Pyridinium-Substituted TetraphenylethyleneEntailing Alkyne Moiety: Enhancement of Photosensitizing Efficiency and Antimicrobial Activity.

Apart from sensing and imaging, luminogens with aggregation-induced emission (AIE) are also interesting for photosensitizing. The photosensitizing behavior and bacteria-killing performance of a pyridinium-substituted tetraphenylethylene with an alkyne group ( TPE-A-Py⁺) is reported herein. Interestingly, TPE-A-Py⁺ exhibits higher photosensitizing efficiency than TPE-Py⁺ (without alkyne group) when I⁻ was used as a counteranion. This is well explained by the fact that the Δ Ε_ST between the excited singlet state ( S₁) and triplet state ( T₁) was lower for TPE-A-Py⁺ than for TPE-Py⁺, according to theoretical calculations. Moreover, replacement of I⁻ with other anions (PF₆⁻, N(SO₂CF₃)₂⁻ and BPh₄⁻) led to a decrease of photosensitizing efficiency for TPE-A-Py⁺. Notably, TPE-A-Py⁺ could be used as an efficient photosensitizer to photo-inactivate ampicillin-resistant (amp^r) E. coli at low concentration under white-light irradiation very quickly. [ABSTRACT FROM AUTHOR]