Optically pure 2-(quinolin-8-yloxy)cyclohexan-1-ol as a practical agent for molecular recognition by NMR and fluorescence spectroscopy

Abstract

Optically pure 2-(quinolin-8-yloxy)cyclohexan-1-ol 1, obtained via simple chemical and bio-catalytic steps, was used as a chiral solvating agent for molecular recognition of the enantiomers of acids. The discrimination of isomers was detected by NMR or fluorescence spectroscopy. Isomers of α-substituted carboxylic acids, phosphoric acids, unprotected amino acids and dipeptides were efficiently detected, while the method can be used for quantitative determination for practical applications. Analysis of the crystal of (R,R)-1 (R)-mandelic acid established a three point supramolecular interaction.

l-Pyroglutamic Acid-Modified CdSe/ZnS Quantum Dots: A New Fluorescence-Responsive Chiral Sensing Platform for Stereospecific Molecular Recognition

“…As well known, due to the homochiral properties of many important biobuilding blocks, l -amino acids preferentially occupy stereoscopic spatial positions, leading to chirality-dependent interactions and physiological activities. , However, due to their similar physicochemical properties of amino acids isomers, determination of enantiomeric purity has been considered as a challenging issue in the biopharmaceutical industry and pathophysiology. , Various chiral materials have been designed and developed for the enantioselective recognition of biologically related chiral molecules. − Among them, those based on fluorescence spectroscopic techniques that have gained special attention as chiral fluorescence sensors are able to sensitively and rapidly translate the changes of chiral signals into fluorescence changes. Moreover, this analytical method is simple and the requirements of instruments and equipment are relatively low, which could be visually distinguished . Chiral fluorescence sensors basically include small organic molecule-based chiral chemosensors and nanomaterial-based chiral probes. , However, they usually suffer from the major drawbacks, including a complicated synthetic process, harsh synthetic conditions, unavailability of enantiopure raw materials, and poor solubility in water.…”

“…Moreover, this analytical method is simple and the requirements of instruments and equipment are relatively low, which could be visually distinguished. 10 Chiral fluorescence sensors basically include small organic molecule-based chiral chemosensors and nanomaterial-based chiral probes. 11,12 However, they usually suffer from the major drawbacks, including a complicated synthetic process, harsh synthetic conditions, unavailability of enantiopure raw materials, and poor solubility in water.…”

A Gallium-based Chiral Solvating Agent Enables the Use of 1H NMR Spectroscopy to Differentiate Chiral Alcohols

“…This useful technique was successfully demonstrated for a variety of substrates with chiral amines and carboxylic acids being the most commonly targeted substrates (Benedict et al., 2018, Chen et al., 2018, Ema et al., 2018, Khanvilkar and Bedekar, 2018, Merino et al., 2018, Liu et al., 2011, Chinchilla et al., 1995). The emphasis on these species is not surprising, because the majority of chiral solvating agents employ non-covalent interactions such as hydrogen bonds and electrostatic attractions for structural recognition (Benedict et al., 2018, Chen et al., 2018, Ema et al., 2018, Khanvilkar and Bedekar, 2018, Merino et al., 2018, Liu et al., 2011, Chinchilla et al., 1995). Substrates that form relatively weak hydrogen bonds and are less strongly coordinating such as alcohols are more challenging to study.…”

Chiral 1H NMR Analysis of Carbonyl Compounds Enabled by Cationic Cobalt Complex

“…Such chiral analysis has been successfully performed with conventional chromatographic methods using high-performance liquid chromatography (HPLC) or gas chromatography (GC) . However, the utilization of 1 H nuclear magnetic resonance ( 1 H NMR) spectroscopy with chiral solvating agents (CSAs) has gained continuous attention as a complementary analytical technique. , In principle, the CSAs provide distinctive 1 H NMR signals obtained from two in-situ -formed diastereomeric adducts between the enantiopure CSA and the two enantiomers of the analyte of interest through noncovalent interactions, such as ion pairing, H bonding, or dipole–dipole interactions . Over the last few decades, several classes of CSAs such as (1) small- to medium-sized organic-based reagents, ,, (2) lanthanides or unsaturated transition-metal complexes, and (3) host compounds, such as cyclodextrins, crown ethers, and synthetic macrocycles, have been developed.…”