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 1 H/ 13 C 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.