Optical limiting properties of 3,5-dipyrenylvinyleneBODIPY dyes at 532nm

Gugu Kubheka; Kayode Sanusi; John Mack; Tebello Nyokong

doi:10.1016/j.saa.2017.10.021

Optical limiting properties of 3,5-dipyrenylvinyleneBODIPY dyes at 532nm

Spectrochim Acta A Mol Biomol Spectrosc. 2018 Feb 15:191:357-364. doi: 10.1016/j.saa.2017.10.021. Epub 2017 Oct 10.

Authors

Gugu Kubheka¹, Kayode Sanusi¹, John Mack², Tebello Nyokong¹

Affiliations

¹ Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa.
² Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa. Electronic address: j.mack@ru.ac.za.

PMID: 29055280
DOI: 10.1016/j.saa.2017.10.021

Abstract

The optical limiting (OL) properties of 3,5-dipyrenylvinyleneBODIPY dyes that contain both electron withdrawing and donating moieties have been investigated by using the z-scan technique at 532nm in the nanosecond pulse range. The extension of the π-conjugation at the 3,5-positions with pyrenylvinylene groups results in a ca. 200nm red shift of the main BODIPY spectral band to ca. 700nm, so there is relatively weak absorbance at 532nm under ambient light conditions. Reverse saturable absorbance (RSA) profiles are observed in response to incident pulsed laser light that is consistent with a two photon absorption-assisted excited state absorption (ESA) mechanism in CH₂Cl₂ solution and when the dyes are embedded in poly(bisphenol carbonate A) (PBC) polymer thin films. This demonstrates that 3,5-divinyleneBODIPY dyes are potentially suitable for use in OL applications, since limiting threshold fluence (I_lim) values of below 0.95Jcm^-2 are observed when thin films are prepared.

Keywords: BODIPY dyes; Knoevenagel condensation; Optical limiting; Z-scan.