Synthesis and Microbiological Properties of Novel Bis-Quaternary Ammonium Compounds Based on Biphenyl Spacer

Novel gemini (tail‐head‐spacer‐head‐tail) bis‐quaternary ammonium compounds (bis‐QACs) with a biphenyl spacer between two pyridinium heads were synthesized and compared with commonly used antiseptics such as benzalkonium chloride (BAC) and chlorhexidine digluconate (CHG). The series of compounds showed high inhibitory activity against five bacterial strains and two fungi. The compounds, which contain C₈H₁₇‐C₁₀H₂₁ aliphatic tails best within the series. A counterion change does not affect MIC in general. Cytotoxicity on human embryonic kidney cells and haemolysis were also investigated. For bis‐QACs cytotoxic effect was lower than for 3,3′‐[1,4‐phenylenebis(oxy)]bis(1‐dodecylpyridinium) dibromide (3PHBO‐12), that is their closest structural analogue, and for BAC.