The synthesis of the small pseudopeptide Boc-L-Phe-D-Imz-OBn (Imz = imidazolidin-2-one-4-carboxylate) is reported. Crystallization of this peptide from methanol, ethanol, and isopropanol leads to isostructural solvates when the solvent is methanol or ethanol with a peptide/solvent ratio of 2:1 and to an unsolvated polymorph in the case of isopropanol. The solvate peptide crystallizes forming infinite chains with the monomers in parallel orientation connected by a single hydrogen bond. The chains are arranged in antiparallel direction and cross-linked through the NH group of the imidazolidin heterocycle with formation of a stable two-dimensional (2D) network. Crystals from isopropanol form a different 2D network. The degree of order in the crystal assembly decreases from methanol and ethanol solvates to the unsolvated pseudopeptide grown from isopropanol. Quantum chemical calculations at the HF/6-31G* level of ab initio MO theory, carried out on the two different packings, show a slight preference for the unsolvated packing. ©2009 American Chemical Society.

A network of small molecules connected by cross-linked NH bonds

ANGELICI, GAETANO;
2010

Abstract

The synthesis of the small pseudopeptide Boc-L-Phe-D-Imz-OBn (Imz = imidazolidin-2-one-4-carboxylate) is reported. Crystallization of this peptide from methanol, ethanol, and isopropanol leads to isostructural solvates when the solvent is methanol or ethanol with a peptide/solvent ratio of 2:1 and to an unsolvated polymorph in the case of isopropanol. The solvate peptide crystallizes forming infinite chains with the monomers in parallel orientation connected by a single hydrogen bond. The chains are arranged in antiparallel direction and cross-linked through the NH group of the imidazolidin heterocycle with formation of a stable two-dimensional (2D) network. Crystals from isopropanol form a different 2D network. The degree of order in the crystal assembly decreases from methanol and ethanol solvates to the unsolvated pseudopeptide grown from isopropanol. Quantum chemical calculations at the HF/6-31G* level of ab initio MO theory, carried out on the two different packings, show a slight preference for the unsolvated packing. ©2009 American Chemical Society.
Angelici, Gaetano; Castellucci, Nicola; Contaldi, Simone; Falini, Giuseppe; Hofmann, Hans Jörg; Monari, Magda; Tomasini, Claudia
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/837874
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