The spectra were recorded at 25 1 8C through quartz cuvettes(1 cm path length) using a Perkin Elmer (Monza, Italy) EZ201 or a Perkin Elmer Lambda 10 spectrophotometer and the relevant PESSW version 1.2/Rev E and UV WinLab version 2.85 software, respectively
(Perkin Elmer, Monza, Italy).