Phosphorescent Complexes of Porphyrin Ketones: Optical Properties and Application to Oxygen Sensing

Abstract

A new class of dyes, platinum(II) and palladium(II) complexes of the porphyrin ketones (or "oxochlorins"), exhibiting strong phosphorescence at room temperature is described. Several representative compounds were prepared and studied by spectral luminescence methods in solution. Compared to the related porphyrin and chlorin complexes, the new dyes display high photochemical stability, long wave spectral characteristics, and good compatibility with semiconductor optoelectronics (e.g., excitation by light-emitting diodes). These properties make the new dyes promising for a number of relevant applications, such as quenched phosphorescence sensing and phosphorescence probing (e.g., in binding assays). Analytical application of the porphyrin ketone complexes to phosphorescence lifetime-based sensing of molecular oxygen is described. Platinum(II) octaethylporphine ketone was dissolved in a polystyrene layer to give an oxygen-sensitive film. Oxygen measurements were performed with a prototype fiber-optic instrument based on solid-state components, such as light-emitting diodes and photodiodes. The instrument measured phosphorescence lifetime via changes in phase shift The phosphorescence lifetime was determined to change from about 61.4 ps at zero oxygen to 16.3 ps in air (210 hPa of oxygen) at 22 °C. The analytically useful range of the sensor was 0-210 hPa of oxygen partial pressure, with a detection limit of 1.5 hPa. The precision of the device was 1.0 hPa at 210 hPa of oxygen and 0.5 hPa at zero oxygen.Platinum (II) and palladium (II) complexes of porphyrins are known to exhibit strong phosphorescence at room temperatures,1-4 with quantum yields of > 10%. Compared to most other types of phosphorescent organic dyes, porphyrin complexes have long (1) Eastwood, D.; Gouterman, M.

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

“…ruthenium(II)-tris-4,7-diphenyl-1,10-phenanthroline (= Ru-dpp, Φ = 0.37), [74] platinum 5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin (= PtTFPP, Φ = 0.09), [75] platinum octaethylporphyrin (Φ = 0.41) [76] and platinum(II) octaethylporphyrin ketone (Φ = 0.12). [12] The quenching by oxygen is indeed very efficient (Fig. 4).…”

“…[1][2][3][4] Most oxygen sensors employ such widespread indicators as ruthenium(II) polypyridyl complexes, [5][6][7] platinum(II) and palladium(II) porphyrins [8][9][10][11] and their analogues. [12][13][14] Other luminescent indicators are less popular which is explained by their inferior photophysical properties (low absorption coefficients and luminescence quantum yields, short luminescence decay times, poor photostability etc.) [3]or by complicated multistep synthesis.…”

Development of an integrated microfluidic platform for dynamic oxygen sensing and delivery in a flowing medium

“…Early work in the area focused on polyaromatic hydrocarbon complexes, 16 with more recent work employing ruthenium diimines, 14,17 18 or remotely with a fiber optic probe. 9,10 Both techniques allow non-invasive, real-time monitoring. In the present work, the former approach was employed to take advantage of the optical clarity of the polydimethylsiloxane (PDMS) microfluidic device and achieve a higher signal-to-noise ratio through better light coupling.…”

Patterning, integration and characterisation of polymer optical oxygen sensors for microfluidic devices

“…18 It exhibits both a long wavelength shift and an extended long-term photostability compared to other fluorescent dyes. 13,19 This allows for the use of standard optical filters and makes sample handling less critical. PS was chosen as polymer matrix because it provides good oxygen permeability, bio-compatibility and low autofluorescence.…”

“…Furthermore, 3 weeks of continuous illumination with only minor signal degradation and the retaining of spectral and quenching characteristics for up to 2 years under storage have been reported for PtOEPK/PS. 19 …”