New TEMPO-Appended 2,2'-Bipyridine-Based Eu(III), Tb(III), Gd(III) and Sm(III) Complexes: Synthesis, Photophysical Studies and Testing Photoluminescence-Based Bioimaging Abilities

Linked to Alzheimer's disease (AD), amyloids and tau-protein are known to contain a large number of cysteine (Cys) residues. In addition, certain levels of some common biogenic thiols (cysteine (Cys), homocysteine (Hcy), glutathione (GSH), etc.) in biological fluids are closely related to AD as well as other diseases. Therefore, probes with a selective interaction with the above-mentioned thiols can be used for the monitoring and visualizing changes of (bio)thiols in the biological fluids as well as in the brain of animal models of Alzheimer's disease. In this study, new Eu(III), Tb(III), Gd(III) and Sm(III) complexes of 2,2'-bipyridine ligands containing TEMPO fragments as receptor units for (bio)thiols are reported. The presence of free radical fragments of the ligand in the complexes was proved by using the electronic paramagnetic resonance (EPR) method. Among all the complexes, the Eu(III) complex turned out to be the most promising one as luminescence- and spin-probe for the detection of biogenic thiols. The EPR and fluorescent titration methods showed the interaction of the resulting complex with free Cys and GSH in solution. To study the practical applicability of the probes for the monitoring of AD in-vivo, by using the above-mentioned Eu(III)-based probe, the staining of the brain of mice with amyloidosis and Vero cell cultures supplemented with the cysteine-enriched medium was studied as well as the fluorescence titration of Bovine Serum Albumin, BSA (as the model for the thiol moieties containing protein), was carried out. Based on the results of fluorescence titration, the formation of a non-covalent inclusion complex between the above-mentioned Eu(III) complex and BSA was suggested.

Idiosyncratic recognition of Zn2+ and CN- using Pyrazolyl-Hydroxy-Coumarin scaffold and live cell imaging: Depiction of Luminescent Zn(II)-Metallocryptand

Multi-responsive sensitive and selective sensor design is one of the stimulating researches in sensor field. We have designed a pyrazolyl-hydroxy-coumarin scaffold, 7-hydroxy-4-methyl-8-(((5-phenyl-1H-pyrazol-3-yl)imino)methyl)-2H-chromen-2-one (H2L) and characterized by spectroscopic data (1H-NMR,13C-NMR, ESI-MS,...

Crystal structure and Hirshfeld surface analysis of 1-[(E)-2-(5-chloro-2-hy-droxy-phen-yl)hydrazin-1-yl-idene]naphthalen-2(1H)-one

The title compound, C16H11ClN2O2, was obtained by diazo-tization of 2-amino-4-chloro-phenol followed by a coupling reaction with β-naphthol. There are two mol-ecules (A and B) in the asymmetric unit. The crystal structure features only one type of inter-molecular inter-action, that is strong hydrogen bonds involving the hydroxyl group. The naphthol and phenol fragments attached to the C=N-N- moiety exhibit an s-trans conformation. In addition, those fragments are almost coplanar, subtending a dihedral angle of 13.11 (2)° in mol-ecule A and 10.35 (2)° in mol-ecule B. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (32.1%), C⋯H/H⋯C (23.1%), Cl⋯H/H⋯Cl (15.2%), O⋯H/H⋯O (12.8%) and C⋯C (9%) contacts.