Stereochemical analysis of chiral amines, diamines, and amino alcohols: Practical chiroptical sensing based on dynamic covalent chemistry

Abstract

Practical chiroptical sensing with a small group of commercially available aromatic aldehydes is demonstrated. Schiff base formation between the electron‐deficient 2,4‐dinitrobenzaldehyde probe and either primary amines, diamines, or amino alcohols proceeds smoothly in chloroform at room temperature and is completed in the presence of molecular sieves within 2.5 hours. The substrate binding coincides with a distinct circular dichroism signal induction at approximately 330 nm, which can be correlated to the absolute configuration and enantiomeric composition of the analyte. The usefulness of this sensing method is highlighted with the successful sensing of 18 aliphatic and aromatic amines and amino alcohols and five examples showing quantitative %ee determination with good accuracy.

Molecular Probes, Chemosensors, and Nanosensors for Optical Detection of Biorelevant Molecules and Ions in Aqueous Media and Biofluids

“…Such a design motif has been widely used to detect small molecule amines from the gas phase, e.g. , in combination with emissive conjugated polymers, for which several excellent literature sources can be consulted. − It is worth pointing out that many powerful probes and chemosensors for amines that are operational in organic solvents have already been reported, for instance, by the Wolf group. − Intuitively, aforementioned amine-reactive probes such as ninhydrin can react with amines in general, even though this was not expected by the time ninhydrin was first described for amino acid detection. − Very recently, Wolf and coworkers demonstrated that the chiral chromophoric adduct formed under mild conditions from the reaction of chiral amines with ninhydrin can be used for chirality sensing of the nonchromophoric amine analytes in a practically convenient and inexpensive method . We would like to refer the reader to the original literature and reviews , as we focus herein on those systems that operate in aqueous media.…”

Wide-Range and Highly Sensitive Chiral Sensing by Discrete 2D Chirality Transfer on Confined Surfaces of Au(I)-Thiolate Nanosheets

“…The responses to 3 / 4 / 5 are much more sensitive, and the linear regions are 1.0 × 10 –7 –5.0 × 10 –5 M for 3 and 4 and 1.0 × 10 –7 –1.0 × 10 –4 M for 5 (Figures f and S38). The maximum obtained g factor of the Au­(I)-MPA-MPBA nanosheets is −0.048 ( 2 (D) ), −0.042 ( 3 ), −0.045 ( 4 ), and −0.041 ( 5 ), respectively (Figure e), which is extremely high in CD sensing. − The association constants between Au­(I)-MPA-MPBA nanosheets and guests ( 2­(D) / 3 / 4 ) were calculated with these curves, and they are 66.74 M –1 ( 2 (D) ), 0.83 × 10 5 M –1 ( 3 ), and 0.66 × 10 5 M –1 ( 4 ) assuming 2 (D) , 3 , and 4 had approached the maximal g factors (details on the calculation are shown in the Supporting Information and Table S3; due to the fact that the CD signal induced by 5 may not reach the maximum for the limited solubility, the corresponding association constant was not calculated). The results suggest that the higher sensitivity (1.0 × 10 –7 M) for 3 and 4 than 2 (D) is because of their higher association constants.…”

“…With the fast development of combinatorial chemistry and parallel synthesis, rapid analysis of the efficiency of each asymmetric synthesis is in urgent need. Among various high-throughput analytical methods such as fast chiral chromatography, − NMR, , and optical chiral sensing, − circular dichroism (CD) spectral sensing is a very competitive one, − owing to the low consumption of solvent, easy operation, and its capability to reveal the absolute configurations of analytes with quantum calculation. , …”

“…In CD sensing, the absolute configuration, concentration, and enantiomeric compositions are revealed directly from the sign and intensity of CD signals induced by linking the chiral analytes to chromophore-bearing sensing hosts through covalent or noncovalent interactions. − ,, In terms of sensing materials and chirality transfer mechanisms, the reported sensing systems can be divided into two types: one is molecular hosts such as ions, , small molecules, ,,− metal complexes, , macrocyclic compounds, , and oligomers, , which have stoichiometric chirality transfer and thus exhibit linear CD response to the analytes in a wide range of concentrations. However, the required concentration for the analyte is usually high (mostly 10 –4 –10 –3 M) because of the weak optical activity of these molecular sensing hosts.…”

Effect of tetraethylene glycol side chain conformation on chiroptical properties of chirality‐induced benzocoumarin

“…[30][31][32] Chiroptical sensing has emerged in the last few decades and provided insightful information on the electronic and conformational properties of non-fluorescent chiral compounds in practical and sustainable ways. [33][34][35][36][37][38][39][40][41][42] The search for versatile reporters in the visible region of the electromagnetic radiation is ongoing to widen the range of applications and standardize these methods.…”