Chiral Microneedles from an Achiral Bis(boron dipyrromethene): Spontaneous Mirror Symmetry Breaking Leading to a Promising Photoluminescent Organic Material

Abstract

Supramolecular self-assembly of a highly flexible and achiral meso bis(BODIPY) dye straightforwardly yields fluorescent microfibers exhibiting an intriguing anisotropic photonic behavior. This performance includes the generation of chiroptical activity by means of spontaneous mirror symmetry breaking (SMSB). Repetition of a number of self-assembly experiments demonstrates that the involved SMSB is not stochastic but quasi deterministic in the direction of the induced chiral asymmetry. The origin of these intriguing (chiro)photonic properties is revealed by fluorescent microspectroscopy studies of individual micrometric objects, combined with X-ray diffraction elucidation of microcrystals. Such a study demonstrates that J-like excitonic coupling between bis(BODIPY) units plays a fundamental role in their supramolecular organization, leading to axial chirality. Interestingly, the photonic behavior of the obtained fibers is ruled by inherent non-radiative pathways from the involved push-pull chromophores, and mainly by the complex excitonic interactions induced by their anisotropic supramolecular organization.

Wood‐Derived Carbon Materials and Light‐Emitting Materials

“…Since then, a number of studies investigating the fascinating properties of CDs have been carried out. [ 70–72 ] Compared with semiconductor quantum dots, [ 73,74 ] upconversion nanoparticles, [ 75,76 ] and organic dyes, [ 77,78 ] photoluminescent CDs prepared from wood‐derived biomass show many advantages, including sustainability, easy preparation, and favorable optical properties. [ 79 ] Additionally, compared to other biomass materials, wood‐derived polysaccharide was easy carbonized and fluorescent carbon dots can be easily prepared via low temperature hydrothermal carbonization method.…”

Tuning CPL by helical pitch modulation in helically flexible small organic multichromophores

“…In this scenario, we envisaged that helically flexible bis(haloBODIPY) 1 (Fig. 1), as the background scaffold of an easily accessible and interesting family of CPL-SOMs developed by us, 26,[28][29][30] could serve to shed light on the possible influence of the helical pitch on the CPL signatures of helically flexible CPL-SOMs. Thus, the helical pitch of 1 should be easily modulated by simply playing with steric factors around the flexible spacer connecting the involved equal BODIPY chromophores (see the central ethane-1,2-diamine bridge in 1 in Fig.…”