The two bands in the absorption profile of the AL(DIPY)3 complexes in the region of 450-500 nm correspond to the excitonic states as a result of exciton coupling, well defined by Kasha et al., which is the apparent splitting of the absorption bands: Davydov splitting. The absorption data match other reported UV-Vis features of similar coordination complexes. Co(III), Rh(III), and Fe(III) tris(dipyrrinato) complexes have a broader band splitting compared with the In(III) or Ga(III) counterparts, which have a more profound double peak, and the same characteristic appears in the aluminum complexes with two bands at 450 -500 nm. Hence, metal coordination can affect the absorption profile as it can alter the excited state features. Another effect that impacts the features of the absorption spectra is the atomic radius of the elements. The excitonic state energy is inversely proportional to the distance between the molecules. Excitonic splitting of the respective energy state is leading to the case where the lowest exciton state is closer to the triplet excited state and therefore can efficiently result in higher intersystem crossing yields, efficiently producing triplet excited states, which is the aim of PDT. Moreover, comparing the UV-Vis of the parent dipyrrins (Error! Reference source not found.) and the AL(DIPY)3 complexes (Error! Reference source not found.) it is evident that not all the dipyrrins display a band in the range of 300-400 nm; however, all the complexes display a band in this range, with some of them exhibiting higher molar absorption coefficient than others. For example, the anthracene moiety absorbs in this region, displaying four peaks as a characteristic feature of both 12j and 13j. Consequently, bands that appear at the region 300-400 nm are related to dipyrrin based charge transfer transitions (intramolecular charge transfer ICT) along with the co-occurrence of the n-* and 1 -* transitions by the various mesosubstituents. Additionally, a possible metal to ligand charge transfer transition has been previously assigned for both low-and high-energy bands in relevant complexes, and may be expected to co-occur with the associated charge transfer within the dipyrrins and the 1 -* transitions. Presumably, in this case the metal to ligand charge transfer is not possible.