Exceptional Oxygen Sensing Properties of New Blue Light‐Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

Abstract

New europium(III) and gadolinium(III) complexes bearing 8-hydroxyphenalenone antenna combine efficient absorption in the blue part of the spectrum and strong emission in polymers at room temperature. The Eu(III) complexes show characteristic red luminescence whereas the Gd(III) dyes are strongly phosphorescent. The luminescence quantum yields are about 20% for the Eu(III) complexes and 50% for the Gd(III) dyes. In contrast to most state-of-the-art Eu(III) complexes the new dyes are quenched very efficiently by molecular oxygen. The luminescence decay times of the Gd(III) complexes exceed 1 ms which ensures exceptional sensitivity even in polymers of moderate oxygen permeability. These sensors are particularly suitable for trace oxygen sensing and may be good substitutes for Pd(II) porphyrins. The photophysical and sensing properties can be tuned by varying the nature of the fourth ligand. The narrow-band emission of the Eu(III) allows efficient elimination of the background light and autofluorescence and is also very attractive for use e.g. in multi-analyte sensors. The highly photostable indicators incorporated in nanoparticles are promising for imaging applications. Due to the straightforward preparation and low cost of starting materials the new dyes represent a promising alternative to the state-ofthe-art oxygen indicators particularly for such applications as e.g. food packaging.

Solid-state oxygen sensors based on phosphorescent diiodo-borondipyrromethene dye

“…In PP, the phosphorescence lifetime of I 2 -BODIPY changed by a factor of ~ 5, when measured in air and in N 2 atmosphere, respectively. [40,41]. Additionally for intensity based measurements, the phosphorescence intensity was also found to depend on the type of the support material ( Mylar® was found to decrease from 65.5 s at 10 C to 46 s at 30 C at 21 kPa O 2 concentration, however, the unquenched lifetime remained fairly unchanged (305.9 ± 5.8 s at 10C compared to 304.2 ± 1.5 s at 30C).…”

Oxygen Sensing Difluoroboron Dinaphthoylmethane Polylactide

“…Typical ratiometric sensing materials are multicomponent, comprised of standard and sensor dyes that are combined in a suitable matrix. 86–88 Fluorescence and phosphorescence wavelengths and signal intensities are easily controlled by dye selection, and intensities, by dye loading. In dual emissive dyes such as BF 2 bdkPLAs, different approaches to wavelength and intensity modulation are required.…”

Room‐Temperature‐Phosphorescence‐Based Dissolved Oxygen Detection by Core‐Shell Polymer Nanoparticles Containing Metal‐Free Organic Phosphors

“…As expected, nanoparticles of both sizes showed very high oxygen sensitivity, which is explained by the long phosphorescence decay time of the metal‐free organic phosphor under oxygen‐free conditions ( τ 0,gas ≈4 ms, see Figure S4). It should be mentioned that although a great number of oxygen indicators with the phosphorescence decay times from 1 to 1000 μs are available, there are only very few examples of probes featuring longer phosphorescence/TADF lifetimes, τ , such as C 70 fullerene ( τ 0 ≈20 ms), BF 2 ‐chelates ( τ 0 ≈4.3 ms; τ 0 ≈360–730 ms), and Gd III complexes ( τ 0 ≈1.3 ms; τ 0 ≈2 ms), which are of particular interest for the design of ultra‐sensitive oxygen sensors. The sensitivity is slightly higher for the 320 nm NPs, which is explained by their longer decay time.…”