The title compound (E-88: Orient Chemical Industries) is an Al-complex which includes salicylic acid derivatives as ligands and is widely used as a charge-control agent (CCA) for full color toners. However, E-88 possesses a relatively low decomposition point around 130-180 °C. For this reason, an attempt has been made in the present investigation to improve the thermal stability by exploring a new polymorph that possesses a higher thermal stability. Recrystallization has therefore been made from solution in various solvents, among which dimethylsulfoxide yielded a hexa-nuclear Al-complex (molecular weight: 3310) that exhibits a decomposition temperature of 270 °C. Furthermore, this phase is found to exhibit an excellent CCA performance. In addition, the temperature dependence of the electrical conductivity has also been made in connection with our previously proposed chargecontrol mechanism of CCAs.
Yuya Kamei, Jin Mizuguchi, "Crystal Structure of a-Salicylic-Acid-Derivative Al-complex Used as a Charge-Control Agent and Its Electrical Properties" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP24), 2008, pp 46 - 49, https://doi.org/10.2352/ISSN.2169-4451.2008.24.1.art00012_1