Design of Peptides that Fold and Self-Assemble on Graphite.

The graphite-water interface provides a unique environment for polypeptides that generally favors ordered structures more than in solution. Therefore, systems consisting of designed peptides and graphitic carbon might serve as a convenient medium for controlled self-assembly of functional materials. Here, we computationally designed cyclic peptides that spontaneously fold into a β-sheet-like conformation at the graphite-water interface and self-assemble, and we subsequently observed evidence of such assembly by atomic force microscopy.

Thermodynamics of Adsorption on Graphenic Surfaces from Aqueous Solution.

Adsorption of organic molecules from aqueous solution to the surface of carbon nanotubes or graphene is an important process in many applications of these materials. Here we use molecular dynamics simulation, supplemented by analytical chemistry, to explore in detail the adsorption thermodynamics of a diverse set of aromatic compounds on graphenic materials, elucidating the effects of the solvent, surface coverage, surface curvature, defects, and functionalization by hydroxy groups. We decompose the adsorption free energies into entropic and enthalpic components and find that different classes of compounds-such as phenols, benzoates, and alkylbenzenes-can easily be distinguished by the relative contributions of entropy and enthalpy to their adsorption free energies.

1,3-Bis{()-[4-(di-methyl-amino)-benzyl-idene]amino}-propan-2-ol: chain structure formation an O-H⋯N hydrogen bond.

The asymmetric unit of the title compound, CHNO, consists of two unique mol-ecules linked by an O-H⋯N hydrogen bond. The conformation of both C=N bonds is and the azomethine functional groups lie close to the plane of their associated benzene rings in each of the independent mol-ecules. The dihedral angles between the two benzene rings are 83.

Crystal structure of 1,3-bis-[()-benzyl-idene-amino]-propan-2-ol.

In the title compound, CHNO, the central carbon atom with the OH substituent and one of the ()-benzyl-idene-amino substituents are disordered over two sets of sites with occupancies of 0.851 (4) and 0.149 (4).

Determinants of Alanine Dipeptide Conformational Equilibria on Graphene and Hydroxylated Derivatives.

Understanding the interaction of carbon nanomaterials with proteins is essential for determining the potential effects of these materials on health and in the design of biotechnology based on them. Here we leverage explicit-solvent molecular simulation and multidimensional free-energy calculations to investigate how adsorption to carbon nanomaterial surfaces affects the conformational equilibrium of alanine dipeptide, a widely used model of protein backbone structure. We find that the two most favorable structures of alanine dipeptide on graphene (or large carbon nanotubes) correspond to the two amide linkages lying in the same plane, flat against the surface, rather than the nonplanar α-helix-like and β-sheet-like conformations that predominate in aqueous solution.

Crystal structure of 1,3-bis-[()-4-meth-oxy-benzyl-idene-amino]-propan-2-ol.

The title Schiff base, CHNO, was synthesized the condensation reaction of 1,3-di-amino-propan-2-ol with 4-meth-oxy-benzaldehyde using water as solvent. The mol-ecule exists in an , conformation with respect to the C=N imine bonds and the dihedral angle between the aromatic rings is 37.25 (15)°.

Crystal structure of 1,3-bis-(3--butyl-2-hy-droxy-5-methyl-benz-yl)-1,3-diazinan-5-ol monohydrate.

In the title hydrate, CHNO·HO, the central 1,3-diazinan-5-ol ring adopts a chair conformation with the two benzyl substituents equatorial and the lone pairs of the N atoms axial. The dihedral angle between the aromatic rings is 19.68 (38)°.

1,3-Bis(3-tert-butyl-2-hy-droxy-5-meth-oxy-benz-yl)hexa-hydro-pyrimidin-5-ol monohydrate.

The asymmetric unit of the title compound, C28H42N2O5·H2O, consists of one half of the organic mol-ecule and one half-mol-ecule of water, both of which are located on a mirror plane which passes through the central C atoms and the hydroxyl group of the heterocyclic system. The hydroxyl group at the central ring is disordered over two equally occupied positions. The six-membered ring adopts a chair conformation, and the 2-hy-droxy-benzyl substituents occupy the sterically preferred equatorial positions.