Biophysical and RNA Interference Inhibitory Properties of Oligonucleotides Carrying Tetrathiafulvalene Groups at Terminal Positions

Table 2

Melting temperatures of duplexes carrying pyrenyl (PYR), 2,3,4,5,6-pentafluorophenyl (PFP), or tetrathiafulvalene (TTF1) units.

	Oligonucleotides	50 mM	𝑇𝑚 (°C) (Δ𝑇𝑚)^(b)	1 M	𝑇𝑚 (°C) (Δ𝑇𝑚)^(b)
		NaCl^(a)		NaCl^(a)
1 + 2		Duplex	55.8 (0)	Duplex	67.4 (0)
1 + 4		Duplex	58.6 (2.8)	Duplex	69.5 (2.1)
3 + 2		Duplex	57.2 (1.4)	Duplex	68.2 (0.8)
3 + 4		Duplex	58.9 (3.1)	Aggregate	—
3 + 5		Duplex	66.7 (10.9)	Duplex	86.2 (18.8)
6 + 2		Duplex	60.0 (4.2)	Duplex	71.5 (4.1)
7 + 2		Duplex	58.3 (3.0)	Duplex	70.2 (2.8)
6 + 4		Duplex	60.9 (5.1)	Duplex	72.8 (5.4)
7 + 4		Duplex	60.7 (4.9)	Duplex	72.6 (5.2)
6 + 5		Duplex	60.2 (4.4)	Duplex	72.3 (4.9)
7 + 5		Duplex	58.6 (2.8)	Duplex	71.0 (3.6)
8		Duplex	Broad	Duplex	62.7 (0)
9		Duplex	Broad	Duplex	67.8 (5.1)
10		Duplex	Broad	Duplex	66.2 (3.5)

(a)The shape of the UV spectra: “Duplex” indicates that a standard UV-vis spectrum of a duplex was observed and “Aggregate” indicates that a broad UV-vis spectrum with a large scattering was measured. (b)Δ𝑇_𝑚 = 𝑇_𝑚 of a modified duplex minus 𝑇_𝑚 of an unmodified duplex under otherwise the same conditions. The arrows indicate the oligonucleotide orientation 5′→3′. Broad indicates a broad transition (supporting information. Figure S5).