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A novel azo-thiourea based anion receptor can be synthesized by coupling a bis-azoaniline motif with butyl isothiocyanate with 45% yield under mild conditions. It was found that azo-thiourea was an excellent receptor to recognize various di-carboxylate anions. It can serve as a colorimetric sensor for azelate ion and led to a significant change in the absorption spectrum. Furthermore, a reversible trans–cis isomerization of azo-thiourea induced by visible lights was confirmed by 1H NMR spectroscopy.

In this paper, an ionic liquid-based aqueous two-phase system (ILATPS) was applied to the chiral separation of α-cyclohexylmandelic acid (α-CHMA) enantiomers with hydroxypropyl-β-cyclodextrin (HP-β-CD) as the chiral selector. Several influencing parameters were investigated including the types and concentration of ionic liquids, the amount of phase-forming salt, temperature, mixing time, pH, and the content of HP-β-CD. The results showed that not all ILATPS had the ability to chirally recognise the selected enantiomers and that [C4mim]BF4/(NH4)2SO4-based ATPS possessed the best enantioseparation ability of the investigated ILATPSs. Under optimal conditions, the separation factor (α) attained 1.59 in a single-step extraction. ILATPS is much “greener” than other liquid-liquid extraction systems, showing its potential for application to the chiral separation.

An alcohol/salt-based aqueous two-phase system (ATPS) was employed for enantioseparation of (R,S)-mandelic acid (MA) and (R,S)-α-cyclohexylmandelic acid (α-CHMA). Sulfonated β-cyclodextrin (Sf-β-CD) with different degrees of substitution (DS) was considered as the chiral selector. The ethanol/(NH4)2SO4 system showed the optimal chiral recognition ability for MA. To optimize the experimental conditions, Sf-β-CD concentration, ethanol and salt concentration, temperature, and pH were studied. The recognition ability of enantiomers was mainly dependent on the type of the chiral selector but the ethanol and (NH4)2SO4 concentrations also had significant influence on the enantiomeric recognition. The maximum values of α and ee up of 1.69 and 16.3 % were obtained, respectively, for MA under the optimal conditions. A potential application of this alcohol/salt ATPS is the scale-up of chiral separation of MA.