EPR study of a copper impurity center in a single crystal of 2-thiothymine.
EPR spectroscopy was used to study the complex formed in crystals of 5-methyl-2-thiouracil (2-thiothymine) containing traces of copper. The copper impurities, originally present as Cu(I)-complex of 2-thiothymine in the lattice of 2-thiothymine, are transformed into paramagnetic Cu(II)-complex by ionizing radiation. It was found that the complex is planar, the plane being defined by two pairs of S and N atoms, from two adjacent 2-thiothymine molecules. The structure of the complex suggests that a pair of hydrogen bonds between two neighboring molecules is replaced by a stronger Cu-coordination bonding, with two sulfur and two nitrogen atoms as ligands. The spectroscopic parameters (g-tensor, A(63Cu) and A(14N) tensors) are essentially similar to those earlier observed for copper planar centers in other systems.
Besić
Erim
E
Faculty of Pharmacy and Biochemistry, University of Zagreb, A. Kovacića 1, 10002 Zagreb, Croatia.
Gomzi
Vjeran
V
Sanković
Kresimir
K
Herak
Janko N
JN
Krilov
Dubravka
D
D003300:Copper / Q000032:analysis* / Q000737:chemistry; D003460:Crystallization; D004578:Electron Spin Resonance Spectroscopy; D008968:Molecular Conformation; D013941:Thymine / Q000031:analogs & derivatives* / Q000737:chemistry
C101233:2-thiothymine; D003300:Copper; D013941:Thymine