title: Theoretical study of intermolecular interactions in meso-tetraphenylporphyrin diacid dimer (H4TPPCl2)2.
abstract: The intermolecular interactions between two meso-tetraphenylporphyrin diacid H(4)TPPCl(2) monomers are investigated by density functional theory with the PBE1PBE functional and 6-31G* basis set. Structures of five stable isomers of (H(4)TPPCl(2))(2) are determined. It is found that the interaction (IMHB-1) of Cl with ortho H atoms in two phenyl groups of H(4)TPPCl(2) is unique in that it is the strongest interaction between two H(4)TPPCl(2) monomers. Natural bond orbital analysis is carried out to explain the subtle differences of hydrogen bondings in these isomers. To understand the interactions of water molecule with H(4)TPPCl(2) and (H(4)TPPCl(2))(2), structures of H(4)TPPCl(2) x H(2)O and nine isomers of (H(4)TPPCl(2))(2) x H(2)O are also determined. The binding energy of H(4)TPPCl(2) x H(2)O is 36.47 kJ mol(-1), less than that of the most stable structure of (H(4)TPPCl(2))(2) dimers, 41.59 kJ mol(-1). The dimers containing the special IMHB-1 interactions may be the elementary building blocks for the aggregation of H(4)TPPCl(2), which is supported by the crystal structure of H(4)TPPCl(2).H(2)O x 2CH(3)CN. Thus, study of the interactions between two or a small number of gas molecules can provide important information for understanding the main interactions and stable structures in related condensed-phase systems.
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China.
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Ma
authors.forename: Sheng-Gui
authors.initials: SG
authors.lastname: He
authors.forename: Xun-Lei
authors.initials: XL
authors.lastname: Ding
authors.forename: Zhe-Chen
authors.initials: ZC
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Xue
authors.forename: Qiang
authors.initials: Q
authors.lastname: Shi