Synthesis of pyridinium-based fluorescence compounds with different counter anions and their piezochromism property and antimicrobial activity

In the field of organic chemistry, synthesizing fluorescence compounds with multiple emission colors is an interesting but great challenging work, which usually requires several tedious steps and is also costly less effective, time-consuming et al. In this contribution, pyridinium-based fluorescence compounds (named as TPB/anion derivatives) were obtained by simply replacing the accompanied anions at room temperature. It was found that the anions totally managed the optical performance of the TPB core, leading to the products with emission wavelength located from 479 to 594 nm in their solid state. Meanwhile, due to the very twisted conformation and intramolecular electron donating (D) and accepting (A) interaction, these TPB/anion derivatives were highly sensitive to the external force, demonstrating the smart behavior of piezochromism property. Hereof, we convinced that the interactions between the negative counter-ion with TPB framework makes great contribution to the multiple emission colors and piezochromism property. Beyond that, three TPB/anion derivatives were successfully employed as antimicrobial materials due to the positively charged skeleton (used as anchor to the bacteria membrane) and excellent reactive oxygen species (ROS) generating capability, this synergetic antimicrobial activity is extremely favorable to overcome the drug resistance in the future. What should be noted that the used TPB/anion derivatives are of excellent selectivity of bacteria killing performance to Methicillin-resistant S. aureus rather than E. coli, E. faecalis and P. aeruginosa. T., the preliminary research result confirmed the better affinity between the TPB derivatives with Methicillin-resistant S. aureus played an important role for the effective antimicrobial activity.