Radiation Sterilization of Anthracycline Antibiotics in Solid State

Table 1

Main characteristic vibrational modes of daunorubicin (DAU), doxorubicin (DOX), and epidoxorubicin (EPI) observed in experimental and calculated spectra.

Calculation (cm^−1)			Experimental (cm^−1)			Band assignment
DAU	DOX	EPI	DAU	DOX	EPI
723	736	736	764	761	761	C–C–C 𝑏 in a ring + def. aglycone group + breathing tetrahydropyran ring in aminosugar group + NH2 𝑤
752	754	749	795	795	795	NH2  𝑤 + C–C–C 𝑏 in aminosugar group + C–H 𝑤 at d ring and in aminosugar group
776	773	774	816	804	805	C–C–C 𝑏 in a ring + def. aglycone group + breathing tetrahydropyran ring in aminosugar group + CH2 𝑟 at d ring
931	930	935	940	939	939	C–O–H 𝑏 at c ring + C–H 𝑤 in aminosugar group
959	957	951	955	949	949	C–C–C 𝑏 in d ring + NH2  w + CH w at d ring and aminosugar group
984	—	—				CH3 w in COCH3 group
1010	1008	1006	986	990	989	Breathing aglycone group + CH2  r + NH2  r + CH3  w in COCH3 + CH2  w in COCH2OH
1021	1029	1032	1008	1005	1005	Breathing a ring + def. aglycone group + C–O s at a ring + C–O–H b at c ring + NH2  w + CH3  w in COCH3 group
1079	1078	1065	1070	1072	1072	C–O s between tetrahydropyran ring and O–H group in aminosugar group
1105	1104	1104	1085	1089	1089	C–O s in metoxy group at a ring + C–C–C b in a ring + CH2  r
1123	1123	1122	1109	1114	1114	C–O s in tetrahydropyran ring + C–O s in glycosidic bond + C–C s in d ring + C–H w in CH3 in aminosugar group
1137	1139	1136	1109	1114	1114	C–C s in d ring and in tetrahydropyran ring in aminosugar group + C–H b at d ring and in tetrahydropyran ring in aminosugar group + CH3  w in COCH3 group + C–O s in COCH2OH group
1157	1157	1156	1153	1143	1143	C–O s in glycosidic bond + C–O s between tetrahydropyran ring and O–H group in aminosugar group + C–H r in CH3 in aminosugar group + def. d ring
1206	1205	1200	1194	1201	1201	C–O s in glycosidic bond + C–C s I d ring + C–H b at d ring and aminosugar group
1226	1225	1221	1205	1211	1211	CH2  t at d ring + breathing a ring + C–O–H b at c ring
—	1239	1239		1235	1235	C–O–H b in COCH2OH group
1278	1275	1275	1262	1263	1263	C–O–H b at c ring + C–C s in aglycone group + CH2  t in COCH2OH group
1291	1290	1293	1289	1284	1285	C–O–H b at c ring + breathing a and c ring
1317	1317	1318	1289	1284	1285	Breathing c ring + C–O 𝑠 at c ring + C–O s at a ring + CH2 𝑤 at a ring +C–H w at d ring
1329	1329	1330	1317	1318	1318	C–O s at a ring + breathing a and c ring
1367	1367	1366	1374	1374	1374	C–C–C b in d ring + C–C 𝑠 in a and b ring + C–O s at c ring + C–O– b at c ring
1404	—	—				CH3  sc in COCH3 group
1425	1427	1423	1404	1413	1413	O–C–H b + N–C–H b
1476	1476	1478	1474	1471	1472	C–O s at c ring + def. c ring + CH3  umbrella mode at a ring + C–O–H b at c ring
1502	1502	1505	1506	1507	1507	C–O–H b at c ring + CH3  sc at a ring + C–C s in aglycone group
1524	1524	1527		1525	1524	C–O–H b at c ring + CH3  sc at a ring + C–C s in aglycone group
1614	1615	1615	1576	1582	1581	C–C s in c ring + C–O–H b at c ring + C=O s at b ring + C–C 𝑠 in a ring
1640	1640	1642	1576	1582	1581	C–C s in a ring + C–O–H b at c ring + CH3  w at a ring
1661	1663	1663	1617	1616	1616	NH2  sc
1688	1688	1688	1617	1616	1616	C=O s at b ring + C–O–H b at c ring
1744	1744	1745	1707	1717	1717	C=O s at b ring
1791	1808	1807	1716	1730	1730	C=O s at d ring
2967–3237			2844–3108			C–H s
3009	3010	2960	2878	2896	2896	O–H s at c ring
3488	3488	3485				N–H s symmetric
3566	3566	3571				N–H s antisymmetric
3630	3634	3639	3161	3326	3329	O–H s
3791	3788	3785		3527	3527	O–H s
3809	3801	—				O–H s
—	3831	3831		3545	3545	O–H s in COCH2OH group

Vibrational modes—s: stretching, b: bending, w: wagging, sc: scissoring, r: rocking, and t: twisting.