Conformational properties of the peptides containing (Δ(Z)Phe)6 with achiral (ΔAla, Gly) and chiral (Ala, Leu) residues at both the N- and C-terminal positions have been studied with a view to design a peptide with desired helical screw sense. In all the peptides, the lowest energy conformational state corresponds to Φ = 0° and Ψ = + 90° or - 90° or both +/- 90°. These structures are characterized by rise per residue of 1.94 Å; rotation per residue of 114° and 3.12 residues per turn and are stabilized by: (i) carbonyl-carbonyl interactions with the carbonyl oxygen of ith residue and carbonyl carbon atom of the carbonyl group of ith+1 residue; and (ii) N-H....π interactions between the amino group of Δ(Z)Phe and its own aromatic moiety. The Ala/Leu residues at the N-terminus further stabilized the structure, through C-H....π interactions with the farthest edge of the aromatic ring of ith+3 Δ(Z)Phe residue. For peptides Ac-L-Ala/L-Leu-(Δ(Z)Phe)6-NHMe, the low energy left handed helical structure (approximately 2.5 Kcalmol⁻¹ higher in energy) state corresponds to Φ = -30°, Ψ = 120° for L-residue and Φ = Ψ = 30° for Δ(Z)Phe residues and is in good agreement with the X-ray crystallography results for the peptide Boc-L-Ala-(Δ(Z)Phe)4-NHMe crystals grown from acetonitrile/ethanol mixture. Computational results suggest that the peptides Ac-DAla/D-Leu-(Δ(Z)Phe)6-NHMe adopt a right handed helical structure in polar solvents with Φ = 30°, Ψ = -120° for D-residues and Φ = Ψ = -30° for Δ(Z)Phe residues. Both in the left handed and right handed structures, the carbonyl oxygen of acetyl group is involved in 10-membered hydrogen bonded ring formation with NH of 3rd Δ(z)Phe residue whereas Δ(Z)Phe residues backbone adopts a 3₁₀ helix structure. Computational results also suggest that the conformational state with Φ = 0° and Ψ = 90° can be realized by keeping D-Ala or D-Leu at the C-terminal. There is hardly any effect of achiral residues Gly/ΔAla on the conformational behaviour of poly-Δ(Z)Phe.