Chain intramolecular

Intermolecular chain transfer reactions may occur between two propagating polymer chains and result in the termination of one of the chains. Alternatively, these reactions take place by an intramolecular reaction by the coiling of a long chain. Intramolecular chain transfer normally results in short branches ... 

When the two monomers are linked by a short flexible chain, intramolecular excimers can be formed. This process is still diffusion-controlled, but in contrast to the preceding case, it is not translational it requires a close approach between the two molecules via internal rotations during the excited-state lifetime. Equations (4.44), (4.45), (4.47) to (4.49) are still valid after replacing k [M] by k because intramolecular excimer formation is independent of the total concentration. Estimation of the local fluidity of a medium can be achieved by means of probes capable of forming intramolecular excimers (see Chapter 8). 

Wall et al. built a binuclear copper(II) complex 43 in order to see acceleration of phosphodiester cleavage (52). With the substrate (50 p.M) shown, the reaction might be considered as a model for the first step of the hydrolysis of RNA, in which the alcohol function of the side chain intramolecularly attacks the Cun-activated phosphate as a nucleophile for a ring closure reaction. Compared to an analogous mononuclear complex 44 (at 1 mM), a rate constant ca. 50 times larger for 43 (at 1 mM) was observed at 25°C and pH 7, implying that the two metal ions probably cooperate. An analogous zinc(II) complex 45 was reported only as a structural model for the active site of phospholi-... 

Recent theory suggests that cyclization phenomena (1) are much more sensitive to excluded volume effects than other properties of polymer chains. Intramolecular fluorescence quenching processes in molecules containing appropriate end groups permit one to study both the dynamics and thermodynamics of end-to-end cyclization. As a consequence, the sensitivity of polymer cyclization to excluded volume can be examined. 

Monodisperse assembly of homogeneous chains intramolecular structure function and form function... 

To study selectively the effect of primary and secondary molecular motions on thrombogenesis, the PNF was subjected to low-dose ultraviolet irradiation the same dose rate as used in the extracorporeal studies. It was anticipated that this low-dose treatment would selectively cross-link the pendant side chains intramolecularly, followed by intramolecular/intermo-lecular cross-linking at higher dose rates. 

FIGURE 2 (A) Toilet roll representation of the main-chain intramolecular hydrogen... 

Suzaki, Y., Osakada, K., 2003. Cyclization of dinuclear aryl- and aroylpalladium complexes with the metal centers tethered by an oUgo(ethylene oxide) chain. Intramolecular transmetalation of the cationic dinuclear arylpalladium complexes. Organometalhcs 22,2193-2195. 

Physico-chemical behaviour in aqueous solution was studied by viscosity measurements. Expected associative behaviour has been evidenced in pure water, while in salt media, the associative behaviour strongly depends on PCL chains length. For shorter PCL chains, intramolecular hydrophobic interactions are predominant, even in the semi-dilute regime. This non-classical behaviour for an associative polyelectrolyte opens the way to the conception of amphiphilic matrices with hydrophobic clusters for controlled release applications. 

Cationic and anionic polymerizations of heterocyclic monomers provide many examples in which the concurrent formation of cyclics of various sizes is observed during the ring-opening polymerization. As illustrated in Scheme 1, in these systems active species follow three pathways they can react with a functional group of the monomer, of its own polymer chain, or of other chains. When the function / involved belongs to a linear polymer chain, intramolecular chain saambling or intermolecular macrocycle formation takes place, as observed in the cationic polymerization of cyclic ethers, acetals, esters, amides, siloxanes, and so forth. 

Native chemical ligation is one of the most successful methods for the formation of linear peptide chains. Intramolecular acyl migration through a... 

Recently, chains grafted to surfaces in a supercritical solvent were simulated with a continuum MC method[77]. Solvent was held in equilibrium between the grafted layers and a pure bulk solvent using a grand canonical ensemble. As in the LFSCF calculations,[72] the grafted chains collapsed as solvent density was decreased. At low densities a loss in solvent screening leads to increased chain-chain intramolecular... 

An active end of the same chain (intramolecular cyclization crosslinked)... 

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