We investigated structures and electronic properties of model systems for metal organic frameworks (MOFs), using density functional theory (DFT) and fragment molecular orbital (FMO) calculations. The DFT calculations reveal that the MOFs composed of the organic ligands having NH2 groups are more stable than the other MOFs. In addition, the FMO calculations elucidate that the interactions between Al metals and the ligands mainly contribute to the stability of the model systems. We therefore proposed novel ligands having more NH2 groups and confirmed that the MOFs composed of these ligands are more stable than the experimentally synthesized MOFs. (C) 2014 Elsevier B.V. All rights reserved.