Photonic properties of star shaped ferrocenyl substituted triazines

• We report C3-Symmetric ferrocenyl substituted triazines 1–4 as an optical limiter.
• The nonlinear optical (NLO) result reveals that triazine 4 with lower HOMO-LUMO gap shows good optical limiting.
• The mode of attachment of ferrocene (donor) with the triazine (acceptor) is important for NLO response.

We report the linear and nonlinear optical properties of the star shaped ferrocenyl substituted thiophene triazines 1–4. The red shift in π→π* absorption and enhancement in molar extinction coefficient (ε) in triazines 1–4 were found to be directly proportional to the conjugation length, whereas the HOMO-LUMO gap in triazines 1–4 were found to be inversely proportional to the conjugation length. The time dependent density functional theory (TD-DFT) at CAM-B3LYP and B3LYP calculations on triazines 1–4 were performed, in which TD-DFT/CAM-B3LYP results show good agreement with the experimental results. The nonlinear optical properties of triazines 1–4 were studied under femtosecond laser pulse excitation at 800 nm using the Z-scan technique. Large two-photon absorption coefficient value (1.8 × 10−13 m/W) was obtained for highly conjugated triazine 4. These triazines can serve as on optical limiter toward, high intensity short pulses.

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