Synthesis and NIR Absorption Properties of Triethylene Glycol Substituted Metallo-Naphthalocyanines

Abstract

Naphthalonitrile substituted with triethylene glycol (TEG) in the presence of transition metals synthesized a series of metallo-naphthalocyanine derivatives (MNPcs), and it was investigated that the optical and near-infrared (NIR) absorption properties. In UV-Vis spectra measurements, these MNPcs exhibited strong absorption in the NIR regions because of the annulated benzene ring of naphthalocyanine and highly electron-donating substituents attached at the nonperipheral positions. The absorption wavelength of MNPcs was effectively adjusted in NIR ranges from 780 to 950 nm by inserting various central metals. Additionally, the presence of TEG-substituents in MNPcs significantly enhanced the solubility in highly polar solvents and the compatibility with the polymer matrix. NIR blocking films were fabricated for taking advantage of high NIR absorption and visible transmittance. When NIR film was fabricated with nickel-napthalocyanine, it was confirmed that the NIR cutting property can be improved while maintaining the visible light transmittance compared to the antimony tin oxide (ATO). From the observations, the feasibility of designed MNPcs as an effective NIR blocking material was evidenced, which is attributed to its strong NIR absorption and compatibility in the polar mediums.