Influence of Axial Linkers on Polymerization in Paddle-Wheel Cu(II) Coordination Polymers for the Application of Optoelectronics Devices

We have synthesized carboxylato-bridged paddle-wheel Cu(II) coordination polymers [Cu-2(DABA)(4)-(4,4'-BPY)](n) (1) and [Cu-4(DABA)(8)(PYZ)(H2O)(2)] (2) by varying the axial linkers 4,4'-bipyridine (4,4'-BPY) and pyrazine (PYZ) (HDABA = 4-diallylamino-benzoic acid). The single-crystal X-ray structure of 1 is a one-dimensional polymer, while 2 is a zero-dimensional tetranuclear Cu(II) complex. Upon light irradiation, the thin film of the compounds increases the electrical conductivity with respect to the dark phase, and the conductivity of 1 is similar to 150 times higher than 2. Magnetic properties were investigated at an applied field 0.5 T in a temperature range 5-300 K. Compound 1 exhibited ferromagnetic behavior, compound 2 exhibited antiferromagnetic behavior at 300 K, and the effective magnetic moment at 300 K is 1.94 and 0.93 B.M. respectively. The capability to switch photoelectricity and magnetism by changing the crystal structure via the axial linker's modification has been rationalized through density functional theory calculations.