In contrast to the lowest energy band, which shifts with the varying position of the pyridine N, the energy of the medium-energy band is largely invariant. It is most red-shifted in 6NICz at 323 nm, while it is the most blue-shifted in 5NICz at 312 nm, a difference of only 11 nm across all five structures. Similar to the profile of the lowest energy band, there is a blue-shifted, lower intensity shoulder of the medium energy band in 4NICz, 6NICz and 6,10NICz, appearing approximately 10 nm shorter in wavelength; however, this shoulder is absent from the spectra of 5NICz and 7NICz.