Chiral Organic Dyes Endowed with Circularly Polarized Laser Emission

Abstract

The direct generation of efficient, tunable, and switchable circularly polarized laser emission (CPLE) would have far-reaching implications in photonics and material sciences. In this paper, we describe the first chiral simple organic molecules (SOMs) capable of simultaneously sustaining significant chemical robustness, high fluorescence quantum yields, and circularly polarized luminescence (CPL) ellipticity levels (|glum|) comparable to those of similar CPL-SOMs. All these parameters altogether enable efficient laser emission and CPLE with ellipticity levels 2 orders of magnitude stronger than the intrinsic CPL ones.

Circularly polarized laser emission in optically active organic dye solutions

“…With peak values of ±4 × 10 3 deg cm 2 dmol −1 , it is at least 50-fold weaker than that obtained for chiral BODIPYs. 28,36 Similarly, the CPL spectra for both solutions show a noisy signal that could overlap the fluorescence spectrum, but the results are inconclusive (Fig. 1c).…”

“…The very same DOP enhancement has been observed in a derivative of PM567 having a pendant dibromoBINOL group, whose rotational relaxation is slowed down due to its bulkier nature. 28 …”

“…In any case, the ellipticity of the CPLE is greatly enhanced with respect to those of ethyl acetate solutions of CPL-simple organic molecules. 28 …”

“…16,22 Whereas CPL has been obtained in simple organic molecules, 23 polymers, 3,24,25 and supramolecular assemblies, 26,27 only one CPL emitting system of many has been shown to lase so far, namely, a chiral dibromoBINOL-based substituted O -BODIPY. 28 Unfortunately, its CPL level – comparable to those of similar CPL-simple organic molecules – was far too low to generate a detectable intrinsic CPLE signal. Hence, there is still a need to find alternative strategies to generate CPLE.…”

Chiroptical behavior of BINOL-based spiranic <em>O</em>-BODIPYs. A study on the influence of the structural factors

“…Among the BODIPYs substituted at boron, those bearing a phenol-based bi(polyarene) unit tethered to the boron center through oxygen atoms constitute an interesting family of O-BODIPYs, useful for the development of photonic applications, such as structurally-simple EET molecular cassettes (arene-BODIPY dyads), as well as sources of circularly polarized light [16e,17b] including circularly polarized laser [18], field that has arisen as one of the most interesting and emerging topics dealing with BODIPYs [9,19]. This is due to three main factors: (1) synthetic accessibility leading to the development of low-cost dyes [17b,20], (2) tunable photonic properties by straightforward chemical transformations [20] and (3) chiral perturbation to the BODIPY chromophore, when a chiral polyarene is used [17b].…”