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Alizarin red S is a sulfonated, water-soluble derivative of alizarin. This work presents femtosecond studies of alizarin red S (ARS) nanoparticles in comparison to ARS in aqueous solution and to alizarin in DMSO. The femtosecond studies cover a probing spectral range of 350–750 nm using different excitation wavelengths, taking into account the variation of the absorption spectra with the pH values of the solvent. Stationary absorption spectra show slight differences between solution and nanoparticles. Excitation at 530 nm results in low and noisy responses, therefore, we additionally recorded transient spectra of the nanoparticles at λex = 267 nm. While the results in DMSO are comparable to previous studies in non-aqueous solvents, we report a relatively fast relaxation of 14 ps in [La(OH)2][ARS] nanoparticles in aqueous solution after excitation at 530 nm, which is similar to Na(ARS) solution (19 ps). The dynamics changed with lower pH, but still without significant differences between nanoparticles and solution. We propose [La(OH)2][ARS] nanoparticles as a suitable alternative to dissolved molecules with similar spectroscopic properties, for example, with regard to biomarker applications.

A one‐pot, fully water‐based synthesis of blue‐ and red‐emitting C‐dots is presented. To this concern, [ZrO]2+[F6P]2− and [Eu(OH)]2+[F6P]2− precursor nanoparticles (F6P: D‐fructose‐6‐phosphate) are prepared in water and converted to C‐dot@[ZrO]2+[HPO4]2− and C‐dot@[Eu(OH)]2+[HPO4]2− composite nanoparticles in boiling water (100 °C) via microwave heating. Composition, structure, and fluorescence of the composite nanoparticles are validated by different analytical methods (e. g., FT‐IR, EA, TG, DLS, SEM, TEM, EDXS). The resulting aqueous suspensions are characterized by high colloidal stability and intense emission. Specifically, C‐dot@[Eu(OH)]2+[HPO4]2− exhibits Eu3+‐type red emission in water. The one‐pot water‐based synthesis with fructose‐containing precursor nanoparticles and the structure of the phosphate‐stabilized C‐dot composite nanoparticles are reported for the first time.

Saline inorganic-organic hybrid nanoparticles (IOH-NPs) [La(OH)2]+[ARS]– (ARS: alizarin red S) are prepared in water as a new compound (particle size: 47±7 nm, ARS load: 65 wt-%). The IOH-NPs not only...

As with cooking, the microwave does the job – and converts [ZrO]2+[F6P]2−/[Eu(OH)]2+[F6P]2− precursor nanoparticles (F6P: D‐fructose‐6‐phosphate) at 100 °C in water to C‐dot@[ZrO]2+[HPO4]2−/C‐dot@[Eu(OH)]2+[HPO4]2− composite nanoparticles. The simple one‐pot reaction results in aqueous suspensions showing intense blue/red emission. More information can be found in the Full Paper by Claus Feldmann et al.