Molecule of the Month
Discovery and History
The word phthalocyanine - from the Greek for naphtha (rock oil) and cyanine (blue) was first used
by Linstead in 1933 to describe a new class of
organic compounds. Phthalocyanine itself was probably discovered by accident in 1907, as a by-product
during the synthesis of o-cyanobenzamide, but it was not until almost 20 years later that a patent
was filed describing a manufacturing process. The extensive chemical studies by Linstead et al were
followed by structural studies by J Monteath Robertson at the Royal Institution and Glasgow - the
first crystal structures of relatively large organic molecules. Studies of semiconductivity and gas adsorption effects followed
soon after in Nottingham.
Properties and Uses
Phthalocyanine has been widely exploited in industry and academia, in a variety of applications ranging from
conventional dye stuffs to catalysis, coatings for read/write CD-ROM's and as an anti-cancer agent. The majority
of applications use the metal-substituted form of the molecule - a process which has been applied to every
group in the periodic table - for example the Royal Mint use the popular copper-substituted variety as a blue dye
in 5 pound notes.
Rewriteable Optical Media
This is an increasingly important topic in the information storage industry - read/write cd-rom technology at low cost has obvious implications for the computer, education and communications
Many types of chemical sensor based on phthalocyanines have been proposed - including thin film resistive devices, FET sensors and Langmuir-Blodgett films.
The fluoraluminium phthalocyanine has been extensively studied for potential use as a target molecule in anti-cancer treatment.
Alan Wilson February 1996