Alkyl chain length dependent morphology and emission properties of the organic micromaterials based on fluorinated quinacridone derivatives

Two-Photon-Responsive "TICT + AIE" Active Naphthyridine-BF2 Photoremovable Protecting Group: Application for Specific Staining and Killing of Cancer Cells

The combined effects of twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AIE) phenomena have demonstrated a significant influence on excited-state chemistry. These combined TICT and AIE features have been extensively utilized to enhance photodynamic and photothermal therapy. Herein, we demonstrated the synergistic capabilities of TICT and AIE phenomena in the design of the photoremovable protecting group (PRPG), namely, NMe2-Napy-BF2. This innovative PRPG incorporates TICT and AIE characteristics, resulting in four remarkable properties: (i) red-shifted absorption wavelength, (ii) strong near-infrared (NIR) emission, (iii) viscosity-sensitive emission property, and (iv) accelerated photorelease rate. Inspired by these intriguing attributes, we developed a nanodrug delivery system (nano-DDS) using our PRPG for cancer treatment. In vitro studies showed that our nano-DDS manifested effective cellular internalization, specific staining of cancer cells, high-resolution confocal imaging of cancerous cells in the NIR region, and controlled release of the anticancer drug chlorambucil upon exposure to light, leading to cancer cell eradication. Most notably, our nano-DDS exhibited a substantially increased two-photon (TP) absorption cross section (435 GM), exhibiting its potential for in vivo applications. This development holds promise for significant advancements in cancer treatment strategies.

The Journey to Precious-Metal-Free Organic Phosphors from Single-Benzene-Cored Fluorophores

This article takes a look back over our research on the development of organic fluorophores that efficiently emit light in the solid state and precious-metal-free phosphors that emit light at room temperature. In particular, we place an emphasis on the prehistory of each project and the relationship between the established molecular designs. Our story starts from the serendipitous discovery of a luminophore with a single benzene core and follows the molecular design and characterization of 2,5-dipiperidyl-1,4-bis(acceptor-substituted ethenyl)benzenes that exhibit solid-state fluorescence with high-to-excellent quantum yields in the blue-to-red region. In addition, the design concepts, luminescence characteristics, and applications of eight novel classes of fluorophores are described, and the discovery, design, and luminescent properties of precious-metal-free compounds that show efficient room-temperature phosphorescence are presented.

An "all-in-one" strategy based on the organic molecule DCN-4CQA for effective NIR-fluorescence-imaging-guided dual phototherapy

Dual phototherapy combining photodynamic therapy (PDT) and photothermal therapy (PTT) is considered to be a more effective therapeutic method against cancer than single treatment. Therefore, the development of a single material with both near-infrared (NIR)-laser-triggered PDT and PTT abilities is highly desirable but remains a great challenge. A design philosophy for photosensitizers for integrated PDT and PTT treatment has been put forward: (1) a high molar extinction coefficient in the NIR region; (2) suitable LUMO and T1 energy levels to regulate intersystem crossing for effective singlet oxygen (1O2) generation for PDT; and (3) the suppression of fluorescence emission to enhance the process of nonradiative transition with appropriate chemical modifications. Herein, an "all-in-one" functional material, di-cyan substituted 5,12-dibutylquinacridone (DCN-4CQA), for diagnosis and therapy was obtained. DCN-4CQA possesses dual-functional phototherapeutic activity and NIR fluorescence and it was produced via a facile synthesis process from the classic organic photoelectric material quinacridone. We then prepared smart water-soluble nanoparticles (NPs), DCN-4CQA/F127, using Pluronic® 127 (F127) as a drug carrier. The NPs exhibited excellent biocompatibility, robust photostability, NIR fluorescence, a high photothermal conversion efficiency (η = 47.3%), and sufficient 1O2 generation (ΦΔ = 24.3%) under NIR laser irradiation. Remarkably, the DCN-4CQA/F127 NPs significantly inhibited tumor growth in mice subjected to NIR laser irradiation. This study provides a new route for the development of highly efficient, low-cytotoxicity photosensitizers for fluorescence-imaging-guided PTT/PDT.

Aggregation-Induced Emission Luminogens with the Capability of Wide Color Tuning, Mitochondrial and Bacterial Imaging, and Photodynamic Anticancer and Antibacterial Therapy

Recently, luminogens with the aggregation-induced emission characteristic (AIEgens) have received much attention in the field of bioimaging and therapeutic applications. However, the development of AIEgens that are derived from the simple core skeleton with emission color tuning for imaging and therapy is still a formidable challenge. To address this constraint, we present a series of cationic AIEgens based on cyanopyridinium salts (CP1-CP5). The AIEgens can be facilely prepared by varying the aromatic electron donor while fixing the cyanopyridinium group as the electron acceptor within a single benzene ring. The obtained AIEgens possess wide color tunability, large Stokes shifts, and bright emission in the condensed state. Due to their good biocompatibility and cationic nature, these AIEgens can be utilized for multiple-color imaging of intracellular mitochondria as well as Gram-negative and Gram-positive bacteria. Importantly, these AIEgens exhibit remarkable structure-dependent singlet-oxygen generation ability under white light illumination (25 mW cm^-2), and CP4 was optimized to serve as an excellent photosensitizer for photodynamic anticancer and antibacterial therapy.

A quinacridone derivative with intensive emission in both solution and the solid state via a facile preparation for cell imaging applications

tert-Butyloxycarbonyl (TBOC) substituted quinacridone (QA) derivative TBOC-QA was synthesized via a one-step simple chemical reaction and showed intense emission in both solution and the solid state.

Controllable morphology and self-assembly of one-dimensional luminescent crystals based on alkyl-fluoro-substituted dithienophenazines

A class of dithienophenazine derivatives, 9,10-difluoro-2,5-dialkyldithieno[3,2-a:2′,3′-c]phenazine (F-n, n = 4, 5, 6, 7 and 8), modified with various lengths of linear alkyl chains were synthesized and used as building blocks to assemble luminescent one-dimensional (1D) nano/microcrystals.

A diphenylamino-substituted quinacridone derivative: red fluorescence based on intramolecular charge-transfer transition

A red emissive quinacridone derivative has been prepared through construction of an ICT system. This resulted in the first efficient and bright red OLED based on a quinacridone derivative.

Anion-controlled morphologies and photophysical features of organic microcrystals by solid-phase anion exchange reactions

Anions play key roles in controlling the morphologies of organic microcrystals fabricated by simple and green solid-phase anion exchange reactions.

Achieving high power efficiency and low roll-off OLEDs based on energy transfer from thermally activated delayed excitons to fluorescent dopants

Achieving high power efficiencies at high-brightness levels is still an important issue for organic light-emitting diodes (OLEDs) based on the thermally activated delayed fluorescence (TADF) mechanism. Herein, enhanced electroluminescence efficiencies were achieved in fluorescent OLEDs using a TADF molecule, (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN), as a host and quinacridone derivatives (QA) as fluorescent dopants.

Assembly of twisted luminescent architectures based on acenaphtho[1,2-k]fluoranthene derivatives

Three DPAF derivatives DPAF-n (n = 8, 12, 16) with identical central aromatic cores and different lengths of flexible alkyl chains have been synthesized and employed as building blocks to fabricate luminescent twisted wires.

Quinoacridine derivatives with one-dimensional aggregation-induced red emission property

A new series of acceptor-donor-acceptor (A-D-A) type quinoacridine derivatives (1-3) with aggregation-induced red emission properties were designed and synthesized. In these compounds, the electron-withdrawing 2-(3,5-bis(trifluoromethyl)phenyl)acetonitrile groups act as electron-accepting units, while the alkyl-substituted conjugated core acts as electron-donating units. The restriction of intramolecular rotation was responsible for the AIE behavior of compounds 1-3. All compounds were employed as building blocks to fabricate one-dimensional (1-D) organic luminescent nano- or microwires based on reprecipitation or slow evaporation approaches. Morphological transition from zero-dimensional (0-D) hollow nanospheres to 1-D nanotubes has been observed by recording SEM and TEM images of aggregated sates of compound 2 in THF/H(2)O mixtures at different aging time. It was demonstrated that the synthesized compounds with different lengths of alkyl chains displayed different wire formation properties. The single-crystal X-ray analysis of compound 2 provided reasonable explanation for the formation of 1-D nano- or microstructures.

Fluorescent one-dimensional nanostructures from a group of uniform materials based on organic salts

Herein we report the synthesis of a fluorescent organic salt through anion exchange and the subsequent fabrication of 1D-nanostructures via a facile templating method.

Sonication-induced molecular gels based on mono-cholesterol substituted quinacridone derivatives

A series of monocholesterol substituted quinacridone derivatives MCC(n) (n = 4, 6, 8) has been designed and synthesized. Compounds MCC(6) and MCC(8) can gelate a wide range of organic solvents upon ultrasound irradiation and afford intriguing well-defined nanostructures composed of three-dimensional sponge-like superstructures or fibrous networks. Interestingly, the gel produced from MCC(6) is sensitive to thermo-, aniline, and formic acid stimulus, giving obviously different aggregation behaviors as well as physical properties. Time-dependent spectroscopic data and theoretical calculation results provided explanation for the possible molecular aggregation mode during the formation of the gels.