Microporous Organic Materials from Hydrophobic Dipeptides

Abstract

In the last few years dipeptides with two hydrophobic residues (hydrophobic dipeptides) have emerged as an unexpected source of stable microporous organic materials. Supramolecular self-assembly of the rather small building blocks is dictated by stringent demands on the hydrogen-bond formation by the peptide main chains and the aggregation of hydrophobic entities in the side chains. A systematic survey of structures derived from single-crystal X-ray diffraction studies has revealed the existence of two large classes of structures, differing in the dimensionality of the hydrogen-bonding patterns in the crystals and the nature of the channels. The present review summarizes the structural properties of the microporous dipeptides and discusses their potential applications.

Hydrophobic dipeptide crystals: a promising Ag-free class of ultramicroporous materials showing argon/oxygen adsorption selectivity

“…We thus think that the size sequence of the three gases established from CMS adsorption experiments is also valid for dipeptide crystals. A lot has also been made of the possibility of using the chiral pores of dipeptide crystals to separate enantiomers 2,8 . However, in the context of adsorption of symmetrical molecules/atoms smaller than the pores, there is not reason to think that pore helicity and chirality influence adsorption.…”

“…The structure of these molecular crystals is stabilised by H-bonds and hydrophobic interactions, being essentially the same for all VA-class dipeptides. This crystal structure displays an array of identical, parallel unidimensional micropores 2,7 . The pore walls are formed by the aliphatic side-chains of the dipeptides, making the pores highly hydrophobic 1 .…”

“…The micropores are helical and have an approximately circular crosssection, somewhat uniform throughout the unit cell 4,7 . Nominal, average pore sizes of VA-class dipeptide crystals range from 0.37 nm to 0.50 nm 2,7 .…”

“…In this article, we report the adsorption isotherms and heats of adsorption of Ar, O2 and N2 in four crystalline dipeptides. The four dipeptides used have the smallest pores of the VA-class; VI, IA, IV and VV, having, respectively, 0.370, 0.374, 0.390 and 0.439 nm average crystallographic diameters 2 , corresponding, respectively, to porosities of 5.7, 6.0, 6.3 and 8.3 % (as determined from the crystal structure) 7 . The adsorbents show inverted Ar/O2 selectivity, a highly abnormal result, extremely interesting in the context of the very important industrial process of O2 production by pressure swing adsorption (PSA).…”

Self–Assembled Peptide Nanostructures for Biomedical Applications: Advantages and Challenges

“…This section offers only a brief description of the assembled structure, whereas a more detailed one of the self-organizing process from hydrophobic dipeptides can be found in , Gorbitz, 2007, 2001, 2006. , Gorbitz, 2007, 2001). backbone along with free amino-and carboxylic groups in either end of the molecule.…”