More Efficient Photolithographic Synthesis of DNA-Chips by Photosensitization

Protecting groups of the o-nitrophenyl type thatare preferentially used for this purpose have rather low absorption coefficientsat 366nm, the wavelength of the most conveniently used mercury line. The weakabsorptivity of these compounds leads to principal limitations of their light sen-sitivity. Since they have photoreactive triplet states, however, this problem can beovercome by introducing a triplet sensitizer that efficiently absorbs the light andtransfers the electronic energy to the reactive protecting group.The sensitized photodeprotection was studied in detail for the o-nitrophenyl-2-propoxycarbonyl (NPPOC) group