Cordierite@MOFs with Easy Recovery in CO2 Cycloaddition.

The objective of this research is to create monolithic heterogeneous catalysts (cordierite@MOFs) through the application of metal-organic framework (MOF) materials onto honeycomb cordierite for CO2 cycloaddition. By employing monolithic catalysts instead of powdered catalysts, the recycling and reusability of catalysts during postreaction treatment can be significantly improved.

High-Activity and High-Selectivity Air-Stable Nickel and Copper Complexes for Copolymerization of Epoxides with Anhydrides.

Ring-opening copolymerization (ROCOP) of epoxides with anhydrides presents a highly promising pathway for the synthesis of diverse polyester copolymers. This process involves the simultaneous opening of the epoxide ring and the anhydride ring, resulting in the formation of copolymer chains with alternating repeating units. Here, we synthesized a series of nickel and copper complexes coordinated by amine-bis(benzotriazole phenolate) ligands (C1NNBiBTP-H2). Different acid-base conditions can result in the synthesis of diverse coordination structures. The six-coordinated mononuclear Ni catalyst synthesized in this study exhibited competitive turnover frequencies (TOF = 450 h-1) compared to previous studies involving copolymerization of epoxides with anhydrides. This indicates the catalyst's high activity in facilitating the copolymerization reaction. The results indicate that the catalyst exhibited a high molecular weight control ability and high polymer selectivity for the ROCOP of epoxides and anhydrides. Thus, this air-stable catalyst has the potential for use in industries.

Well-Defined and Highly Effective Nickel Catalysts Coordinated on Tridentate SNO Schiff-Base Derivatives for Alternating Copolymerization of Epoxides and Anhydrides.

A series of Ni complexes supported by SNO Schiff-base derivatives were synthesized in this study. Complex synthesis and characterization data are reported herein. Treatment of the pro-ligands [L1-H = 2-(((2-(methylthio)ethyl)imino)methyl)phenol, L2-H = 2,4-di-tert-butyl-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L3-H = 2-(((2-(methylthio)ethyl)imino)methyl)-4,6-bis(2-phenylpropan-2-yl)phenol, L4-H = 4-bromo-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L5-H = 4-chloro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with Ni(OAc)2·4H2O in refluxing ethanol afforded six-coordinate mono-Ni(II) complexes [L2nNi] (n = 1-5). Noteworthy, a heptanuclear nickel(II) octacarboxylate species complex 6 and dinuclear nickel complex 6a resulted from treatment of L6-H [4-fluoro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with different metal precursors [Ni(OAc)2·4H2O for 6; NiBr2 for 6a] giving a quantitative yield. The reaction of nickel acetate tetrahydrate and L7-H to L9-H [L7-H = 2-methoxy-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L8-H = 5-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L9-H = 4-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol] produced the four-coordinate complexes [L2nNi] (n = 7-9). The highest performing catalyst was complex 3, which was highly efficient for the ring-opening copolymerization of phthalic anhydride (PA) and cyclohexene oxide (CHO) in the presence of a cocatalyst (4-dimethylaminopyridine). In addition, the same copolymerization conditions produced narrowly dispersed polyesters, with high selectivity and polymerization control. In addition to PA-CHO copolymerization, efficient diglycolic anhydride-PA and PA-propene oxide copolymerization was achieved under the same conditions. These catalysts are straightforward to produce and extend the scope of potential substrates.

Chemoenzymatic Synthesis of Globo-series Glycosphingolipids and Evaluation of Their Immunosuppressive Activities.

Glycosphingolipids (GSLs) play essential roles in many important biological processes, making them attractive synthetic targets. In this paper, a viable chemoenzymatic method is described for the synthesis of globo-series GSLs, namely, Gb4, Gb5, SSEA-4, and Globo H. The strategy uses a chemically synthesized lactoside acceptor equipped with a partial ceramide structure that is uniquely extended by glycosyltransferases in a highly efficient one-pot multiple enzyme (OPME) procedure. A direct and quantitative conversion of Gb4 sphingosine to Globo H sphingosine is achieved by performing two-sequential OPME glycosylations. A reduction and N-acylation protocol allows facile incorporation of various fatty acids into the lipid portions of the GSLs. The chemically well-defined lipid-modified Globo H-GSLs displayed some differences in their immunosuppressive activities, which may benefit the structural modifications of Globo H ceramides in finding new types of immunosuppressive agents. The strategy outlined in this work should be applicable to the rapid access to other complex GSLs.

Uniform Core-Shell Microspheres of SiO2@MOF for CO2 Cycloaddition Reactions.

A SiO2@MOF core-shell microsphere for environmentally friendly applications was introduced in this study. Several types of metal-organic framework core-shell microspheres were successfully synthesized. To achieve high stability and favorable catalytic performance, modification and coating methods were necessary for optimization. The improved SiO2@MOF core-shell microspheres were used in the cycloaddition reaction of carbon dioxide and propylene oxide. Dispersion ability was enhanced by the addition of core-shell microspheres, which also produced high catalytic activity. Accompanied with tetrabutylammonium bromide as a co-catalyst, SiO2@ZIF-67 had a maximum conversion of 97%, and the results revealed that SiO2@ZIF-67 could be used for 5 reaction cycles while maintaining high catalytic performance. This recycling catalyst was also reacted with a series of terminal epoxides to form corresponding cyclic carbonates with high conversion rates, indicating that SiO2@MOF core-shell microspheres exhibit promise in the field of catalysis.

Second-Sphere Interaction Promoted Turn-On Fluorescence for Selective Sensing of Organic Amines in a TbIII -based Macrocyclic Framework.

Guided by a second-sphere interaction strategy, we fabricated a Tb(III)-based metal-organic framework (MMCF-4) for turn-on sensing of methyl amine with ultra-low detection limit and high turn-on efficiency. MMCF-4 features lanthanide nodes shielded in a nonacoordinate geometry along with secondary coordination spheres that are densely populated with H-bond interacting sites. Nonradiative routes were inhibited by binding-induced rigidification of the ligand on the second coordination sphere, resulting in luminescence amplification. Such remote interacting mechanism involved in the turn-on sensing event was confirmed by single-crystal X-ray diffraction and molecular dynamic simulation studies. The design of both primary and secondary coordination spheres of Tb(III) enabled the first turn-on sensing of organic amines in aqueous conditions. Our work suggests a promising strategy for high-performance turn-on sensing for Ln-MOFs and luminous materials driven by other metal chromophores.

Synthesis and characterization of di-nuclear bis(benzotriazole iminophenolate) cobalt complexes: catalysis for the copolymerization of carbon dioxide with epoxides.

A family of di-nuclear bis(benzotriazole iminophenolate) (BiIBTP) cobalt complexes containing diverse ancillary carboxylate derivatives have been synthesized and structurally characterized. The one-pot synthesis of the BiIBTP ligand precursor with cobalt perchlorate salt (2.0 equiv.) and carboxylic acid derivatives (2.0 or 5.0 equiv.) in the presence of triethylamine (5.0 equiv.) under refluxing methanolic solution generated bimetallic di-carboxylate Co(ii)/Co(ii) complexes [(C83CBiIBTP)Co2(O2CR)2] (R = C6H5 (1), C6F5 (2), 4-CF3-C6H4 (3), 4-OMe-C6H4 (4), CF3 (5)) in ≧65% yields. Interestingly, the Co(ii)/Co(iii) mixed-valence complex 6 resulted from the treatment of 1 with silver perchlorate (1.0 equiv.) as the oxidizing agent under an O2-atmosphere in 50% yield. The crystal structure of 6 reveals an ionic and di-nuclear benzoate species composed of a cationic moiety formulated as [(C83CBiIBTP)Co2(O2CC6H5)2]+ and a counterbalanced perchlorate anion, and both metal atoms are attributed to hexa-coordinated cobalt ions with varied coordination environments. Catalysis results of CO2/epoxide copolymerization indicated that complex 1 was more efficient than 2-6 where compound 6 was shown to be the least active. Co complex 1 incorporating benzoate coligands was demonstrated to effectively catalyze the CO2-copolymerization of cyclohexene oxide (CHO), 4-vinyl-1,2-cyclohexene oxide or cyclopentene oxide, producing the associated CO2-based polycarbonates with >99% carbonate repeated units under optimal conditions. Not only the controllable character of complex 1 for CO2/CHO copolymerization is enabled, but also 1 has been shown to catalyze such a copolymerization in the "immortal" manner. Using the same di-cobalt catalyst in combination with excess ratios of neopentyl glycol (up to 150 equiv.) as the chain transfer agent could give low molecular weight poly(cyclohexene carbonate) polyols with monomodal molecular weight distributions. This work offers the facilely prepared di-nuclear cobalt complexes as catalysts for the efficient catalysis of CO2-copolymerization.

Mono- and dinuclear copper complexes coordinated on NNO-tridentate Schiff-base derivatives for copolymerization of cyclohexene oxide and cyclic anhydrides.

A series of bimetallic penta-coordinated copper complexes [Ln2Cu2(OAc)2] (1, 3-7), a mononuclear tetra-coordinated copper complex [LnCu(OAc)] (8 and 9), and a penta-coordinated copper complex [L2Cu(OAc)(H2O)] (10) were prepared by the reaction of Cu(OAc)2·H2O with a variety of NNO-tridentate Schiff-base ligands (L1-H-L9-H) in refluxing 95% ethanol, respectively. However, a dinuclear copper complex [(L2)2Cu2(OAc)2] (2) can be obtained from the treatment of L2-H with a stoichiometric amount of anhydrous Cu(OAc)2 in refluxing absolute EtOH under a dry nitrogen atmosphere. All of these copper complexes are active for the alternating copolymerization of cyclohexene oxide and cyclic anhydride, affording polyesters with moderate polydispersity. In particular, dinuclear copper complexes 1 and 2 performed satisfactorily to produce polyesters with controllable molecular weights and high ester linkages. This is the first example of well-defined copper acetate catalysts active for the copolymerization of cyclohexene oxide-phthalic anhydride or cyclohexene oxide-succinic anhydride which may be advantageous in terms of obviating the use of co-catalysts and low cost as well as an effective copolymerization for the formation of biodegradable polyesters in a controlled fashion.

Microporous 2D indium metal-organic frameworks for selective CO2 capture and their application in the catalytic CO2-cycloaddition of epoxides.

Four new 2D indium metal-organic frameworks (MOFs) (Me2NH2)[In(SBA)2] (1), (Me2NH2)[In(SBA)(BDC)] (2), (Me2NH2)[In(SBA)(BDC-NH2)] (3), and (NH4)3[In3Cl2(BPDC)5] (4), (H2SBA = 4,4'-sulfonyldibenzoic acid; H2BDC = 1,4-benzenedicarboxylic acid; H2BDC-NH2 = 2-amino-1,4-benzenedicarboxylic acid; H2BPDC = 4,4'-biphenyldicarboxylic acid) have been synthesized under solvothermal reaction conditions for compounds 1 to 3 and the DES (deep eutectic solvent) reaction has been attempted for compound 4. The structure of these MOFs has been determined by using single crystal X-ray diffraction study and all of theses four 2D monolayer framework with porous properties. The N2 gas sorption measurements indicated that Brunauer-Emmer-Teller (BET) and Langmuir surface areas of compound 1 are 207 and 301 m2 g-1, respectively, which is probably the first one having substantial gas uptake properties in the entire 2D In-MOF family to date. Furthermore, these new indium MOFs on the addition of n-Bu4NBr were active for the cycloaddition of CO2 and propylene oxide, generating propylene carbonates in high conversions under mild conditions. Particularly, the most active MOF 4 was found to efficiently couple CO2 with a series of terminal epoxides to give the corresponding cyclic organic carbonates with high selectivities.

Synthesis and characterization of trimetallic cobalt, zinc and nickel complexes containing amine-bis(benzotriazole phenolate) ligands: efficient catalysts for coupling of carbon dioxide with epoxides.

New trimetallic cobalt, nickel and zinc complexes 1-3 coordinated by amine-bis(benzotriazole phenolate) ligands and ancillary acetate groups have been developed for the use of CO2/epoxide coupling. All complexes were structurally characterized by single crystal X-ray crystallography; tri-Co complex 1 is the first solid-state example in which three different geometrical configurations exist in the same benzotriazole phenoxide metal complex. Tri-nuclear complexes 1 and 2 with cobalt and zinc metal centers were demonstrated to be very active catalysts for cycloaddition of cyclohexene oxide with CO2 in the presence of ammonium salt co-catalysts to give cis-cyclohexene carbonate under the conditions of 80 °C and 300 psi initial CO2 pressure. Particularly, tri-cobalt complex 1 was found to efficiently couple CO2 with epoxides showing broad substrate scope, producing the corresponding cyclic organic carbonates with good activities and high selectivities. This is a successful example of catalysis for cyclic carbonate synthesis using one cobalt(ii) complex as a homogeneous catalyst.

Copolymerization of Carbon Dioxide with Epoxides Catalyzed by Structurally Well-Characterized Dinickel Bis(benzotriazole iminophenolate) Complexes: Influence of Carboxylate Ligands on the Catalytic Performance.

A series of structurally well-defined dinickel carboxylate complexes based on the RBiIBTP derivatives [RBiIBTP = bis(benzotriazole iminophenolate), where R = 3C for the propyl-bridged backbone and 5C for the 2,2-dimethyl-1,3-propyl-bridged backbone] were synthesized and developed for copolymerization of CO2 and epoxides. The one-pot reactions of nickel perchlorate with the RBiIBTP-H2 proligands and an appropriate amount of carboxylic acid derivatives (CF3COOH or 4-X-C6H4CO2H; X = H, CF3, OMe) upon the addition of triethylamine in refluxing methanol (MeOH) afforded dinuclear nickel dicarboxylate complexes, which could be formulated as either [(RBiIBTP)Ni2(O2CCF3)2] (1 and 2) or [(RBiIBTP)Ni2(O2CC6H4-4-X)2] (3-7). The dinickel monobenzoate complexes [(RBiIBTP)Ni2(O2CPh)(ClO4)(H2O)] [R = 3C (8) and 5C (9)] were prepared by using a similar synthetic route in tetrahydrofuran under reflux with a ligand precursor to metal salt to benzoic acid ratio of 1:2:1 in the presence of NEt3. Recrystallization of neutral nickel perchlorate complex 8 in a saturated MeOH or ethanol (EtOH) solution gave ionic and alcohol-solvated monobenzoate bimetallic analogues [(3CBiIBTP)Ni2(O2CPh)(S)2]ClO4, where S = MeOH (10) and EtOH (11). Single-crystal X-ray crystallography of dinickel analogues 1-11 indicates that the BiIBTP scaffold performs as a N,O,N,N,O,N-hexadentate ligand to chelate two Ni atoms, and the ancillary carboxylate group adopts a bridging bidentate bonding mode. Catalysis for copolymerization of carbon dioxide (CO2) with cyclohexene oxide (CHO) by complexes 1-9 was systematically investigated, and the influence of carboxylate ligands on the catalytic behavior was also studied. Trifluoroacetate-ligated dinickel complex 1 efficiently catalyzed CO2 and CHO with a high turnover frequency (>430 h-1) in a controlled fashion, generating perfectly alternating poly(cyclohexenecarbonate) with large molecular weight (Mn > 50000 g/mol). In addition to CO2/CHO copolymerization, bimetallic complex 1 was found to effectively copolymerize CO2 with 4-vinyl-1,2-cyclohexene oxide (VCHO) or cyclopentene oxide, producing the high carbonate contents of poly(VCHC-co-VCHO)s and highly alternating poly(cyclopentene carbonate)s, respectively. This study also enabled us to compare the catalytic efficiency of using cyclic epoxides with different ring strains or functional groups as comonomers by the dinickel catalyst 1.

Metal complexes containing nitrogen-heterocycle based aryloxide or arylamido derivatives as discrete catalysts for ring-opening polymerization of cyclic esters.

The development of well-defined homogeneous catalysts for the ring-opening polymerization (ROP) of cyclic esters has made enormous progress over the past decade. This perspective focuses on some recent advances in the field of discrete metal complexes modified by various aryloxide or arylamido ligands bearing the nitrogen-containing heterocycle moiety, and their catalytic applications in ROP of lactones. It mainly highlights aryloxide/arylamido ligands that are directly installed by the N-heterocyclic group. The complex structure-ROP performance relationships and the observed trends with respect to their catalytic efficiency affected by ligand modifications are also discussed.

Dinuclear and Trinuclear Nickel Complexes as Effective Catalysts for Alternating Copolymerization on Carbon Dioxide and Cyclohexene Oxide.

A series of novel nickel complexes 1-9 supported by NNO-tridentate Schiff-base derivatives have been synthesized and characterized. Treatment of the pro-ligands [L(1)-H = 2,4-di-tert-butyl-6-(((2-(dimethylamino)ethyl)imino)methyl)phenol, L(2)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)-4,6-bis(2-phenylpropan-2-yl)phenol, L(3)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)phenol] with Ni(OAc)2·4H2O in refluxing ethanol afforded mono- or bimetallic nickel complexes {[(L(1))Ni(OAc)] (1); (L(2))Ni(OAc)] (2); (L(3))2Ni2(OAc)2(H2O)] (3)}. Alcohol-solvated trimetallic nickel acetate complexes {[(L(3))2Ni3(OAc)4(MeOH)2] (4); (L(3))2Ni3(OAc)4(EtOH)2] (5)} could be generated from the reaction of L(3)-H and anhydrous nickel(II) acetate with a ratio of 2:3 in refluxing anhydrous MeOH or EtOH. The reaction of nickel acetate tetrahydrate and L(4)-H to L(6)-H [L(4)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)-5-methoxyphenol, L(5)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)-4-methoxy-phenol, L(6)-H = 2-(((2-(dimethylamino)ethyl)imino)(phenyl)methyl)phenol] produced, respectively, the alcohol-free trinuclear nickel complexes {[(L(4))2Ni3(OAc)4] (7); [(L(5))2Ni3(OAc)4] (8); [(L(6))2Ni3(OAc)4] (9)} with the same ratio in refluxing EtOH under the atmospheric environment. Interestingly, recrystallization of [(L(3))2Ni3(OAc)4(MeOH)] (4) or [(L(3))2Ni3(OAc)4(EtOH)] (5) in the mixed solvent of CH2Cl2/hexane gives [(L(3))2Ni3(OAc)4] (6), which is isostructural with analogues 7-9. All bi- and trimetallic nickel complexes exhibit efficient activity and good selectivity for copolymerization of CO2 with cyclohexene oxide, resulting in copolymers with a high alternating microstructure possessing ≥99% carbonate-linkage content. This is the first example to apply well-defined trinuclear nickel complexes as efficient catalysts for the production of perfectly alternating poly(cyclohexene carbonate).

Interpenetrating Metal-Metalloporphyrin Framework for Selective CO2 Uptake and Chemical Transformation of CO2.

Herein we report a robust primitive cubic (pcu)-topology metal-metalloporphyrin framework (MMPF), MMPF-18, which was constructed from a ubiquitous secondary building unit of a tetranuclear zinc cluster, Zn4(µ4-O)(-COO)6, and a linear organic linker of 5,15-bis(4-carboxyphenyl)porphyrin (H2bcpp). The strong π-π stacking from porphyrins and the lengthy H2bcpp ligand affords a 4-fold-interpenetrating network along with reduced void spaces and confined narrow channels. Thereby, MMPF-18 presents segmented pores and high-density metalloporphyrin centers for selective CO2 uptake over CH4 and size-selective chemical transformation of CO2 with epoxides forming cyclic carbonates under ambient conditions.

Mono-, di- and tetra-zinc complexes derived from an amino-benzotriazole phenolate ligand containing a bulkier N-alkyl pendant arm: synthesis, structure and catalysis for ring-opening polymerization of cyclic esters.

Zinc complexes constructed from the amino-modified benzotriazole phenol pro-ligand, 2-(2H-benzotriazol-2-yl)-6-((diisopropylamino)methyl)-4-(2,4,4-trimethylpentan-2-yl)phenol ((C8DIA)BTP-H, 1), were synthesized stepwise and structurally characterized. The reaction of (C8DIA)BTP-H (1) with one equivalent of diethyl zinc (ZnEt2) generates a dimeric and four-coordinated zinc complex, [(µ-(C8DIA)BTP)ZnEt]2 (2), which is doubly bridged by two phenolate groups of C8DIABTP ligands. Further reaction of 2 with benzyl alcohol (BnOH) in stoichiometric proportions affords a tetranuclear zinc benzylalkoxide complex [(µ-OBn)((C8DIA)BTP)Zn]4 (3) that possesses a saddle-shaped core with four µ2-bridging benzylalkoxy groups upon four Zn centres. Interestingly, the di-nuclear Zn alkoxide [(µ-OBn)((C8DIA)BTP)Zn(DMAP)]2 (4) could be prepared by treatment of 3 with a stoichiometric amount of 4-(dimethylamino)pyridine (DMAP). ZnEt2 reacts with two equivalents of 1 in the presence of DMAP (1.0 mol equiv.) to yield a five-coordinated mononuclear zinc complex, [((C8DIA)BTP)2Zn(DMAP)] (5). All complexes adopt an N,O-bidentate coordination mode from the phenoxy oxygen atom and benzotriazole nitrogen atom, in which the nitrogen atom of the pendent arm substituent is not coordinated to the zinc centre. Ring-opening polymerization of ε-caprolactone and ß-butyrolactone catalysed by 2 and 3 was investigated.

Persistent hypoglycemia as an early, atypical presentation of hepatocellular carcinoma: A case report and systematic review of the literature.

The current study presents a case of persistent hypoglycemia as the initial manifestation of advanced hepatocellular carcinoma (HCC), as well as a systematic review of the management of hypoglycemia associated with HCC. A 42-year-old female presented with loss of consciousness and a blood glucose level of 30 mg/dl (normal range, 80-140 mg/dl). Abdominal ultrasound and computed tomography were performed to investigate tenderness in the right upper quadrant, and the results revealed a hepatic mass of 15 cm in diameter, with metastasis. A diagnosis of insulinoma was ruled out by examining the insulin level. Prednisolone treatment was ineffective for relieving the persistent hypoglycemia, however, a single dose of palliative radiotherapy reduced the hypoglycemic episodes to once monthly. Due to the advanced disease, the patient refused further treatment, with the exception of a palliative therapy with glucose fluid. The patient succumbed to pneumonia with sepsis. A systematic review of the literature indicated that steroids were the most commonly used drug for hypoglycemia associated with HCC, however, in the majority of cases no effect was noted as observed in this study. Cytoreduction by surgery or systemic chemotherapy has been the most effective treatment. Although rare, hypoglycemia may be the initial symptom of HCC. Cytoreduction is the most effective method of treating hypoglycemia associated with HCC.

Structurally diverse copper complexes bearing NNO-tridentate Schiff-base derivatives as efficient catalysts for copolymerization of carbon dioxide and cyclohexene oxide.

Structurally diverse copper acetate complexes based on NNO-tridentate Schiff-base ligands were synthesized and characterized as mono-, di-, and trinuclear complexes with respect to varied ancillary ligands. Treatment of the ligand precursors (L(1)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-4-methylphenol, L(2)-H = 4-chloro-2-(1-((2-(dimethylamino)ethyl)imino)ethyl)phenol, and L(3)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-5-methylphenol) with Cu(OAc)2·H2O (1 equiv) in refluxing ethanol afforded five-coordinate mono- or bimetallic copper complexes ([(L(1))Cu(OAc)(H2O)] (1); [(L(2))Cu(OAc)(H2O)] (2); [(L(3))2Cu2(OAc)2] (3)) in high yields. Dinuclear copper acetate analogue [(L(1))2Cu2(OAc)2] (4) resulted from treatment of L(1)-H as the ligand precursor in refluxing anhydrous MeOH with equimolar proportions of metal acetate salt under a dry nitrogen atmosphere. However, a trinuclear complex, [(L(4))2Cu3(OAc)4] (5), was obtained on utilizing 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-5-methoxyphenol (L(4)-H) as the proligand under the same synthetic route of 1-3; this complex was also synthesized in the reaction of L(4)-H and copper(II) acetate monohydrate in the ratio of 2:3, giving a quantitative yield. All complexes are active catalysts for copolymerization of cyclohexene oxide (CHO) and CO2 without cocatalysts. In particular, dinuclear Cu complex 3 performed satisfactorily to produce polycarbonates with controllable molecular weights and high carbonate linkages. These copper complexes are the first examples that are effective for both CO2/CHO copolymerization and formation of polymers in a controlled fashion.

Dung-shen (Codonopsis pilosula) attenuated the cardiac-impaired insulin-like growth factor II receptor pathway on myocardial cells.

Previous studies from our lab showed that increase in AngII in H9c2 cells causes elevated IGFII and IGFIIR through MEK and JNK, leading to rise in intracellular calcium, calcineurin activation by PLC-ß3 via Gαq, insertion into mitochondrial membranes of Bad, and apoptosis via caspases 9 and 3. Codonopsis pilosula is traditionally used to lower blood pressure. The purpose of our study is to investigate if C. pilosula attenuates AngII plus Leu(27)-IGFII-induced calcium influx and apoptosis in H9c2 cardiomyoblasts. C. pilosula significantly attenuated AngII induced IGFIIR promoter activity. Leu(27)-IGFII was applied to enhance the AngII effect. C. pilosula also reversed Ca(2+) influx, MOMP and apoptosis increased by AngII plus Leu(27)-IGFII. Molecular markers in IGFIIR apoptotic pathway (IGFIIR, calcineurin, etc.) and IGFIIR-Gαq association were downregulated by C. pilosula. However, p-Bad(Ser136) and Bcl-2 were increased. Therefore, C. pilosula suppresses AngII plus Leu(27)-IGFII-induced IGFII/IGFIIR pathway in myocardial cells.

NADPH oxidase-derived superoxide anion-induced apoptosis is mediated via the JNK-dependent activation of NF-κB in cardiomyocytes exposed to high glucose.

Hyperglycemia-induced generation of reactive oxygen species (ROS) can lead to cardiomyocyte apoptosis and cardiac dysfunction. However, the mechanism by which high glucose causes cardiomyocyte apoptosis is not clear. In this study, we investigated the signaling pathways involved in NADPH oxidase-derived ROS-induced apoptosis in cardiomyocytes under hyperglycemic conditions. H9c2 cells were treated with 5.5 or 33 mM glucose for 36 h. We found that 33 mM glucose resulted in a time-dependent increase in ROS generation as well as a time-dependent increase in protein expression of p22(phox), p47(phox), gp91(phox), phosphorylated IκB, c-Jun N-terminal kinase (JNK) and p38, as well as the nuclear translocation of NF-kB. Treatment with apocynin or diphenylene iodonium (DPI), NADPH oxidase inhibitors, resulted in reduced expression of p22(phox), p47(phox), gp91(phox), phosphorylated IκB, c-Jun N-terminal kinase (JNK) and p38. In addition, treatment with JNK and NF-kB siRNAs blocked the activity of caspase-3. Furthermore, treatment with JNK, but not p38, siRNA inhibited the glucose-induced activation of NF-κB. Similar results were obtained in neonatal cardiomyocytes exposed to high glucose concentrations. Therefore, we propose that NADPH oxidase-derived ROS-induced apoptosis is mediated via the JNK-dependent activation of NF-κB in cardiomyocytes exposed to high glucose.

An outbreak of coxsackievirus A6 hand, foot, and mouth disease associated with onychomadesis in Taiwan, 2010.

BACKGROUND: In 2010, an outbreak of coxsackievirus A6 (CA6) hand, foot and mouth disease (HFMD) occurred in Taiwan and some patients presented with onychomadesis and desquamation following HFMD. Therefore, we performed an epidemiological and molecular investigation to elucidate the characteristics of this outbreak. METHODS: Patients who had HFMD with positive enterovirus isolation results were enrolled. We performed a telephone interview with enrolled patients or their caregivers to collect information concerning symptoms, treatments, the presence of desquamation, and the presence of nail abnormalities. The serotypes of the enterovirus isolates were determined using indirect immunofluorescence assays. The VP1 gene was sequenced and the phylogenetic tree for the current CA6 strains in 2010, 52 previous CA6 strains isolated in Taiwan from 1998 through 2009, along with 8 reference sequences from other countries was constructed using the neighbor-joining command in MEGA software. RESULTS: Of the 130 patients with laboratory-confirmed CA6 infection, some patients with CA6 infection also had eruptions around the perioral area (28, 22%), the trunk and/or the neck (39, 30%) and generalized skin eruptions (6, 5%) in addition to the typical presentation of skin eruptions on the hands, feet, and mouths. Sixty-six (51%) CA6 patients experienced desquamation of palms and soles after the infection episode and 48 (37%) CA6 patients developed onychomadesis, which only occurred in 7 (5%) of 145 cases with non-CA6 enterovirus infection (p < 0.001). The sequences of viral protein 1 of CA6 in 2010 differ from those found in Taiwan before 2010, but are similar to those found in patients in Finland in 2008. CONCLUSIONS: HFMD patients with CA6 infection experienced symptoms targeting a broader spectrum of skin sites and more profound tissue destruction, i.e., desquamation and nail abnormalities.