Apparatus
UV–Vis spectra were acquired with 1 cm quartz cells
on a Perkin–Elmer 320 UV–Vis spectrophotometer
connected to a model 3600 Data Station equipped with
software packages ‘IF-320’, for instrument control. The
scan speed was adjusted at 30 nm min−1
, slit width=1
nm, response time=0.5 s. The spectrophotometer was
connected with a ‘Colora’ ultra-thermostat (25.09
0.1°C)