Table 3.

Fourier transform infrared (FT-IR) spectra of the nanoparticles synthesized from Asteraceae family.

Plant Name	FTIR Absorption Bands (cm−1)		Possible Functional Group	References
	Plant Extract	NPs
Silver NPs
Acanthospermum hispidum	3786	-	-OH	[17]
	2964	-	C-H
	1706	-	C=O
	1601	-	C=C
	1016	-	C-O
Ageratum conyzoides	-	3440.29	N-H stretching	[13]
	-	2358.95	C-H
	1383.98	-	Alcohol, ethers, esters, carboxylic acids, and amino acids
	1613.99	-	C=O
	1074.83	-	C-OH
Ambrosia arborescens	-	1570	C=C	[21]
	-	1050	CO
	1337.47	-	O-H
	3280	-	OH
	-	-
Anthemis atropatana	-	1014	C-O	[22]
	-	1048	C-O stretching
	3344	1595	N-H bending
	-	2368	Cyanide
Arctium lappa	596	632	C-Cl stretching	[6]
	1033	1036	C-N
	1336	1384	N-H
	2870	2853	C-H stretching
	3375	3375	O-H stretching
Arnicae anthodium	3284	-	-OH stretching	[23]
	2853	-	-C-H stretching
	1735	-	C=C
	1622	-	C=O
	1370	-	-C-O
	1027	-	-C-O-C
	-	430, 395	-OH
Artemisia marschalliana	3463	-	O-H	[24]
	3510	-	Protein binding
	2962, 2823	-	C-H
	1624	-	C-O
	-	1398	C-N
	1049	1038	C-O-C
Artemisia turcomanica	13,429	3429–3473	O-H	[25]
	3029	-	C-H
	2929	-	Aliphatic group
	1635	-	C=O
	1459	-	CH2
	1273	-	C-O-C phenolic stretching
	1064, 1119, 1168	-	C-O-C
	1201	-	C-O-C stretching
	1000	-	C=C-H
	-	1635–1624	Carbonyl amide group
	-	1382	N=O
Artemisia vulgaris	3419, 3151	-	O=H	[26]
	1619	-	-C=O
	1400	-	-C-N
	1069	-	-C-O
Carthamus tinctorius	3293	-	-OH	[33]
	2932	-	C-H
	1725	-	C=O
	1599	1533	C=C
	1414	-	C=C aromatic
	1053	-	C-O
	860	-	C-H
	818	-	#ERROR!
	776	323	N-H
Chrysanthemum indicum	3293	-	–OH	[38]
	2932	-	C–H
	1725	-	C=O
	1053	-	C=C,C–O–H
	1599	-	C=C
	-	1288 to 1299	Ag
Chrysanthemum morifolium	1406	-	C=C group	[39]
	1078	-	C–O stretch
	2921	-	C–H
	3384	-	O–H
Cichorium intybus	3413.05	-	O–H alcoholic group	[40]
	2922.98	-	Aliphatic C–H group
	1619.08	-	C=C
	1384.6	-	C–H
	1114.28	-	C–O–C
	-	874.47	N–H
Cosmos caudatus	3364.81	-	O–H	[41]
	2925.49	-	C–H
	1650.59	-	C=O
	1384.67	-	C-N
	1067.62	-	O–H secondary alcohols
Cosmos Sulphureus	-	1643.35	––C==C––	[42]
	-	2980.02	C––H
	-	3421.72	O––H
	1637.56	-	––C==C––
	2981.95, 3748.2	-	C––H
Cynara scolymus	-	538	Ag+ to Ag	[45]
Dahlia pinnata	1064 and 3265	-	Aromatic compounds	[46]
	2916	-	C-H stretching of aldehydes
	673 and 1595	-	Halo-alkanes and bending of C-H bonds
Echinacea purpurea	3,203	-	OH stretching	[49]
	2929 and 2829	-	C–H bonds
Echinops sp.	3395	-	OH stretching frequencies	[50]
	1718	-	C=O vibration of ketonic groups
	2925	-	C−H stretching mode
	601	-	Ag–O bond
Eclipta alba	3603 and 3471	-	O–H stretch	[51]
	3379 and 3278	-	Primary and secondary amines and amides
	2931	-	C–H stretch
	1064	-	C–N stretch represents aliphatic amines
Elephantopus scaber	1611 to 1400	-	Presence of aromatic rings in the leaf extract.	[52]
	1109	-	Presence of OH groups
Erigeron bonariensis	3376	-	-OH groups of phenolic compounds and -NH stretching of the proteins	[53]
	-	3434	Intensity of Ag
Helichrysum graveolens	2927	-	C–O stretching, free	[60]
	1608	-	C=O stretching
	1035	-	C–N stretching
	1417	-	O–H bend
	-	820	C–O stretching
	-	606	C–X stretching vibration
	2358	-	C–H asymmetric stretching
Oedera genistifolia	1117	-	Plant extract	[67]
	1118	-	NP synthesized
Spilanthes calva	3919.31	-	O-H-stretch	[80]
	3435	-	O-H-stretch
	1412.79	-	C-F stretch
	1257.83	-	C-F stretch
Tagetes erecta	3401	-	O–H group	[83]
	2940	-	Aromatic compounds
	1673	-	–C=C– bond
	1104	-	C–N bond
Taraxacum officinale	3360 to 3400	-	-NH2 in primary aromatic amines and -OH groups	[85]
	2300 to 2990	-	C-H
	1421	-	C=C
	1610	-	C=O
	1063	-	C-OH
Tithonia diversifolia	3398	-	O–H stretching vibrations of polyols	[86]
	1641	-	Stretching vibration of (NH) C O group
	-	672	N–H
Tragopogon Collinus	3385	-	OH	[88]
	2921	-	NH
	-	1640	C–O in amide I
	-	1413	NH2 group in amide II
Vernonia cinerea	1633	-	Amide I, C=O groups	[91]
	3431	-	O–H stretching
	1515 and 1540	-	–C=C (aromatic ring)
	1380	-	O–H in-plane bend of phenol
Wedelia chinensis	1022	-	C–O	[92]
	1326	-	C-O-C stretching
	1696	-	C=O
Gold NPs
Arctium lappa	3307	-	-OH stretching and the aliphatic methylene group -C-H stretching	[94]
	2151	-	Alkynes group
	1634	-	Carboxyl stretching
	-	415, 406, 394 and 383	Metal biomolecules found in the extract
Erigeron annuus	3100, 2850, 2620, 1300, 1100, and 620	-	Extract	[100]
	2900	-	C-H stretching vibration in methylene group
	1405	-	Hydrocarbons of methylene group
Rhanterium epapposum	1622 to 1630	-	C=O stretching of carbonyl groups	[72]
	-	925 to 553	Stretching of haloalkanes
Stevia rebaudiana	1078	-	Nitrogen–carbon C-N bond stretching of aliphatic amine groups	[104]
	240 and 1634	-	Amides III and II bands of proteins
	-	1629	Amide I
Copper NPs
Ageratum houstonianum	3264.96	-	O–H stretch	[159]
	2916.19	-	N+–H stretch
	2359.9	-	C–H stretching
	-	1074.64	O-C stretching
	-	667.81	Aromatic H bending
	-	597.86
Blumea balsamifera	3378	-	OH bond of phenolic compound such as flavonoids, tannins, and glycoside	[108]
	1100 and 1700		C-O and C=O
		610	Cu NPs
Eclipta prostrata	3333	-	Hydroxy group	[109]
	2917	-	Methylene C-H asym./sym. stretch
	1615	-	Aromatic ring stretch
	-	1610	NH C=O to metals CuNPs
Pluchea sericea	3341	-	O-H stretching	[110]
	2935	-	C-H and N-H bonds
	1623–1410	-	C=N stretching vibrations
	1046	-	C=O
	-	622	Cu NPs
Titanium oxide NPs
Ageratina altissima	3287	-	Alcohol, phenols with O-H stretches	[137]
	2922	-	Ammonium ions with N-H stretching
	1645	-	Acyclic compound with C-C stretching
	1537	-	Aliphatic of the nitro compound with stretching of N-O
	1238	-	C-O stretching
	1150	-	Alcohol compound with C-O stretching
Echinacea purpurea	1024	-	C-O stretching alcohols	[138]
	1385	-	C-H rock alkenes
	1590	-	C=C characteristic of saturated hydrocarbons
	3320	-	O-H
Sonchus asper	3937	-	OH stretching vibrations	[139]
	3190	-	N-H stretching
	2851	-	Symmetric CH2 stretching bands
	2600	-	H bonded NH vibrations
	-	1000 and 500	Ti-O-Ti linkage in TiO2
Copper oxide NPs
Eupatorium odoratum	3976	-	Adsorbed water molecules	[136]
	3406	-	-OH stretching vibrations of phenolic group
	1520	-	C‚ C stretch in aromatic rings
	1420	-	O-H bend of polyphenol
	-	1121	Cu-OH vibrations
	-	815 and 613	-CH bending vibrations
	-	653 and 610	Cu-O signals

Note: NPs: nanoparticles;—: not applicable.