Syntheses and Highly Enantioselective Fluorescent Recognition of α-Aminocarboxylic Acid Anions Using Chiral Oxacalix[2]arene[2]bisbinaphthes

Synthesis of a BINOL-Based C3 Symmetric Schiff Base and Its Fluorescence Response to Zn2

A novel C₃ symmetric 1,1'-bi-2-naphthol-based Schiff base (R,R,R)-6 has been synthesized which shows highly selective fluorescence enhancement with Zn²⁺ among 21 metal cations examined. Its sensitivity and selectivity are found to be greater than other related C₂ (1) and C₁ [(R)-9] symmetric compounds in the fluorescent recognition of Zn²⁺ . The mechanistic study reveals that the selective fluorescence enhancement of the probe can be attributed to the formation of a unimolecular multidentate 6-coordinated Zn²⁺ complex.

Triazine- and Binaphthol-Based Chiral Macrocycles and Cages: Synthesis, Structure, and Solid-State Assembly

A series of triazine- and binaphthol-based homochiral and heterochiral macrocycles and cages were easily synthesized. Either fragment coupling or a one-pot approach afforded the desired products in 52-91% yields on a multigram scale as enantiopure forms. As disclosed by the crystal structures, these macrocycles and cages possess intriguing chiral cavities and assembly properties. In particular, (S,S,S)-Cage features a D₃-symmetric double-faced propeller-like structure with three chiral pockets at the side. It forms a highly ordered hexagonal column-like assembly and multiple distinct helical channels in its crystal.

Recent advances of BINOL-based sensors for enantioselective fluorescence recognition

Enantioselective fluorescent sensors show large potential for fast, real-time, and highly sensitive measurement of the concentration and enantiomeric composition of chiral molecules. Among all of the sensors, BINOL-based sensors have been actively investigated and extensively used to carry out highly enantioselective, sensitive recognition of chiral α-hydroxycarboxylic acids, amino acids, amino acid derivatives, amino alcohols and amines. In this manuscript, the recent progress of chiral BINOL-based sensors for enantioselective fluorescence recognition of different substrates is reviewed and discussed. The structure of BINOL is tuned by introducing various groups or molecules which systematically changed its fluorescence properties and offered potential for rapid assays of chiral organic molecules. From the development of this area, we gain fresh insight into the challenges and chances of BINOL-based sensors.

Pd(0)-catalyzed amination in the synthesis of chiral derivatives of BINAM and their evaluation as fluorescent enantioselective detectors

A mini-review covers recent successes in the synthesis of (S)-1,1′-binaphthyl-2,2′-diamine (BINAM) using Pd(0)-catalyzed amination reactions. As a result, versatile compounds with C2-chiral backbone were synthesized, among them are derivatives bearing additional chiral amino and fluorophore groups like dansyl amide, 7-methoxycoumarin, 6-aminoquinoline, different macrocyclic compounds with oxadiamine and polyamine linkers were obtained as well. BINAM derivatives of various structures were evaluated as fluorescent enantioselective detectors for a series of model amino alcohols. Many of them were shown to be efficient in sensing certain enantiomers of the amino alcohols by selective changes in the emission in the presence of these analytes. Small changes in the structure of the BINAM derivatives lead to serious difference in the recognition ability of the compounds under investigation.

Optically active crown ether-based fluorescent sensor molecules: A mini-review

This mini-review focuses on fluorescent optically active crown ethers (polymeric derivatives are not included) reported in the literature (according to our knowledge), of which enantiomeric recognition ability, and in some cases, also inorganic cation complexation properties, were investigated by the sensitive and versatile fluorescence spectroscopy. These crown ether-based chemosensors contain various fluorophore signaling units such as binaphthyl, anthracene, pyrene, tryptophan, benzimidazole, terpyridine, acridine, phenazine, acridone, BODIPY, and another conjugated aromatic one.

A pair of chiral fluorescent sensors for enantioselective recognition of mandelate in water

A pair of chiral compounds S-1 and R-1 derived from (1S, 2S) or (1R, 2R)-1, 2-diphenylethane-1, 2-diamine were designed and synthesized, the interactions of S-1 and R-1 with mandelate were studied in H2O (0.01 M HEPES buffer, pH=7.4) by fluorescence titration experiments. The sensors S-1 and R-1 were found to present enantioselective fluorescent sensing ability to mandelate. The results indicated that the sensors S-1 and R-1 were very promising to be used as fluorescent sensors in determining the enantiomeric composition of mandelate in H2O.