A series of near infrared (NIR) absorbing dinuclear ruthenium dicarbonylhydrazine complexes (DCH-Ru)

[{Ru(bpy)2)2μ-DCH]n+ (where bpy = 2

2'-bipyridinc and n = 2

3 or 4)

were prepared. The DCH-Ru complexes areelectrochromic in the NIR region with a high absorption coefficient at 1550-1600 nm typically over 10000 M-1cm-1. DCH-Ru complex polymers with good NIR electrochromic properties were also obtained and processed to make a device foroptical attenuation at a wavelength of 1550 nm. The potential of these DCH-Ru polymers for use in a variable optical attenuator has been demonstrated with an attenuating power at the 1550-nm telecommunication wavelength over 7.0 dB per micron of polymer film thickness.Other classes of NIR active materials are the pentacenediquinones and the corresponding poly(ether pentacenediquinone)s.These polymers can be electrochemically reduced to the corresponding semiquinone (radical anion )having NIR absorption within a telecom window(e.g.

1310 nm).