Synthesis, crystallization, X‐ray structural characterization and solid‐state assembly of a cyclic hexapeptoid with propargyl and methoxyethyl side chains. Issue 3 (1st June 2017)

• Record Type: Journal Article
• Authors: Tedesco, Consiglia; Macedi, Eleonora; Meli, Alessandra; Pierri, Giovanni; Della Sala, Giorgio; Drathen, Christina; Fitch, Andrew N.; Vaughan, Gavin B. M.; Izzo, Irene; De Riccardis, Francesco
• Is Part Of: Acta crystallographica. Volume 73:Issue 3(2017:Jun.)
• Page Start: 399
• Page End: 412
• Publication Date: 2017-06-01
• Subjects: cyclic peptoids -- solid‐state assembly -- single‐crystal X‐ray diffraction -- Rietveld refinement
• DOI: 10.1107/S2052520617002505
• Languages: English
• ISSNs: 2052-5206

Abstract

Abstract : The synthesis and the structural characterization of a cyclic hexapeptoid with four methoxyethyl and two propargyl side chains allows a discussion of the solid‐state assembly of a hydrate crystal form (I) and an anhydrous crystal form (II). The relative amounts of forms (I) and (II) in the as‐purified product were determined by Rietveld refinement and depend on the purification procedures. Abstract : The synthesis and the structural characterization of a cyclic hexapeptoid with four methoxyethyl and two propargyl side chains have disclosed the presence of a hydrate crystal form [form (I)] and an anhydrous crystal form [form (II)]. The relative amounts of form (I) and form (II) in the as‐purified product were determined by Rietveld refinement and depend on the purification procedures. In crystal form (I), peptoid molecules assemble in a columnar arrangement by means of side‐chain‐to‐backbone C=CH…OC hydrogen bonds. In the anhydrous crystal form (II), cyclopeptoid molecules form ribbons by means of backbone‐to‐backbone CH2 …OC hydrogen bonds, thus mimicking β‐sheet secondary structures in proteins. In both crystal forms side chains act as joints among the columns or the ribbons and contribute to the stability of the whole solid‐state assembly. Water molecules in the hydrate crystal form (I) bridge columns of cyclic peptoid molecules, providing a more efficient packing.