Table 2.

IC₅₀ values (μm) for platinum–chromophore hybrids in lung cancer cell lines^[a] and acid/base properties of their fully protonated, dicationic forms.^[b]

Compd	NCI-H460[c]	NCI-H520[d]	NCI-H522[d]	NCI-H1435[d]	A549[c]	pKa
P1–A1	0.0052±0.0001 (520)[e]	0.043±0.004 (100)	0.010±0.001	0.84±0.07	0.0065±0.0002	9.4±0.2
P1–B1	0.24±0.01 (3.8)	0.52±0.01 (3.5)	0.12±0.02	1.48±0.01	0.32±0.06	7.6±0.3
P1–B2	2.4±0.5 (0.9)	2.2±0.1 (1.5)	3.62±0.08	11.0±0.2	12.4±0.9	4.9±0.6

^[a]Concentrations of compound that reduce cell viability by 50%, extracted from dose-response curves for 72 h drug incubations using a colorimetric (MTS) cell proliferation assay. Values are means of two individual experiments performed in triplicate ±standard deviations.

^[b]Determined from Henderson-Hasselbalch plots of UV-visible absorbance data (averages for three titrations ±standard deviations; see the Supporting Information).

^[c]Wild-type p53.

^[d]Mutated p53.

^[e]Values in parentheses are enhancement factors relative to Pt-free ligands A1, B1, and B2 (see Supporting Information).