nonsolvated

Nonsolvated refers to a chemical species that exists without coordination or association with solvent molecules. In solution chemistry, most solutes are surrounded by solvent molecules forming a solvation shell, so a truly nonsolvated ion or molecule in liquid solution is typically transient or not present under ordinary conditions. Nonsolvated species are more commonly discussed in contexts where no solvent or only negligible solvent interactions are present.

Contexts where nonsolvated species appear include the gas phase, matrix isolation, or solvent-free environments. In the gas phase, ions, electrons, and neutral molecules can exist with no solvent shell. In mass spectrometry, desolvation steps aim to remove solvent molecules to produce nonsolvated ions for measurement, and these species often differ in reactivity and stability from their solvated counterparts. Nonsolvated ions can also arise in ultra-dilute or nonpolar solvents where solvent–solute interactions are weak, but such cases are less common than in the gas phase.

Properties of nonsolvated species differ from solvated ones, typically being higher in energy and more reactive due to the absence of stabilizing solvent interactions. They tend to rapidly become solvated or react if they encounter available ligands or solvent molecules. In cluster chemistry and catalysis, nonsolvated fragments can serve as reactive intermediates before solvent coordination occurs.

See also solvation, hydration shell, desolvation, and bare ion.