Observation of Chiral Channels in Helical Covalent Organic Frameworks.

Unraveling the mechanism of chirality transfer across length scales is crucial to the rational development of functional materials with hierarchical chirality. The key obstacle is the lack of structural information, especially at the mesoscopic level. We report herein the structural identification of helical covalent organic frameworks (COFs) with hierarchical chirality, which integrate molecular chirality, channel chirality, and morphology chirality into one crystalline entity.

Enhancing the Electrochemiluminescence of Porphyrin via Crystalline Networks of Metal-Organic Frameworks for Sensitive Detection of Cardiac Troponin I.

Porphyrins easily aggregate due to unfavorable π-π accumulation, causing luminescent quenching in the aqueous phase and subsequently reducing luminescent efficiency. It is a feasible way to immobilize porphyrin molecules through metal-organic framework materials (MOFs). In this study, 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (TCPP) was introduced into the metal-organic skeleton (PCN-224) as a ligand.

Divergent Synthesis of Chiral Covalent Organic Frameworks.

Featuring the simultaneous generation of a library of compounds from a certain intermediate, divergent synthesis has found increasing applications in the construction of natural products and potential medicines. Inspired by this approach, presented herein is a general strategy to introduce functionality, in a divergent manner, into covalent organic frameworks (COFs). This modular protocol includes two stages of covalent assembly, through which functional COFs can be constructed by a three-step transformation of a key platform molecule, such as 4,7-dibromo-2-chloro-1H-benzo[d]imidazole (DBCBI).

Chiral counteranion synergistic organocatalysis under high temperature: efficient construction of optically pure spiro[cyclohexanone-oxindole] backbone.

The combination of a cinchona-based chiral primary amine and a BINOL-phosphoric acid has been demonstrated as a powerful and synergistic catalyst system for the double Michael addition of isatylidene malononitriles with α,β-unsaturated ketones, to provide the novel chiral spiro [cyclohexane-1,3'-indoline]-2',3-diones in high yields (88-99%) with excellent diastereo- and enantioselectivities (94:6-99:1 dr's, 95-99% ee's).