Tuning of the Emission Efficiency and HOMO–LUMO Band Gap for Ester-Functionalized {Al(salophen)(H₂O)₂}⁺ Blue Luminophors

A series of [Al<b>L</b>(H₂O)₂(NO₃)] complexes, with <b>L</b> standing for an ester substituted salophen-type ligand, has been synthesized, and the luminescence properties have been investigated. These derivatives differ by the nature of the ester-R group introduced at the C5 position of their salicylidene rings (i.e., phenyl, <b>7a,a</b>′; naphthyl, <b>7b,b</b>′; pentafluorophenyl, <b>7c,c</b>′; and <i>p</i>-nitrophenyl, <b>7d</b>) and by the bis-imino bridge (i.e., 1,2- phenylene, <b>7a</b>–<b>d</b>; and 1,2-naphthalene, <b>7a</b>′<b>–c</b>′). All the complexes are characterized by luminescence in the blue range, the chemical diversity having no effect on the emission wavelength (480–485 nm). However, the emission efficiency was found to be strongly dependent on the Schiff-base ligand with quantum yields ranging from ϕ = 22% to 44%, the highest values being for the salophen derivatives with the electron-withdrawing ester-R groups (<b>7a</b>, 34%; <b>7a</b>′, 23%; <b>7b</b>, 31%; <b>7b</b>′, 22%; <b>7c</b>, 40%; <b>7c</b>′, 29%, and <b>7d</b>, 44%). Both the electrochemical data and DFT calculations show that the HOMO–LUMO band gap is modified as a function of the ester R group (from 2.92 to 3.16 eV, based on the redox potentials). The crystal structures for the <i>N,N</i>′-bis­(5-(phenoxycarbonyl)­salicylidene)-1,2-phenylenediamine and the <i>N,N</i>′-bis­(5-(<i>p</i>-nitrophenoxycarbonyl)­salicylidene)-1,2-phenylenediamine aluminum complexes (<b>7a</b> and <b>7d</b>) are reported

Tuning of the Emission Efficiency and HOMO–LUMO Band Gap for Ester-Functionalized {Al(salophen)(H₂O)₂}⁺ Blue Luminophors

A series of [Al<b>L</b>(H₂O)₂(NO₃)] complexes, with <b>L</b> standing for an ester substituted salophen-type ligand, has been synthesized, and the luminescence properties have been investigated. These derivatives differ by the nature of the ester-R group introduced at the C5 position of their salicylidene rings (i.e., phenyl, <b>7a,a</b>′; naphthyl, <b>7b,b</b>′; pentafluorophenyl, <b>7c,c</b>′; and <i>p</i>-nitrophenyl, <b>7d</b>) and by the bis-imino bridge (i.e., 1,2- phenylene, <b>7a</b>–<b>d</b>; and 1,2-naphthalene, <b>7a</b>′<b>–c</b>′). All the complexes are characterized by luminescence in the blue range, the chemical diversity having no effect on the emission wavelength (480–485 nm). However, the emission efficiency was found to be strongly dependent on the Schiff-base ligand with quantum yields ranging from ϕ = 22% to 44%, the highest values being for the salophen derivatives with the electron-withdrawing ester-R groups (<b>7a</b>, 34%; <b>7a</b>′, 23%; <b>7b</b>, 31%; <b>7b</b>′, 22%; <b>7c</b>, 40%; <b>7c</b>′, 29%, and <b>7d</b>, 44%). Both the electrochemical data and DFT calculations show that the HOMO–LUMO band gap is modified as a function of the ester R group (from 2.92 to 3.16 eV, based on the redox potentials). The crystal structures for the <i>N,N</i>′-bis­(5-(phenoxycarbonyl)­salicylidene)-1,2-phenylenediamine and the <i>N,N</i>′-bis­(5-(<i>p</i>-nitrophenoxycarbonyl)­salicylidene)-1,2-phenylenediamine aluminum complexes (<b>7a</b> and <b>7d</b>) are reported

Tuning of the Emission Efficiency and HOMO–LUMO Band Gap for Ester-Functionalized {Al(salophen)(H₂O)₂}⁺ Blue Luminophors

A series of [Al<b>L</b>(H₂O)₂(NO₃)] complexes, with <b>L</b> standing for an ester substituted salophen-type ligand, has been synthesized, and the luminescence properties have been investigated. These derivatives differ by the nature of the ester-R group introduced at the C5 position of their salicylidene rings (i.e., phenyl, <b>7a,a</b>′; naphthyl, <b>7b,b</b>′; pentafluorophenyl, <b>7c,c</b>′; and <i>p</i>-nitrophenyl, <b>7d</b>) and by the bis-imino bridge (i.e., 1,2- phenylene, <b>7a</b>–<b>d</b>; and 1,2-naphthalene, <b>7a</b>′<b>–c</b>′). All the complexes are characterized by luminescence in the blue range, the chemical diversity having no effect on the emission wavelength (480–485 nm). However, the emission efficiency was found to be strongly dependent on the Schiff-base ligand with quantum yields ranging from ϕ = 22% to 44%, the highest values being for the salophen derivatives with the electron-withdrawing ester-R groups (<b>7a</b>, 34%; <b>7a</b>′, 23%; <b>7b</b>, 31%; <b>7b</b>′, 22%; <b>7c</b>, 40%; <b>7c</b>′, 29%, and <b>7d</b>, 44%). Both the electrochemical data and DFT calculations show that the HOMO–LUMO band gap is modified as a function of the ester R group (from 2.92 to 3.16 eV, based on the redox potentials). The crystal structures for the <i>N,N</i>′-bis­(5-(phenoxycarbonyl)­salicylidene)-1,2-phenylenediamine and the <i>N,N</i>′-bis­(5-(<i>p</i>-nitrophenoxycarbonyl)­salicylidene)-1,2-phenylenediamine aluminum complexes (<b>7a</b> and <b>7d</b>) are reported

CH Bond Activation of Unsaturated Hydrocarbons by a Niobium Methyl Cyclopropyl Precursor. Cyclopropyl Ring Opening and Alkyne Coupling Reaction

The transient intermediate η²-cyclopropene/bicyclobutane niobium complex [Tp^Me2Nb­(η²-<i>c</i>-C₃H₄)­(MeCCMe)] <b>A</b>, generated by an intramolecular β-H abstraction of methane from the methyl cyclopropyl complex [Tp^Me2NbMe­(<i>c</i>-C₃H₅)­(MeCCMe)] (<b>1</b>), is able to cleave the CH bond of a variety of unsaturated hydrocarbons RH in a selective manner to give the corresponding hydrocarbyl complexes [Tp^Me2NbR­(<i>c</i>-C₃H₅)­(MeCCMe)] (R = 2-furyl, 2-thienyl, 1-alkynyl, 1-cyclopentenyl, 1-ferrocenyl (Fc), pentafluorophenyl). The activation of the C–H bond occurs stereospecifically via a 1,3-CH addition across the Nb­(η²-cyclopropene) bond of <b>A</b>. Full characterization of several of these complexes includes multinuclear NMR spectroscopy, X-ray diffraction, UV/vis spectroscopy, and electrochemical data. A charge transfer between the ferrocenyl moiety and the niobium center is responsible for the characteristic purple color of the bimetallic complex [Tp^Me2NbFc­(<i>c</i>-C₃H₅)­(MeCCMe)]. The reactivity of these complexes with benzene follows qualitatively the strength and the p<i>K</i>_a of the CH bond that is cleaved. The pentafluorophenyl complex [Tp^Me2Nb­(C₆F₅)­(<i>c</i>-C₃H₅)­(MeCCMe)] undergoes cyclopropyl ring opening and alkyne coupling to give two isomeric η⁴-butadienyl complexes, with [Tp^Me2Nb­(C₆F₅)­(η⁴-CMeCMeCHCHMe)] as the major isomer

Heteroleptic Bis(<i>cis</i>-1,2-disubstituted ethylene-1,2-dithiolato)nickel Complexes Obtained by Ligand-Exchange Reaction: Synthesis and Properties

The ligand-exchange reaction has been investigated to synthesize nickel bis­(dithiolene) complexes bearing one hydroxyl functional group aimed at being grafted thereafter onto polymer materials. This reaction leads easily to heteroleptic complexes with the ethylene-1,2-dithiolato core substituted by either alkyl or aryl moieties. Details on synthetic parameters are given. A direct link between the electronic properties of the obtained molecules and those of the parent complexes involved in the ligand-exchange reaction is highlighted and also demonstrates that this reaction is a powerful method for preparing nickel complexes with tailor-made frontier orbital energies