Enhanced optical limiting performance of substituted metallo-naphthalocyanines with wide optical limiting window

• Octa-(4-tert-butylphenoxy) substituted Ga and In naphthalocyanines were synthesized.
• Optical limiting properties of the naphthalocyanines were investigated with 532 nm laser.
• The metal naphthalocyanines might be potential optical limiting materials for practical applications.

Octa-(4-tert-butylphenoxy) substituted naphthalocyanines coordinated with different central metals (Ga, In) were synthesized and their photophysical and optical limiting properties were investigated. The naphthalocyanines substituted peripherally with bulky groups have good solubility in organic solvents and the Q band absorption shows an obvious red shift to the near-IR region at about 800 nm. Studies on transient absorption spectra, photophysical parameters and optical limiting properties indicate that these compounds exhibit good optical limiting performance. The optical limiting thresholds of the naphthalocyanines are 0.26, 0.15 J cm−2 for Gallium naphthalocyanines and Indium naphthalocyanines, respectively. The naphthalocyanines possess higher triplet state quantum yields (ФT) and triplet-minus-ground state extinction coefficients (ΔεT) than other simple phthalocyanines, which results in better optical limiting behaviour.