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 (O2−.) by the Type‐I process upon light irradiation. The triplet formation originates from an effective excited‐state relaxation from the initially populated singlet (S1) to triplet (T1) states via an intermediate triplet (T2) state. The low reduction potential and ultralong lifetime of the T1 state facilitate the efficient generation of O2−. by inter‐molecular charge transfer to molecular oxygen. The energy gap of T1‐S0 is smaller than that between 3O2 and 1O2 thereby precluding the generation of singlet oxygen by the Type‐II process. The trimer exhibits superior PDT performance under the hypoxic environment.
Heavy‐atom‐free boron dipyrromethene (BODIPY)‐based photosensitizers generate ROS exclusively by the Type‐I process upon near‐infrared light illumination for tumor ablation.
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 S1–T1 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 S0 energies of the S1 and T1 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.
Organic sunset: A time‐dependent afterglow color in a single‐component organic molecular crystal was observed. It originates from well‐separated, long‐persistent thermally activated delayed fluorescence and room‐temperature phosphorescence with different but comparable decay rates.
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 glum (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.
We report on a rational strategy to clamp the molecular conformation and facilitate parallel packing of achiral D‐A molecules. This leads to spontaneous symmetry breaking during crystallization. When this emergent homochirality is coupled with the optical gain of the molecules, the homochiral crystals can be explored as excellent circularly polarized micro‐lasers with low lasing threshold (16.4 μJ cm−2) and high dissymmetry factor glum (0.9).
Simple thiol derivatives, such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play key roles in biological processes, and the fluorescent probes to detect such thiols in vivo ...selectively with high sensitivity and fast response times are critical for understanding their numerous functions. However, the similar structures and reactivities of these thiols pose considerable challenges to the development of such probes. This review focuses on various strategies for the design of fluorescent probes for the selective detection of biothiols. We classify the fluorescent probes for discrimination among biothiols according to reaction types between the probes and thiols such as cyclization with aldehydes, conjugate addition-cyclization with acrylates, native chemical ligation, and aromatic substitution-rearrangement.
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.
Here, an ultra‐small nano photosensitizer is presented through a facile self‐assembly strategy that can target a disease state, boost reactive oxygen species (ROS) generation, as well as be cleared efficiently from the body in a reasonable amount of time.
Pure organic room temperature phosphorescence (RTP) is highly preferable because of its long lifetime and potential applications. However, these kinds of materials are still very scarce due to the ...weak spin–orbit coupling between singlet and triplet states and easily nonradiative decay of the excited states. Achieving room temperature phosphorescence under visible light excitation is particularly challenging in aqueous solution. Herein, a micelle‐assisted assembling strategy has been developed to realize pure organic RTP in water by using donor–acceptor molecules. A visible‐light responsive long‐lived RTP in water with a lifetime more than 3 ms is obtained by the prepared nanocrystals. However, the same molecules show no RTP as rigid bulk crystals. Spectroscopic studies, single‐crystal structure analysis, X‐ray diffraction patterns, and density functional theory calculations reveal that the intermolecular interactions, heavy atom effect, and the molecular packing way play critical role to the long‐lived RTP character for the assembled nanocrystals in water and thermally activated delayed fluorescence for crystals in solid.
A micelle‐assisted assembly strategy to realize long‐lived pure organic room temperature phosphorescence under visible light excitation in water is reported. The molecular packing plays a critical role to the room temperature phosphorescence character in the assembled nanocrystals and delayed fluorescence in the crystals.
A facile approach for the preparation of supramolecular polymer‐based fluorescent nanoparticles (FNPs) is reported. FNPs with homogeneous shape and size distribution are fabricated from ...low‐molecular‐weight molecules, and thus, different compositional constituents can be efficiently incorporated via copolymerization. The emission color of the FNPs covers a wide region from blue to near infrared and can be easily tuned using efficient excitation energy transfer. The photoswitchable fluorescent nanoparticles with high on–off fluorescence contrast are also simply prepared by copolymerization of monomers containing a fluorophore and a photochromic unit. Our FNPs are successfully applied in living cell imaging and as fluorescent inks.
A new set of fluorescent nanoparticles (FNPs) are fabricated from hydrogen‐bonded supramolecular polymers. Their preparation is straightforward, and nanoparticles with homogeneous shape and size are obtained. The emission color of the FNPs covers a wide region from blue to near infrared and is easily tunable by excitation energy transfer. These FNPs are successfully used in bioimaging and as fluorescent inks.
Given that Type-I photosensitizers (PSs) have hypoxia tolerance, developing general approaches to prepare Type-I PSs is of great importance, but remains a challenge. Here, we report a supramolecular ...strategy for the preparation of Type-I photodynamic agents, which simultaneously generate strong oxidizing cationic radicals and superoxide radicals, by introducing electron acceptors to the existing Type-II PSs. As a proof-of-concept, three electron acceptors were designed and co-assembled with a classical PS to produce quadruple hydrogen-bonded supramolecular photodynamic agents. The photo-induced electron transfer from the PS to the adjacent electron acceptor occurs efficiently, leading to the generation of a strong oxidizing PS
and an anionic radical of the acceptor, which further transfers an electron to oxygen to form O
. In addition, these photodynamic agents induce direct photocatalytic oxidation of NADH with a turnover frequency as high as 53.7 min
, which offers an oxygen-independent mechanism to damage tumors.
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