Experimental and theoretical interpretation of the magnetic behavior of two Dy(iii) single-ion magnets constructed through β-diketonate ligands with different substituent groups (-Cl/-OCH).

Two Dy(iii) single-ion magnets, formulated as [Dy(Phen)(Cl-tcpb)] (Cl-1) and [Dy(Phen)(CHO-tmpd)] (CHO-2) were obtained through β-diketonate ligands (Cl-tcpb = 1-(4-chlorophenyl)-4,4,4-trifluoro-1,3-butanedione and CHO-tmpd = 4,4,4-trifluoro-1-(4-methoxyphenyl)-1,3-butanedione) with different substituent groups (-Cl/-OCH) and auxiliary ligand, 1,10-phenanthroline (Phen). The Dy(iii) ions in Cl-1 and CHO-2 are eight-coordinate, with an approximately square antiprismatic (SAP, ) and trigonal dodecahedron ( ) NO coordination environment, respectively, in the first coordination sphere. Under zero direct-current (dc) field, magnetic investigations demonstrate that both Cl-1 and CHO-2 display dynamic magnetic relaxation of single-molecule magnet (SMM) behavior with different effective barriers ( ) of 105.4 cm (151.1 K) for Cl-1 and 132.5 cm (190.7 K) for CHO-2, respectively. As noted, compound CHO-2 possesses a higher effective barrier than Cl-1. From calculations, the energies of the first excited state (KD) are indeed close to the experimental as 126.7 cm 105.4 cm for Cl-1 and 152.8 cm 132.5 cm for CHO-2. The order of the calculated energies of KD is same as that of the experimental . The superior SIM properties of CHO-2 could have originated from the larger axial electrostatic potential (ESP) felt by the central Dy(iii) ion when compared with Cl-1. The larger ESP of CHO-2 arises from synergic effects of the more negative charge and shorter Dy-O distances of the axial O atoms of the first sphere. These charges and distances could be influenced by functional groups outside the first sphere, , -Cl and -OCH.