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Herein we report on circularly polarized luminescence (CPL) emission originating from supramolecular chirality of organic microcrystals with a |glum| value up to 0.11. The microcrystals were prepared from highly emissive difluoroboron β-diketonate (BF2dbk) dyes R-1 or S-1 with chiral binaphthol (BINOL) skeletons. R-1 and S-1 exhibit undetectable CPL signals in solution but manifest intense CPL emission in their chiral microcrystals. The chiral superstructures induced by BINOL skeletons were confirmed by XRD analysis. Spectral analysis and theoretical calculations indicate that intermolecular electronic coupling, mediated by the asymmetric stacking in the chiral superstructures, effectively alters excited-state electronic structures and facilitates electron transitions perpendicular to BF2bdk planes. The coupling increases cosθµ,m from 0.05 (monomer) to 0.86 (tetramer) and triggers intense optical activity of BF2bdk. The results demonstrate that optical activity of chromophores within assemblies can be regulated by both orientation and extent of intermolecular electronic couplings., (© 2024 Wiley‐VCH GmbH.)

We herein present an approach of photo-induced disproportionation for preparation of Type-I photodynamic agents. As a proof of concept, BODIPY-based photosensitizers were rationally designed and prepared. The photo-induced intermolecular electron transfer between homotypic chromophores leads to the disproportionation reaction, resulting in the formation of charged intermediates, cationic and anionic radicals. The cationic radicals efficiently oxidize the cellularimportant coenzyme, tetrahydrobiopterin (BH 4 ), and the anionic radicals transfer electrons to oxygen to produce superoxide radicals (O 2 - ⋅). One of our Type-I photodynamic agents not only self-assembles in water but also effectively targets the endoplasmic reticulum. It displayed excellent photocytotoxicity even in highly hypoxic environments (2 % O 2 ), with a half-maximal inhibitory concentration (IC 50 ) of 0.96 μM, and demonstrated outstanding antitumor efficacy in murine models bearing HeLa tumors., (© 2024 Wiley-VCH GmbH.)

Chirality, with its intrinsic symmetry-breaking feature, is frequently utilized in the creation of acentric crystalline functional materials that exhibit intriguing optoelectronic properties. On the other hand, the development of chiral crystals from achiral molecules offers a solution that bypasses the need for enantiopure motifs, presenting a promising alternative and thereby expanding the possibilities of the self-assembly toolkit. Nevertheless, the rational design of achiral molecules that prefer spontaneous symmetry breaking during crystallization has so far been obscure. In this study, we present a series of six achiral molecules, demonstrating that when these conformationally flexible molecules adopt a cis-conformation and engage in multiple non-covalent interactions along a helical path, they collectively self-assemble into chiral superstructures consisting of single-handed supramolecular columns. When these homochiral supramolecular columns align in parallel, they form polar crystals that exhibit intense luminescence upon grinding or scraping. We therefore demonstrate our molecular design strategy could significantly increase the likelihood of symmetry breaking in achiral molecular synthons during self-assembly, offering a facile access to novel chiral crystalline materials with unique optoelectronic properties., (© 2024 Wiley-VCH GmbH.)

It is a challenge to design photosensitizers to balance between the tumor-targeting enrichment for precise treatment and efficient clearance within a reasonable timescale for reducing side effects. Herein, an ultra-small nano-photosensitizer 1a with excellent tumor-specific accumulation and renal clearance is reported. It is formed from the self-assembly of compound 1 bearing three triethylene glycol (TEG) arms and two pyridinium groups in water. The positively charged surface with neutral TEG coating enables 1a to efficiently target the tumor, with the signal-to-background ratio reaching as high as 11.5 after tail intravenous injection. The ultra-small size of 1a with an average diameter of 5.6 nm allows its fast clearance through kidney. Self-assembly also endows 1a with an 18.2-fold enhancement of reactive oxygygen species generation rate compared to compound 1 in organic solution. Nano-PS 1a manifests an excellent photodynamic therapy efficacy on tumor-bearing mouse models. This work provides a promising design strategy of photosensitizers with renal clearable and tumor-targeting ability., (© 2023 Wiley-VCH GmbH.)

Without external chiral intervention, it is a challenge to form homochirality from achiral molecules with conformational flexibility. We here report on a rational strategy that uses multivalent noncovalent interactions to clamp the molecular conformations of achiral D-A molecules. These interactions overcome the otherwise dominant dipole-dipole interactions and thus disfavor their symmetric antiparallel stacking. It in turn facilitates parallel packing, leading to spontaneous symmetry breaking during crystallization and thus the formation of homochiral conglomerates. When this emergent homochirality is coupled with optical gain characteristics of the molecules, the homochiral crystals are explored as excellent circularly polarized micro-lasers with low lasing threshold (16.4 μJ cm -2 ) and high dissymmetry factor g lum (0.9). This study therefore provides a facile design strategy for supramolecular chiral materials and active laser ones without the necessity of intrinsic chiral element., (© 2022 Wiley-VCH GmbH.)

Developing Type-I photosensitizers is considered as an efficient approach to overcome the deficiency of traditional photodynamic therapy (PDT) for hypoxic tumors. However, it remains a challenge to design photosensitizers for generating reactive oxygen species by the Type-I process. Herein, we report a series of α,β-linked BODIPY dimers and a trimer that exclusively generate superoxide radical (O 2 -. ) by the Type-I process upon light irradiation. The triplet formation originates from an effective excited-state relaxation from the initially populated singlet (S 1 ) to triplet (T 1 ) states via an intermediate triplet (T 2 ) state. The low reduction potential and ultralong lifetime of the T 1 state facilitate the efficient generation of O 2 -. by inter-molecular charge transfer to molecular oxygen. The energy gap of T 1 -S 0 is smaller than that between 3 O 2 and 1 O 2 thereby precluding the generation of singlet oxygen by the Type-II process. The trimer exhibits superior PDT performance under the hypoxic environment., (© 2021 Wiley-VCH GmbH.)

An organic crystal of 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (pCBP) exhibits time-dependent afterglow color from blue to orange over 1 s. Both experimental and computational data confirm that the color evolution results from well-separated, long-persistent thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) with different but comparable decay rates. TADF is enabled by a small S 1 -T 1 energy gap of 0.7 kcal mol -1 . The good separation of TADF and RTP is due to a 11.8 kcal mol -1 difference in the S 0 energies of the S 1 and T 1 structures, indicating that apart from the excited-state properties, tuning the ground state is also important for luminescence properties. This afterglow color evolution of pCBP allows its applications in anticounterfeiting and data encryption with high security levels., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first example of the synthesis of mono-N,O-B-chelated dipyrromethene (BODIPY) derivatives through an unexpected intramolecular nucleophilic displacement of the fluorine by alkenols in the presence of boron trifluoride as Lewis acid is reported. The chlorine in the indacene core allowed for further structural modifications through nucleophilic substitutions or palladium-catalysed coupling reactions to afford new fluorophores with tuneable photophysical properties. Their expanded conjugation structure resulted in distinct red-shifted absorption and emission spectra in organic solutions. Furthermore, the twisted steric hindrance of the benzene substitution patterns suppressed aggregation-induced quenching, leading to an enhanced NIR emission in the aggregate/solid state, which was rarely observed for BODIPY dyes. Nanoparticles of the fluorophores formed by the assembly with the polymeric surfactant F127 were successfully used for bioimaging of living cells and for tumour-targeted imaging in a tumour-bearing mouse model., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A platinum(II) bipyridyl complex bearing bis-ureidopyrimidinone (Pt-bisUPy) has been designed and its self-assembling behavior has been thoroughly investigated by 1 H NMR, DOSY NMR, Ubbelohde viscometry analysis, UV/Vis, and emission spectroscopies. Pt-bisUPy underwent concentration-dependent ring-chain polymerization in apolar solvents. Hydrogen-bonding interactions play an important role during the formation of the supramolecular polymers. Hydrogen-bonded supramolecular polymers were transformed to nanoparticles in water through the miniemulsion method. These nanoparticles showed strong π-π excimeric emission. Metal-metal-to-ligand charge transfer (MMLCT) from Pt-Pt interactions was not significant in the emission spectrum. The phosphorescence of the nanoparticle persisted even under aerobic conditions. The triplet state of these phosphorescent nanomaterials were long-lived and possessed moderate emission quantum yields. Furthermore, the low toxicity of these materials promises a place for them in in vitro and in vivo bioimaging., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the first highly efficient artificial light-harvesting systems based on nanocrystals of difluoroboron chromophores to mimic the chlorosomes, one of the most efficient light-harvesting systems found in green photosynthetic bacteria. Uniform nanocrystals with controlled donor/acceptor ratios were prepared by simple coassembly of the donors and acceptors in water. The light-harvesting system funneled the excitation energy collected by a thousand donor chromophores to a single acceptor. The well-defined spatial organization of individual chromophores in the nanocrystals enabled an energy transfer efficiency of 95 %, even at a donor/acceptor ratio as high as 1000:1, and a significant fluorescence of the acceptor was observed up to donor/acceptor ratios of 200 000:1., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The preparation of functionalized bis-ureidopyrimidinones (Bis-UPy) through the thiol-yne reaction is described. Various Bis-UPys with different functional groups were synthesized by using the readily available functionalized alkynes and UPy-thiol to affirm the simplicity and versatility of the methodology., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)