"Alkyl-Substituted Phenoxy" Spacer Strategy: Antiaggregated and Highly Soluble Zinc Phthalocyanines for Color Films

A series of zinc phthalocyanine derivatives (ZnPcs) were designed by introducing different volumes of steric hindrance groups (chlorine atom, n-propyloxy, isopropyloxy, n-butoxy, isobutoxy, tert-butoxy, 2,4-di-tert-butylphenoxy, 2,4-di-tert-pentylphenoxy) on the peripheral and nonperipheral positions of phthalocyanine. Density functional theory (DFT) calculations presented that the substitution of sterically hindered 2,4-di-tert-butylphenoxy or 2,4-di-tert-pentylphenoxy on the peripheral positions effectively reduced the aggregation of ZnPcs, improving the solubility of ZnPcs, and the simultaneous substitution on the peripheral and nonperipheral positions could achieve ZnPcs with different colors. From the calculation results, six low-aggregation ZnPcs were synthesized for the first time. The solubilities of the synthesized ZnPcs are above 6.0/100 g. Furthermore, their color films displayed excellent transmittance because of the introduction of sterically hindered 2,4-di-tert-butoxyphenoxy or 2,4-di-tert-pentylphenoxy moieties. Also, the color films exhibit great photo and thermal stability (ΔE < 3).