title: EPR study of a copper center in a single crystal of cytosine monohydrate.
abstract: Copper is found incorporated into the crystal structure of cytosine monohydrate grown from aqueous solution of commercially available cytosine. Upon ionizing irradiation, the crystals exhibited the electron paramagnetic resonance (EPR) spectra characteristic of Cu(II) complex. Planar coordination bonding to the cupric ion, having three nitrogen atoms and an oxygen as ligands, is interpreted to bridge two cytosine molecules, replacing the two cytosine-cytosine hydrogen bonds present in pure crystals. The EPR signals are much stronger for crystals grown from the solutions to which small amount of copper powder were added.
authors.affiliation: Medical School, University of Zagreb, Salata 3b, 10001 Zagreb, Croatia.
authors.forename: Dubravka
authors.initials: D
authors.lastname: Krilov
authors.forename: Andrica
authors.initials: A
authors.lastname: Lekić
authors.forename: Erim
authors.initials: E
authors.lastname: Besić
authors.forename: Janko N
authors.initials: JN
authors.lastname: Herak