ABSTRACT Phosphorus‐containing functional materials have diverse applications in optoelectronics and bioscience owing to their unique properties. However, polycyclic π‐conjugated phosphonium salts have been rarely explored due to their complex synthesis. In this work, a facile and efficient method for constructing polycyclic π‐conjugated phosphonium salts (TBPIMe derivatives) is proposed, based on the photocyclization of phosphindolium salts (TPPIMe derivatives). Systematic experimental and theoretical investigations reveal the changed photophysical and photochemical properties when TPPIMe derivatives are converted to TBPIMe derivatives. Notably, the novel polycyclic π‐conjugated phosphonium salt p ‐MOTBPIMe exhibits improved reactive oxygen species generation ability and much stronger specific affinity toward DNA than phosphindolium salts p ‐MOTPPIMe. Moreover, in vitro experiments demonstrate that p ‐MOTPPIMe can also be efficiently converted into p ‐MOTBPIMe under 405 nm laser irradiation in living cells, accompanied by the migration from cytoplasm to nucleus to enhance the photodynamic effect. Additionally, p ‐MOTBPIMe shows superior antibacterial activity against not only Gram‐positive drug‐resistant bacteria but also fungi, by leveraging both dark and light cytotoxicity. This work opens up a new chemical toolkit for novel polycyclic π‐conjugated phosphonium salts, which are promising for developing advanced theranostic agents with satisfactory accuracy and efficacy.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Abstract Organic materials with switchable dual circularly polarized luminescence (CPL) are highly desired because they can not only directly radiate tunable circularly polarized light themselves but also induce CPL for guests by providing a chiral environment in self‐assembled structures or serving as the hosts for energy transfer systems. However, most organic molecules only exhibit single CPL and it remains challenging to develop organic molecules with dual CPL. Herein, novel through‐space conjugated chiral foldamers are constructed by attaching two biphenyl arms to the 9,10‐positions of phenanthrene, and switchable dual CPL with opposite signs at different emission wavelengths are successfully realized in the foldamers containing high‐polarizability substitutes (cyano, methylthiol and methylsulfonyl). The combined experimental and computational results demonstrate that the intramolecular through‐space conjugation has significant contributions to stabilizing the folded conformations. Upon photoexcitation in high‐polar solvents, strong interactions between the biphenyl arms substituted with cyano, methylthio or methylsulfonyl and the polar environment induce conformation transformation for the foldamers, resulting in two transformable secondary structures of opposite chirality, accounting for the dual CPL with opposite signs. These findings highlight the important influence of the secondary structures on the chiroptical property of the foldamers and pave a new avenue towards efficient and tunable dual CPL materials.
Abstract Organic materials with switchable dual circularly polarized luminescence (CPL) are highly desired because they can not only directly radiate tunable circularly polarized light themselves but also induce CPL for guests by providing a chiral environment in self‐assembled structures or serving as the hosts for energy transfer systems. However, most organic molecules only exhibit single CPL and it remains challenging to develop organic molecules with dual CPL. Herein, novel through‐space conjugated chiral foldamers are constructed by attaching two biphenyl arms to the 9,10‐positions of phenanthrene, and switchable dual CPL with opposite signs at different emission wavelengths are successfully realized in the foldamers containing high‐polarizability substitutes (cyano, methylthiol and methylsulfonyl). The combined experimental and computational results demonstrate that the intramolecular through‐space conjugation has significant contributions to stabilizing the folded conformations. Upon photoexcitation in high‐polar solvents, strong interactions between the biphenyl arms substituted with cyano, methylthio or methylsulfonyl and the polar environment induce conformation transformation for the foldamers, resulting in two transformable secondary structures of opposite chirality, accounting for the dual CPL with opposite signs. These findings highlight the important influence of the secondary structures on the chiroptical property of the foldamers and pave a new avenue towards efficient and tunable dual CPL materials.
Yellow, orange to red iridium(iii) complexes bearing oxadiazol-substituted amide ancillary ligand have been synthesized and their electroluminescent properties were investigated.
Developing long-chain molecules with stable helical structures is of significant importance for understanding and modulating the properties and functions of helical biological macromolecules, but challenging. In this work, an effective and facile approach to stabilize folded helical structures by strengthening through-space conjugation is proposed, using new ortho-hexaphenylene (o-HP) derivatives as models. The structure-activity relationship between the through-space conjugation and charge-transport behavior of the prepared folded helical o-HP derivatives is experimentally and theoretically investigated. It is demonstrated that the through-space conjugation within o-HP derivatives can be strengthened by introducing electron-withdrawing pyridine and pyrazine rings, which can effectively stabilize the helical structures of o-HP derivatives. Moreover, scanning tunneling microscopy-break junction measurements reveal that the stable regular helical structures of o-HP derivatives open-up dominant through-space charge-transport pathways, and the single-molecule conductance is enhanced by more than 70 % by strengthening through-space conjugation with pyridine and pyrazine. However, the through-bond charge transport pathways contribute much less to the conductance of o-HP derivatives. These results not only provide a new method for exploring stable helical molecules, but also provide a stepping stone for deciphering and modulating the charge-transport behavior of helical systems at the single-molecule level.
ABSTRACT Control of the dissymmetry of circularly polarized luminescence (CPL) is intriguing and has great potential for applications in the field of optics. The traditional control strategy involves using the opposite enantiomers to achieve reversal of CPL signs. However, regulating CPL reversal by controlling only the transition dipole moments without changing molecular or supramolecular chirality remains a challenge. Herein, we developed a couple of crystal materials based on axially chiral aggregation‐induced emission luminogens (AIEgens). These materials exhibit achiral solvent‐induced CPL sign inversion with identical helical structures and molecular chirality in their crystalline states. ( R )‐BPAuCz T displays (+)‐CPL with a dissymmetry factor of luminescence ( g lum ) value of +9.81 × 10 −4 (560 nm), while ( R )‐BPAuCz C exhibits (−)‐CPL with a g lum value of −1.02 × 10 −3 (560 nm). Time‐dependent density functional theory calculations show that the magnetic and electric transition dipole moments at S 1 → S 0 of the ( R )‐BPAuCz C unit cell are considerably influenced by the cocrystallized solvent molecules, revealing a solvent‐induced CPL inversion mechanism. The nonbonding interactions between the solvent molecules (i.e., tetrahydrofuran or CDCl 3 ) and AIEgens in the crystal play a crucial role in the manipulation of the transition dipole moment of these crystal materials. Moreover, microrods of ( R )‐BPAuCz T , ( R )‐BPAuCz C , and ( R )‐BPAuCz DCE exhibit optical waveguide properties with relatively low optical‐loss coefficients of 187.3, 567.4, and 65.2 dB/cm, respectively. These findings can help in developing a new strategy toward controlling CPL signals and providing a potential application for future integrated photonic circuits.
Multi-resonance (MR) materials hold an intriguing feature of narrow emission spectra and have attracted considerable attention in the manufacture of high-definition organic light-emitting diodes (OLEDs). However, the majority of MR materials are composed by a boron-nitrogen skeleton, which is unfavorable for expanding the scope of luminescent materials with narrow emission spectra to meet various application demands. In this work, we wish to report a new carbonyl-nitrogen (C = O/N) skeleton of 5,12-dihydroquinolino[2,3-b]acridine-7,14-dione (QA), and three tailored C = O/N MR molecules are synthesized and fully characterized by crystallography, thermal measurement, cyclic voltammetry, steady-state and transient spectroscopy and theoretical calculation. They show efficient green emissions with narrow full width at half maximum (FWHM) of about 27 nm and high photoluminescence quantum yields of up to 93% in doped films. Efficient hyperfluorescence OLEDs are fabricated using these materials as emitters, providing pure green lights with electroluminescence peaks at 526‒538 nm, narrow FWHMs of 29‒33 nm, excellent external quantum efficiencies of up to 29.48% and small efficiency roll-offs. These results reveal that QA could be a potential skeleton for exploring efficient C = O/N MR molecules. Multi-resonance materials possess narrow emission spectra, desirable for high-definition organic light-emitting diodes, but most are based on a boron-nitrogen skeleton, providing limited opportunities to expand the scope of these materials. Here, the authors report carbonyl-nitrogen skeleton 5,12-dihydroquinolino[2,3-b]acridine-7,14-dione and develop three multi-resonance materials with efficient green emissions and high photoluminescence quantum yields, and further demonstrate their promise through the fabrication of efficient hyperfluorescence OLEDs.
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