Infrared dyes dithiolenes

A few years after these events, a review article by McCleverty4 in 1968 provided (in over 170 pages) the first thorough overview of this field. This review contains a multitude of details which still merits its mention as a valuable source of information on this class of compounds. Several other reviews dealing with different aspects of dithiolene chemistry have appeared in the meantime.5"11 The field has expanded in different directions, spurred by the synthesis of several structurally unique compounds and of materials of particular use in quite diverse areas such as highly conducting molecular crystals and as infrared dyes for various applications. Dithiolenes thus represent a class of materials which are not only of significance on their own, but which also find some applications in which their unique electronic properties can be employed. 

The Liquid Crystal Point Diffraction Interferometer (LCPDI) can be employed to evaluate the Omega Laser system for optimum firing capabilities. This device utilizes a nickel dithiolene infmred absorbing liquid crystal dye dissofved in a liquid crystal host medium (Merck E7). Three nickel dithiolene dyes were characterizedfior both their solubility in the E7 host and their infrared spectral absorption. 

Previous work has shown the nickel dithiolene dye as a desirable candidate for the LCPDl. The nickel dithiolene has a unique aromatic ring structure, which imparts a relatively high infrared absorption and a high thermal and photochemical stability. With 2 alkoxyphenyl substitutions onto the nickel dithiolene core, these complexes possess optical absorbance bands at the desirable wavelength of the laser. However, these alkoxyphenyl substituted compounds have demonstrated limited solubility in the host liquid crystal medium. The potential of an alkyl-phenyl substituents to increase the solubility of the dithiolene dye in the host liquid crystal medium was the primary topic of this investigation. 

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