Vibrational Fingerprint of Erlotinib: FTIR, RS, and DFT Studies

Table 2

Calculated (vacuum) and experimental wavenumbers for the RS and FTIR spectra of erlotinib in the solid state.

Calculated wavenumbers (cm^−1)	Assignment^a		Experimental wavenumbers (cm^−1)
	B3LYP/6-311G(d, p) (PED > 5%)	Literature [9, 37–42]	RS	FTIR
2200	ν(C≡C)		2112
1623	ν(CC)Phe, ρb(NH), ν(CN)Q		1619	1633
1612	ν(CC)Phe, ρb(NH), ν(C=N)Q, ν(CC)Q	ν(CC)Q	1611
1595	ν(CC)Q, ν(CN)Q, ν(CC)Phe	ν(CC)Phe	1589
1571	ρb(NH), ν(NC)Q-NH, ν(C=N)Q, ν(CC)CΦC, ρb(CH)Phe, ν(CC)Q	ν(CC)Phe	1572	1575
1532	ν(CC)Q, ρb(CH)Q, ρs(CH2)OCH2	ν(Phe), ρb(NH)	1533
1518	ρs(CH2)CH2O, ρs(CH2)CH3
1513	ρs(CH2)OCH2, ρs(CH2)CH3, ρs(CH2)CH2O		1514	1513
1441	ρw(CH2)CH2O, ρw(CH2)OCH2, ρw(CH3)	ρb(NH), ν(Phe)	1445	1447
1413	ν(C=N)Q, ν(CC)Q, ρb(CH)Q, ρb(NH)	ν(Q), ρb(NH), ρb(CH)	1409	1403
1373	ρb(CH)Q, ν(CC)Q, ρb(CH)Phe
1364	ρw(CH2)CH2O, ρw(CH2)OCH2, ρb(NH), ρb(CH)Phe, ν(NC)Q-NH, ν(NC)Q		1372	1368
1303	ρt(CH2)CH2O, ρt(CH2)OCH2, ρb(CH)Phe, ν(CC)Phe, ν(CN)Q, ν(CC)Q		1310	1309
1285	ρb(CH)Phe-Q, ν(CC)Q, ν(NC)Q, ρb(CH)Phe, ν(CC)Phe	ν(CN)	1275	1278
1242	ρt(CH2)OCH2, ρt(CH2)CH2O, ρb(CH)Phe-Q, ν(CC)Q, ν(NC)Q, ρb(CH)Phe, ν(CC)Phe	ρb(CH), ρb(NH), ν(CN)	1247	1243
1226	ρw(CH2)CH3, ρt(CH2)CH3, ν(CO)CH2O, ρw(CH2)CH2O			1230
1222	ρw(CH2)CH3, ρt(CH2)CH3, ν(CO)CH2O, ρt(CH2)OCH2, ρw(CH2)CH2O
1215	ρt(CH2)OCH2, ρt(CH2)CH2O, ν(CQO), δ(Q), ρb(CH)Phe, δ(Phe)	ν(CN), δ(PYMD)	1219	1218
1179	ρb(CH)Phe	ρb(CH)	1193
1178	ρw(CH2)CH3, ρt(CH2)CH3
1173	ρw(CH2)CH3, ρt(CH2)CH3, ρb(CH)Phe, δ(Phe), ρb(CH)Q, δ(Q), ν(CQO)	ρb(CH), ρb(CH)Phe	1170	1166
1158	ρw(CH2)CH3, ρt(CH2)CH3, ν(OC)OCH3, ρt(CH2)CH2O, ρt(CH2)OCH2
1150	ν(OC)OCH3, ρw(CH2)CH3, ρt(CH2)CH3, ρt(CH2)CH2O, ρt(CH2)OCH2	νas(OCH3), ν(COC)	1153	1152
1126	ρt(CH2)CH3, ρt(CH2)CH2O, ρw(CH2)CH3, ρt(CH2)CH3	δ(CH)		1128
1120	ρb(CH)Phe, δ(Phe)
1088	ρb(CH)Q, δ(Q), ρb(CH)Phe, ν(OC)OCH2			1099
1083	ν(CC)CH2-CH2, ρw(CH2)CH3, ρt(CH2)CH3			1083
1072	ν(OC)OCH2, ρr(CH2), ρw(CH2)CH3, ρt(CH2)CH3, δ(Q)			1075
1052	ν(CC)CH2-CH2, ν(OC)OCH3, ρw(CH2), ρt(CH2), ρw(CH2)CH3, ρt(CH2)CH3			1049
1026	ν(OC)OCH2, ρb(CH)Phe-Q, ν(CO)CH2O, ρw(CH2)CH3, ρt(CH2)CH3			1021
1009	δ(Phe)	δ(Phe)	1001	1004
972	ρboop(CH)Phe			970
941	ρboop(CH)Phe		945	941
928	δ(Q), δ(Phe), δ(CPheNCQ), ρt(CH2)			929
922	δ(Q), ρt(CH2), ν(NC)Q-NH			921
891	ρboop(CH)Phe-Q,δoop(Q), ρboop(CH)Phe,δoop(Phe)			908
889	ρboop(CH)Phe,δoop(Phe), ρboop(CH)Phe-Q,δoop(Q)
871	ρr(CH2), ν(OC)OCH3, ν(CO)CH2O, ρboop(CH)Phe-Q,δ(CQOC)	ρr(OC2H4)		877
861	ρboop(CH)Phe-Q,δoop(Phe-Q), δ(CQOC), ρr(CH2), δ(PYMD-Q)		860	860
798	δoop(Q), ρboop(CH)Phe-Q			796
791	ρboop(CH)Phe,δoop(Phe)
785	ρboop(CH)Phe-Q,δoop(Q), δ(CPheNCQ), δ(CQOC), ρr(CH2), δ(Phe)			779
730	δ(CPheNCQ), ρboop(CH)Phe-Q,δoop(Phe-Q), δ(CQOC), ρr(CH2), δ(PYMD-Q)	ρb(Q)	730
715	ρboop(CH)Phe-Q,δoop(Phe-Q), δ(PYMD-Q), ρr(CH2), δ(CQOC), δ(CPheNCQ), δ(Phe)		716	713
700	δ(CQOC), ρb(CH)Phe,δ(Phe)		702	702
687	ρb(CH)C≡CΗ			686
669	δ(Q), δ(Phe), δ(CQOC), ρr(CH2), δ(CPheNCQ), ρb(CH)C≡CΗ
668	δoop(Q), δoop(CPheNCQ), δoop(CQOC), ρb(CH)C≡CΗ, ρr(CH2)	δoop(PYMD), δ(Phe)		658
641	ρb(CH)C≡CΗ, ρboop(CH)Phe,δoop(Phe)	δ(acetylene), δ(NH)	651	649
619	δoop(Phe), ρb(CH)C≡CΗ, δoop(CPheNCQ)		623	624
601	δ(Phe), δ(Q), ρb(CH)C≡CΗ	δ(Phe)	598
574	ρr(CH2), δ(OCC), δ(Phe), δ(Q)		586	585
565	δoop(Q), ρboop(CH)PYMD-Q,ρb(NH)			576
551	ρb(CC)CΦC, δ(Phe), δ(Q)			540
512	ρboop(CH)Phe-Q,δoop(Phe-Q), ρb(NH), δoop(CQOC), δoop(OCC)			514
477	ρb(NH), ρboop(CH)Phe, ρboop(CC)CΦC, δoop(Phe)			482
465	ρb(NH), ρboop(CH)Phe, ρboop(CC)CΦC, δoop(Phe), δoop(Q), ρboop(CH)PYMD-Q, δ(CQOC), δ(CCO), δ(COC)
462	δ(CCO), δ(COC), δ(CQOC), δ(Q), ρb(NH)		463	455

^aAbbreviations: ν, stretching; ρ_b, bending; ρ_w, wagging; ρ_s, scissoring; δ, deformation; as, antisymmetric; oop, out-of-plane; Phe, phenyl ring; Q, quinazoline group.