Spectrophotometric, FTIR and theoretical studies of the charge-transfer complexes between isoniazid (pyridine-4-carboxylic acid hydrazide) and the acceptors (p-chloranil, chloranilic acid and tetracyanoethylene) in acetonitrile, their association constant

► Thermodynamics of charge-transfer complexes of isoniazid and acceptors in solution. ► Correlation of the theoretical (using DFT) and experimental charge-transfer energies. ► Calculation of ID of isoniazid. ► Measurements and interpretation of FTIR spectra of the complexes. ► Similarities between charge-transfer and electrovalent compound formations.