title: Interlayer charge-transfer in impacting the second hyperpolarizabilities: radical and cation species of hexathiophenalenylium and its nitro dimers.
abstract: Hexathiophenalenylium (HTPLY) has gained increasing attention for its interesting and potentially useful optical properties as a result of the enhancement in spin delocalization and charge-transfer of phenalenyl radicals, occasioned by the attachment of successive three disulfide linkages. Herein, we performed density functional theory to calculate the binding interactions, electronic absorption spectra and the second hyperpolarizabilities of cation and radical dimers of HTPLY and its nitro derivatives. It is found that the equilibrium structures of the π dimers at fully staggered position are most stable. Among these π dimers, radical dimers exhibit stronger binding interactions with respect to cation dimers. In addition, obvious red shifts in electronic spectra of radical dimers are dependent on the large interlayer charge-transfers. More importantly, radical dimers [4]dim3 and [5]dim1 exhibit a significant increase in the second hyperpolarizabilities as compared to cation dimers, which is due to lower excitation energies and larger interlayer charge-transfers. We believe that the results presented in this article shall provide important evidence for the large interlayer charge-transfers in enhancing the NLO properties of the π dimers.
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024, People's Republic of China.
authors.forename: Wen-Yong
authors.initials: WY
authors.lastname: Wang
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024, People's Republic of China.
authors.forename: Na-Na
authors.initials: NN
authors.lastname: Ma
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024, People's Republic of China.
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Tian
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024, People's Republic of China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024, People's Republic of China. Electronic address: qiuyq466@nenu.edu.cn.
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Qiu
mesh_terms: D002412:Cations; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry*; D004583:Electrons; D008968:Molecular Conformation; D043803:Phenalenes / Q000737:chemistry*; D013816:Thermodynamics; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D002412:Cations; D004220:Disulfides; D043803:Phenalenes; D013876:Thiophenes
keywords: DFT; Dimer; Interlayer charge-transfer; Radical and cation; The second hyperpolarizability