Disassembly of Chromophore-Guided DNA Duplexes through Site-Selective Binding of Coralyne to Pyrene-Modified Adenine Bases

Under ambient conditions the disassembly of self-duplexes of ^PyA-modified oligodeoxyadenylates (i.e., chromophore-guided DNA assemblies) through intercalative binding of coralyne units to pyrene-modified adenine (^PyA) bases was carried out. The coralyne units, intercalated site-selectively on the 3′ sides of the ^PyA units, are stabilized through π–π stacking interactions. This competitive intercalation destabilizes the stacking interactions of pairs of ^PyA units, resulting in dissociation of the self-duplexes. This behavior, which is opposite to that of coralyne-induced self-duplex formation of natural oligodeoxyadenylates, was exploited to prepare new types of DNA modules that can be switched between two different duplex states.