title: Synthesis and EPR-spectroscopic characterization of the perchlorotriarylmethyl tricarboxylic acid radical (PTMTC) and its13C labelled analogue (13C-PTMTC).
abstract: A hydrophilic tris(tetrachlorotriaryl)methyl (tetrachloro-TAM) radical labelled 50% with13C at the central carbon atom was prepared. The mixture of isotopologue radicals was characterised by continuous wave and pulsed X-band electron paramagnetic spectroscopy (EPS). For the pharmaceutical and medical applications planned, the quantitative influence of oxygen, viscosity, temperature and pH on EPR line widths was studied in aqueous buffer, DMSO, water-methanol and water-glycerol mixtures. Under in vivo conditions, pH can be disregarded. There is a clear oxygen dependence of the width of the12C isotopologue single EPR line in aqueous solutions while changes in rotational motion (viscosity) are observable only in the doublet lines of the central carbon of the13C isotopologue. The tetrachloro-TAM proved to be very stable as a solid. Its thermal decay was determined quantitatively by thermal annealing. Towards ascorbic acid as a reducing agent and towards an oocyte cell extract it had a half-life of approx. 60 and 10 min. Thus for in vivo applications, 50%13C tetrachloro-TAMs are suitable for selective and simultaneous oxygen and macroviscosity measurements in a formulation, e.g. nanocapsules.
authors.affiliation: Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany. peter.imming@pharmazie.uni-halle.de and Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt.
authors.forename: Marwa
authors.initials: M
authors.lastname: Elewa
authors.affiliation: Institut für Chemie, Physikalische Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle, Germany. dariush.hinderberger@chemie.uni-halle.de.
authors.forename: Nadica
authors.initials: N
authors.lastname: Maltar-Strmečki
authors.affiliation: Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt.
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Said
authors.affiliation: Faculty of Pharmacy, Suez Canal University, P.O. 41522, Ismailia, Egypt.
authors.forename: Hosam A
authors.initials: HA
authors.lastname: El Shihawy
authors.affiliation: Faculty of Pharmacy, Zagazig University, Zagazig, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: El-Sadek
authors.affiliation: Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany. peter.imming@pharmazie.uni-halle.de.
authors.forename: Juliane
authors.initials: J
authors.lastname: Frank
authors.affiliation: Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany. peter.imming@pharmazie.uni-halle.de.
authors.forename: Simon
authors.identifier: http://orcid.org/0000-0002-3272-1721
authors.initials: S
authors.lastname: Drescher
authors.affiliation: Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany.
authors.forename: Malte
authors.initials: M
authors.lastname: Drescher
authors.affiliation: Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany. peter.imming@pharmazie.uni-halle.de.
authors.forename: Karsten
authors.initials: K
authors.lastname: Mäder
authors.affiliation: Institut für Chemie, Physikalische Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle, Germany. dariush.hinderberger@chemie.uni-halle.de.
authors.forename: Dariush
authors.identifier: http://orcid.org/0000-0002-6066-7099
authors.initials: D
authors.lastname: Hinderberger
authors.affiliation: Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany. peter.imming@pharmazie.uni-halle.de.
authors.forename: Peter
authors.identifier: http://orcid.org/0000-0003-2178-3887
authors.initials: P
authors.lastname: Imming