Spectral-Sensing System for Distinguishing CHOH and CDOD.

Spectrally discriminating CHOH and CDOD, and even detecting CHOH contents in the CDOD solvent, are important yet have not been achieved so far, likely owing to their very similar chemical/physical properties. Herein, dynamic transesterification reactions, which can be achieved via two-step proton transfers, can be signaled via ultraviolet UV-visible (UV/vis) absorption and fluorescence spectroscopies under mild experimental conditions. Introduction of strong electron-withdrawing groups, such as -NO, to the aromatic ring (benzoic acid moiety or phenol moiety) of carboxylate esters to activate the esters is important for transesterification reactions and is an intriguing method for modulating the selectivity of the spectral response.

[Determination of four fatty acid ethyl esters in olive oil by solid phase extraction-gas chromatography].

The fatty acid ethyl ester (FAEE) content of olive oil is an important indicator of its quality. At present, the international standard method used to detect FAEEs in olive oil is silica gel (Si) column chromatography-gas chromatography (GC); however, this technique presents a number of disadvantages, including complex operation, long analysis times, and high reagent consumption. In this study, a method based on Si solid phase extraction (SPE)-GC was established to determine four FAEEs in olive oil, namely, ethyl palmitate, ethyl linoleate, ethyl oleate, and ethyl stearate.

A Non-Hydrolysis Reaction-Based Imine for Fluorescence Response toward Al Ions with Extremely High Selectivity.

Designing an imine-based fluorescent probe capable of greatly suppressing the tendency of intrinsic hydrolysis reaction is an attractive topic in the field of chemo-/biosensing. In this work, hydrophobic 1,1'-binaphthyl-2,2'-diamine containing two amine groups was introduced to synthesize probe R-1 bearing two imine bonds linked by two salicylaldehyde (SAs). The hydrophobicity of binaphthyl moiety and the unique clamp-like structure formed from double imine bonds and from ortho-OH on SA part make probe R-1 is able to function as an ideal receptor to coordinate with Al ions, leading to the fluorescence originated from the complex rather than from the assumed hydrolyzed fluorescent amine is turned on.

Modulating Dual Fluorescence Emissions in Imine-Based Probes to Distinguish DO and HO.

How to distinguish DO and HO and determine the trace HO content in DO solvent, by using molecule-based spectral probes, is an intriguing topic in analytical chemistry, yet considerably few examples remain up to now, likely due to the very similar physical/chemical properties between DO and HO. In this work, we found that both the hydrolysis reactions to release fluorescent amines and aggregation-induced emission (AIE) of imines, functioning as dual fluorescence signals to distinguish DO and HO, could be modulated by changing the imine structures. The hydrophobicity of imines showed an important contribution to the ability of modulating the hydrolysis reactions and AIE, demonstrating a significant difference on fluorescence signals in DO and HO solvents.

Enantioselective Dynamic Exchange Reactions of Imines.

Although dynamic reactions of imines have been extensively studied, the dynamic behaviors manipulated by chirality remain nearly unexplored. In this work, enantioselective amine exchange reactions were demonstrated as a first example via the reaction of enantiomeric chiral amines such as natural amino acids with a series of innovative axially chiral 1,1'-binaphthyl-2,2'-diamine (BNDA)-based imines that were prepared from the condensation reactions between BNDA and salicylaldehyde (SA) or its derivatives. This enantioselective dynamic behavior can be directly indicated by the degree of the fluorescence response of the -configuration of imines to the d-enantiomer of chiral amine, because the released BNDA can serve as the fluorescence signal output when the amine exchange reaction occurs, which is far higher than the response to its l-enantiomer under identical experimental conditions.

Self-Assembled Multivalent Ag-SR Coordination Polymers with Phosphatase-Like Activity.

We show herein the phosphatase-like catalytic activity of coordination polymers obtained after adding Ag -ions to thiols bearing hydrophobic alkyl chains terminated with a 1,4,7-triazacyclononane (TACN) group. The subsequent addition of Zn -ions to the self-assembled polymers resulted in the formation of multivalent metal coordination polymers capable of catalysing the transphosphorylation of an RNA-model compound (2-hydroxypropyl-4-nitrophenyl phosphate, HPNPP) with high reactivity. Analysis of a series of metal ions showed that the highest catalytic activity was obtained when Ag -ions were used as the first metal ions to construct the backbone of the coordination polymer through interaction with the -SH group followed by Zn -ions as the second metal ions complexed by the TACN-macrocycle.

Extraction, structural elucidation and immunostimulating properties of water-soluble polysaccharides from wheat bran.

A water-soluble polysaccharide was extracted from wheat bran (WBP) and investigate their structural characteristics and immunostimulatory activities. The chemical composition of WBP and purified fraction (WBP-F) mainly consists of neutral sugars (91.2 ± 1.