Monitoring the amount of oxygen in living tissues accurately is a valuable tool in biomedical science, because it enables the elucidation of the course of metabolic processes or the detection of diseases or anomalies.
Metal complexes that absorb and emit light are useful as sensors, and metal complexes of porphyrins and their derivatives are especially good candidates for such applications, as the porphyrin macrocycle can easily be modified.
Sergey M. Borisov and his co-workers at Graz University of Technology (Austria), developed new, strongly phosphorescent porphyrin complexes of iridium(III), which were applied as dyes in advanced optical oxygen-sensing materials and published them in the European Journal of Inorganic Chemistry.
Photophysical properties of porphyrin complexes of metals such as palladium or platinum have been studied before; however, there are fewer studies on iridium complexes, which are more difficult to synthesize. The absorption bands of iridium complexes are broader and are shifted to lower wavelengths in comparison to those of their platinum analogues. This enables them to be excited by visible light. Furthermore, iridium(III) is hexacoordinate, which opens up the added possibility of introducing axial ligands directly on the metal instead of modifying the porphyrin macrocycle, in contrast to the square-planar platinum(II) and palladium(II) analogues. A π-extended iridium(III)–benzoporphyrin and four iridium(III)–octaethylporphyrin complexes with high room-temperature phosphorescence quantum yields of up to 30% were synthesized. Axial ligands were used to change their solubility or to introduce binding groups. In this way, the complexes were rendered soluble in organic solvents, and they were incorporated into polystyrene or other polymers to yield oxygen sensors. In addition, other axial ligands, such as an imidazole ligand bearing a carboxyl group, were used to make the complexes soluble in polar solvents such as ethanol and even in aqueous buffer at physiological pH, which enabled coupling to biomolecules such as proteins, antibodies, or lipids, as demonstrated by coupling to bovine serum albumin.
The importance of these new compounds is their tunable photophysical properties and versatility, as demonstrated by their application as a water-soluble oxygen probe (by staining bovine serum albumin) and a trace oxygen sensor (by coupling to amino-modified silica gel). The obtained sensor is sensitive to small oxygen concentrations and features a highly linear calibration plot. The new dyes are particularly promising as indicators for oxygen sensors with tailor-made sensitivity.
Author: Sergey Borisov, Technische Universität Graz (Austria), http://www.analytchem.tugraz.at/sensors/borisov.php
Title: Strongly Phosphorescent Iridium(III)–Porphyrins—New Oxygen Indicators with Tuneable Photophysical Properties and Functionalities
European Journal of Inorganic Chemistry, Permalink to the article: http://dx.doi.org/10.1002/ejic.201100089
Sergey Borisov | Wiley-VCH
Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory
Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine