Seven heptapeptide derivatives have been prepared. The peptide structure is (Gly)₃Xxx(Gly)₃ in which Xxx stands for a variable amino acid. The amino acid variations include azetidine carboxylic acid, pipecolic acid, meta-aminobenzoic acid, proline, and leucine. All seven compounds have a C-terminal benzyl group. In all cases, the heptapeptide’s N-terminus was linked to diglycolic acid and a dialkylamine. In five cases, the N-terminal group was didecylamine and in two cases, N-ethyl-N-decyl. Chloride and carboxyfluorescein release from phospholipid vesicles was studied with the result that C₁₀H₂₁N(C₂H₅)COCH₂OCH₂CO–NH–(Gly)₃Leu(Gly)₃–OCH₂Ph was the most active. Hill analysis showed that this compound involves pore formation by four monomer units rather than two, as previously found for other members of this family.