. Author manuscript; available in PMC: 2013 Aug 9.

Published in final edited form as: J Phys Chem B. 2012 Jul 30;116(31):9387–9395. doi: 10.1021/jp305083t

Table 2.

Experimental vibrational frequencies (cm⁻¹)¹ for 4-methylimidazole and histidine in the indicated protonation states.

ν_i	Protonated				Neutral								Deprotonated
ν_i	MeImH₂⁺	MeImD₂⁺	HisH₂⁺	HisD₂⁺	τ-MeImH	τ-MeImD	τ-HisH	τ-HisD	π-MeImH	π-MeImD	π-HisH	π-HisD	MeIm⁻	His⁻
4a	1634	1610	1634	1610	1577	1572	1575	1561	1596	1579	1593	1570	1536	1531
5a	1490	1412	1493	1412	1454	1308	1453	1322	1426	1326	1435	1336	1260	1259
6a	1205	985	1200	992	1158	--	1164	--	1158	--	1164	--
7a	1184	1260	1186	1260	1260	1227	1286	1234	1260	--	1269	1197	1233	1235
9a	1089	1110	1097	1114	1087	1019	1090	1023	1103	1019	--	1007	1010	1009
10a	929	918	928	921	936	926	940	926	--	945	--	947	951	953
5b	1535	--	1535	1523	1494	1489	1498	1486	1494	1489	1498	1486	1441	1438
6b	1430	--	--
7b	1270	1372	--	--	1305	1375	1324	1376	1344	1366	1360	1359	1297	1315
8b	1296	--	1270	--	1231	1260	1239	1274	1231	--	1239	--	--	--
9b	1008	1023	998	1007	997	--	993	1099	1015	1100	1011	1100	1100	1104
10b	978	--	--	--	--	982	--	991	977	982	969	991	--	--

Vibrational frequencies listed are from resonance Raman spectra excited at 229 nm (Figure 6 & 7).