Table 4.

Computed change in imino proton (H1) NMR chemical shift of the G_δ residue

Modification type	Optimization basis set	Computed change in Gδ H1 chemical shift (ppm)
		NMR basis set
		6-31G(d)	6-31G(d,p)	6-31++G(d,p)	6-311+G(d)	6-311++G(d,p)
8-BromoG	6-31G(d)	−0.289	−0.311	−0.304	−0.300	−0.307
	6-31G(d,p)	−0.289	−0.311	−0.305	−0.300	−0.307
	6-31++G(d,p)	−0.235	−0.249	−0.243	−0.245	−0.242
	6-311++G(d,p)	−0.208	−0.216	−0.208	−0.214	−0.205
8-OmethylG	6-31G(d)	0.398	0.461	0.442	0.347	0.453
	6-31G(d,p)	0.402	0.465	0.447	0.351	0.458
	6-31++G(d,p)	0.398	0.461	0.443	0.350	0.455
	6-311++G(d,p)	0.424	0.489	0.472	0.376	0.484
8-AminoG	6-31G(d)	0.235	0.272	0.261	0.234	0.279
	6-31G(d,p)	0.241	0.279	0.267	0.239	0.285
	6-31++G(d,p)	0.242	0.280	0.269	0.242	0.288
	6-311++G(d,p)	0.248	0.286	0.275	0.247	0.294

Values indicate the computed change in NMR imino proton chemical shift of the G_δ residue. Change in chemical shift is measured with respect to the computed spectra of the unmodified tetrad. NMR chemical-shift calculations were performed using multiple basis sets for each method of geometry optimization.