(R,R)-salen/salan-based polymer fluorescence sensors for Zn2+ detection

Electronic Impacts on the Solvent-Free Mechanochemical Synthesis of Salophen Ligands in Ball Mill

To realize the scope of the solid-solid reaction, the functional solid diamines reacted with solid 3-ethoxysalicylaldehyde under high-speed ball milling in a solvent-free environment. The findings showed that a wide range of Salophen ligands could be produced in good to excellent yields. In comparison to the similar Salophen synthesis to date, the current study provided solvent-free, fast reaction, high yield, and easy work-up.

Substrate-dependent allosteric regulation by switchable catalytic molecular tweezers

Allosteric regulation is exploited by biological systems to regulate the activity and/or selectivity of enzymatic reactions but remains a challenge for artificial catalysts. Here we report switchable terpy(Zn-salphen)2 molecular tweezers and their metal-dependent allosteric regulation of the acetylation of pyridinemethanol isomers. Zinc-salphen moieties can both act as a Lewis acid to activate the anhydride reagents and provide a binding site for pyridinemethanol substrates. The tweezers’ conformation can be reversibly switched between an open and a closed form by a metal ion stimulus. Both states offer distinct catalytic profiles, with closed tweezers showing superior catalytic activity towards ortho substrates, while open tweezers presenting higher rate for the acetylation of meta and para substrates. This notable substrate dependent allosteric response is rationalized by a combination of experimental results and calculations supporting a bimetallic reaction in the closed form for ortho substrate and an inhibition of the cavity for meta and para substrates.

Synthesis and fluorescence study of conjugated polymers based on 2,4,6-triphenylpyridine moieties

Three novel 2,4,6-triphenylpyridine-based conjugated polymers showed strong fluorescence emission with large Stokes' shifts, tunable band gaps and high quantum yields.

How the stereochemistry decides the selectivity: an approach towards metal ion detection

The orientation of the coordination sites in a polymer system decide the metal ion selectivity.

Dopamine fluorescent sensors based on polypyrrole/graphene quantum dots core/shell hybrids

A facilely prepared fluorescent sensor was developed for dopamine (DA) detection with high sensitivity and selectivity based on polypyrrole/graphene quantum dots (PPy/GQDs) core/shell hybrids. The composites exhibit strong fluorescence emission, which is dramatically enhanced as high as three times than pristine GQDs. The prepared sensor allows a highly sensitive determination of DA by fluorescent intensity decreasing with the addition of DA and presents a good linearity in range of 5-8000 nM with the detection limit of 10 pM (S/N = 3). Furthermore, the application of the proposed approach have been demonstrated in real samples and showed promise in diagnostic purposes.

Synthesis, characterization, and luminescence modulation of a rare barium-tetracarboxylate framework with I2O1 connectivity

Solvothermal reaction of a tetracarboxylic acid with Ba(NO₃)₂ afforded a barium–organic framework whose single crystal X-ray structure was characterized to have I²O¹ connectivity and 1 D channels 15.1 Å in diameter. This MOF has high thermal stability up to 540 °C, and its luminescence intensity can be modulated by ion exchange.