Fig. 3: NHC formation studies with OIM1-6-CH (1). | Nature Communications

Fig. 3: NHC formation studies with OIM1-6-CH (1).

From: Carbene formation as a mechanism for efficient intracellular uptake of cationic antimicrobial carbon acid polymers

Fig. 3

A Detection of NHC by the reaction of some carbene (II) monomers with D2O or AuCl(SMe2). B Hydrogen-deuterium exchange in 1H NMR of OIM1-6-CH (1) in aqueous solution as a function of time at pH 6.63, pH 6.81, pH 7.16, and pH 8.21 in D2O. C Schematic of interaction of phosphatidylcholines/phosphatidylglycerol (PC/PG) liposome containing NHC probes (carbazole dye or AuCl(SMe2) or TCNQ) with OIM-1-6-CH (1). Created in BioRender. Chan, M. (2025) https://BioRender.com/srca3b3. D Fluorescence of carbazole embedded in liposome bilayer with OIMs or stable carbene (IPr) in solution. E–H Proof of NHC formation by OIM (1) using AuCl(SMe2) embedded in liposome bilayer and LC-MS/MS: E Total ion chromatogram (TIC) of Au(lipids)-OIM1-6-CH (1) obtained by LC-ESI-MS (+). F Extracted ion chromatogram (EIC) of (i) OIM1-6-CH (m/z 199.15), and (ii) Au-OIM1-6-CH containing one Au atom (m/z 330.52) (both at pH 7.4). G Assigned chemical structures of (i) m/z = 199.15 to be OIM1-6-CH (1) containing 4 cations and 2 NHCs, (ii) m/z = 330.52 to be 1Au-OIM1-6-CH containing 1Au-NHC cation, 2 imidazolium cations (without Au), and 3 NHCs. H Mass spectrum (MS) of (i) m/z = 199.15 (retention time 3.55 min) with m/z difference of 0.25 Da, indicating z = 4, and total ion mass = 796.60, and (ii) m/z 330.52 (retention time 4.04 min) with m/z difference of 0.33 Da, indicating z = 3, and total ion mass = 991.56. (I) Electron paramagnetic resonance (EPR) signals of OIM1-6-CH (1) added to TCNQ(lipids) in PBS at (i) pH 7.4 and at (ii) pH 6.6.

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