title: Experimental and theoretical studies on pyrene-grafted polyoxometalate hybrid.
abstract: A novel pyrene covalently-attached polyoxometalate (POM) hybrid has been synthesized and fully characterized. The attractive electronic and photophysical properties of pyrene derivatives make the hybrid promising for studying and understanding electron transfer mechanisms in organic-functionalized POMs. The hybrid has an electronic absorption at 450 nm, indicating that there is a strong electronic interaction between the organic pyreneimido group and inorganic hexamolybdate cluster. The electron transfer mechanism of the as-prepared hybrid is illuminated via the combined studies of theoretical calculations and transient absorption spectroscopy. Time-dependent density functional theory studies revealed that the strong electronic absorption at the visible region mainly comes from the optically allowed π-π* transitions of the pyreneimido component (S(0) to S(2) transition). The electron transfer process from the excited pyreneimido moiety to the inorganic POM cluster is at the time scale of ~700 fs, which could be ascribed to the internal conversion of singlet excited states from S(2) state to S(1) state. This study provided a clear understanding of the mechanism governing the electron transfer process in organoimido derivatives of POMs. This result might offer a new route for the design of new charge transfer hybrid clusters of organic functionalized POMs and crucial guidance for their applications in optical and electrical devices.
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
authors.forename: Junkuo
authors.initials: J
authors.lastname: Gao
authors.forename: Xinfeng
authors.initials: X
authors.lastname: Liu
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: Lingling
authors.initials: L
authors.lastname: Yu
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Feng
authors.forename: Hongyu
authors.initials: H
authors.lastname: Chen
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Li
authors.forename: Ganguly
authors.initials: G
authors.lastname: Rakesh
authors.forename: Cheng Hon Alfred
authors.initials: CH
authors.lastname: Huan
authors.forename: Tze Chien
authors.initials: TC
authors.lastname: Sum
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Qichun
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry*; D011721:Pyrenes / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D011721:Pyrenes; D008982:Molybdenum; C004482:1-aminopyrene