The mass spectra of potential antidiabetics: 4-Arylhydrazono-3-methyl isoxazol-5-ones and pyrazol-5-ones

The mass spectra of variously substituted 4-arylhydrazono-3-methyl isoxazol-5-ones and pyrazol-5-ones have been examined, and the fragmentation pathways elucidated. The spectra of the former compounds differ from previously reported 4-arylidene derivatives and this difference has been attributed to fragmentation involving the ? NH? N?moiety. The investigation has shown up some interesting ‘ortho effects’ as well as the facile loss of HN?C?NH from N-amidino derivatives of the pyrazol-5-ones.     

The mass spectra of 2-aryl-4-arylidene-oxazol-5-ones,and the related thiazol-5-ones and imidazol-5-ones

Examination of the mass spectra of a series of substituted oxazol-5-ones and other related heterocycles showed no evidence of electron-impact induced isomerism. The electron-impact fragmentations of these compounds were characterized by a single dominant fragmentation process.     

Photoinduced work function changes by isomerization of a densely packed azobenzene-based SAM on Au: a joint experimental and theoretical study

Responsive monolayers are key building blocks for future applications in organic and molecular electronics in particular because they hold potential for tuning the physico-chemical properties of interfaces, including their energetics. Here we study a photochromic SAM based on a conjugated azobenzene derivative and its influence on the gold work function (Φ(Au)) when chemisorbed on its surface. In particular we show that the Φ(Au) can be modulated with external stimuli by controlling the azobenzene trans/cis isomerization process. This phenomenon is characterized experimentally by four different techniques, kelvin probe, kelvin probe force microscopy, electroabsorption spectroscopy and ultraviolet photoelectron spectroscopy. The use of different techniques implies exposing the SAM to different measurement conditions and different preparation methods, which, remarkably, do not alter the observed work function change (Φ(trans)-Φ(cis)). Theoretical calculations provided a complementary insight crucial to attain a deeper knowledge on the origin of the work function photo-modulation.     

N-terminus 4-Chloromethyl Thiazole Peptide as a Macrocyclization Tool in the Synthesis of Cyclic Peptides: Application to the Synthesis of Conformationally Constrained RGD-Containing Integrin Ligands

The synthesis of conformationally constrained RGD-containing integrin ligands via an efficient solid-phase intramolecular thioalkylation reaction is described. The reaction of S-nucleophiles with newly generated N-terminal 4-chloromethyl thiazoles leads to the desired cyclic RGD products 5 in high purities and good overall yields.