A Deep-Red Emissive Sulfur-Doped Double [7]Helicene Photosensitizer: Synthesis, Structure and Chiral Optical Properties.

Doping of polycyclic conjugated hydrocarbons (PCHs) with sulfur atoms is becoming more and more important as a means of creating unique functional materials. Recently, thiophene-containing multiple helicenes have garnered enormous attention due to their intriguing electronic and (chir)optical properties compared with carbohelicenes. However, the efficient synthesis of thiopyran-containing multiple helicenes and the underlying sulfur doping mechanisms are rather unexplored. Herein, the synthesis and structural analysis of a thiopyran-containing double [7]helicene 3 are reported. X-ray crystallographic analysis reveals 3 and its dication with C2-symmetric propeller-shape structure and compact p-p interaction in the solid state. 3 exhibits deep-red to near-infrared (NIR) fluorescence emission. Tunable aromaticity of the central benzene ring and thiopyran rings is found by chemical oxidation, which is further confirmed by nucleus-independent chemical shift (NICS), anisotropy of the induced current density (AICD) and harmonic oscillator model of aromaticity (HOMA) analysis. Furthermore, the chiral and photosensitizing characters of 3 are investigated. The excellent deep-red to NIR fluorescence, circularly polarized luminescence (CPL) and photosensitizing activities suggest that 3 can be used as an outstanding photosensitizer in photodynamic therapy (PDT) and bioimaging, especially paving the way for future CPL-PDT and CPL-bio-probe applications.

Visible-light-driven photocatalytic degradation of ibuprofen by Cu-doped tubular C3N4: Mechanisms, degradation pathway and DFT calculation.

The copper-modified tubular carbon nitride (CTCN) with higher specific surface area and pore volume was prepared by a simple in-situ hydrolysis and self-assembly. Increased ∼4.7-fold and ∼2.3-fold degradation rate for a representative refractory water pollutant (Ibuprofen, IBP) were achieved with low-energy light source (LED, 420 ± 10 nm), as compared to graphitic carbon nitride (GCN) and tubular carbon nitride (TCN), respectively. The high efficiency of IBP removal was supported by narrow band gap (2.15 eV), high photocurrent intensity (1.10 µA/cm2) and the high surface -OH group (14.75 µg/cm3) of CTCN. According to analysis of the various reactive species in the degradation, the superoxide radical (•O2-) played a dominant role, followed by •OH and h+, responsible for IBP degradation. Furthermore, Fukui functions were employed to predict the active sites of IBP, and combined with the HPLC-MS/MS results, possible mechanisms and pathways for photocatalytic degradation were indicated. This study will lay an important scientific foundation and a possible new approach for the treatment of emerging aromatic organic pollutants in visible-light-driven heterogeneous catalytic oxidation environment.