Near-infrared absorbing dyes at 1064 nm: Soluble dithiolene nickel complexes with alkylated electron-donating, groups as Peripheral substituents

Soluble dithiolene nickel complexes are designed and synthesized as near-infrared (NIR) absorbing dyes through the introduction of strong electron-donating groups at the molecular periphery. The resulting complexes are characterized by H-1/C-13 NMR, IR, ESI-MS, UV-vis NIR, TG, DSC, XPS and elemental analysis. The identification results are in accord with the chemical structure of designed dithiolene nickel complexes. The XPS results suggested that the dithiolene ligands in carbazole-containing nickel complex take a radical monoanion, which depends on the substituent electron-donating ability to a large extent. The TG and DSC measurements indicated that the resulting complexes have an excellent thermal stability and take on a glassy state at low temperature. The laser transmittance measurement suggested that the optical filters fabricated through static solution-casting approach with dithiolene nickel complexes as NIR absorbing dyes could be well applied to the NIR laser protection at 1064 nm. (C) 2016 Elsevier Ltd. All rights reserved.