A Highly Fluorescent Dinuclear Aluminium Complex with Near‐Unity Quantum Yield**

Abstract

The high natural abundance of aluminium makes the respective fluorophores attractive for various optical applications, but photoluminescence quantum yields above 0.7 have yet not been reported for solutions of aluminium complexes. In this contribution, a dinuclear aluminium(III) complex featuring enhanced photoluminescence properties is described. Its facile one-pot synthesis originates from a readily available precursor and trimethyl aluminium. In solution, the complex exhibits an unprecedented photoluminescence quantum yield near unity (Φ absolute 1.0 � 0.1) and an excited-state lifetime of 2.3 ns. In the solid state, J-aggregation and aggregation-caused quenching are noted, but still quantum yields of 0.6 are observed. Embedding the complex in electrospun non-woven fabrics yields a highly fluorescent fleece possessing a quantum yield of 0.9 � 0.04.

A tetranuclear magnesium hydride cluster with a four-coordinate hydride in near square-planar geometry

“…Double deprotonation of the β-oxo-δ-diimine (BODDI)H 2 13 with diethylmagnesium dioxane adduct affords (BODDI) 2 (MgEt) 2 , which is subsequently reacted with phenyl silane at 80 °C, Scheme 1. Thereby, a single product is formed and its rather simple 1 H NMR spectrum (C 6 D 6 ), with one septet for the methine and two doublets for the methyl groups of the Dipp residues, is indicative for a symmetrical or – on the NMR timescale – averaged structure as previously reported for other β-oxo-δ-diiminate complexes; 13,14 the NMR spectra of the “crude” reaction product and those obtained from dissolving crystalline material are comparable. The hydride ligand within (BODDI) 2 (MgH) 4 resonates as a sharp singlet at 3.66 ppm in the 1 H NMR spectrum, similar to previous reports on magnesium β-diketiminate hydride complexes (3.83–4.03 ppm).…”

Easy access to strongly fluorescent higher homologues of BODIPY

“…In contrast, reports on the solid-state fluorescence quantum yields of related heavier BODIPYs are so far lacking. 30,51 Therefore, the solid-state values obtained for 2a and 3a are the best compared to those of highly fluorescent BODIPYs, whose solid-state quantum yields range from 0 to about 30%. 52,53 This strong discrepancy between fluorescence Excitation with a 325 nm He-Cd continuous wave laser (the signal at 650 nm is the second diffraction order of the laser).…”

Efficient fluorescence of alkali metal carbazolides

“…observed quantum yields up to 16% in solution with the corresponding precursor compounds, the protonated ligand as well as the monodeprotonated ligand, being nonluminescent. 21 Recently, main group metal compounds with various different ligand sets were discovered, including Mg 2,2'pyridylpyrrolide complexes, 22 phosphine-functionalised diamido compounds of alkaline earth metals 23 and a dinuclear Al complex 24 that featured luminescence with high quantum yields. Monodentate carbazolides of the alkali metals frequently aggregate in absence of strong donors as shown for the parent carbazole.…”

“…Hohloch, Guldi and Munz have only recently reported on Li and Mg ( B ) complexes of a carbazole-based CNC pincer ligand and observed quantum yields of up to 16% in solution with the corresponding precursor compounds, the protonated ligand and the monodeprotonated ligand, being non-luminescent. 21 Recently, main group metal compounds with various different ligand sets have been discovered, including Mg 2,2′-pyridylpyrrolide complexes, 22 phosphine-functionalised diamido compounds of alkaline earth metals 23 and dinuclear Al complexes 24 that feature luminescence with high quantum yields.…”