Electrical Conductivity and Luminescence in Coordination Polymers Based on Copper(I)-Halides and Sulfur-Pyrimidine Ligands

The solvothermal reactions between pyrimidinedisulfide
(pym2S2) and CuI or CuBr2 in CH2Cl2:CH3CN lead to the formation of [Cu11I7(pymS)4]n (pymSH = pyrimidine-2­(1H)-thione) (1) and the dimer [CuII(μ-Br)­(Br)­L]2 (L
= 2-(pyrimidin-2-ylamino)-1,3-thiazole-4-carbaldehyde) (2). In the later reaction, there is an in situ S–S, S–C­(sp2), and C­(sp2)–N multiple bond cleavage of
the pyrimidinedisulfide resulting in the formation of 2-(pyrimidin-2-ylamino)-1,3-thiazole-4-carbaldehyde.
Interestingly, similar reactions carried out just with a change in
the solvent (H2O:CH3CN instead of CH2Cl2:CH3CN) give rise to the formation of coordination
polymers with rather different architectures. Thus, the reaction between
pym2S2 and CuI leads to the formation of [Cu3I­(pymS)2]n (3) and [CuI­(pym2S3)] (pym2S3 = pyrimidiltrisulfide) (4), while [Cu3Br­(pymS)2]n (5) is isolated
in the reaction with CuBr2. Finally, the solvothermal reactions
between CuI and pyrimidine-2-thione (pymSH) in CH2Cl2:CH3CN at different ratios, 1:1 or 2:1, give the
polymers [Cu2I2(pymSH)2]n (6) and [Cu2I2(pymSH)]n (7), respectively.
The structure of the new compounds has been determined by X-ray diffraction.
The studies of the physical properties of the novel coordination polymers
reveal that compounds 3 and 5 present excellent
electrical conductivity values at room temperature, while compounds 1, 3, and 5–7 show luminescent strong red emission at room temperature.