Synthesis, characterization and antibacterial susceptibility testing of manganese complexes of doxycyline with bipyridine and phenanthroline

Three manganese complexes of the antibiotic doxycyline viz.: manganese doxycyline, [MnDox2]Cl2‧2H2O (1), and manganese doxycyline with bipyridine, [MnDox2(bpy)]Cl2‧8H2O (2), and phenanthroline, [MnDox2(phen)]Cl2‧8H2O (3), as the ancillary ligand were synthesized and characterized by FT-IR, elemental analysis and electrospray mass spectroscopy. The three complexes show good solubility in DMF and DMSO. Data obtained from spectroscopic techniques used show that doxycycline coordinates to the central manganese atom through the oxygen of the amide group and the carbonyl oxygen atom of ring A while bipyridine/phenanthroline coordinates through the two diimine nitrogen atoms. The stoichiometry of manganese-doxycycline is 1:2 and octahedral geometry is the preferred coordination in all the complexes.

Crystal structure of bis(2-{[1,1-bis(hydroxymethyl)-2-oxidoethyl]iminomethyl}-6-methoxyphenolato)manganese(IV) 0.39-hydrate

The title compound, [Mn(C12H15NO5)2]·0.39H2O, is a 0.39 hydrate of the isostructural complex bis(2-{[1,1-bis(hydroxymethyl)-2-oxidoethyl]iminomethyl}-6-methoxyphenolato)manganese(IV) that has previously been reported by Back, Oliveira, Canabarro & Iglesias [Z. Anorg. Allg. Chem.(2015),641, 941–947], based on room-temperature data. The current structure that was determined at 100 K reveals a lengthening of theccell parameter compared with the published one due to the incorporation of the partial occupancy water molecule. The title compound crystallizes in the tetragonal chiral space groupP41212; the neutral [MnIV(C12H15NO5)2] molecule is situated on a crystallographicC2axis. The overall geometry about the central manganese ion is octahedral with an N2O4core; each ligand acts as a meridional ONO donor. The coordination environment of MnIVat 100 K displays a difference in one of the two Mn–O bond lengths, compared with the room-temperature structure. In the crystal, the neutral molecules are stacked in a helical fashion along thec-axis direction.