Enantiomorphic Microvortex‐Enabled Supramolecular Sensing of Racemic Amino Acids by Using Achiral Building Blocks

Chiral-Controlled Cyclic Chemiluminescence Reactions for the Analysis of Enantiomer Amino Acids

The similarity and complexity of chiral amino acids (AAs) in complex samples remain a significant challenge in their analysis. In this work, the chiral metal-organic framework (MOF)-controlled cyclic chemiluminescence (CCL) reaction is developed and utilized in the analysis of enantiomer AAs. The chiral MOF of d-Co_0.75Zn_0.25-MOF-74 is designed and prepared by modifying the Co_0.75Zn_0.25-MOF-74 with d-tartaric acid. The developed chiral bimetallic MOF can not only offer the chiral recognize sites but also act as the catalyst in the cyclic luminol-H₂O₂ reaction. Moreover, a distinguishable CCL signal can be obtained on enantiomer AAs via the luminol-H₂O₂ reaction with the control of d-Co_0.75Zn_0.25-MOF-74. The amplified difference of enantiomer AAs can be quantified by the decay coefficient (k-values) which are calculated from the exponential decay fitting of their obtained CCL signals. According to simulation results, the selective recognition of 19 pairs of AAs is controlled by the pore size of the MOF-74 and their hydrogen-bond interaction with d-tartaric acid on the chiral MOF. Furthermore, the k-values can also be used to estimate the change of chiral AAs in complex samples. Consequently, this chiral MOF-controlled CCL reaction is applied to differentiate enantiomer AAs involved in the quality monitoring of dairy products and auxiliary diagnosis, which provides a new approach for chiral studies and their potential applications.

Visible Helicity Induction and Memory in Polyallene toward Circularly Polarized Luminescence, Helicity Discrimination, and Enantiomer Separation

Inspired by biological helices (e.g., DNA), artificial helical polymers have attracted intense attention. However, precise synthesis of one-handed helices from achiral materials remains a formidable challenge. Herein, a series of achiral poly(biphenyl allene)s with controlled molar mass and low dispersity were prepared and induced into one-handed helices using chiral amines and alcohols. The induced one-handed helix was simultaneously memorized, even after the chiral inducer was removed. The switchable induction processes were visible to naked eye; the achiral polymers exhibited blue emission (irradiated at 365 nm), whereas the induced one-handed helices exhibited cyan emission with clear circularly polarized luminescence. The induced helices formed stable gels in various solvents with helicity discrimination ability: the same-handed helix gels were self-healing, whereas the gels of opposite-handed helicity were self-sorted. Moreover, the induced helices could separate enantiomers via enantioselective crystallization with high efficiency and switchable enantioselectivity.

Enantiospecific Detection of D-Amino Acid through Synergistic Upconversion Energy Transfer

D-amino acids (DAAs) are indispensable in regulating diverse metabolic pathways. Selective and sensitive detection of DAAs is crucial for understanding the complexity of metabolic processes and managing associated diseases. However, current DAA detection strategies mainly rely on bulky instrumentation or electrochemical probes, limiting their cellular and animal applications. Here we report an enzyme-coupled nanoprobe that can detect enantiospecific DAAs through synergistic energy transfer. This nanoprobe offers near-infrared upconversion capability, a wide dynamic detection range, and a detection limit of 2.2 μM, providing a versatile platform for in vivo noninvasive detection of DAAs with high enantioselectivity. These results potentially allow real-time monitoring of biomolecular handedness in living animals, as well as developing antipsychotic treatment strategies.

Static Retention of Dynamic Chiral Arrangements for Achiral Shear Thinning Metal-Organic Colloids

Chiral compounds are known to be important not only because they are the fundamental components of living organisms, but also for their unique chiroptical properties. In recent years, scientists have fabricated several chiral organic supramolecular aggregates by using chiral physical fields, such as vortex flow. Herein, the relationship between dynamic chiroptical properties and rheological nature is discussed, suggesting the shear thinning properties of non-Newtonian fluids might help colloidal particles adopt a chiral arrangement in vortices. Furthermore, the storage modulus of colloids could be increased by adding a linking agent, which successfully kept the dynamic chiroptical properties in the static state. Moreover, the salt effect on the host-guest interaction involved in the colloids was studied, the results suggested a significant enhancement of the transferred dynamic circular dichroism for the achiral guest molecule.

Circularly Polarized Luminescence of Achiral Metal-Organic Colloids and Guest Molecules in a Vortex Field

Recently, scientists have reported a range of chiral fluorescence materials or chiral composites that can emit circularly polarized luminescence. Herein, two achiral metal-organic colloidal solutions were studied, showing active circularly polarized luminescence, which is observed in vortex stirring. The absolute values for g_lum are 0.05 and 0.03 and the plus or minus sign of g_lum depends on the colloidal structure and stirring direction, which make the property easy to manipulate. Further, the host-guest interaction study suggests both electrostatic interactions and coordination bonding may influence the chiroptical property from the colloidal solution to the guest molecule. Rhodamine 6G and its carboxylic acid derivative exhibit good quantum yields and acceptable g_lum values in the colloidal solution.