title: Long-lived excited states of zwitterionic copper(I) complexes for photoinduced cross-dehydrogenative coupling reactions.
abstract: Four heteroleptic copper(I) complexes containing phenanthroline and monoanionic nido-carborane-diphosphine ligands have been prepared and structurally characterized by various spectroscopic techniques and X-ray diffraction. These complexes exhibit intense absorptions in the visible range and excited-state lifetimes on the microsecond scale. Their application in visible-light-induced cross-dehydrogenative coupling reactions was investigated. Preliminary studies showed that one of the four copper(I) complexes is an efficient catalyst for photoinduced oxidative C-H functionalization using oxygen as oxidant. Furthermore, α-functionalized tertiary amines were obtained in good-to-excellent yields by light irradiation (λ>420 nm) of a mixture of our Cu(I) complex, tertiary amines, and a variety of nucleophiles (nitroalkane, acetone, or indoles) under aerobic conditions. Electron paramagnetic resonance measurements provided evidence for the formation of superoxide radical anions (O2(-⋅)) rather than singlet oxygen ((1)O2) during these photocatalytic reactions.
authors.affiliation: Tianjin Key Laboratory of Structure and Performance for Functional Molecules, Key Laboratory of Inorganic-Organic Hybrid Functional Materials Chemistry, Ministry of Education, College of Chemistry, Tianjin Normal University, Tianjin 300387 (China).
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Deepak Prakash
authors.initials: DP
authors.lastname: Shelar
authors.forename: Xian-Zhu
authors.initials: XZ
authors.lastname: Han
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Li
authors.forename: Xiangguo
authors.initials: X
authors.lastname: Guan
authors.forename: Wei
authors.initials: W
authors.lastname: Lu
authors.forename: Kun
authors.initials: K
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Wen-Fu
authors.initials: WF
authors.lastname: Fu
authors.forename: Chi-Ming
authors.initials: CM
authors.lastname: Che
keywords: UV/Vis spectroscopy; carboranes; copper; cross-coupling; photocatalysis