Triphenylamine (TPA) is a weak fluorophore with an aggregation-caused quenching (ACQ) effect. By integrating pyrene and different substituents (such as benzene, pyrene, phenylcarbazole, tetraphenylethylene (TPE)), a set of new pyrene-based TPA analogues have been prepared in order to understand the stereoscopic effects on the emission behavior both in solution and in the solid state. These compounds contain the pyrene unit (such Py2Ph, 2PyPh and PyCz) can improve the fluorescence intensity but still exhibit an ACQ feature, while the TPE decorated compound PyTPE exhibited a typical aggregation-induced emission (AIE) characteristic. Moreover, the degree of π-conjugation and the electronic effects can affect the molar absorbance coefficients. Due to the stereoscopic effect of these TPA analogues, the emission compounds show slight changes before and after grinding. Furthermore, due to their good thermal stability and quantum yields, the compounds PyCz and PyTPE were selected as light emitting layers for fabricating organic light emitting diodes (OLEDs) which exhibited good electroluminescence properties.

In the photopolymerization 3D printing technology, preparing solid fluorescent biomaterials with fine structure is difficult due to the light barrier, aggregation quenching, and osmotic dissolution caused by adding fluorescent dyes, which severely limits their application in clinical practice. In this study, a bioactive fluorescence dye was prepared by coupling collagen type I and Cyanine IR-780 (Cyan) by dihydrolipoic acid (DHLA), in which 75.0% of primary amine of collagen was coupled with carboxyl of DHLA, and 48.4% of SH was coupled with Cyanine IR-780. The obtained collagen-based dye showed light stability under 405 nm LED light source and can be used in digital light processing-3D printing to fabricate hydrogel scaffolds containing bone collagen with fluorescent properties. The retained SH group in this macromolecular fluorescent dye can participate in the polymerization reaction in the photopolymerization process and improve the photopolymerization speed. With the formation of photopolymerized collagen polymer, the dye molecule shows fluorescence enhancement and antiaggregation caused quenching (anti-ACQ effect). The presented methods provide a foundation for the manufacturing of high-resolution solid 3D printed fluorescent structures, with direct relevance to biomedical optics and the broad adoption of fast manufacturing methods in fluorescence imaging.

As a species tightly associated with inflammation, superoxide anion radical (O2·-) is generally recognized a biomarker for interstitial cystitis (IC) but the reliable detection of such species has been remaining a challenge owing to its elusive nature. Herein, we developed a merocyanine dye-based fluorescent probe, MC-O-TBS, capable of detecting O2·- species with a limit of detection down to 49.3 nM, recognition specificity against other potential interfering species and two-photon excitation fluorescence (TPEF) property for bioimaging with satisfactory depth. As another particularly salient feature, MC-O-TBS generates O2·--mediated fluorescence contrast with response time less than 10 s, an unexampled response agility of probe in O2·- fluorescence sensing as compared to the counterpart probes developed to date. The superior performance of MC-O-TBS probe in terms of recognition specificity, detection sensitivity, TPEF for bioimaging with satisfactory depth and response rate as well as the preliminary in vitro experiment results regarding mapping O2·- level in bladder organ unequivocally proclaimed its potential for reliably monitoring the highly elusive O2·- species and clinically diagnosing IC featured with abnormal O2·- level.

The macrocycles with the features of large cavity, optical property and CPL response to guest simultaneously are rarely reported but very attractive based on their potential application. Herein, a macrocycle (BiCDB-MC) with dynamically racemic feature, inwardly directed functional groups, a large hollow with size of 1.3 nm and fluorescent property was designed and synthesized. BiCDB-MC was found to have two equally chiral conformations and was dynamically racemic in solution based on their rapidly interconvertion via macrocycle flipping. It was interesting that BiCDB-MC exhibited a selective turn-on CPL response with glum = 0.00248 toward ursolic acid since one of the stable chiral conformations could form a more stable inclusion complex. This kind of turn-on CPL emission for dynamical-racemic macrocycle with CPL recognition for complicated natural chiral compound was described for the first time.

Realizing solution-processable orange-red thermally activated delayed fluorescence (TADF) emitters is still challenging owing to the severe aggregation-caused quenching. In this study, N3,N3,N6,N6-tetraphenyl-9H-carbazole-3,6-diamine (DDPACz) with high triplet energy and good hole transport ability was chosen as host unit. And 1,8-naphthimide-9,9-dimethyl-9,10-dihydroacridine (NDMAC) was used as red TADF unit. Then, these two functional units were linked to the inactive calix[4]resorcinarene (CRA) core to construct a series of hyper-structured molecules (HSMs), CRA-NDMAC(x)-DDPACz(8-x) (x = 0, 1, 2, 4, 6, 7 or 8). 1H NMR, MALDI-TOF MS and FT-IR spectra indicated that HSMs were successfully synthesized. UV–Vis, PL and CV results demonstrated that these HSMs inherited the photophysical and electrochemical properties of functional units. Spin-coating CRA-NDMAC(x)-DDPACz(8-x) (x = 1, 2, 4, 6, 7 or 8) as light-emitting layer, all the non-doped solution processed organic light-emitting diodes (OLEDs) showed orange-red emission. Among them, CRA-NDMAC(1)-DDPACz(7)-based device showed the highest maximum external quantum efficiency (EQEmax) of 0.94% with the emission peak at 613 nm. Furthermore, bright orange emission at a central wavelength of 592 nm with EQEmax of 9.73% and luminance of 5428 cd/m2 was achieved in the doped OLED based on CRA-NDMAC(7)-DDPACz(1) using CBP as host. These results indicate that hyper-structured molecules could be a potential strategy for the construction of orange-red TADF emitters.

Phycocyanobilin (PCB), a tetrapyrrole chromophore compound of Phycocyanin (PC) from Arthrospira platensis. Previous studies have shown that it has anti-inflammatory and immunomodulatory biological activities. In this work, we found that it can be used as a new anticancer photosensitizer, which is almost non-toxic readily available and less costly. A rapid production process of PCB was developed, with a yield of 19.2 ± 1.1 mg/g. By using semi-preparative liquid chromatography and silica gel column chromatography, PCB was refined to a purity of 99.97 ± 0.02%. Nuclear magnetic resonance spectroscopy and mass spectrometry were used to determine the PCB structure. The optimized wavelength of the light source that caused PCB to produce reactive oxygen species (ROS) was 660 nm. PCB had an estimated active oxygen quantum yield of 0.1595, 14.5 times that of PC (0.0110). Meanwhile, PCB produced ROS in MCF-7 cells under light conditions. After the protein of PC was partially removed, the quantum yield of active oxygen in PCB is greatly improved, which was helpful to enhance its anticancer activity. The photodynamic anticancer activity of PCB (IC50:8.26 ± 1.19 μM) was significantly enhanced compared with PC (IC50:255.29 ± 1.72 μM). PCB (without light) had no significant anticancer activity in vitro, but it showed strong anticancer activity in vivo, which was equivalent to the activity of the positive drug group: Zinc-Phthalocyanine (ZnPc) with light. This may be because PCB had the effect of eliminating inflammation and improving immunity. PCB significantly enhanced its anticancer activity under light conditions due to the production of reactive oxygen species. The experimental results showed that PCB had dual anticancer effects of chemotherapy and phototherapy in vivo, and had potential to become a new anticancer photosensitizer.

New boron-locked substituted anilido-pyridines were obtained. The compounds exhibit high Stokes shift (up to 147 nm) and practical luminescence quantum yield (up to 62%), both in solution and in a solid state. The compounds demonstrate reversible electrochemical behavior and intrinsic electrofluorochromism. The possibility to modulate the fluorescence by direct electrochemical repetitive on/off switching was demonstrated by the spectroelectrochemical measurements, opening up prospects for creating fluorescent redox-switches based on these compounds.

Silacycloalkane molecules are very attractive due to the intriguing structures and properties yet impeded by very limited synthetic methods. Herein a new spiral eight-membered disilacycle linked with dibenzosiloles has been readily synthesized by one-step dimerization of the dibenzosilacyclobutane. As a pluralistic building core the disilacycle molecule with four Br groups provides rich and promising strategies to develop versatile multifunctional materials by classic cross-coupling reactions. The derivatives installed with a variety of aryl groups render them with prominent photoluminescent properties, thermal stability and self-assembly to highly emissive microspheres and microribbons. The emission colors can be finely tuned from deep blue to green with the quantum yield up to 0.96 in solution and 0.34 in the powder form. The compound 4c with four peripheral tetraphenylethylene substituents was demonstrated to have great potential for persistent latent fingerprints (LFPs) on various substrates. The FLPs readily developed by soaking method illustrate the all-round advantages of high sensitivity (25 μM), ultrafast development (3 s), details up to level−3 (mainly referring to the sweat pores), and outstanding stability, attributed to the novel disilacycle core and dendritic AIEgens. This work provides a facile synthetic strategy of the pluralistic silacycle and inspirations for design and development of high-performace multifunctional fluorescent organic materials in practical applications.

Sharing with anthocyanins the 2-phenyl-1-benzopyrylium structural motif, flavylium derivatives are strongly colored bio-inspired dyes that have been explored in dye-sensitized solar cells (DSSCs). Following on the fact that the most efficient flavylium-based dyes for DSSCs require amine electron-donating groups, a diethylamino group and the corresponding rigidified julolidine group were introduced in the benzopyrylium core. This structural variation was combined with another structural parameter – increased planarization of the flavylium ring system – to yield four flavylium derivatives all with a catechol anchoring group. The several pKa values of the new dyes and the UV–vis absorption data at different pH values and upon adsorption to TiO2 (corroborated by TD-DFT calculations) demonstrate a stronger delocalization of the nitrogen lone pair in the julolidine systems when compared to the diethylamino ones, reflecting the stronger electron-donating ability of the former. However, the julolidine-based dyes resulted in a decrease in all DSSC parameters, with efficiencies of 0.6% vs. 2.3% for the diethylamino devices. Discarding eventual increased self-aggregation processes of the more planar julolidine derivatives through studies with a de-aggregating agent (CDCA), and determining comparable dye loadings for all dyes, the presence of increased back-electron transfer processes for the julolidine-based compounds is advanced to explain their lower efficiencies. Rigidification of the flavylium dyes by bridging the benzopyrylium and the phenyl rings is demonstrated by higher fluorescence quantum yields and by electrochemical data and leads to a slight increase in the efficiency of the respective DSSCs. The results contribute to consolidate the potential of flavylium dyes as sensitizers for DSSCs.

The pH test is particularly important in many fields, such as chemical production and medical diagnosis. However, the most commonly used pH test strips for pH detection have disadvantages such as low strength, poor stability, only qualitative measurement and only a single-color response. Therefore, a dual-mode pH sensor prepared by a phase conversion method with Poly(m-phenylene isophthalamide) (PMIA) as the substrate and carbon quantum dots (CQDs) as probes was developed. This sensor is capable of producing dual changes in fluorescence color and fluorescence intensity over the full range of pH. The -COOH and -NH2 groups in CQDs can interact with the amide group in PMIA to make the sensor highly stable. Three correlations were established based on the fluorescence color and fluorescence intensity at different pH, which compensated the shortage of traditional pH test paper that could not be quantitatively detected. More importantly, the sensor can be used for pH detection in a wide range of water samples, and both colorimetric and fluorescence detection modes exhibit extremely high fit coefficients (R2 > 0.99) and short response times (∼5 s). Therefore, the dual-mode pH sensor provides an important solution for the development of pH detection devices with high stability and accuracy.

Phthalocyanine compounds are a class of macrocyclic conjugated structures with 18 π-electrons. And have better photophysical properties. However, the π-π electron interactions lead to aggregation between phthalocyanine molecules, which affects optical limiting properties. In this work, the conjugated organic small molecule antiphenylenediamine (PDA) is grafted onto the phthalocyanine conjugate system through the azo condensation reaction, and the covalent organic framework polymer (PDA-InPc) was obtained. Then it is doped into the polymethyl methylmethacrylate (PMMA) matrix to produce a phthalocyanine solid device with different thickness (PMMA-PDA-InPc). The aggregation-free phthalocyanine covalent organic frameworks avoids intramolecular aggregation of the phthalocyanine units, and dispersing it in PMMA solid devices can also reduce intermolecular π-π stacking. As a result, the fluorescence lifetime of PMMA-PDA-InPc is τ1 = 0.52 ns (A1 = 95.71%) and τ2 = 11.5 ns (A2 = 4.29%), indicating that the phthalocyanine conjugated unit exists mainly as monomers (95.71%), while the proportion as aggregates is very small (4.29%). At the input laser energy of 9 μJ, the nonlinear absorption coefficient of PMMA-PDA-InPc device is (2.2 × 10−9 m/W), which is significantly better than PMMA-InPc device (1.0 × 10−9 m/W), indicating that PMMA-PDA-InPc has improved nonlinear absorption and reverse saturation absorption. This design idea of non-aggregated phthalocyanine covalent organic frameworks and its solid device expands a new idea for the development of useable phthalocyanine optical limiters.

Covalent organic Frameworks (COFs) are a class of crystalline macromolecular materials build-up by monomers with specific symmetries or functionalities. There are important limitations in the synthesis of highly ordered COFs, such as the shape and packing of the building blocks. Thus, the presence of fluorine atoms that lie perpendicular to the bisecting plane of BODIPY derivatives together with the presence of four bulky methyl groups could hinder the crystallization process in COF synthesis. For that reason, BODIPY-based COFs are rarely incorporated to COF networks. In this work, following the mixed linker strategy, a pre-synthetic method to dope COF structures with BODIPY units was developed. The materials have been processed into fluorescent Covalent Organic Nanosheets (CONs) with defined particle-size distributions around 100 nm, suitable for cellular biomedical applications. The viability of the CONs was evaluated using Sk-Mel-103 cells, demonstrating the internalization showing 100% cell viability. We envisage that this work could accelerate the discovery of new COF-based materials for biomedical sciences.

Diabetes is a significant public health issue worldwide and can cause serious consequences for daily functioning and health. Several molecular design strategies have been proposed to detect glucose, among these, phenylboronic acid (PBA) is considered to have the potential as a glucose binder. Nevertheless, most of the PBA derivatives are used in alkaline media to achieve glucose sensing. In this work, we first report the glucose sensor based on hydrazide-hydrazone PBA molecules that can function without the need for adding an alkaline agent. A series of novel pyrene-based hydrazide-hydrazone PBA with 1,2-, 1,3- and 1,4-substituted derivatives, namely 3a, 3b and 3c, respectively, were synthesized. The experimental and theoretical studies demonstrated that compound 3a might have intramolecular Lewis acid-base interactions between the boron and nitrogen atoms, leading to high sensitivity to glucose. Alternatively, compound 3c revealed intermolecular Lewis acid-base interactions and resulted in the selective glucose detection. We proved the cooperative effect of Lewis acid-base interaction, π-π stacking and hydrogen bonding may play an important role in the design of the alkaline-free activated glucose sensor.

In the present study, we propose a general synthetic strategy toward potential push-pull chromophores containing furan, benzofuran, pyrrole and indole π-spacers based on the reactivity of substituted furans that act as nucleophilic or electrophilic relays. The results suggest that the strategy could be employed for the design of potential dyes for further studies in organic solar cells or dye-sensitized solar cells.

The synthesis of novel [1,2,4]triazolo[1,5-a]pteridine (TPt) derivatives was carried out starting from [1,2,4]triazolo[1,5-a]pyrimidine-6,7-diamines and 1,2-dicarbonyl compounds. For obtained TPt DFT/TD-DFT calculations were performed with subsequent complex photophysical and electrochemical studies. The substituent in the pyrazine ring of TPt framework proved to have a higher effect on photophysical properties than that in the triazole ring. The fluorescence quantum yields of studied compounds were generally low (3–23%). However, it was shown that some of TPt was sensitive to trace amounts of organic peroxides (about 100 ppm), which will make it possible to create test systems based on them. On the other hand, low-lying HOMO energy levels and the energy gap values of TPt (2.63 eV < E0-0 < 2.97 eV) as well as the electron mobility in solid-state films measured by the conventional CELIV technique (approximately 10−4 cm2 V−1 s−1) make these materials promising for the further use in organic electronic devices.

A novel series of D-A-D type conjugated dyes (Py-CyP1-7) centred on a strongly electron-withdrawing cyanopyridone scaffold (A) linked to highly electron-donating pyrene unit (D) and varied auxiliary donors (D) were designed and synthesized, for applications in green organic light-emitting diodes (OLEDs). All the hybrids were systematically subjected to theoretical, optical, electrochemical, and thermal studies to validate their efficiency in behaving as green emitters. Finally, we employed the dyes as sole and dopant emitters in OLEDs. The OLED with 3 wt % Py-CyP4 in the CBP host shows maximum efficiencies of 14.38 cd A−1, 12.04 lm W−1, and 5.91%.

In this work aggregation-induced emission (AIE) type green non-traditional intrinsic luminescence (NTIL) polymer with acid/base stimuli-responsive behavior has been achieved by AB-type Barbier polymerization-induced emission (PIE). DFT calculations illustrate that NTIL mechanism is due to intramolecular charge transfer and through-space conjugation under polymer chain confinement. Furthermore, the AIE type green NTIL polymer exhibits potential for explosive detection at ppm level in solution and ng level at solid state. Due to the reversible acid/base responsive luminescent properties of AIE type green NTIL polymer, potential applications for luminescent encryption and decryption have been demonstrated as well.

Organic light-emitting diodes (OLEDs) play a key role in modern flexible displays. Although stable and efficient red- and green-emitting phosphors have been developed, the applications of blue emitters are limited due to their poor chemical and electrochemical stability, and thus, they require further development. Herein, we report the preparation and full characterization of IrTrz, a 3-methyl-5-phenyl-1H-1,2,4-triazole-ligand-based facial-homoleptic iridium complex. Single-crystal X-ray diffractometry results suggested that the complex is a facial isomer with C3 point symmetry. The complex exhibited a blue emission band centered at ∼450 nm in both solution and the film state at ambient temperature; moreover, it showed a very narrow full-width at half maximum value (55 nm) and a moderate photoluminescence quantum yield (33%). The complex showed high thermal stability, with 5%-weight-loss and glass-transition temperatures of 324 and 210 °C, respectively. Consecutive cyclic voltammetry measurements revealed outstanding electrochemical stability of the complex. Therefore, multilayer phosphorescent OLEDs that use IrTrz as the blue emitter were fabricated with two types of host material: (3,3′-di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP) and 9-(dibenzo[b,d]thiophen-4-yl)-9H-3,9′-bicarbazole (4DBTCz)). In particular, the 4DBTCz-based devices exhibited low turn-on voltages (∼5.0 V) and high external quantum efficiencies (>11%) with a Commission Internationale de l’Eclairage y-coordinate of 0.2. Moreover, the devices demonstrated stable operational lifetimes that exceeded 690 h (for mCBP) and 390 h (for 4DBTCz) at 100 cd/m2. Therefore, we believe that the 1,2,4-triazole-ligand-based Ir(III) complex is a promising blue-phosphorescent emitter material for applications in stable and efficient OLED devices.

Dual functional electrochromic (EC)/electrofluorochromic (EFC) materials play a pivotal role in wearable and smart electronic equipments. Developing new materials with high performance of EC/EFC properties is still a big challenge. Here a new D-A structure polymer PPDOTTPD based on thieno(3,4-c)pyrrole-(4,6)dione (TPD) was synthesized by Stille coupling, and the EC/EFC properties were investigated for the first time. PPDOTTPD film exhibits reversible color changes from purple neutral state to transparent colored state in the process of reversible redox. Photophysical and electrochemical studies revealed that the polymer has outstanding EC properties, including high optical contrast (52%), fast response time (0.5 s/0.7 s), high coloring efficiency (427.1 cm2 C−1) and good stability. What's more, PPDOTTPD exhibited EFC phenomenon. PPDOTTPD film showed an intense red near-infrared fluorescence with a peak of 672 nm, which gradually doped with the increase of applied potential with a maximum contrast ratio of 12.9. The EC/EFC dual-functional device based on PPDOTTPD was also successfully fabricated, which exhibited high optical and fluorescence contrast. The fine dual-functional performance indicates TPD can be further explored as potential acceptors for synthesizing high performance D-A molecules for intelligent optical devices.

Herein, we designed a potent ClO− probe named ETMC, which exhibited aggregation-induced emission (AIE) characteristic in solid state and water/EtOH binary solvent. Probe ETMC exhibited an colormetric from yellow to blue and ratiometric response to ClO− with high selectivity and sensitivity, and a low detection limit of 3.66 × 10−7 M. Moreover, probe ETMC could be applied to visibly and quantitatively detect the different concentraction of ClO− in test paper. Importantly, probe ETMC could effectively detect endogenous and exogenous ClO− in living A549 cells by an outstanding ratio signal change. Also, the sensing mechanism of probe ETMC for ClO− was confirmed by FT-IR, 1H NMR, HRMS, DLS, TEM and DFT calculation.