TABLE 7.
Proton Affinity (top) and Gas-Phase Basicity (bottom) values for RNA like sugar molecules: 2-hydroxy-tetrahydrofuran (THF), 2-hydroxy-1,3,4-trimethyl-tetrahydrofuran (Methyl), and 2-hydroxy-l,4-dimethyl-3-methoxy-tetrahydrofuran (Ribose). Figures in supporting information. All molcules are given in conformations consistant with B-form and A-form DNA/RNA. All quantities are in kcal/mol.
| Pucker | Model | CBS | G3B3 | G3MP2 | PBE0 | B1B95 | B3LYP | QCRNA |
|---|---|---|---|---|---|---|---|---|
| Proton Affinity | ||||||||
| C2’a | THF | 369.2 | 369.1 | 370.1 | 370.2 | 370.6 | 368.2 | 368.3 |
| Methyl | 366.4 | 367.0 | 367.4 | 367.3 | 367.4 | 365.6 | 365.7 | |
| Ribose | 360.4 | 361.2 | 361.6 | 362.9 | 363.2 | 360.8 | 361.5 | |
| C3’b | THF | 370.2 | 370.9 | 371.2 | 370.8 | 371.3 | 368.7 | 368.8 |
| Methyl | 367.7 | 368.3 | 368.7 | 368.2 | 368.6 | 366.4 | 366.5 | |
| Ribose | 364.9 | 365.7 | 366.1 | 365.6 | 365.8 | 363.9 | 363.9 | |
| Gas Phase Basicity | ||||||||
| C2’a | THF | 361.2 | 360.9 | 362.0 | 362.1 | 362.4 | 360.1 | 360.1 |
| Methyl | 358.0 | 358.6 | 359.0 | 358.7 | 358.8 | 357.1 | 357.2 | |
| Ribose | 354.5 | 355.4 | 355.8 | 354.9 | 355.1 | 355.1 | 353.5 | |
| C3’b | TFIF | 362.9 | 363.5 | 363.9 | 363.6 | 364.1 | 361.4 | 361.5 |
| Methyl | 360.3 | 360.9 | 361.3 | 360.8 | 361.2 | 359.0 | 359.2 | |
| Ribose | 357.8 | 358.6 | 359.0 | 358.5 | 358.7 | 356.8 | 356.8 | |
a
P=163.797, τm4=34.495.
b
P=13.506, τm=37.747.