Design and synthesis of perfluoroalkyl decorated BODIPY dye for random laser action in a microfluidic device

Abstract

New and highly emissive 2,6-diacetynyl and 2,6-bis-(phenylacetynyl) functionalized pentamethyldifluoroboron-dipyrromethane (BODIPY) derivatives (FBDP1–2) with perfluorinated pendant groups at the boron center have been synthesized successfully by the combination of two strategies: extending the π-conjugation and functionalization at the boron centre. The newly synthesized dyes have been characterized unambiguously by using various analytical tools such as multinuclear NMR, MALDI-TOF, and single crystal XRD analysis. The dyes (FBDP1–2) exhibit excellent photophysical properties in the yellow to red spectral region (λ_abs = 530 nm and 555 nm, and λ_em = 555 nm and 596 nm, respectively) with relatively good Stokes shifts (849 cm⁻¹ and 1240 cm⁻¹), high quantum efficiency (ϕ_F = 0.72 and 0.61) and excellent brightness (2.95 × 10⁴ and 2.38 × 10⁴ M⁻¹ cm⁻¹). Most importantly, under a transverse pumping condition at 532 nm, the dyes show efficient and stable laser action, having a good tunable range (20 nm and 13 nm) with a maximum lasing efficiency of 45% and 38% for FBDP1 and FBDP2, respectively. Moreover, the random lasing behavior of FBDP1 has been investigated in a dye-circulated polydimethylsiloxane (PDMS) based disordered microfluidic device. The appearance of randomly positioned sharp spikes with a full width at half maximum (FWHM) of less than 0.3 nm around 555 nm indicates the random laser (RL) emission. The relationship between input pump energy and output random lasing intensity has also been demonstrated, with the random lasing threshold of 0.5 mJ.