Reusable deep eutectic solvents for efficient metal-free synthesis of soluble phthalocyanines

In this study, we report a highly efficient and sustainable protocol for the synthesis of soluble metal-free phthalocyanine ( tBu 4 PcH 2 ) using deep eutectic solvents (DESs). A series of DESs prepared from various combinations of hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs), was systematically evaluated as reaction media. Among the investigated DESs, glycine: sorbitol (Gly:sor, 1:3) and tetraethylammonium bromide: sorbitol ([N 2224 ][Br]:sor, 1:2) identified as the most effective systems, affording tBu 4 PcH 2 in high yields of 68% and 62%, respectively, significantly outperforming conventional ionic liquids media such as [C 2-OH m 2 im][Br] (38%). Notably, the [N 2224 ][Br]:sor system exhibited excellent reusability, maintaining its catalytic activity and yield for at least three consecutive cycles. This enhanced recyclability, combined with a straightforward recovery procedure that avoids severe foaming, offers a distinct advantage over conventional media, demonstrating the potential of the present DES architecture for practical and sustainable operations.