Water contaminant: Use it but do not shield it to synthesize co-polymers with multiple emission colours.

Due to the high affinity with water molecules, amide compounds are easily contaminated by moisture; therefore, the water interference effect cannot be totally excluded from the amide-involved reactions. Thus, the perfect solution is to use the interference effect but not shield it in a real application. In this work, we introduced different contents of sodium acrylate (AAS) to scavenge water from the monomers of N-isopropylacrylamide (NIPAm) when copolymerized with TPA-Vinyl-4CN. Herein, water molecules play a role as nucleophilic reagents to attack highly active functional groups as -C=C-CN from TPA-Vinyl-4CN, leading to a blue emissive TPA-Vinyl-2CHO. From this study, we made a deep awareness of the interactions between three reaction partners of AAS and NIPAm as well as TPA-Vinyl-4CN. Our results clearly demonstrated the fact that water can be perfectly used and controlled by the water absorbent of AAS, developing a new approach to synthesizing multiple emission-coloured polymers by using only one luminogen of TPA-Vinyl-4CN.

A fluorescent quaternary phosphonium main-chain-type polymer: an opportunity to fabricate functional materials with excellent antibacterial activity and bacterial imaging capability.

The large-scale transmission and infection of pathogens worldwide have encouraged scientists to develop new antibacterial agents that do not succumb to bacterial resistance, which is not only of significant research interest but also challenging. In this work, we fabricated two main-chain (MC)-type cationic polymers (TPE-ammonium polymer and TPE-phosphonium polymer) through a one-step 100% atomic economic reaction. The two polymers demonstrated very promising antibacterial activity and their minimal inhibitory concentration (MIC) values are lower than that of most previously reported antibacterial agents. Especially, the phosphonium-doped MC polymer exhibited very small MICs of 0.24 and 0.98 µg mL-1 against S. aureus and E. coli, respectively. This excellent antibacterial performance by the TPE-phosphonium polymer is attributed to the advantages of the MC-type polymer such as its large molecular weight (Mn = 103 011) and stronger polarization effect from the P atom. More impressively, depending on the typical aggregation-induced emission (AIE) property and excellent antibacterial behaviors, the TPE-phosphonium polymer was successfully used for bacterial imaging and real-time monitoring of bacterial viability.

Simple Way to Fabricate Emissive Boron-Containing Covalent Organic Frameworks.

Highly fluorescent covalent organic frameworks (COFs) are rarely obtained because of the π-π stacked layers with aggregation-caused quenching behavior. Unarguably, highly fluorescent COFs with tunable emission colors are even more rarely achieved. Herein, a general strategy to modify the classical COF material (named COF-1) by different fluorescent molecules via N → B interaction was developed. In this method, the boron-containing COF-1 acted as a porous and crystalline matrix as well as a reaction partner of Lewis acid; after interacting with fluorescent molecules with the anchoring group of pyridine (Lewis base), COF-1 takes a gorgeous transfiguration from a non-emissive powder into a highly fluorescent COF material with tunable emission colors. This disclosed method endowed the typical COFs with new emissive life and is speculated with the general research concept for all boron-containing COFs. Benefiting from the prominent fluorescent emission in the aggregation state, sensitive probes toward amines are achieved.

Hypochlorite Detection by Fluorescent Sensors Bearing Long Alkyl Chains: The Role of Chain Length in Sensing Properties.

Three pyridinium derivatives bearing alkyl chains of different lengths (C1, C8, and C18) that show aggregation-enhanced emission were synthesized. These compounds can be used to detect ClO- ion as the reaction releases the fluorescent core with an increase in emission intensity and change in absorption wavelength. The lowest detection limit of TPA-Pyr-18C was 6.04 µM. The length of the alkyl chain and resulting lipophilicity allowed the targeting of different subcellular structures. TPA-Pyr-18C could be used for staining yolk lipids in zebrafish.

A Cost-Effective Way to Produce Gram-Scale 18O-Labeled Aromatic Aldehydes.

Obtaining 18O-labeled organic substances is of great research importance and also an extremely challenging work. In this work, depending on the reversed Knoevenagel reaction, 18O-labeled aromatic aldehydes (3a-3x) are successfully obtained with high total yields (52-72%) and sufficient 18O abundance (90.90-96.09%).

Incorporating spin-orbit coupling promoted functional group into an enhanced electron D-A system: A useful designing concept for fabricating efficient photosensitizer and imaging-guided photodynamic therapy.

Intersystem crossing (ISC) is of great significance in photochemistry, and has a decisive influence on the properties of photosensitizers (PSs) for use in photodynamic therapy (PDT). However, the rationally design PSs with efficient ISC processes to implement superb reactive oxygen species (ROS) production is still a very challenging work. In this contribution, we described how a series of high-performance PSs were constructed through electron acceptor and donor engineering by integrating the smaller singlet-triplet energy gap (ΔEST) and larger spin-orbit coupling (SOC)-beneficial functional groups into the PS frameworks. Among the yielded various PSs, TaTIC was confirmed as the best candidate for application in PDT, which was due to its most outstanding ROS generation capability, bright near-infrared (NIR) fluorescence with peak over 840 nm, as well as desired aggregation-induced emission (AIE) features. Importantly, the ROS generation efficiency of TaTIC was even superior to that of some popularly used PSs, including the most reputable PS of Rose Bengal. In order to further extend therapeutic applications, TaTIC was encapsulated with biocompatible amphiphilic matrix and formulated into water-dispersed nanoparticles (NPs). More excitedly, the as-prepared TaTIC NPs gave wonderful PDT performance on tumor-bearing mouse model, actualizing complete tumor elimination outcomes. Coupled with excellent biosecurity, TaTIC NPs would be a promising theranostic agent for practical clinical application.

Precise Molecular Engineering of Small Organic Phototheranostic Agents toward Multimodal Imaging-Guided Synergistic Therapy.

Precise molecular engineering is the most fundamental and even a great challenging task for the development of small organic fluorophores used as phototheranostic agents in multimodal imaging-guided synergistic therapy. To the best of our knowledge, there have been no previous reports regarding the fine fabrication of molecular structure from a proof-of-concept study, providing a single molecule with all phototheranostic modalities. Herein, an electron donating-accepting (D-A) system is constructed by using triphenylamine derivatives as donors and diverse electron-deficient partners as acceptors, yielding aggregation-induced emission luminogens with tunable emission wavelength (up to 933 nm) and light absorption capability (ε up to 6.9 × 104 M-1 cm-1). Notably, by integrating the spin-orbit coupling-promoted carbonyl group and the strong stretching vibrations of -CN to the D-A systems, a highly performing phototheranostic agent, namely, MeTIC, is constructed. When encapsulating MeTIC into nanovehicles, the obtained MeTIC nanoparticles show excellent performance in multimodality theranostics for cancer treatment. This work is expected to provide an organic phototheranostic agent designing principle for potential clinical trials.

Functional Copolymers Married with Lanthanide(III) Ions: A Win-Win Pathway to Fabricate Rare Earth Fluorescent Materials with Multiple Applications.

Lanthanide(III)-based luminescent materials have attracted great research interests due to their unique optical, electronic, and chemical characteristics. Up to now, how to extend these materials into large, broad application fields is still a great challenging task. In this contribution, we are intended to present a simple but facile strategy to enhance the luminescence from lanthanide ions and impart lanthanide(III)-based luminescent materials with more applicable properties, leading to meet the requirements from different purposes, such as being used as highly emissive powders, hydrogels, films, and sensitive probes under external stimuli. Herein, a water soluble, blue color emissive, temperature sensitive, and film-processable copolymer (Poly-ligand) was designed and synthesized. Upon complexing with Eu3+ and Tb3+ ions, the red color-emitting Poly-ligand-Eu and green color-emitting Poly-ligand-Tb were produced. After finely tuning the ratios between them, a standard white color emitting Poly-ligand-Eu1:Tb4 (CIE = 0.33 and 0.33) was obtained. Furthermore, the resulted materials not only possessed the emissive luminescent property but also inherited functions from the copolymer of Poly-ligand. Thus, these lanthanide(III)-based materials were used for fingerprint imaging, luminescent soft matters formation, colorful organic light-emitting diode device fabrication, and acid/alkali vapors detection.

Facile Polymerization Strategy for the Construction of Eu3+-Based Fluorescent Materials with the Capability of Distinguishing D2O from H2O.

Aggregation-induced emission (AIE) and antenna effect (AE) are two important luminescence behaviors. Connecting them into polymers is a promising but challenging work, which can supply opportunities for luminescence materials with extensive applications. In this work, AIE-active Eu3+-coordinated polymers (Poly-Eu-1, -2, -3, and -4) have been synthesized, and the efficient AE was verified. This finding presents a facile approach to obtain the Ln3+-based solid luminescence materials due to the synergistic effect from AIE and AE. Also, benefiting from the film-processing ability and water solubility, Poly-Eu-1, -2, -3, and -4 could be employed with different application purposes. In the solution phase, they can be used as sensitive optical probes to detect trace amounts of H2O and D2O, and the limit of detection (LOD) of Poly-Eu-2 toward D2O in H2O is determined to be 7.8 ppm. This discovery is a novel strategy for the construction of D2O optical sensors with a totally intervention-free style.

Incorporating Thiourea into Fluorescent Probes: A Reliable Strategy for Mitochondrion-Targeted Imaging and Superoxide Anion Tracking in Living Cells.

Three aggregation-induced emission active fluorescent compounds, TPA-Pyr-Octane, TPA-Pyr-Br, and TPA-Pyr-Thiourea (TPA = triphenylamine pyridinium), are synthesized; their tiny differences in chemical structures result in a huge difference in cell-imaging applications. Especially, incorporating thiourea into fluorescent probes is found as a reliable strategy for mitochondrion-targeted imaging and superoxide anion tracking in living cells, which is possibly due to the presence of hydrogen bonding between thiourea and mitochondrion proteins. This finding is very useful for the design of biosensors and delivery carriers in disease treatment.

Synthesis of AIE-Active Materials with Their Applications for Antibacterial Activity, Specific Imaging of Mitochondrion and Image-Guided Photodynamic Therapy.

In comparison with fluorescence molecules with aggregation-caused quenching (ACQ), fluorescence molecules with aggregation-induced emission (AIE) have great advantages in cell imaging, image-guided photodynamic therapy (PDT), and antibacterial activity. However, the reasonable design and synthesis of related molecules are still of great challenges. Herein, a consecutive strategy via several reliable reactions to prepare a series of AIE-active luminogens by adjusting their structures is reported. Having concentrated on the factors for the principle purpose of 1O2 generation, TPA-18 is picked out within all triphenylamine (TPA) derivatives according to its longer emission wavelength (640 nm in solid), the lowest energy gap between HOMO and LUMO (calculated as 2.04 eV), the totally separated orbital distributions of HOMO and LUMO, and typical AIE characteristics. Meanwhile, owing to the presence of the positive structural charge and the bright emission color, TPA-18 in aggregated form is detected as an impressive probe for the mitochondria-targeted imaging and living zebrafish embryos imaging in vivo. Accordingly, TPA-18 can effectively generate 1O2 reactive oxygen species; it provides an effective application for image-guided photodynamic cancer treatment and antibacterial activity. Therefore, this study not only synthesized AIE photosensitizer with tunable emission wavelength (from blue to red color) but also raised a new concept for the constructing AIEgens with versatile applications in cell imaging, antibacterial activity, and image-guided PDT.

One immunoassay probe makes SERS and fluorescence two readout signals: Rapid imaging and determination of intracellular glutathione levels.

In this paper, one probe (TPPA-VCh) with fluorescence and Surface-enhanced Raman Scattering (SERS) two readout signals, which has high sensitivity and specificity to glutathione in both vitro and cell image applications, is designed and synthesized. Furthermore, the quenched emissions and intensified SERS signals is obtained by loading TPPA-VCh on the surfaces of gold nanoparticles.

Two aggregation-induced emission (AIE)-active reaction-type probes: for real-time detecting and imaging of superoxide anions.

Fluorescent probes are powerful tools for investigating reactive oxygen species (ROS) in living organisms. The overproduced "primary" ROS of superoxide anions (O2˙-) cause a chain of oxidative damage. In order to monitor O2˙- level fluctuations in living cells, we synthesized two reaction-type probes of TPA-DHP-1,2,3 and TPA-PPA-1,2,3, which were composed of an electron-rich triphenylamine (TPA) and the very active functional groups of dihydropyridine (DHP) and pyridinium (PPA). Intriguingly, DHP and PPA were able to carry out easy proton abstractions and nucleophilic reactions in the presence of O2˙-, resulting in the corresponding products with sharp wavelength shifts, and elevated fluorescence intensities. Therefore, undesirable background fluorescence interference can be reduced during the monitoring and imaging process. Meanwhile, the developed dual-channel monitoring strategy not only provides observations of the O2˙- level fluctuations, but could also be employed to image the dynamic accumulation process of probes in the different cell organelles. Therefore, the design could provide a simple, accurate and universal platform for biological applications in future research work.

Synthesis of π-conjugated network polymers based on triphenylamine (TPA) and tetraphenylethylene (TPE) as building blocks via direct Pd-catalyzed reactions and their application in CO2 capture and explosive detection.

In this study, we report the synthesis of π-conjugated network polymers via palladium-catalyzed direct arylation polycondensation of triphenylamine (TPA) and tetraphenylethylene (TPE) with different active substrates. Moreover, six conjugated porous polymers were obtained (named as TPA-TPA-MA, TPA-PB-MA, TPA-TFB-MA, TPA-TPE-MA, TPE-PB-MA, and TPE-TFB-MA). Then, the fluorescence properties in the solid and dispersed states, the corresponding microporous structures, and the Brunauer-Emmett-Teller (BET) surface areas of all polymers were well studied. Among the obtained materials, TPA-PB-MA possessed not only largest BET surface area (686 m2 g-1) and largest pore volume (0.716 cm3 g-1), but also the smallest pore size of 0.823 nm. These properties are very beneficial for the application of TPA-PB-MA in CO2 storage and PA sensing. At 1 bar, TPA-PB-MA demonstrated the significant CO2 uptake of 2.70 and 1.35 mmol g-1 at 273 and 298 K, respectively. Furthermore, TPA-PB-MA was most sensitive and selective towards PA recognition. The K SV constant was measured as 4.0 × 104 M-1.

Positively Charged Hyperbranched Polymers with Tunable Fluorescence and Cell Imaging Application.

Fluorescence-tunable materials are becoming increasingly attractive because of their potential applications in optics, electronics, and biomedical technology. Herein, a multicolor molecular pixel system is realized using a simple copolymerization method. Bleeding of two complementary colors from blue and yellow fluorescence segments reproduced serious multicolor fluorescence materials. Interestingly, the emission colors of the polymers can be fine-tuned in the solid state, solution phase, and in hydrogel state. More importantly, the positive fluorescent polymers exhibited cell-membrane permeable ability and were found to accumulate on the cell nucleus, exhibiting remarkable selectivity to give bright fluorescence. The DNA/RNA selectivity experiments in vitro and in vivo verified that [tris(4-(pyridin-4-yl)phenyl)amine]-[1,8-dibromooctane] has prominent selectivity to DNA over RNA inside cells.

One bioprobe: a fluorescent and AIE-active macromolecule; two targets: nucleolus and mitochondria with long term tracking.

Specific organelle imaging and long-term cellular tracking are of paramount importance in monitoring biological processes, pathological pathways, and therapeutic effects, etc. Herein, we report a novel macromolecule fluorescent probe (TPPA-DBO), which is synthesized from tris(4-(pyridin-4-yl)phenyl)amine (TPPA) and 1,8-dibromononane (DBO) with a gram scale by a simple method. TPPA-DBO demonstrates a highly specific nucleolus-targeting ability, which is very challenging in the bioimaging research field. We have shown that the green nucleolus-specificity probe TPPA-DBO has advantages over the commercially available nucleolus-staining probes such as DAPI, Hoechst dyes and SYTOs in terms of its AIE-performance, large Stokes shift (175 nm), excellent photostability, and promising usefulness in live cell imaging experiments. Surprisingly, after internalizing TPPA-DBO into the nucleus region for a period of time, some TPPA-DBO are reversely diffused from nucleolus into the cytoplasm, thus resulting in the staining of mitochondria with a redder emission color. This research result may provide a new concept of cellular tracker design and provide insight into biological questions, understanding disease mechanismss, and designing new therapeutic strategies.

Aggregation-induced emission (AIE)-active fluorescent probes with multiple binding sites toward ATP sensing and live cell imaging.

Aggregation-induced emission (AIE)-active compounds are attractive fluorescent materials for applications in chemical and biological sensing. The AIE effect of such materials amplifies changes in the fluorescence signal due to the physical state transformation from aggregation to disaggregation, which can be employed for detecting various analytes with high sensitivity. In particular, specific bio-active analyte recognition is not only very interesting but also challenging. In this paper, we report a set of novel AIE-active fluorescent probes containing pyridiniums and boric acid groups (TPA-PP, TPA-PPA-1, TPA-PPA-2, TPA-PPA-3), which has been developed for adenosine 5'-triphosphate (ATP) recognition. These probes with two types of interaction modes and multiple connection sites toward ATP molecules are able to selectively discriminate ATP among other bioactive anions with a significant enhancement in fluorescence emission. In particular, in the application of cell imaging, as the number of positive charges and boric acid group increased further, the probes could penetrate into cells, and then enter into the nucleus very specifically. These results clearly demonstrate that the newly developed sensors are suitable for specific tracing of different cell organelles with a height visualization and retention ability. Therefore, all of them are confirmed as promising alternatives for live cell imaging in the future.

AIE-Active Tetraphenylethylene Cross-Linked N-Isopropylacrylamide Polymer: A Long-Term Fluorescent Cellular Tracker.

There is a great demand to understand cell transplantation, migration, division, fusion, and lysis. Correspondingly, illuminant object-labeled bioprobes have been employed as long-term cellular tracers, which could provide valuable insights into detecting these biological processes. In this work, we designed and synthesized a fluorescent polymer, which was comprised of hydrophilic N-isopropylacrylamide polymers as matrix and a hydrophobic tetraphenylethene (TPE) unit as AIE-active cross-linkers (DDBV). It was found that when the feed molar ratio of N-isopropylacrylamides to cross-linkers was 22:1, the produced polymers demonstrated the desirable LCST at 37.5 °C. And also, the temperature sensitivity of polymers could induce phase transfer within a narrow window (32-38 °C). Meanwhile, phase transfer was able to lead the florescent response. And thus, we concluded that two responses occur when one stimulus is input. Therefore, the new cross-linker of DDBV rendered a new performance from PNIPAm and a new chance to create new materials. Moreover, the resulted polymers demonstrated very good biocompatibility with living A549 human lung adenocarcinoma cells and L929 mouse fibroblast cells, respectively. Both of these cells retained very active viabilities in the concentration range of 7.8-125 µL/mg of polymers. Notably, P[(NIPAm)22-(DDBV)1] (P6) could be readily internalized by living cells with a noninvasive manner. The cellular staining by the fluorescent polymer is so indelible that it enables cell tracing for at least 10 passages.

Study of Red-Emission Piezochromic Materials Based on Triphenylamine.

Two conjugated molecules based on triphenylamine and 1,3-indandione have been synthesized by employing Knoevenagel condensation. Both materials demonstrated aggregation-induced emission behavior, and solvato- and piezochromic properties. These red luminescence materials are able to respond to F- and I- sensitively. The emission wavelength changed by almost 100 nm in the presence of F- and I- , and could be observed by the naked eye under daylight and UV light.

Water-Soluble Fluorescent Probes for Selective Recognition of Lysine and Its Application in an Object Carry-and-Release System.

A water-soluble fluorescent probe PEG-TPA-5' was synthesized, which shows an excellent selectivity to detect Lys in aqueous phase. An object carry-and-release system is established by applying PEG-TPA-5' as carrier and Lys as chemical stimulating source.