Synthesis of Fluorescent Dansyl Derivatives of Methoxyamine and Diphenylhydrazine as Free Radical Precursors

Starting from dansyl-chloride, in reaction with 1,1-diphenylhydrazine and methoxyamine, two new fluorescent derivatives 1 and 2 were obtained and characterized by NMR, IR, UV-Vis, HR-MS, and fluorescence spectroscopy. The single-crystal X-ray structure was obtained for compound 2. Both compounds generate free radicals by oxidation, as demonstrated by ESR spectroscopy. Compound 1 generates the corresponding hydrazyl-persistent free radical, evidenced directly by ESR spectroscopy, while compound 2 generates in the first instance the methoxyaminyl short-lived free radical, which decomposes rapidly with the formation of the methoxy radical, evidenced by the ESR spin-trapping technique. By oxidation of compounds 1 and 2, their fluorescence is quenched.

UHPLC-HRMS determination of adrenaline and dopamine dansyl derivatives in human saliva

In the last decade, the quantification of catecholamines in human biological fluids has been of great interest. Changes in catecholamine levels, such as adrenaline and dopamine, in the body lead to neurological disorders as well as several diseases, namely Alzheimer’s and Parkinson’s diseases, neuroendocrine catecholamine - producing tumors - pheochromocytoma, paraganglioma, carcinoid tumors and neuroblastoma. Moreover, different drug combinations can lead to the distortions in the human biological passport, containing the information not only about the erythropoiesis and steroid profile, but also about catecholamine levels, which are difficult to quantify in terms of sample preparation and analysis. A method has been proposed for the determination of adrenaline and dopamine dansyl derivatives in human saliva, including the derivatization and determination of analytes by ultra-high-performance liquid chromatography (UHPLC) with high resolution mass spectrometric detection. The derivatization procedure allowed obtaining less polar catecholamine derivatives, which is especially important for their quantification by reversed-phase ultra-high-performance liquid chromatography since it ensures their better retention on the sorbent. The sensitivity of these substances quantification by the proposed method was estimated; the highest sensitivity was achieved using the mobile phase consisting of the 0.1% formic acid aqueous solution and acetonitrile. The lower limit of quantification was 5 ng/mL for dansyldrenaline and 10 ng/mL for dansyldopamine respectively. The proposed technique was tested on real saliva samples obtained from volunteers to quantify catecholamine dansyl derivatives by reversed-phase high-performance liquid chromatography with high-resolution mass spectrometric detection. High sensitivity of the technique allows using it for adrenaline and dopamine determination in clinical diagnosis.

Crystal structure of 5,5′-bis(dimethylamino)-N,N′-(3-methyl-3-azapentane-1,5-diyl)di(naphthalene-1-sulfonamide)

In the title compound, C29H37N5O4S2, two arms substituted with dansyl derivatives are connected to a central tertiary amine, where the dihedral angle between the planes of two dansyl units is 56.39 (4)°. Each arm contains a sulfonamide functional group and both N—H groups in the compound are pointed to the same side. The central part of the molecule is disordered over three sets of sites with a refined occupancy ratio of 0.547 (4):0.328 (4):0.125 (3). No intramolecular π–π or hydrogen-bonding interactions are observed. In the crystal, molecules are linkedviapairs of N—H...O interactions involving the same acceptor atom, forming inversion dimers. In addition, C—H...O interactions exist between molecules, providing further stabilization of dimers.