Highly efficient one-pot assembly of peptides by double chemoselective coupling.

This study describes a methodological advancement in solution-phase peptide synthesis via the development of a convenient and operational protocol to synthesize oligopeptides in a one-pot three-step cascade method, in which two peptide bonds are introduced chemoselectively. Tri- to hexapeptides were obtained in high global yields (80-95%) with virtually no epimerization as determined via HPLC. The methodology described herein represents a faster, easier and milder approach to the synthesis of peptides, and it operates at equimolar amounts.

A novel generation of hybrid photochromic vinylidene-naphthofuran silica nanoparticles through fine-tuning of surface chemistry.

Novel photochromic 1-vinylidene-naphtho[2,1-b]furan derivatives (VNF-1 and VNF-2) were successfully anchored onto silica nanoparticles (SiO NPs) through direct adsorption (SiO@VNF-1) and covalent post-grafting (SiO@VNF-2). SiO NPs with different sizes (15 ± 3 and 123 ± 7 nm) and surface chemistry (pH in the range of 5-9) were used, offering a wide range of possibilities to fabricate tailor-made photochromic materials. The characterization of VNF-based SiO NPs confirmed the efficient VNF immobilization and the integrity of both organic and inorganic components.

Novel l-prolyl-l-leucylglycinamide (PLG) tripeptidomimetics based on a 2-azanorbornane scaffold as positive allosteric modulators of the DR.

An efficient and straightforward orthogonal methodology was successfully developed to achieve constrained l-prolyl-l-leucylglycinamide (PLG) analogues starting from two proline mimetics based on a 2-azanorbornane scaffold. A preliminary dopamine D receptor radiolabeled binding assay with [H]-N-propylnorapomorphine shows that enantiopurity of PLG peptidomimetics based on 2-azanorbornane is a requirement to achieve statistically significant positive modulators of the D receptor. This is the first documented active peptidomimetic of PLG whose bioactivity is not correlated with the C-terminal carboxamide pharmacophore and which cannot adopt the hypothesized type II β-turn conformation.

Screen-Printed Photochromic Textiles through New Inks Based on SiO@naphthopyran Nanoparticles.

Photochromic silica nanoparticles (SiO@NPT), fabricated through the covalent immobilization of silylated naphthopyrans (NPTs) based on 2H-naphtho[1,2-b]pyran (S1, S2) and 3H-naphtho[2,1-b]pyran (S3, S4) or through the direct adsorption of the parent naphthopyrans (1, 3) onto silica nanoparticles (SiO NPs), were successfully incorporated onto cotton fabrics by a screen-printing process. Two aqueous acrylic- (AC-) and polyurethane- (PU-) based inks were used as dispersing media. All textiles exhibited reversible photochromism under UV and solar irradiation, developing fast responses and intense coloration.

Naphthopyran-Based Silica Nanoparticles as New High-Performance Photoresponsive Materials.

Hybrid nanomaterials based on the covalent grafting of silylated naphthopyrans (NPTs) onto silica nanoparticles (SiO2 NPs) were successfully prepared and studied as new photochromic materials. They were prepared by a two-step protocol consisting of (i) NPTs (derivatives from 2H-naphtho[1,2-b]pyran (2H-NPT) and 3H-naphtho[2,1-b]pyran (3H-NPT)) silylation by a microwave-assisted reaction between hydroxyl-substituted NPTs and 3-(triethoxysilyl)propyl isocyanate, followed by (ii) covalent post-grafting onto SiO2 NPs. In order to study the role of the silylation step, the analogous non-silylated nanomaterials were also prepared by direct adsorption of NPTs.

New L-serine derivative ligands as cocatalysts for diels-alder reaction.

New L-serine derivative ligands were prepared and tested as cocatalyst in the Diels-Alder reactions between cyclopentadiene (CPD) and methyl acrylate, in the presence of several Lewis acids. The catalytic potential of the in situ formed complexes was evaluated based on the reaction yield. Bidentate serine ligands showed good ability to coordinate medium strength Lewis acids, thus boosting their catalytic activity.

The role of aromatic interactions in the structure and energetics of benzyl ketones.

A qualitative and quantitative energetic and structural study of dibenzyl ketone (DBK) and benzyl ethyl ketone (BEK) was carried out in order to obtain insights into the type and magnitude of aromatic interactions that these systems present in their different phases. The crystal structure of DBK was obtained by X-ray crystallography, and it shows that the conformation adopted in the crystalline state is governed by the intermolecular interactions. The standard (p(0) = 10(5) Pa) molar enthalpy of formation in the gaseous state at T = 298.

(1RS,4RS,5RS)-Methyl 2-(3,5-dinitro-benzo-yl)-2-oxa-3-aza-bicyclo-[3.3.0]oct-7-ene-4-carboxyl-ate.

The title compound, C(15)H(13)N(3)O(8), comprises two crystallographically independent mol-ecules in the asymmetric unit. In the crystal, intermolecular C-H⋯O hydrogen bonds link the molecules and short C=O⋯π contacts are seen.

Methyl 2-diphenyl-phosphor-yloxy-2-aza-bicyclo-[2.2.1]hept-5-ene-3-exo-carboxyl-ate.

In the title compound, C(20)H(20)NO(4)P, the dihedral angle between the phenyl rings is 68.52 (7)°. In the crystal structure, the mol-ecules are linked by a weak C-H⋯π(arene) inter-action along [010] involving the phenyl CH group and the phenyl rings.