Semiconductive and Magnetic One-Dimensional Coordination Polymers of Cu(II) with Modified Nucleobases

Four
new copper­(II) coordination complexes, obtained by reaction of CuX2 (X = acetate or chloride) with thymine-1-acetic acid and
uracil-1-propionic acid as ligands, of formulas [Cu­(TAcO)2(H2O)4]·4H2O (1), [Cu­(TAcO)2(H2O)2]n (2), [Cu3(TAcO)4(H2O)2(OH)2]n·4H2O (3), and [Cu3(UPrO)2Cl2(OH)2(H2O)2]n (4) (TAcOH = thymine-1-acetic
acid, UPrOH = uracil-1-propionic acid) are described. While 1 is a discrete complex, 2–4 are one-dimensional coordination polymers. Complexes 2–4 present dc conductivity values between 10–6 and 10–9 S/cm–1. The magnetic behavior of complex 2 is typical for
almost isolated Cu­(II) metal centers. Moderate–weak antiferromagnetic
interactions have been found in complex 3, whereas a
combination of strong and weak antiferromagnetic interactions have
been found in complex 4. Quantum computational calculations
have been done to estimate the individual “J” magnetic coupling constant for each superexchange pathway
in complexes 3 and 4. Compounds 2–4 are the first known examples of semiconductor
and magnetic coordination polymers containing nucleobases.