Preparation and Characterization of Carboxylic Acid Adducts of Gabapentin

Abstract

Abstract. Gabapentin, C9H17NO2, 2-[1-(aminomethyl)cyclohexyl]acetic acid, is used as an anticonvulsant drug to help control partial seizures in the treatment of epilepsy and to manage postherpetic neuralgia after 'shingles'. Cocrystals of gabapentin with a series of hydroxyl carboxylic acids and a cocrystal of gabapentin with oxalic acid were previously reported. The adduct with salicylic acid was prepared, along with adducts of two dicarboxylic acids, succinic acid and adipic acid, and an adduct with 1,2,4,5-benzenetetracarboxylic acid. Formation of new materials is demonstrated by new unique physical properties, including lower melting points (102.8-105.1 ºC, 90.0-93.0 ºC, and 152.4-154.8 ºC for succinic acid, adipic acid, and 1,2,4,5-benzenetetracarboxylic acid products, respectively) than those of the individual starting materials. Shifts in infrared bands for ν (O-H), ν(N-H), and ν(C=O) bands confirm adduct formation and indicate the nature of the interactions between the two components in the lattice.

Diversity in Supramolecular Solid-State Architecture Formed by Self-Assembly of 1-(Diaminomethylene)thiourea and Aliphatic Dicarboxylic Acids

“…In order to gain insight into the structure and the nature of the interaction between the 1-(diaminomethylene)­thiourea and aliphatic dicarboxylic acids in the crystalline form of supramolecular complexes 1 – 8 , the vibrational spectra were measured and discussed with those of 1-(diaminomethylene)­thiourea and aliphatic dicarboxylic acids. − Assignment of the IR bands was supported by the spectra of their deuterated analogues. The infrared spectra (protonated and deuterated) and Raman spectra (protonated) of 1 – 8 complexes are included in the Supporting Information (Figures S15–S22).…”