Controlled fluorescence in a beetle's photonic structure and its sensitivity to environmentally induced changes, Mouchet et al. Controlled fluorescence in a beetle's photonic structure and its sensitivity to environmentally induced changes

Supplementary materia

Bipyridine-Based Nanosized Metal–Organic Framework with Tunable Luminescence by a Postmodification with Eu(III): An Experimental and Theoretical Study

A gallium 2,2′-bipyridine-5,5′-dicarboxylate metal–organic framework, Ga­(OH)­(bpydc), denoted as COMOC-4 (COMOC = Center for Ordered Materials, Organometallics and Catalysis, Ghent University) has been synthesized via solvothermal synthesis procedure. The structure has the topology of an aluminum 2,2′-bipyridine-5,5′-dicarboxylate – the so-called MOF-253. TEM and SEM micrographs show the COMOC-4 crystals are formed in nanoplates with uniform size of 30–50 nm. The UV–vis spectra of COMOC-4 in methanol solution show maximal electronic absorption at 307 nm. This results from linker to linker transitions as elucidated by time-dependent density functional theory simulations on the linker and COMOC-4 cluster models. When excited at 400 nm, COMOC-4 displays an emission band centered at 542 nm. Upon immersion in different solvents, the emission band for the framework is shifted in the range of 525–548 nm depending on the solvent. After incorporating Eu³⁺ cations, the emission band of the framework is shifted to even shorter wavelengths (505 nm). By varying the excitation wavelengths from 250 to 400 nm, we can fine-tune the emission from red to yellowish green in the CIE diagram. The luminescence behavior of Eu³⁺ cations is well preserved and the solid-state luminescence lifetimes of τ₁ = 45 μs (35.4%) and τ₂ = 162 μs (64.6%) are observed

Light Conversion Control in NIR-Emissive Optical Materials Based on Heterolanthanide Er_<i>x</i>Yb_3–<i>x</i> Quinolinolato Molecular Components

Homo- and heterobimetallic homoleptic complexes of general formula Er_<i>x</i>Yb_3–<i>x</i>Q₉ (Q = 8-quinolinolato; <i>x</i> = 0, <b>1</b>; <i>x</i> = 1, <b>2</b>; <i>x</i> = 2, <b>3</b>) and the corresponding heteroleptic complexes Er_<i>x</i>Yb_3–<i>x</i>Q₈NO₃ (<i>x</i> = 0, <b>1b</b>; <i>x</i> = 1, <b>2b</b>; <i>x</i> = 2, <b>3b</b>), where one Q ligand is replaced by a nitrate anion, have been synthesized and fully characterized by means of compositional (energy-dispersive X-ray spectrometry, inductively-coupled plasma-mass spectrometry, and electrospray ionization mass spectrometry) and structural (X-ray diffraction) investigations to study the effects of ligand substitution and variation of metal composition on their chemical and photophysical properties. Advanced spectroscopic and photophysical studies in the visible and near-infrared spectral regions have allowed the achievement of a detailed picture of the photocycle leading to narrow-band lanthanide luminescent emission, providing evidence of highly efficient ligand-to-metal and metal-to-metal (Yb-to-Er) resonance energy transfers thanks to the short intermetallic distances in heterolanthanide molecular species. Highly homogeneous silica thin films doped with <b>2</b> have shown to retain the optical properties of the dopant complex in solution, proving the suitability of this class of complexes for preparing Er/Yb codoped optical materials for potential applications as waveguides or amplifiers with controlled composition and distribution of the optically active metals