A novel rhodamine-based receptor bearing a morpholine (RDM) was developed as a fluorescent chemosensor with high selectivity toward Hg2+. After the addition of Hg2+ to RDM, the color of the solution changed from colorless to pink, and the new absorption band appears
at 580 nm. The fluorescent of RDM appears to orange color in the presence of Hg2+. Upon the addition of Hg2+, ring-opening of the corresponding spirolactam gives rise to fluorescence, and a 1:1 metal-ligand complex formed.
Biodiesel fuels contain unsaturated fatty acid ester, which can easily oxidize, especially when exposed to ultraviolet light. The products formed by this oxidation give rise to sediment or gum formation. As a result, the fuel can contribute to the corrosion and plugging of the filter pump. Antioxidants have been used in an effort to stabilize biodiesels, but there is still a need for a biodiesel composition with improved oxidation stability. In general, good fuel compositions should provide synergistic combinations of a biodiesel and antioxidants. Our work involved the synthesis of antioxidants to improve the oxidative stability of biodiesel fuel.
Small metal complexes are highly interesting for bioimaging because of their excellent near-infrared (NIR) absorption properties. In this study, neutral complexes of platinum(II) connected to two monoreduced 1,3-diisopropylimidazoline-2,4,5-trithione ligands—namely, [Pt(iPr2timdt)2]—were investigated. Theoretical studies using the density functional theory (DFT) and GW-BSE approximation verified the effects of the geometry of the isopropyl moieties on the NIR absorption spectra. The calculated absorption spectra showed excellent correspondence with the experimental results. The geometry of the isopropyl groups considerably influenced the electronic structures of the metal complexes, which altered the absorption profiles of the respective geometries, as demonstrated in this research.
We report the design and synthesis of a novel chemosensor (Rh6G-Cin) rhodamine-based indicator for selective detection of Zn2+ ion. Rh6G-Cin displayed high selectivity towards Zn2+ from various metal ions, including Ca2+, Ag+, Cd2+, Co2+, Cu2+, Al3+, Zn2+, Cr3+, Ba2+, Fe2+, Fe3+, Gd3+, Hg2+, Mg2+, Mn2+, Nd3+, Pb2+, Sr2+ and Ni2+, and the resultant complex is [Rh6G-Cin-Zn2+]. The obvious change from colorless to pink upon the addition of Zn2+ could make it a suitable "naked eye" indicator for Zn2+. More significantly, the sensor displayed a remarkable colorless to yellowish green fluorescence switch in the presence of Zn2+ ions. The ring-opening mechanism of the rhodamine spirolactam was induced by Zn2+ binding, and the 3:1 stoichiometric structure between Rh6G-Cin and Zn2+ was adequately supported by the Job's plot evaluation, optical titration and 1H NMR results.
A rhodamine-based fluorescent chemosensor (Rh6G-2HC) was synthesized easily by a one-step condensation reaction. The structure was characterized using NMR, MS and EA spectroscopies. As soon as Cu 2+ was added into the chemosensor solution, a color change from colorless to pink color was observed, and a considerable change in the absorption and fluorescence spectra. However, no spectral changes were indicated for other heavy metals such as Ag + , Zn 2+ , Cd 2+ , and Co 2+. In order to provide a more detailed metal sensing performance, the optical and structural properties for the Cu 2+ sensing effect were investigated using UV-Vis, fluorescence and H-NMR spectroscopies.
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