Table 3.

Photoinduced DNA-strand cleavage by benzoquinolizinium 3f under different conditions.^a

Additive	c Additive	Atmosphere	Strand cleavage / %b
–		anaerobicc	50
DMSO	5 vol %	anaerobicc	34
t-BuOH	5 vol %	anaerobicc	28
2-PrOH	5 vol %	anaerobicc	23
TEMPOd	1.3 × 10−2 M	anaerobicc	13
2-mercaptoethanol	2.0 × 10−2 M	anaerobicc	18
2-mercaptoethylamine·HCl	2.0 × 10−2 M	anaerobicc	16
–		aerobic	36
–		O2 saturated	30
–		O2 saturatede	65
–		O2 saturatedf	85
NaN3	2.5 × 10−4 M	aerobic	25
D2O (solvent)		aerobic	23

^aIn all cases: c_3f = 2.5 × 10^–5 M, c_DNA = 3.5 × 10^–9 M (pBr322), irradiation time = 2 min; λ_ex = 366 nm. ^bDetermined by agarose gel electrophoresis and staining with ethidium bromide. ^cAr saturated. ^dTEMPO = 2,2,6,6-tetramethylpiperidine 1-oxyl. ^eIrradiation time = 5 min. ^fIrradiation time = 10 min.