Research on the structure of amino acid ILs and its solubility for chitosan with chemical software

In the present study, some different amino acid ionic liquids(ILs) were designed in order to find new solvent which is of excellent solubility and poor degradation for chitosan. The designed ILs contain different amino acid cations and organic acid anions: amino acids cations included [Gly], [Pro], [Thr] and [Ser]; organic acids anions included [HCOOH], [CH3COOH], [CH3CH2COOH], [CH2aCHCOOH] and [CH2aC(CH3)COOH]. At the same time we used chemical software to construct the original structure of three excellent-dissolving ILs which were selected from the amino acid ILs we prepared, and the calculation results of chemical software showed [Thr][CH3CH2COO] that of EHOMO and ELUMO are −0.17699 and −0.02997 which was the easiest to form hydrogen bond with chitosan and caused the dissolution of chitosan. The present work could guide us to design more new solvent to dissolve chitosan, which can enlarge the usage range of chitosan.