(A) COSY spectrum of the unmodified 2BD duplex. (B) COSY spectrum of the freshly prepared OPdG-2BD duplex. (C) COSY spectrum of the freshly prepared M1dG-2BD duplex. Cross-peaks: a, C12 H5 → C12 H6; b, C1 H5 → C1 H6; c, C3 H5 → C3 H6; d, C17 H5 → C17 H6; e, C16 H5 → C16 H6; f, C8 H5 → C8 H6; g, C5 H5 → C5 H6; h, C19 H5 → C19 H6; i, M1dG H7 → H8; j, M1dG H6 → H7. The experiments were performed at 800 MHz and 25 °C.