A small-size crown either ring, 1,4,8,11-tetraoxacyclotetradecane, which is generally called 14-crown-4, is highly selective for lithium ion. Modification of the 14-crown-4 ring brings about enhanced lithium ion selectivities and attractive functionalities. The 14-crown-4 derivatives are excellent lithium ionophores for ion sensors, spectrophotometry, flow injection analysis, and membrane separation.