Electron-donating moiety

There are dozens of linkers available for synthesis, and nearly all of them, once acylated by a protected amino acid, provide a benzyl ester or a benzyl amide that has been sensitized to cleavage by acid by the presence of electron-donating moieties such as alkoxy, phenyl, or substituted phenyl. There are cases in which a peptide chain is bound to a support through two different linkers in series. This allows for versatility in synthesis. The distinction between designation of a moiety affixed to a support as a handle or linker is sometimes arbitrary. 

In the context of oligo-fluorene (oFL) molecular wires, we will conclude with an outlook that focuses on donor-acceptor conjugates bearing Ceo electron-accepting units and zinc porphyrin (ZnP) or ferrocene (Fc) electron-donating moieties, respectively. Both, the donor and acceptor are covalently connected by oFL bridges of variable length. 

Table XIII gives typical examples of 7t-barriers for planar heterocycles comparing the electron-attracting or electron-donating moiety to push-pull ethylenes. Steric effects destabilize the ground state and thus greatly reduce the 71-barriers to rotation. In these push-pull ethylenes the large entropy of activation and solvent effects hampered easy comparison of the barriers without high-quality determination of the activation parameters.

K, k —> k, % However, it can be rationalized by the formation of an intramolecular charge transfer state between the dihydropynyl ring (ring A, electron-donating moiety) and the anhydride structure (ring B, electron-accepting moiety) in the... 

The interaction of the hard, Lewis acidic Ln(III) centers with neutral electron-donating moieties is a ubiquitous feature of organolanthanide complexes. In addition to the electron deficiency of the lanthanide center, steric unsaturation directs this stabilization of the complexes via adduct formation. 

Electron-withdrawing side chains are able to withdraw electron density firom TT-conjugated backbones and the energy level of the material is lowered. Similar to electron-donating moieties, electron-withdrawing side chains can also generate intramolecular interactions. 

MPs are widely applied to supramolecular SCs as electron-donating moieties because of their outstanding convenience of use as building blocks . That is, they can be used in the form of single molecules, dimers, oligomers, liquid crystals, or polymers. The acceptor moieties most commonly used in supramolecular SCs include carbon nanomaterials, such as fuUerenes and carbon nanombes (CNTs). 

The inner surfaces of the pillar[5]- and pillar[6]arene cavities are negative because alkojq groups on the rims are electron-donating moieties. Compared with an open-ended calix[5]arene structure, their pillar-shaped structures contribute to enhance the 7t-electron density of their cavity. Therefore, pillar[5]- and pillar[6]arenes prefer to accommodate electron-poor molecules, such as cationic molecules and molecules containing electron-with-drawing groups, in their cavities. ... 

To decrease to the Schottky barrier for electron injection in LEDs, compounds with electron donating moieties and carboxylic acid alligator clips... 

In cationic polymerizations, electron-deficient initiators (mostly Bronsted or Lewis acids) react with electron-rich monomers. The active chain end (ACE) bears a positive charge with the active sites being either carbenium or 0x0-nium ions. Molecular weights are often limited by the inherent sensitivity to impurities, chain transfer, and rearrangement reactions. Suitable monomers for cationic polymerizations are vinyl monomers with electron-donating moieties or cyclic structures containing heteroatoms, while the latter case is termed cationic ROP. Eligible monomers include cyclic ethers, acetals, and amines as well as lactones and lactams (Scheme 3). 

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