Hash-Mark-Shaped Azaacene Tetramers with Axial Chirality

Abstract

The tetramers of azapentacene derivatives with unique hash mark (#)-shaped structures were prepared in a quite facile manner. The #-shaped tetramers are optically active due to possessing extended biaryl skeletons, and the structure of the tetramer composed of four dihydrodiazapentacene (DHDAP) units (1) was investigated as the first example of this kind of molecule. The tetramer 1 showed characteristic chiroptical properties reflecting its orthogonally arranged quadruple DHDAP moieties, as well as redox activity. The solution of enantiopure 1 exhibited intense circularly polarized luminescence (CPL) with a dissymmetry factor of 2.5 × 10. The absolute configuration of the enantiomers of 1 was experimentally determined by X-ray crystal analysis for the dication salt of the enantiomer of 1 with SbCl counterions. The solutions of enantiopure 1·2[SbCl] also showed NIR circular dichroism (CD) spectra over the entire range from visible to 1100 nm, enabling the modulation of the chiroptical properties by redox stimuli.

Amplified circularly polarized phosphorescence from co-assemblies of platinum(ii) complexes

“…Two strategies have been pursued for the development of molecular CPL emitters. One strategy is based on asymmetric coupling between excitons within a molecular dyad; for example, CPL can be obtained through the asymmetric Davydov splitting of fluorophores, such as perylene diimide,9,10 5,6-biscarbazolylphthalimide,11 terthiophene,12 pyrene,13 anthracene,14 and azaacene,15 in chiral arrangements. Exciton coupling is reinforced in aggregate states, leading to improvements in | g lum | 16.…”

Water-soluble chiral tetrazine derivatives: towards the application of circularly polarized luminescence from upper-excited states to photodynamic therapy

“…Although some papers report general fluorescence emission from S n states,1–6 circularly polarized luminescence (CPL) from S n states has not yet been developed. Interest in CPL has grown in recent years, especially because of its utilization as a source of information about the chiral structures of emitting excited states, as well as its potential for smart photonic applications such as 3D displays and information storage 10–15. In particular, the development of CPL from S n states may increase the number of potential applications of chiral materials.…”

Of Twists and Curves: Electronics, Photophysics, and Upcoming Applications of Non‐Planar Conjugated Organic Molecules

“…The enantiomerically pure 28 showed strong CPL in both neutral ( g lum =0.009) and acidic ( g lum =0.008) conditions with high racemization barrier. Recently, enantiopure hash‐shaped aza‐acene tetramers 29 exhibited CPL with g lum value of 2.5×10 −3 at 442 nm in DCM (Figure d) …”