Circularly Polarized Luminescence and Circular Dichroism of Bichromophoric Difluoroboron‐β‐diketonates: Inversion and Enhanced Chirality Based on Spatial Arrangements and Self‐Assembly

Abstract

We synthesized two bichromophoric difluoroboron‐β‐diketonates (DFB) connected in para and meta positions by using cyclohexane diamine as a chiral bridge (para and meta (R/S)‐CyDFB). TD‐DFT calculations revealed that the variation in connectivity of the DFB units leads to different spatial arrangements and a chirality inversion of the bichromophoric DFB. Higher gabs values were obtained in (R/S)‐CyDFB connected in para as compared to meta position. Aggregation of para (R/S)‐CyDFB in mixture of solvents increase the glum values as compared to its monomeric form. Ultrasonication and heating induced the formation of highly ordered nano‐helical wires of para (R/S)‐CyDFB that increased the glum values to 0.015. On the other hand, meta (R/S)‐CyDFB failed to form highly ordered self‐assembled wires due to hindered H‐binding sites. These observations indicate that the chiroptical properties of DFB bi‐chromophore system can be modulated with self‐assembly and spatial arrangement of the chromophores.

Clear Disclosure of Hierarchical Chirality Transfer Mechanism and Wide Full‐Color and White‐Light CPL Emissions with Both High glum and Intensity by TPE Helicates

“…[8][9][10] For boosting the CPL g lum values of chiral fluorophores, chirality transfer and amplification are frequently exploited. [10][11][12][13][14] For example, chiral additives have been doped into achiral liquid crystals (LC) to induce chirality of LC [15] and significantly enhance the CPL signals [16] by chirality transfer from the chiral dopant to LC. The chiral dopants generally possess central and axial chirality, and contain some group such as long alkyl chains that are similar to those of LC molecule for increasing miscibility.…”

C3‐Symmetric Luminescent Diketone with Amido‐Linkage as a Polymorphic Fluorescence Emitter

“…The compound was deposited on a glass plate (see details about surface treatment of glass in supporting information). Fluorescence decay curves were obtained by the time‐correlated single‐photon counting (TCSPC) method [32] . Sample for FESEM imaging was prepared by drop casting 10 μL of aggregated samples into a copper grid coated with a thin layer of carbon for adhesion.…”

“…Fluorescence decay curves were obtained by the time-correlated single-photon counting (TCSPC) method. [32] Sample for FESEM imaging was prepared by drop casting 10 μL of aggregated samples into a copper grid coated with a thin layer of carbon for adhesion. The grids were dried under a vacuum overnight to remove all the residual solvents prior to imaging.…”

“…These are versatile compounds known for their chelating properties and play a fundamental role as basic building blocks in pharmaceutical chemistry [28,29] . We have also reported on the photophysical and luminescence properties of various diketone derivatives and coordination substances, as well as their self‐assembling properties [30–32] . Significant interchromophore interactions influence their fluorescence behavior and encouraged one to explore C 2 ‐symmetric dimeric derivatives [33] .…”

From 0 toN: circularly polarized luminescence generation from achiral luminophores in fibrous morphologies

“…Because of the higher g lum , the helical organization of luminescent molecules in onedimensional fibrous morphology is superior for CPL generation over those in spheroidal or planar structures. [19][20][21][22] The length of fibers (that is, the aspect ratio of the fiber) is responsible for g lum , where the longer fibers produce a higher anisotropic factor. 23,24 The arrangement of fibers is another factor that contributes to the properties of CPL and the development of new types of chiral materials for practical applications.…”