C–H⋯O hydrogen bonding in a 4-fluorobenzoate multilayer induced by silver nanoparticles

SERS, SEIRA, and DFT calculations showed silver nanoparticles can stimulate C–H⋯O hydrogen bonding in 4-fluorobenzoate ion/n-heptane multilayers. SERS/DFT demonstrated that 4-fluorobenzoic acid (4FBA) adsorbed as a 4-fluorobenzoate (4FBT) monolayer on nanosilver. Ionization of 4FBA to 4FBT occurred in the multilayer when 4FBA was deposited in n-heptane onto nanosilver. Frequency shifts in SEIRA bands of 4FBT COO stretch and n-heptane CH bend modes illustrated a change in the degree of C–H⋯O hydrogen bonding as more 4FBT/n-heptane was adsorbed to the multilayer. This work will influence many research areas such as sensors formed from thin organic layers on metal nanoparticles.