Mariana Mitewa

Bio: Mariana Mitewa is an academic researcher from Sofia University. The author has contributed to research in topics: Ligand & Denticity. The author has an hindex of 18, co-authored 138 publications receiving 1395 citations. Previous affiliations of Mariana Mitewa include Bulgarian Academy of Sciences & University of Zagreb.

2-Acetylindan-1,3-dione and its Cu2+ and Zn2+ complexes as promising sunscreen agents

Abstract: Synopsis In continuation of a previous spectroscopic and quantum chemical study on 2-acetylindan-1,3-dione (2AID), the spectral properties and photostability of 2AID and its Cu2+ and Zn2+ complexes in different solvents are reported. Comparison is made with the photostability of two commercially available sunscreens: benzophenone-3 and octylmethoxycinnamate. 2AID exhibits a higher photostability, high molar absorption coefficient (42 000 m−1 cm−1) at λmax and broad-spectrum UV-protection properties. The hypothesis that the strong intramolecular H-bonding is responsible for the higher photostability was confirmed by studying the photodegradation upon irradiation with UV light of 2AID in hydrogen bond-breaking solvent, DMSO. The data obtained show that 2AID undergoes rapid degradation in this solvent. It is found that Cu2+ and Zn2+−2AID complexes show higher photostability in DMSO than 2AID itself. Resume A la suite d'une etude prealable en Chimie Spectroscopique et quantique, portant sur le 2-Acetylindan-1,3 dione (2AID), les proprietes spectrales et de photo stabilite du 2AID et ses complexes de Cu2+ et Zn2+ dans differents solvants sont rapportees ici. La comparaison avec la photo stabilite de 2 filtres solaires commerciaux – Benzophenone-3 et l'Octylmethoxycinnamate a ete conduite. Le 2AID montre une photo stabilite superieure, un coefficient d'extinction eleve (42 000 m−1 cm−1) a sa λmax et des proprietes de protection a large spectre. L'hypothese que la forte liaison Hydrogene intramoleculaire est responsable de la plus forte photo stabilite a ete confirmee par l'etude de sa photo degradation sous irradiation UV du 2AID dans un milieu solvant dissociant ces liaisons, le DMSO. Il est montre, de plus, que les complexes de Cu2+ et Zn2+ du 2AID sont plus photo stables dans ce solvant que le 2AID seul.

Crystal structures and spectral properties of new Cd(II) and Hg(II) complexes of monensic acid with different coordination modes of the ligand

Abstract: The single crystal X-ray structures and the spectroscopic properties of complexes of monensic acid (C36H62O11·H2O) with toxic metal ions of Cd(II) and Hg(II) are discussed. The cadmium(II) complex (1) is of composition [Cd(C36H61O11)2(H2O)2] and crystallizes in the monoclinic system (space group P2(1), Z = 2) with a = 12.4090(8), b = 24.7688(16), c = 14.4358(11) A, β = 91.979(7)°. Two ligand monoanions are bound in a bidentate coordination mode to Cd(II) via the carboxylate and the primary hydroxyl oxygens occupying the equatorial plane of the complex. The axial positions of the inner coordination sphere of Cd(II) are filled by two water molecules additionally engaged in intramolecular hydrogen bonds. The Hg(II) complex (2), [Hg(C36H60O11)(H2O)], crystallizes in the orthorhombic system (space group P2(1)2(1)2(1), Z = 4) with a = 12.7316(2), b = 16.4379(3), c = 18.7184(4) A. The monensic acid reacts with Hg(II) in a tetradentate coordination manner via both oxygen atoms of the carboxylate function and oxygens of two hydroxyl groups. The twofold negative charge of the ligand is achieved by deprotonation of carboxylic and secondary hydroxyl groups located at the opposite ends of the molecule. Hg(II) is surrounded by five oxygen atoms in a distorted square pyramidal molecular geometry. Open image in new window