24-Mar-2010 - Wiley-VCH Verlag GmbH & Co. KGaA

Room Temperature Liquid Porphyrins: Potential Optical Limiters

Porphyrins have received a great deal of attention in the scientific community owing to their useful application in a wide variety of areas, such as the treatment of cancer and systems that mimic photosynthesis. A common shortcoming observed in using porphyrins arises from their tendency to form stacks and aggregates, as is common for planar aromatic systems, which results in low solubility, high crystallinity, and high melting point. In the journal Chemistry—An Asian Journal, a team led by Daniel T. Gryko, based at the Polish Academy of Sciences (Warsaw, Poland), describe the design and synthesis of liquid porphyrin-based compounds that, after suitable structural modifications, may be used as optical limiters.

The study focuses on a homologous series of meso-substituted A4-porphyrins bearing aryl groups with long alkoxy chains. The alkyl chain length ranges from 8 to 18 carbon atoms. The synthesis of these compounds involves a high-yielding two-step process using commercially available starting materials. All porphyrins synthesized are found to be highly soluble in organic solvents. Differential scanning calorimetry (DSC) is used to investigate the thermal properties of the series of porphyrins.

"The behavior of the compounds in the DSC thermograms is very sensitive to the alkoxy chain lengths present in the molecule" writes Gryko. A gradual decrease in the temperature for the crystalline-to-isotropic-liquid phase transition is observed as the length of the alkoxy side chains increase. A minimum is observed for the decycloxy compound, with subsequent elongation of the alkyl chain causing an increase in the melting point. 5,10,15,20-Tetrakis[3,4,5-tri(undecyloxy)phenyl]porphyrin and its decyloxy analogue are both observed to be liquids at room temperature and are shown to have melting points of -24°C and -55°C, respectively.

Such compounds are unprecedented, and these results provide significant insight into the possibilities for the design and synthesis of room temperature liquid porphyrins in a very simple and efficient way. It is known that liquid porphyrins maintain the same spectroscopic features as their solid analogues, therefore, this discovery not only opens the way to design porphyrins possessing such substituents in optical limiting devices but also allows its broader use in other applications where liquidity or very high solubility are desirable.

Original publication: Daniel T. Gryko et al.; "Meso-Substituted Liquid Porphyrins"; Chemistry—An Asian Journal 2010, 5, No. 4.

Facts, background information, dossiers
More about Wiley-VCH
  • News

    Chemical hydrogen storage system

    Hydrogen is a highly attractive, but also highly explosive energy carrier, which requires safe, lightweight and cheap storage as well as transportation systems. Scientists at the Weizmann Institute of Science, Israel, have now developed a chemical storage system based on simple and abundant ... more

    For a Better Contrast

    Magnetic resonance imaging (MRI) has emerged as one of the most powerful clinical imaging tools because of its superb spatial resolution and soft tissue contrast, especially when using contrast agents. In the European Journal of Inorganic Chemistry, scientists have presented a new kind of n ... more

    A Successful Coupling

    Coupled oxygen transfer and electron transfer reactions that use cofactors are enzymatic reactions of crucial significance to all lifeforms from bacteria to vertebrates. In the European Journal of Inorganic Chemistry, scientists have introduced a model for the enzyme sulfite oxidase. It is ... more

  • Companies

    Wiley-VCH Verlag GmbH & Co. KGaA

    Wiley-VCH publishes monographs, textbooks, major references works and journals in print or online. Wiley-VCH can look back on over 80 years of publishing in chemistry, materials sciences, physics and the life sciences. more

More about Polish Academy of Sciences
  • News

    World's first video recording of a space-time crystal

    A German-Polish research team has succeeded in creating a micrometer-sized space-time crystal consisting of magnons at room temperature. With the help of the scanning transmission X-ray microscope MAXYMUS at Bessy II at Helmholtz Zentrum Berlin, they were able to film the recurring periodic ... more

    This computer program makes pharma patents airtight

    Routes to making life-saving medications and other pharmaceutical compounds are among the most carefully protected trade secrets in global industry. Building on recent work programming computers to identify synthetic pathways leading to pharmaceutically complex molecules, researchers in Pol ... more

    The most exotic fluid has an unexpectedly low viscosity

    Collisions of lead nuclei in the Large Hadron Collider (LHC) particle accelerator take place at such great energies that quarks that are normally confined inside nucleons are released and, together with the gluons that hold them together, form a stream of particularly exotic fluid: quark-gl ... more