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The current luminescent metal-organic framework (MOF) based fluorescence detection mostly focuses on achiral molecules. The stereospecific recognition and determination of MOF-based detection remain challenging. A novel luminescent terbium-based MOF (Tb-MOF) based biosensing system with excellent performance for stereoselective detection of D-amino acids (D-AAs) was introduced in this paper. D-Amino acid oxidase catalyzes stereospecific oxidative deamination of D-AAs, producing H2O2. The generated H2O2 effectively quenches the fluorescence of Tb-MOF. Under optimum conditions, the D-AAs were detected with excellent efficiency. The linear working range was 0.5-100 mM for D-Alanine (D-Ala) and 0. 5-5 mM for D-Proline (D-Pro), respectively. The limit of detection (Ksv detection) for D-Ala and D-Pro was 0.09 mM and 0.14 mM, respectively. The detection can be performed within 30 min with high selectivity and long-term stability. The fluorescent sensing platform required simple fabrication and operation and was free from complicated reaction processes and expensive reagents. The present sensing system was successfully applied in D-AA detection in human serum with good recovery, indicating its potential application in detection in biological samples. [ABSTRACT FROM AUTHOR]

In this paper, we present four Co-MOFs using R-substituted isophthalic acid (R-H2BDC, R = H, OH and COOH) along with trigonal n-TBT (n = 3 or 4) as organic ligands. These Co-MOFs are formulated as {[Co(1,3-BDC)(4-TBT)2/3]·(H2O)(DMF)1.5}n (Co-MOF-1), {[Co(HO-BDC)(4-TBT)]·(EtOH)2(DMF)2}n (Co-MOF-2), {[Co(HO-BDC)(4-TBT)2/3]·(H2O)3(MeOH)3(DMA)}n (Co-MOF-3) and {[Co3(BTC)2(3-TBT)2(H2O)2]·(H2O)2(EtOH)5(DMA)1.5}n (Co-MOF-4), where H2BDC = isophthalic acid, OH–H2BDC = 5-hydroxyisophthalic acid and H3BTC = 1,3,5-tricarboxybenzene, 4-TBT = 1,3,5- tris(4-pyridyl)benzene and 3-TBT = 1,3,5-tris(3-pyridyl)benzene. Co-MOF-1, 2 and 3 are constructed from the dimeric Co2(COO)2 unit and exhibit 3D frameworks. In Co-MOF-4, the dimeric Co2(COO)2 unit and single nuclear CoII center are connected by BTC3− and 3-TBT ligands into a 3D network. The catalytic experiments revealed that four Co-MOFs can catalyze the oxidative coupling reaction of benzyl alcohols and aniline to imines with good to excellent conversions under solvent-free conditions and an air atmosphere. Co-MOF-4 exhibited the best catalytic performance and the catalyst could be reused for at least five cycles without losing its structural integrity and catalytic activity. [ABSTRACT FROM AUTHOR]

Recently, ionic liquids have been widely used for chiral separation. However, several papers have reported the use of ionic liquids as the sole chiral selector. In this work, a novel capillary electrophoresis method using the ionic liquid 3-methyl-1-(3-sulfopropyl)-1H-imidazol-3-ium lactobionate (MSI-LA) as a chiral selector was developed for the enantioseparation of propranolol, metoprolol, bisoprolol, esmolol, atenolol, sotalol, terbutaline and clenbuterol. Method optimization was conducted and the optimized method (40 mM borax buffer, v/v 30% methanol, pH 8.5, 160 mM MSI-LA; +10 kV voltage; capillary temperature, 15 °C; 50 mbar/5 s injection; detection wavelength, 230 nm) was successful for the baseline separation of the eight basic drugs. The LA (lactobionic acid) system was compared. The possible mechanisms of enantioseparation were investigated using molecular modeling. Both the cation and anion of MSI-LA provided interactions between the chiral selector and analytes, and finally enhanced chiral recognition capability compared with LA. [ABSTRACT FROM AUTHOR]

Quinaldic acids are important fine chemicals. Nowadays, industrial methods to synthesize quinaldic acids rely heavily on a three-step process established based on the Reissert reaction, which involves however the use of highly toxic potassium cyanide. In this paper, a novel cyclization of aniline with ethyl 4,4-diethoxycrotonate was realized, which offered ethyl quinaldate in good yield. Based on this reaction, an eco-efficient method to prepare quinaldic acids was developed, which involves the following three steps: (i) synthesis of ethyl 4,4-diethoxycrotonate through photooxidation of furfural and a consecutive ring-opening alcoholysis; (ii) cyclization of ethyl 4,4-diethoxycrotonate with aniline, and (iii) hydrolysis of the generated ethyl quinaldate. This new method not only avoids the use of toxic potassium cyanide but also meets many salient features of green chemistry, such as the use of bio-based feedstocks, environmentally benign metal-free conditions and good reaction yields. [ABSTRACT FROM AUTHOR]

Surface functionalized titania particles are obtained using a high energy planetary ball mill. A parameter that is often overseen while applying this technique is the grinding bowl and grinding sphere material which has a crucial influence on the energy impact in the milling process. In this paper we describe the influence of the grinding bowl focusing on a zirconia ceramic material and comparing the results with experiments performed using a WC/Co-hard metal grinding bowl. The degrees of surface coverage as well as tribochemical phase transitions are dependent on the grinding bowl material. Due to the lower density of ZrO2-ceramic the overall energy input is lower. As a result the surface coverage and amount of phase transition decreased when using a zirconia ceramic grinding bowl instead of the WC/Co-hard metal grinding bowl. Lower impurity concentration in the final material was achieved due to the better abrasion behavior of the zirconia grinding bowl. [ABSTRACT FROM AUTHOR]

In this paper, two bio-based epoxy curing agents were synthesized using rosin acids. The chemical structures of the rosin derivatives were confirmed in detail by 1H NMR, 13C NMR, FT-IR and ESI-MS. The synthesis methods of the rosin-based curing agents, curing behaviors and properties of the cured epoxy resins were studied. Two commercial curing agents, which have similar functionality and structural resemblance to the rosin-based curing agents, were also used in the study for comparison. Compared with the synthesis of petrochemical curing agents, the synthesis of rosin-based curing agents was simpler and more environmentally friendly, and has less strict requirements on reactors and catalysts. Non-isothermal curing of a commercial liquid epoxy was studied using differential scanning calorimetry (DSC). The thermal mechanical properties and thermal stability of the cured epoxy resins were evaluated using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. Results showed that the curing behaviors of the rosin-based curing agents were similar to those of the commercial curing agents. The epoxies cured by rosin-based curing agents also demonstrated similar thermal mechanical properties and thermal stability to the epoxies cured by commercial curing agent analogs. [ABSTRACT FROM AUTHOR]