Thermodynamic parameters of 2′-OCF₃ modified RNA obtained by UV melting profile analysis (including unmodified and 2′-SCF₃ modified reference RNAs)^a.

Sequence (5′ → 3′)	T m [°C]	ΔG°298 [kcal mol−1]	ΔH° [kcal mol−1]	ΔS° [cal mol−1 K−1]
GGUCGACC	59.1	−14.3	−72.0	−193
GGUCGA̲CC	52.7	−12.6	−69.1	−189
GAAGG-GCAA-CCUUCG	73.3	−6.0	−46.0	−134
GAA̲GG-GCAA-CCUUCG	70.3	−5.8	−46.7	−137
GAGG-GCAA-CCUUCG30	57.4	−5.5	−57.9	−176
GAAGG-GCAA-CC̲UUCG	66.8	−4.9	−41.7	−124
GAAGG-GCAA-CUUCG29	53.3	−4.4	−50.4	−154
GAAGG-GCA̲A-CCUUCG	74.0	−8.3	−60.9	−177

^aA̲ 2′-OCF₃ adenosine, C̲ 2′-OCF₃ cytidine, 2′-SCF₃ adenosine,³⁰ 2′-SCF₃ cytidine.²⁹ Buffer: 10 mM Na₂HPO₄, 150 mM NaCl, pH 7.0. ΔH and ΔS values were obtained by van't Hoff analysis according to ref. 37 and 38. Errors for ΔH and ΔS, arising from non-infinite cooperativity of two-state transitions and from the assumption of a temperature-independent enthalpy, are typically 10–15%. Additional error is introduced when free energies are extrapolated far from melting transitions; errors for ΔG are typically 3–5%.