0000000001307836
AUTHOR
Luís Cunha-silva
New structural motifs in Mn cluster chemistry from the ketone/gem-diol and bis(gem-diol) forms of 2,6-di-(2-pyridylcarbonyl)pyridine: {MnII4MnIII2} and {MnII4MnIII6} complexes
The employment of the tripyridyl/diketone ligand 2,6-di-(2-pyridylcarbonyl)pyridine [(py)CO(py)CO(py)], in conjunction with azides (N3−), in Mn cluster chemistry has afforded the mixed-valence (II/III) complexes [MnII4MnIII2(N3)6Cl4(L1)2(DMF)4] (1) and [MnII4MnIII6O2(N3)12(L1)2(L2H)2(DMF)6] (2) in good yields. The resulting ligands L12− and L2H3− are the dianion and trianion of the ketone/gem-diol (L1H2) and bis(gem-diol) (L2H4) forms of (py)CO(py)CO(py), respectively, as derived from the metal-assisted hydrolysis of the parent dicarbonyl organic compound. Under the same synthetic conditions (i.e., reaction solvents, temperature and stirring time), the chemical identity of the two complexes…
Fluoroquinolone–metal complexes: A route to counteract bacterial resistance?
Abstract Microbial resistance to antibiotics is one of the biggest public health threats of the modern world. Antibiotic resistance is an area of much clinical relevance and therefore research that has the potential to identify agents that may circumvent it or treat resistant infections is paramount. Solution behavior of various fluoroquinolone (FQ) complexes with copper(II) in the presence and absence of 1,10-phenanthroline (phen) was studied in aqueous solution, by potentiometry and/or spectrophotometry, and are herein described. The results obtained showed that under physiological conditions (micromolar concentration range and pH 7.4) only copper(II):FQ:phen ternary complexes are stable.…
Chemistry and Photochemistry of 2,6-Bis(2-hydroxybenzilidene)cyclohexanone. An Example of a Compound Following the Anthocyanins Network of Chemical Reactions
The kinetics and thermodynamics of the 2,6-bis(2-hydroxybenzilidene)cyclohexanone chemical reactions network was studied at different pH values using NMR, UV-vis, continuous irradiation, and flash photolysis. The chemical behavior of the system partially resembles anthocyanins and their analogue compounds. 2,6-Bis(2-hydroxybenzilidene)cyclohexanone exhibits a slow color change from yellow to red styrylflavylium under extreme acidic conditions. The rate constant for this process (5 × 10(-5) s(-1)) is pH independent and controlled by the cis-trans isomerization barrier. However, the interesting feature is the appearance of the colorless compound, 7,8-dihydro-6H-chromeno[3,2-d]xanthene, isolat…
1,3-Dipolar cycloadditions with meso-tetraarylchlorins – site selectivity and mixed bisadducts
The 1,3-dipolar cycloaddition reaction of meso-tetraarylporphyrins with nitrones gives isoxazolidine-fused chlorins. Depending on the substitution pattern on the meso-aryl groups and the nitrone, the chlorins can be obtained in high yields (up to 91%). Bacteriochlorin-type bisadducts are also obtained, although in low yield, from the reaction of meso-tetrakis(pentafluorophenyl)porphyrin with N-methyl, N-cyclohexyl or N-benzyl nitrone. The structure of a bis(N-benzyl isoxazolidine-fused) bacteriochlorin was determined by single-crystal X-ray diffraction and rationalized by DFT calculations. To further explore the nature of site selectivity in the formation of bisadducts, isomeric mixed bacte…
The Influence of the Amide Linkage in the FeIII-Binding Properties of Catechol-Modified Rosamine Derivatives
The two new fluorescent ligands RosCat1 and RosCat2 contain catechol receptors connected to rosamine platforms through an amide linkage and were synthesized by using microwave-assisted coupling reactions of carboxyl- or amine-substituted rosamines with the corresponding catechol units and subsequent deprotection. RosCat1 possesses a reverse amide, whereas RosCat2 has the usual oriented amide bond (HNCO vs. CONH, respectively). The ligands were characterized by means of NMR spectroscopy, mass-spectrometry, and DFT calculations and X-ray crystallography studies for RosCat1. The influence of the amide linkage on the photophysical properties of the fluorescent ligands was assessed in different …
CCDC 990231: Experimental Crystal Structure Determination
Related Article: Maria J. Feio, Isabel Sousa, Mariana Ferreira, Luís Cunha-Silva, Raúl G. Saraiva, Carla Queirós, José G. Alexandre, Vasco Claroa, AdéliaMendes, RosaOrtiz, Sandra Lopes, Ana Luísa Amaral, João Lino, Patrícia Fernandes, Ana João Silva, Lisete Moutinho, Baltazar de Castro, Eulália Pereira, Lourdes Perelló, Paula Gameiro|2014|J.Inorg.Biochem.|138|129|doi:10.1016/j.jinorgbio.2014.05.007
CCDC 1503292: Experimental Crystal Structure Determination
Related Article: Dimosthenis P. Giannopoulos, Luís Cunha-Silva, Rafael Ballesteros-Garrido, Rafael Ballesteros, Belén Abarca, Albert Escuer, Theocharis C. Stamatatos|2016|RSC Advances|6|105969|doi:10.1039/C6RA22953K
CCDC 990233: Experimental Crystal Structure Determination
Related Article: Maria J. Feio, Isabel Sousa, Mariana Ferreira, Luís Cunha-Silva, Raúl G. Saraiva, Carla Queirós, José G. Alexandre, Vasco Claroa, AdéliaMendes, RosaOrtiz, Sandra Lopes, Ana Luísa Amaral, João Lino, Patrícia Fernandes, Ana João Silva, Lisete Moutinho, Baltazar de Castro, Eulália Pereira, Lourdes Perelló, Paula Gameiro|2014|J.Inorg.Biochem.|138|129|doi:10.1016/j.jinorgbio.2014.05.007
CCDC 1488184: Experimental Crystal Structure Determination
Related Article: José Almeida, António Aguiar, Andreia Leite, André M. N. Silva, Luís Cunha-Silva, Baltazar de Castro, Maria Rangel, Giampaolo Barone, Augusto C. Tomé, Ana M. G. Silva|2017|Org.Chem.Front.|4|534|doi:10.1039/C6QO00771F
CCDC 1503291: Experimental Crystal Structure Determination
Related Article: Dimosthenis P. Giannopoulos, Luís Cunha-Silva, Rafael Ballesteros-Garrido, Rafael Ballesteros, Belén Abarca, Albert Escuer, Theocharis C. Stamatatos|2016|RSC Advances|6|105969|doi:10.1039/C6RA22953K