Synthesis of a nickel bis(dithiolene) complex with strong near-infrared two-photon absorption

The diketones 4,4'-di[3,4-bis(n-dodecyloxy)styryl]benzil and 4,4'-di[3,4-bis(n-dodecyloxy)phenylethynyl]benzil have been synthesized from 4,4'-dibromobenzil using Heck coupling with the appropriate styrene and Sonogashira coupling with the appropriate phenylalkyne, respectively. Treatment of the distyrylbenzil derivative with phosphorus pentasulfide followed by nickel(II) chloride gave the corresponding extended nickel bis(dithiolene) derivative which shows strong near-infrared two-photon absorption with a cross-section of over 440 GM (1 GM = 10(-50) cm(4) S photon(-1) molecule(-1)) throughout the telecommunications range and a peak cross-section of 5300 GM at ca. 1.2 mu m.