Synthesis and assembly with mesoporous silica of platinum (II) porphyrin complexes bearing carbazyl groups: Luminescent and oxygen sensing properties

Abstract

A series of platinum meso-tetrakis [3-methoxy-4-(N-carbazyl)n-alkyloxyphenyl]porphyrin (Pt-4Cn-TPP, n = 4, 6 and 8) are synthesized. Pt-4C4-TPP, Pt-4C6-TPP and Pt-4C8-TPP exhibit similar luminescent properties in solution and solid state. Three protonated platinum (II) porphyrins are assembled with mesoporous silica MCM-48, respectively, resulting in assembly materials Pt-4Cn-TPP 4+ / MCM-48 (n = 4, 6 and 8). The luminescent intensity of Pt-4Cn-TPP 4+ /MCM-48 can be extremely quenched by molecular oxygen with high sensitivity (I 0 /I 100 > 9). The Stern-Volmer plots of these assembly materials display considerable linearity within a wide range of oxygen concentration (0 to 100%). The response time is all ≤ 1 s and recovery time ≤ 22 s for these assembly materials.Keywords: platinum (II) porphyrin, oxygen sensor, mesoporous silica.Determination of oxygen is very important in various fields such as analytical chemistry, medical chemistry and environmental and industrial applications [1] . The optical oxygen sensors are based upon the principle that oxygen is a powerful quencher of the luminescent intensity and lifetime of luminescent complex, and the key factors that play a role in including the optical properties of luminescent complex and the solubility and diffusion coefficient of oxygen in the matrix. The classical method for oxygen determination is using the Clark electrode [2] , which was based on the measurement of the current at an electrode surface by the selective reduction of O 2 . For this kind of oxygen sensor, the electrodes are easily damaged and tend to consume oxygen. While for the optical oxygen sensors, the stability is very good and the calibration is easier in that this method is less susceptible to the signal intensity changes resulting in the instrumental fluctuations. The most commonly used complexes for this application are transition metal complexes especially ruthenium (II) polypyridyl or phenanthroline complexes [3] and metalloporphyrins [4] owing to their high quantum yields, large Stokes shifts and long luminescent lifetimes. And the host materials used to encapsulate the luminescent complexes are sol-gel and polymer films. Some interesting systems based on sol-gel or polymer immobilized transition metal complexes have been reported [4,5] .The transition metal complexes-based oxygen sensors that simultaneously displayed high sensitivity, linear Stern-Volmer plot and fast response/recovery are very rare [6][7][8][9] . Over the past decade, it has been demonstrated that mesoporous silicas are the excellent support for developing functional materials, because mesoporous silicas have large accessible pore size, high surface areas and periodic nano-scale pores [10][11][12][13][14][15][16] . Recently, we reported new oxygen sensing materials based on platinum (II) porphyrin complexes assembled in mesoporous silica [17] . This work has demonstrated that the assembly between platinum meso-tetrakis-(4-N-methylpyridyl)porphyrin (PtTMPyP 4+ ) and mesoporous silica MCM-41 can lead to the formation...

Platinum(ii) and palladium(ii) complexes with electron-deficient meso-diethoxyphosphorylporphyrins: synthesis, structure and tuning of photophysical properties by varying peripheral substituents

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Novel concept of polymers preparation with high photoluminescent quantum yield

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The Mechanism of Nitrogen Removal in Domestic Sewage of High Ammonia Nitrogen by Three-Step Series Constructed Rapid Infiltration System

“…Constructed Rapid Infiltration System (CRI) is a new sewage treatment technology developed by the School of Water Resources and Environment, China University of Geosciences (Beijing) in recent years [1][2][3]. This technology is mainly used in the research of sewage, bath water, micro-polluted river water in China recently, and applied in practical projects.…”