title: Synthesis, structure, ultrafast kinetics, and light-induced dynamics of CuHETPHEN chromophores.
abstract: Five heteroleptic Cu(i)bis(phenanthroline) chromophores with distinct variation in the steric bulk at the 2,9-phenanthroline position were synthesized using the HETPHEN method, and their ground and excited state properties are described. Analysis of the crystal structures reveals a significant distortion from tetrahedral geometry around the Cu(i) centre which is attributed to favourable aromatic interactions between the two phenanthroline ligands. Ultrafast and nanosecond transient optical spectroscopies reveal that the excited state lifetime can be tuned across two orders of magnitude up to 74 nanoseconds in acetonitrile by changing the 2,9-substituent from hydrogen to sec-butyl. X-ray transient absorption spectroscopy at the Cu K-edge confirmed Cu(i) oxidation to Cu(ii) and revealed a decrease of the Cu-N bond lengths in the excited state. The ground and excited state characterization presented here will guide the integration of CuHETPHEN chromophores into complex electron donor-acceptor architectures.
authors.affiliation: Division of Chemical Sciences and Engineering, Argonne National Laboratory, 9700 South Cass Ave, Argonne, IL 60439, USA. mulfort@anl.gov.
authors.forename: Lars
authors.initials: L
authors.lastname: Kohler
authors.affiliation: Division of Chemical Sciences and Engineering, Argonne National Laboratory, 9700 South Cass Ave, Argonne, IL 60439, USA. mulfort@anl.gov.
authors.forename: Dugan
authors.initials: D
authors.lastname: Hayes
authors.affiliation: Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
authors.forename: Jiyun
authors.initials: J
authors.lastname: Hong
authors.affiliation: Division of Chemical Sciences and Engineering, Argonne National Laboratory, 9700 South Cass Ave, Argonne, IL 60439, USA. mulfort@anl.gov.
authors.forename: Tyler J
authors.initials: TJ
authors.lastname: Carter
authors.affiliation: Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
authors.forename: Megan L
authors.initials: ML
authors.lastname: Shelby
authors.affiliation: Division of Chemical Sciences and Engineering, Argonne National Laboratory, 9700 South Cass Ave, Argonne, IL 60439, USA. mulfort@anl.gov.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Fransted
authors.affiliation: Division of Chemical Sciences and Engineering, Argonne National Laboratory, 9700 South Cass Ave, Argonne, IL 60439, USA. mulfort@anl.gov and Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
authors.forename: Lin X
authors.initials: LX
authors.lastname: Chen
authors.affiliation: Division of Chemical Sciences and Engineering, Argonne National Laboratory, 9700 South Cass Ave, Argonne, IL 60439, USA. mulfort@anl.gov.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Mulfort