title: Triazolyl, Imidazolyl, and Carboxylic Acid Moieties in the Design of Molybdenum Trioxide Hybrids: Photophysical and Catalytic Behavior.
abstract: Three organic ligands bearing 1,2,4-triazolyl donor moieties, (S)-4-(1-phenylpropyl)-1,2,4-triazole (trethbz), 4-(1,2,4-triazol-4-yl)benzoic acid (trPhCO2H), and 3-(1H-imidazol-4-yl)-2-(1,2,4-triazol-4-yl)propionic acid (trhis), were prepared to evaluate their coordination behavior in the development of molybdenum(VI) oxide organic hybrids. Four compounds, [Mo2O6(trethbz)2]·H2O (1), [Mo4O12(trPhCO2H)2]·0.5H2O (2a), [Mo4O12(trPhCO2H)2]·H2O (2b), and [Mo8O25(trhis)2(trhisH)2]·2H2O (3), were synthesized and characterized. The monofunctional tr-ligand resulted in the formation of a zigzag chain [Mo2O6(trethbz)2] built up from cis-{MoO4N2} octahedra united through common μ2-O vertices. Employing the heterodonor ligand with tr/-CO2H functions afforded either layer or ribbon structures of corner- or edge-sharing {MoO5N} polyhedra (2a or 2b) stapled by tr-links in axial positions, whereas -CO2H groups remained uncoordinated. The presence of the im-heterocycle as an extra function in trhis facilitated formation of zwitterionic molecules with a protonated imidazolium group (imH+) and a negatively charged -CO2-group, whereas the tr-fragment was left neutral. Under the acidic hydrothermal conditions used, the organic ligand binds to molybdenum atoms either through [N-N]-tr or through both [N-N]-tr and μ2-CO2-units, which occur in protonated bidentate or zwitterionic tetradentate forms (trhisH+and trhis, respectively). This leads to a new zigzag subtopological motif (3) of negatively charged polyoxomolybdate {Mo8O25}n2n-consisting of corner- and edge-sharing cis-{MoO4N2} and {MoO6} octahedra, while the tetradentate zwitterrionic trhis species connect these chains into a 2D net. Electronic spectra of the compounds showed optical gaps consistent with semiconducting behavior. The compounds were investigated as epoxidation catalysts via the model reactions of achiral and prochiral olefins (cis-cyclooctene and trans-β-methylstyrene) with tert-butylhydroperoxide. The best-performing catalyst (1) was explored for the epoxidation of other olefins, including biomass-derived methyl oleate, methyl linoleate, and prochiral dl-limonene.
authors.affiliation: Inorganic Chemistry Department, Taras Shevchenko National University of Kyiv , Volodimirska Street 64, Kyiv 01033, Ukraine.
authors.forename: Andrey B
authors.identifier: http://orcid.org/0000-0002-0342-5122
authors.initials: AB
authors.lastname: Lysenko
authors.affiliation: Inorganic Chemistry Department, Taras Shevchenko National University of Kyiv , Volodimirska Street 64, Kyiv 01033, Ukraine.
authors.forename: Ganna A
authors.initials: GA
authors.lastname: Senchyk
authors.affiliation: Inorganic Chemistry Department, Taras Shevchenko National University of Kyiv , Volodimirska Street 64, Kyiv 01033, Ukraine.
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Domasevitch
authors.affiliation: Institut für Anorganische Chemie, Universität Leipzig , Johannisallee 29, D-04103 Leipzig, Germany.
authors.forename: Merten
authors.initials: M
authors.lastname: Kobalz
authors.affiliation: Institut für Anorganische Chemie, Universität Leipzig , Johannisallee 29, D-04103 Leipzig, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Krautscheid
authors.affiliation: Faculty of Chemistry, University of Wroclaw , 14 Joliot-Curie Street, 50-383 Wroclaw, Poland.
authors.forename: Jakub
authors.initials: J
authors.lastname: Cichos
authors.affiliation: Faculty of Chemistry, University of Wroclaw , 14 Joliot-Curie Street, 50-383 Wroclaw, Poland.
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Karbowiak
authors.affiliation: Department of Chemistry, CICECO - Aveiro Institute of Materials, University of Aveiro , Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Neves
authors.affiliation: Department of Chemistry, CICECO - Aveiro Institute of Materials, University of Aveiro , Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Anabela A
authors.initials: AA
authors.lastname: Valente
authors.affiliation: Department of Chemistry, CICECO - Aveiro Institute of Materials, University of Aveiro , Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Isabel S
authors.initials: IS
authors.lastname: Gonçalves