Trifluoroacetic Anhydride Promoted Copper(I)-Catalyzed Interrupted Click Reaction: From 1,2,3-Triazoles to 3-Trifluoromethyl-Substituted 1,2,4-Triazinones

A "Polymer Template" Strategy for Carbonized Polymer Dots with Controllable Properties

Limited avenues are available for property control of carbonized polymer dots (PDs) owing to the unsatisfactory understanding of PDs" formation. Herein, a de novo "polymer template" strategy is presented for PDs with customizable functional surface groups (FSG), size, and underlying fluorescence, with a detailed mechanism. The strategy relies on novel di-active site polymers (DASPs) prepared from alkenyl azides via [3+2] cycloaddition and guanidino hydrolysis. Benefiting from these specific reactions, the DASPs were convenient for mass production and stable for storage, and could be transformed to PDs upon addition of nucleophilic agents through nucleophilic addition and substitution at 70 °C. By regulating the types of alkenyl azides, nucleophilic agents, and reaction conditions, the as-prepare PDs could be tailored with controlled types of core, FSG, and particle size, as well as fluorescence properties of quantum yield from 8.2-55.6 %, and emission maximum from 380-500 nm. These specialties make this "polymer template" strategy a promising start for building PDs-based sensor platforms. Moreover, the strategy could further our understanding towards PDs' formation, and open up a new way to customize PDs for specific needs in the fields of analysis, catalysis, images, etc.

Highly Stable Copper(I)-Thiacalix[4]arene-Based Frameworks for Highly Efficient Catalysis of Click Reactions in Water

Environmentally friendly metal-organic frameworks (MOFs) have gained considerable attention for their potential use as heterogeneous catalysts. Herein, two Cu^I -based MOFs, namely, [Cu₄ Cl₄ L]⋅CH₃ OH⋅1.5 H₂ O (1-Cl) and [Cu₄ Br₄ L]⋅DMF⋅0.5 H₂ O (1-Br), were assembled with new functionalized thiacalix[4]arenes (L) and halogen anions X^- (X=Cl and Br) under solvothermal conditions. Remarkably, catalysts 1-Cl and 1-Br exhibit great stability in aqueous solutions over a wide pH range. Significantly, MOFs 1-Cl and 1-Br, as recycled heterogeneous catalysts, are capable of highly efficient catalysis for click reactions in water. The MOF structures, especially the exposed active Cu^I sites and 1D channels, play a key role in the improved catalytic activities. In particular, their catalytic activities in water are greatly superior to those in organic solvents or even in mixed solvents. This work proposes an attractive route for the design and self-assembly of environmentally friendly MOFs with high catalytic activity and reusability in water.