Sensing and Imaging of Oxygen with Parts per Billion Limits of Detection and Based on the Quenching of the Delayed Fluorescence of ¹³C₇₀ Fullerene in Polymer Hosts

Abstract

We report on a new method for sensing trace oxygen in the gas phase. It is based on the extreme efficiency of the quenching of the thermally activated delayed fluorescence of isotopically enriched carbon-13 fullerene C(70) ((13)C(70)). This fullerene was dissolved in polymer matrixes of varying oxygen permeability, viz., polystyrene (PS), ethyl cellulose (EC) and an organically modified silica gel ("ormosil"; OS). The sensor films (5-10 μm thick), on photoexcitation at 470 nm, display a strong delayed photoluminescence with peaks between 670 and 700 nm. Its quenching by molecular oxygen was studied at 25 and 60 °C and at concentrations from zero up to 150 ppmv of oxygen in nitrogen. The rapid lifetime determination (RLD) method was applied to determine oxygen-dependent lifetimes and for fluorescence lifetime imaging of oxygen. The lower limits of detection (at 1% quenching) vary with the polymer used (EC ∼250 ppbv, OS ∼320 ppbv, PS ∼530 ppbv at 25 °C) and with temperature. The oxygen sensors reported here are the most sensitive ones described so far.

Tailoring Oxygen Sensitivity with Halide Substitution in Difluoroboron Dibenzoylmethane Polylactide Materials

“…BF 2 dbmPLA: 11b , τ 1 /τ 0 = 7%). 61 Therefore, the detected phosphorescence at 1% oxygen may be the result of a different detectable solid-state species (i.e. aggregates or dimers) within the PLA matrix as BF 2 dbm type fluorophores are well known to form in polymer matrices.…”

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

“…As shown in Table 2, the K SV 1 for I 2 -BODIPY in PP (1.60 kPa -1 at 20C) is significantly higher than the K SV 1 in PSu (0.95 kPa -1 at 20C), which suggests that the sensitivity of the system can be readily tuned by changing the encapsulating medium. The limits of detection for oxygen (LOD); was determined from 1% quenching (τ/τ 0 = 0.99) [44] and found to be 0.02 kPa for both PSu and PP. …”

Difluoroboron β-diketonate materials with long-lived phosphorescence enable lifetime based oxygen imaging with a portable cost effective camera

“…31 Samples 1 (BF 2 dbmPLA, 20 kDa) and 2 (BF 2 nbmPLA, 19 kDa) show predominantly RTP, while BF 2 dnmPLA polymers (sample 3 , 30 kDa and sample 4 , 16 kDa) show more significant TADF. 27 Because TADF is a thermal process, the delayed emission color, lifetime, and oxygen sensitivity 39 change dramatically with variations in temperature. 38 BF 2 nbmPLA ( 2 ) polymers have the largest singlet-triplet gaps (465-545 nm), and long unquenched phosphorescence lifetimes (222 ms), making this dye scaffold optimal for long-lived phosphorescence applications.…”

“…38 BF 2 nbmPLA ( 2 ) polymers have the largest singlet-triplet gaps (465-545 nm), and long unquenched phosphorescence lifetimes (222 ms), making this dye scaffold optimal for long-lived phosphorescence applications. 26,39,40 All polymers 1-4 have long-lived triplet emissions, resulting in hypersensitivity to oxygen quenching. Because these dyes are covalently linked to the polymer matrix, fabrication into nanoprobes is easily achieved for biomedical application to acquire spatial information.…”