Room Temperature Liquid Porphyrins

Mar 23, 2010

(PhysOrg.com) -- 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 . 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 . 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 . 5,10,15,20-Tetrakis[3,4,5-tri(undecyloxy)phenyl]porphyrin and its decyloxy analogue are both observed to be liquids at 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.

Explore further: Incorporation of DOPA into engineered mussel glue proteins

More information: Daniel T. Gryko, Meso-Substituted Liquid Porphyrins, Chemistry—An Asian Journal 2010, 5, No. 4, dx.doi.org/10.1002/asia.200900693

Related Stories

New use found for tunneling microscope

Apr 23, 2007

Dutch researchers have found a new use for scanning tunneling microscopes: visualizing individual catalysts at work at a solid-liquid interface.

When liquid crystals with a metal center are 'shaking hands'

Mar 14, 2005

Without liquid crystals (LC's) our cell phones and notebook computers would not be possible, for these compounds keep our display screens flat and lightweight. Being a phase of matter whose order is intermediate between that ...

Recommended for you

Smartgels are thicker than water

3 hours ago

Transforming substances from liquids into gels plays an important role across many industries, including cosmetics, medicine, and energy. But the transformation process, called gelation, where manufacturers ...

Separation of para and ortho water

Sep 18, 2014

(Phys.org) —Not all water is equal—at least not at the molecular level. There are two versions of the water molecule, para and ortho water, in which the spin states of the hydrogen nuclei are different. ...

User comments : 0