Meso-tetrakis{4-[2-(trimethylsilyl)ethynyl]phenyl}porphyrin [TPP(4-CCTMS)_H2] and its complexes with metals Zn(II), Ni(II), Ga(III), In(III) and Sn(IV) were synthesized and characterized. Their optical limiting properties were determined under the irradiation of a 532 nm/5 ns pulse laser at the repetition rate of 20 Hz. The optical limiting performance of the zinc derivative, Zn(II)-meso-tetrakis{4-[2-(trimethylsilyl)ethynyl]phenyl}porphyrin, [TPP(4-CCTMS)_Zn], is better than that of its analogues, Zn(II)-meso-tetraphenylporphyrin, [TPP_Zn], and Zn(II)-meso-tetratolyl-porphyrin, [TTP_Zn], indicating that optical limiting property can be improved via fine molecular modification on the para-position of the meso-phenyl rings. In this way, the Soret band of the porphyrin is not red-shifted thereby high photopic transmission of the samples can be maintained. The optical limiting performance can be further enhanced via insertion of closed-shell metal ions. Particularly, In(III)Cl-meso-tetrakis{4-[2-(trimethylsilyl)ethynyl]phenyl}porphyrin, [TPP(4-CCTMS)_InCl], exhibited optical limiting behavior better than C60 and comparable to the state-of-the-art phthalocyanine dye, Chloro-(tetra-(tert-butyl)phthalocyanato)indium (III), [Pc(t-Bu)_InCl]. Furthermore, the samples with photopic transmissions as high as 75% were tested under the same laser setup and [TPP(4-CCTMS)_InCl] again demonstrated its efficient optical limiting, which is comparable to that of C60 and much better than that of [Pc(t-Bu)_InCl].
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