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The development of straightforward and efficient synthetic methods toward ring-fused heteroaromatic polymers with attractive functionalities has great significance in both chemistry and materials science. Herein, we develop a facile cascade C-H-activated polyannulation route that can in situ generate multiple ring-fused aza-heteroaromatic polymers from readily available monomers in an atom-economical manner. A series of complex polybenzimidazole derivatives with high absolute molecular weights of up to 24000 are efficiently produced in high yields within 2 hours. Benefiting from their unique imidazole-containing ring-fused structures with multiple aryl pendants, the obtained polymers show excellent thermal and morphological stability, good solution processability, high refractive index, small chromic dispersion, as well as remarkable acid-base-responsive fluorescence. Taking advantage of the ratiometric fluorescence response of the triphenylamine-substituted heteroaromatic polymer to pH variations, we successfully apply it as a sensitive fluorescence probe for the mapping and quantitative analysis of intracellular pH changes in live cells. Furthermore, through the simple N-methylation reaction of the ring-fused polybenzimidazoles, diverse azonia-containing polyelectrolytes are readily produced, which can efficiently kill cancer cells via the synergistic effects of dark toxicity and photo-toxicity.

As two important subcellular organelles in eukaryotic cells, the Golgi apparatus (GA) and endoplasmic reticulum (ER) have recently captivated much interest due to their considerable importance in many biofunctions and role as critical biomarkers for various diseases. The development of efficient GA- and ER-specific probes is of great significance, but remains an appealing yet significantly challenging task. Herein, we reported for the first time the construction of an aggregation-induced emission (AIE) platform for GA and ER fluorescent probes, termed as AIE-GA and AIE-ER, by facile synthesis and simple functionalization. Their excellent targeting specificity to GA or ER, remarkable photostability, high brightness, and low working concentration make AIE-GA and AIE-ER significantly impressive and superior to commercially available probes. Moreover, molecular docking calculations are performed to validate the targeting mechanism of the two AIE probes., As two important subcellular organelles in eukaryotic cells, the Golgi apparatus (GA) and endoplasmic reticulum (ER) have recently captivated much interest due to their considerable importance in many biofunctions and role as critical biomarkers for various diseases.

A mitochondrial pH sensing fluorescent probe namely 2-(2-(6-hydroxynaphthalen-2-yl)vinyl)-3-(6-(triphenyl-phosphonio)hexyl)benzothiazol-3-ium bromide (HTBT2) was designed and facilely synthesized via the Knoevenagel condensation reaction. HTBT2 displayed a linear fluorescence enhancement at 612 nm in response to pH changes between 8.70 and 7.20. The pKa value was determined to be 8.04 ± 0.02, which might be ideal for mitochondrial pH (pHmito ∼8.0) detection. HTBT2 also exhibited a remarkable large Stokes shift of 176 nm, which could diminish the interference of excitation light. The results of live cell imaging studies suggested that HTBT2 showed excellent targeting ability for mitochondria. Importantly, it was successfully applied to visualize mitochondrial pH changes in live cells and differentiate the pHmito difference between cancer cell lines and normal cell lines. Our results consistently supported that HTBT2 held practical promise for the investigation of physiological processes related to pHmito changes and clinical potential for cancer cell differentiation.

A facile Schiff-base ligand 8-hydroxyjulolidine-pyridyl hydrazone ( L ) as the fluorescent probe was synthesized and characterized. L was selective toward Al3+ ions with a visible color change from pale-to-yellow and fluorescence enhancement at 480 nm. L forms complex with Al3+ in 1:1 ratio as supported by Job’s plot analysis and ESI-MS. The binding mode was further confirmed by 1H NMR titrations. The detection limit was calculated to be 8.22×10−8 M for Al3+. These merits of L , i.e., requiring facile one-step synthesis and displaying high sensitivity make L a promising candidate as a chemosensor for Al3+ion.

A facile, economical and green one-step hydrothermal method for N-doped CDs is presented by using citric acid as carbon source and urea as nitrogen source. The as-prepared N-doped CDs possess an average size of 5.23 nm and exhibit a high fluorescent quantum yield of 25.4%, good water solubility, and excellent photostability. The fluorescence of N-doped CDs may be quenched dramatically from curcumin via the inner filter effect. The sensitive detection method of curcumin in aqueous solution was developed with the linear range of 2.0 × 10−7 to 1.0 × 10−5 mol L−1 and detection limit of 8.48 × 10−8 mol L−1 (S/N = 3). The other common ions and related compounds could not interfere with the detection of curcumin enabling good selectivity. The proposed method was successfully applied to the determination of curcumin in urine samples and the recoveries were 95.71–103.81%.