. 2023 Feb 6;13(7):4612–4622. doi: 10.1039/d2ra07900c

IR vibrational frequency (ν) and frequency shifts (Δν) for different functional groups due to hydrogen bonding^a.

Structure	Group	ν (free) cm⁻¹	ν (bonded) cm⁻¹	Δν cm⁻¹
H-bond (a)	Pyridine^b	995 (993^f)	1010 (1013^f)	15 (20^f)
	Pyridine^c	1615 (1597^f)	1618 (1600^f)	3 (3^f)
	O–H_EP^d	3776 (3828^g)	3142 (3196^g)	634 (632^g)
H-bond (b)	Pyridine^b	995 (993^f)	1008	13
	Pyridine^c	1615 (1597^f)	1616 (1600^f)	1 (3^f)
	O–H_P^e	3776 (3828^g)	3157 (3196^g)	619 (632^g)

Data given in parentheses refer to the corresponding values from references.

Pyridine ring of 4VP.

Stretching of pyridine group of 4VP.

Stretching of ethynylphenolic OH group of 4.

Stretching of phenolic OH group of 4.

From ref. 24.

From ref. 55.

IR vibrational frequency (ν) and frequency shifts (Δν) for different functional groups due to hydrogen bondinga.