| Oxygen concentration is a key parameter in numerous fields of science and technology. Oxygen sensor has accompanied mankind from the early days to now. The frequent use of oxygen sensor in chemical industry, environmental monitoring, clinical analysis applications in oceanography and recent investigations of chemical imaging of intrinsically fluorescent chemical species have proven that. Based on fluorescence quenching, a new type of luminescent oxygen sensor had been developed. One of the main composes of the luminescent oxygen sensor is the transition-metal complex, which is usually immobilized on a polymer film and acts as an oxygen sensitizer. Oxygen diffuses from the surrounding medium into the film and plays a role as a powerful quencher of the electronically excited state of the metal complex. Transition-metal complexes (Ru(â…¡), Ir(â…¢), Pt(â…¡) and Pd(â…¡) complexes) display a strong oxygen dependence of their luminescence lifetime which have the highest oxygen sensitivity. Pt(â…¡) complexes are known to exhibit strong phosphorescence at room temperature, with quantum yields higher. Compared to most other types of phosphorescent organic dyes, Pt(â…¡) complexes have long wave spectral characteristics of phosphorescence and significantly longer lifetimes. So far, a number of articles mainly focusing on luminescence oxygen sensors have appeared, but the more recent examples were restricted to Pt(â…¡) complexes with porphyrin ligands, only few Pt(â…¡) complexes from other cyclometalating ligands were reported.Triphenylamine (TPA) derivatives, due to the non-coplanarity of the three phenyl substituents, strong electron-donating nature, good hole-transporting capability and high light-to-electrical energy-conversion efficiency, are important structural motifs in numerous organic electroluminescence materials. Quinoline skeleton is often used synthetically to design compounds. To the best of our knowledge, no example of quinoline or triphenylamine-based cyclometalated Pt(â…¡) complexes containing aryl moieties for efficient luminescent oxygen sensing has been reported to date. So we design Pt(â…¡) complexes from two cyclometalating ligands. The main contents are as follows:1. We report the synthesis, structure-photoelectric performances of novel cyclometalated platinum complexes based on4-(2-pyridyl)-substituted TPA derivatives, which were used to investigate the relationship of structure-photoelectric properties of the Pt(â…¡) complexes and to evaluate the performances in oxygen sensing. The results showed that the HOMO and LUMO levels were little influenced by the4,5or6-methyl on the pyridyl ring. The photophysical properties of the complexes exhibited that introducing an electron-withdrawing group like trifluoromethyl or cyano group on the5-position of the pyridine ring affected the energy gap of the Pt(â…¡) complex significantly, resulting in a marked decrease in energy gap. Moreover, the complex with a cyano group at the5-position imparts a substantial red-shift up to56nm. The results of the02-sensing sensitivity of the Pt(â…¡) complexes (LSTP) demonstrated that the complex with LSTP7exhibited the highest sensitivity (Kappsv=0.1017Torr-1).2. We describe the synthesis, structure-photoelectric performances of novel cyclometalated Pt(â…¡) complexes based on2-phenylquinoline derivatives, which were used to investigate the relationship of structure-photoelectric properties of the Pt(â…¡) complexes and to evaluate the performances in oxygen sensing. The photophysical properties of the complexes demonstrated that introducing a diphenylamino group at the4-position of the phenyl ring affected the energy gap of the Pt(â…¡) complex significantly, resulting in a marked decrease in energy gap and imparted a substantial red-shift of emission up to13nm. The results of the02-sensing sensitivity of the Pt(â…¡) complexes (LSQU) exhibited that the complex LSQU9demonstrated the highest sensitivity (Kappsv=0.0206Torr-1). |
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