Strikingly, each compound now exhibits a second, less-intense emission band at longer wavelengths (Figure , solid lines). In 6NICz and 6,10NICz this band is partially masked by the tail of the higher energy emission, assigned to emission from S1, but in 4NICz, 5NICz and 7NICz distinct peaks can be observed at ca. 450, 475 and 500 nm, with an additional peak at 590 nm in 4NICz only.