrostatic interaction. rCaIFNα/RTB@PEI10000 is more stable than rCaIFNα/RTB at various pH and temperature levels, and it possesses enhanced antiviral activity. Our findings facilitate further research on the role of type I IFN in antiviral defense responses in Canis lupus familiaris.

Exploiting radical-pair intersystem crossing for maximizing singlet oxygen quantum yields in pure organic fluorescent photosensitizers.

Fluorescent photosensitizers (PSs) often encounter low singlet oxygen (1O2) quantum yields and fluorescence quenching in the aggregated state, mainly involving the intersystem crossing process. Herein, we successfully realize maximizing 1O2 quantum yields of fluorescent PSs through promoting radical-pair intersystem crossing (RP-ISC), which serves as a molecular symmetry-controlling strategy of donor-acceptor (D-A) motifs. The symmetric quadrupolar A-D-A molecule PTP exhibits an excellent 1O2 quantum yield of 97.0% with bright near-infrared fluorescence in the aggregated state. Theoretical and ultrafast spectroscopic studies suggested that the RP-ISC mechanism dominated the formation of the triplet for PTP, where effective charge separation and an ultralow singlet-triplet energy gap (0.01 eV) enhanced the ISC process to maximize 1O2 generation. Furthermore, in vitro and in vivo experiments demonstrated the dual function of PTP as a fluorescent imaging agent and an anti-cancer therapeutic, with promising potential applications in both diagnosis and theranostics.

Self-quenching synthesis of coordination polymer pre-drug nanoparticles for selective photodynamic therapy.

The design and preparation of a photoactive coordination polymer nanoplatform with tumor-related stimuli-activatability and biodegradability is highly desirable for achieving highly precise photodynamic therapy (PDT). Herein, novel "pre-photodynamic" nanoparticles (Fe-IBDP NPs) with a tumor microenvironment (TME)-activatable PDT and good biodegradability were synthesized by carrying out facile coordination assembly of an IBDP photosensitizer with an Fe3+ quenching agent. After being taken up by cancer cells, our "inactive" Fe-IBDP NPs were activated by the TME and as a result decomposed and released the photoactive carboxyl-functionalized diiodo-substituted BODIPY (IBDP) photosensitizer, which generated cytotoxic singlet oxygen (1O2) under light irradiation. By contrast, these NPs showed relatively low cytotoxicity in normal cells. This work also provided a feasible method for preparing the next generation of photoactive nanomedicines for use in precise phototherapy.