To fabricate N-CQDs hybrid thermo-sensitive polymer (poly-N-CQDs), N-doped carbon quantum dots (N-CQDs) with strong blue fluorescence and poly(N-isopropylacrylamide-co-acrylic acid) (poly(NIPAAm-co-AAc)) copolymer with thermo-sensitivity were synthesized, respectively. Subsequently, the coupling reaction between. the -COOH groups of poly(NIPAAm-co-AAc) and the -NH2groups on the surface of the N-CQDs was carried out. The fluorescence spectra show that the coil-globule transition of the poly-N-CQDs coincided with intensity changes in the scattering peak at excitation wavelength with the temperature variations. The phase transition temperature and the fluorescent intensity of poly-N-CQDs can be regulated by modulating the composition and concentration of poly-N-CQDs as well as the temperature and pH of the local medium. The thermo-sensitivity and fluorescent properties of the poly-N-CQDs displayed good stability and reversibility. The fluorescence intensity and emission wavelengths of the poly-N-CQDs significantly changed in different solvents for solvent recognition. The poly-N-CQDs was employed as a fluorescent probe for Fe3+detection ranging from 0.025 to 1 mM with a limit of detection (LOD) of 9.49 μM. The hybrid polymer materials have the potential to develop an N-CQDs-based thermo-sensitive device or sensor.Keywords:N-doped carbon quantum dots;thermo-sensitive polymer;phase transition temperature;solvent recognition;ion detection
Graphical Multicolor fluorescence emission : Copper nanocluster (CuNC) assemblies with multicolor fluorescence emission and excellent reversibility were constructed on the basis of aggregation-induced emission and the solvent effect of glutathione (GSH)-capped CuNCs. On the basis of these stimuli-responsive fluorescent nanoswitches, a fluorescence sensing platform for the identification of organic solvents was designed. Copper nanoclusters (CuNCs) as a new class of fluorescent materials have attracted a great deal of interest due to their outstanding fluorescence properties. In this work, a variety of organic solvents were used to induce self-assembly of glutathione-capped CuNCs (GSH-CuNCs) to form ordered assemblies with enhanced fluorescence properties. Assemblies with multicolor fluorescence emission were constructed on the basis of the aggregation-induced emission (AIE) of GSH-CuNCs and the solvent effect. The fluorescence emission from these GSH-CuNCs assemblies can also be tuned from yellow to purple by changing the organic solvent. A possible mechanism based on the size of the assemblies and electron transfer was explored to explain the solvent effects on GSH-CuNCs. Stimuli-responsive nanoswitches with excellent reversibility can be controlled by changing the type of organic solvent and the ratio of the organic solvent to the aqueous solution of GSH-CuNCs. As the CuNCs assemblies exhibit strong, stable, and color-tunable fluorescence, they were employed as color-conversion materials for recognizing different organic solvents.
Qiang Zhao,Han Peng,He-zhen Wang,Shu-ran Gao,Jun-zhao Wang,Lin-Xi Qin,Meng-ting Fan
In order to better study the properties of rare earth complexes in terms of fluorescence, magnetism, and fluorescent probes, in this work, 5-(2-carboxyphenoxy)isophthalic acid (H 3 ocpia) and rare metal ions Eu 3+ , Tb 3+ , Dy 3+ were used to synthetic metal complexes by solvothermal reaction. Then three complexes Eu(ocpia) (1) , Tb(ocpia) (2) and Dy(ocpia) (3) were synthesized, their structural formulas are as follows: EuC 15 H 7 O 7, TbC 15 H 7 O 7 and DyC 15 H 7 O 7 . Data on the structure acquired via an X - ray single - crystal diffractometer indicates that complexes 1, 2 , and 3 possess the same spatial structures. They are two-dimensional planar structures with undulating ripples. Moreover, solid - state fluorescence tests were carried out on complexes H 3 ocpia, 1 , and 2 , and magnetic property tests were done on complexes 2 and 3 . Fluorescence recognition studies were conducted on complexes 1 and 2 in dispersed systems. The solid-state fluorescence results show that complexes 1 and 2 have excellent fluorescence properties, with higher fluorescence intensity than the ligand. The CIE chromaticity coordinates of complexes 1 and 2 are (0.59, 0.34) and (0.33, 0.62), respectively, and exhibit bright characteristic lights of europium and terbium under fluorescent lamps. Magnetic susceptibility measurements reveal that compounds 2 and 3 exhibit antiferromagnetic coupling behavior between adjacent metal centers. Fluorescence recognition studies have shown that complexes 1 and 2 exhibit good recognition of acetone in dispersed systems, the detection thresholds were determined to be 0.063 vol.% for complex 1 and 0.136 vol.% for complex 2 .
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