Intramolecular potentials

The amino acid sequence of our first aPNA (which we termed backbone 1 or bl) was designed based on this amphipathic hehx sequence (Fig. 5.3 B). Specifically, this aPNA backbone included hydrophobic amino acids (Ala and Aib), internal salt bridges (Glu-(aa)3-Lys-(aa)3-Glu), a macrodipole (Asp-(aa)i5-Lys), and an N-ace-tyl cap to favor a-helix formation. The C-termini of these aPNA modules end in a carboxamide function to preclude any potential intramolecular end effects. Each aPNA module incorporates five nucleobases for Watson-Crick base pairing to a target nucleic acid sequence. 

An experimental probe for the presence of radical intermediates resulting from thermally induced homolytic cleavage of the N-0 bond was derived by incorporating an alkene into a model substrate to act as a potential intramolecular radical trap (Scheme 6.25) [11]. In a control experimental, thermal reaction of 73 gave the desired product 74 in 66% isolated yield. On the other hand, thermal rearrangement of the unsaturated compound 75 under our typical conditions gave the desired hydroxypyrimidinone 76 in only 38% isolated yield. When the vinyl ami-doxime mixture 75Z/E was heated in o-xylene at 125 °C in the presence of a... 

The last question still open addresses the alkynyl ketones. The reaction of 64 shows an example with a potential intramolecular competition and here it is possible to isomerize the propargyl substitutent on the ketone quantitatively without changing the 1-hexynyl substituent on the other side [125] (Scheme 1.28). From the publication it is not clear whether the isomerization is really a thermal reaction or occurs during the workup of the thermolysis reaction, for example by chromatography (compare the discussion above [110]). 

It is rather surprising that only a few diorganomagnesium compounds have been reported in which intramolecular coordination of a heteroatom-containing substituent is present. The synthesis of (2-Me2NCH2C6H4)2Mg (67) was reported. It has been used in a study on the infiuence of the presence of potentially intramolecular coordinating substituents on Schlenk equilibria However, it has never been structurally characterized. 

FIGURE 16.3 Potential intramolecular hydrogen bonding vtMhMannich bases. 

Here we review our work aimed at correlating the reactivity of a series of M(II) N4-ligands, see Figure 12.1, (M = Co, Fe, Mn and N4 = porphyrin (P), phthalocyanine (Pc), teraphenylporphyrin (TPP), tetrabenzoporphyrin (TBP) and tetraazaporphyrin (TAP)) towards the electrocatalytic oxidation of 2-mercaptoethanol. Different effects will be analysed, namely the role of the metal atoms, the role of the N4 functionalisation, solvent and the impact of the adsorption on the electrode on the electrochemical activity. The whole machinery of DFT and the notions of hardness, chemical potential, intramolecular hardness and elec-trophilicity are used to better quantify these effects and discriminate between the examined molecular complexes. 

From theory ii) Specific -dependent Raman activity peculiar of polycon jugated molecules ( just discussed in this work) must be located, iii) the shape of the phonon dispersion curves should be known. Indeed the appearance of distinct frequencies for A1/A2 and E modes is possible only if phonon branches are significantly dispersed, i.e. if kinetic and potential intramolecular coupling occurs between neighbouring chemical units. Dispersion curves for the in-plane phonons have been calculated for a PTh chain in trans planar conformation (D2h symmetry) with two different approaches. The group of Milano has calculated with a force field which takes into account the effec-... 

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