After a washing step with medium to remove any non-internalized compound, 200 µL of a medium without red phenol were added (RPMI, culture media: Roswell Park Memorial Institute) and the cells were irradiated with a LED broadband lamp (400 -700 nm). The correction factor from the overlap of the absorption spectra between the LED and each group of compounds was calculated and applied in order to achieve accurate light doses. The cells were irradiated with a light dose of 1 J cm -2 (10 mW cm -2 broadband lamp, 8 min) or 2.6 J cm -2 (10 mW cm -2 broadband lamp, 48 min). After an additional incubation of 24 h, resazurin assay was applied to determine the cell viability (150 µL in each well, 0.1 mg mL -1 ). The experiment was repeated three to four times and the final cell viability was accessed after merging the mean values of the individual experiments. In the case of dyads the experiment was performed one time for each L.D. A statistical significance analysis was applied by using Graphpad software. Significance was evaluated with one-way ANOVA in comparison to the untreated cells with the Dunnett′s Multiple Comparison Test and it is displayed with stars in the respective figures; for the p-value: p < 0.05 for *, p < 0.01 for **, p < 0.001 for ***. 20% and C87 Cl11, Cl12 3% occupied. Compound 13k has weak diffraction at higher angle, leading to a high R(int) and 16 also displays disorder in one dipyrromethene benzoic acid group over a 2-fold axis. The benzoic acid moiety is modelled as a complete unit with half occupancy using restraints (ISOR, SIMU, SADI). There are partially occupied water molecules (2×25% occupancy in the ASU) as well as hexane (15% occupied in ASU) and all modelled with restraints (SIMU, DFIX, ISOR and DANG). Lastly, AL(DIPY)3 20 was more challenging with a diffraction limit = 0.97 Å due to weak diffraction. The diffuse contribution of solvent in the voids was accounted for by using the SQUEEZE routine in PLATON, with two voids of 2688 and 2689 Å 3 with 729 electrons each removed. Two arms (biphenyl-dipyrromethane) were disordered over two locations and modelled with a combination of rigid groups (AFIX 66 and AFIX 176) using restraints (SADI, SIMU, ISOR) with occupancies of 70:30% (C50:C50B) and 65:35% (C84:C84a). a Angle between the dipyrrin plane and the 5-substituent; b average of Al-N distance; c parameter which presents the sum of the deviation from 90° of the octahedron configuration.