Estimation of the molar absorption coefficient of copper salicylate within the spectral range 300-350nm.

Additional absorption was detected in absorption spectra within the range 300-350nm after addition of copper sulfate CuSO4(aq) to a solution of sodium salicylate NaНSal (рН=7.8). The additional maximum absorption was observed at 320nm. Assuming that the additional absorption depends on the formation of copper salicylate CuSal, the molar absorption coefficient εCuSal of this complex was determined to be (3.8±0.02)·103М-1сm-1. This value is almost equal to that of monoanion HSal-, εHSal-=(3.6±0.04)·103М-1сm-1, and is 2.5 times as much as εFe3+HSal-=(1.55±0.05)·103М-1сm-1 for iron salicylate. The difference in εCuSal and εFe3+HSal- is due to the difference in the initial electron states of Cu2+ and Fe3+ ions that have the d9 and d5 configurations, respectively.