. 2021 Jan 25;6(4):2626–2637. doi: 10.1021/acsomega.0c04779

Table 1. Summary of the Characteristic FTIR Peaks Representing the Key Functional Groups in Metformin Hydrochloride and Various Lipophilic Metformin Salts^a.

metformin/metformin salts	metformin–NH₂	carbonyl group C=O	imine C=N stretch	N–H bending	C–N stretch
metformin	3368.17 and 3294.06		1622.87	1544.76	1059.73
metformin–docusate	3346.99	1734.72	1639.26	1558.26	1035.63
metformin–oleate	3368.20	1737.62	1623.43	1560.19	1040.22
metformin–caprate	3361.46	1737.62	1641.19	1553.44	1047.20
metformin–laurate	3369.17	1731.83	1640.23	1554.41	1052.98
metformin–cholate	3368.20	1736.65	1651.80	1579.48	1079.98

The characteristic FTIR peaks of metformin show considerable shifts in the lipophilic salts of metformin, indicating the formation of metformin salts.

Table 1. Summary of the Characteristic FTIR Peaks Representing the Key Functional Groups in Metformin Hydrochloride and Various Lipophilic Metformin Saltsa.

Table 1. Summary of the Characteristic FTIR Peaks Representing the Key Functional Groups in Metformin Hydrochloride and Various Lipophilic Metformin Salts^a.