2-azapurine compounds and their uses

A nucleic acid binding compound comprising a backbone, said backbone having attached heterocyclic groups capable of base pairing to natural nucleobases at least one of said heterocyclic groups being one of the naturally occurring nucleobases characterized in that at least one other of said heterocyclic groups is a group of the general formula I

• wherein
• W is selected independently from X, Y and Z from the group consisting of N and CR2,
• Z is selected from the group consisting of N and C with the proviso that
• if Z is N, then
• X independently from W and Y is selected from the group consisting of N and CR3, and
• Y independently from W and X is selected from the group consisting of N and CR4,
• and the bond between X and Y is a double bond and the bond between Y and Z is a single bond, and
• if Z is C, then
• X is NR33, and
• Y is selected from the group consisting of N and CR4 and the bond between Z and Y is a double bond and the bond between X and Y is a single bond,
• R1, R2, R3 and R4 are independently selected from the group consisting of —H, -halogen, —OR13, —SR19, —(C1-C10)-alkyl, —(C2-C10)-alkenyl, —(C2-C10)-alkynyl, —NO2, —NR5R6, -cyano, and —C(═O)R11,
• R11 is selected from the group consisting of —OH, —(C1-C6)-alkoxy, —(C6-C22)-aryloxy, and NHR12,
• R5, R6, R12, R13, R19 and R33 are selected independently from the group consisting of —H, —(C1-C10)-alkyl, —(C2-C10)-alkenyl, —(C2-C10)-alkinyl, —(C6-C22)-aryl, a protecting group and a reporter group,
• D is the position of attachment of the group to the rest of the nucleic acid binding compound, and
• said alkyl, alkenyl and alkynyl being unsubstituted or substituted by one or more moieties selected from the group consisting of -halogen, —SH, —S—(C1-C6)-alkyl, —(C1-C6)-alkoxy, —OH, —NR5R6, —COR11, —NH—CONR5R6, —NH—CSNR5R6 —[O—(CH2)r]s—NR5R6, and
• r and s are independently of each other an integer of 1 to 18.