Polyamines open chain

Polyamines are usually open chain compounds with primary, secondary, or tertiary amino groups. Instead of polyamines, polyimines are used without a sharp difference. Actually, imines are compounds with the =N— group or cycles such as ethyleneimine. Examples of oligoamines and polyamines are ethylenediamine, propanediamine, and 1,4-butanediamine and the respective products of condensation such as diethyleneamine, dipropylenetriamine, and triethylenetetramine. The compounds are colorless to yellowish liquids or solids with alkaline reaction. 

Open chain polyamine ligands have been widely studied. Often the coordination of zinc is compared with other first row transition metals and factors, such as behavior across a pH range, studied. The protonation patterns and stability constants are of particular interest. Octahedral zinc tris(ethylenediamine) structures have been characterized by X-ray diffraction with a number of different counter anions.94 The X-ray structure of zinc tris(ethylenediamine) with fluoride counter ions reveals extensive hydrogen bonding.95... 

Complexation of Cd with a series of polyamine macrocycles, but also related open-chain polyamines, comprising or attached to the 2,2 -bipyridine (bipy) and 1,10-phenanthroline (phen) moieties, has been studied by combined UV/vis spectrometry and potentiometry.24 Formation constants and distribution diagrams of the species present have been evaluated. As a result the thermodynamic stabilities, i.e., the formation constants, are lower for the bipy- and phen-contain-ing ligands than those for Cd complexes with aliphatic oligoaza macrocycles containing the same number of N donors. The probable reason is loss of flexibility of the ligands caused by the size and stiffness of the inserted heteroaromatic moieties. 

Aromatic polyamines react with sugar lactones to give heterocyclic compounds having an attached open-chain polyhydroxyalkyl substituent. Thus, treatment of aldonolactones with o-phenylenediamine afforded (117) 2-polyhydroxyalkylimidazoles (100). 

With most metal ions the complex stability decreases as the size of the chelate rings formed by open-chained polyamine ligands increases from five to six membered. Examples of this effect are presented in Table 8.1, where experimental data are com-... 

The synthesis of secondary amines from azides is efficient in terms of chemos-electivity [57] and has found valuable applications in the preparation of diamines [58,59], m-alkylaminoboronic esters [60], and in Diels-Alder-based amination reactions [61]. A convenient general route to open-chain polyamines, which play major roles in cellular differentiation and proliferation, has also been developed using the reductive alkylation of aliphatic aminoazides by (co-halogenoalk-yi)dichloroboranes as a key step [62] (Scheme 21). 

The appropriate conditions for the synthesis of tris-azamacrocyclic clathrochelates containing dioximate fragments in polyazamacrocyclic rings were not selected. Attempts to use open-chain polyamines, as well as their complexes with transition metals, primarily Ni2+, gave no desired results. 

The peraza macrocycles, in general, form more stable complexes with a variety of metal ions than do the open-chain polyamines containing the same number of amine groups. This characteristic is called the macrocyclic effect. Triaza-crowri macrocycles, in nearly every case, form 1 1 complexes with metal ions that are thermodynamically more stable than those with dieth-ylenetriamine. Only complexes of the open-chain triamine with and Hg- are more stable than those with the cyclic triamines (Bianchi et al., 1991). Triaza-9-crown-3 (23) forms stronger complexes with most cations than the larger triazacyclodecane (24), triazacycloundecane (25), or triazacyclo-dodecane (26) (Bhula et al., 1988 Chaudhuri and Wieghardt, 1987). 

Indeed, most of the interest in open-chain polyamines has focused on their use for the preparation of biologically active compounds including the peraza-crowns (cyclams). 

Pietraszkiewicz and Gasiorowski (1990) used this type of reaction with a rigid aromatic dialdehyde and an open-chain polyamine to make two peraza-cy-... 

Open-chain polyamines such as 1,4,8,11-tetraazaundccane and its complexes with Cu", Ni" and Zn" are chemical sensitizers as well, although the effect of the chelates may be ascribable in part to their being a source of the free amine (a possible reduction sensitizer, another important class of chemical sensitizers). 

Whereas for anion binding, the charge and shape of the macrocycle are of paramount importance the stability and selectivity in metal complexation are governed by several other factors, which have been summarized into the term macrocyclic effect <88Mi 928-01 >. The higher stability of metal complexes with cyclic polyamines compared to that with open-chain polyamines is, however, only found for smaller rings such as 1,4,7-triazacyclononane and 1,4,8,11-tetraazacyclotetradecane, for which a favorable enthalpic contribution to the stability has been observed. 

Cabbiness and Margerum have given preliminary accounts of the effect of macrocyclic structures on the rate of formation and dissociation of Cu + complexes. They have compared the rates of reaction of aquo-copper with the somewhat flexible fourteen-membered macrocyclic ligand shown (7 also similar macrocycles), with a comparable open-chain polyamine (2,3,2-tet), and with a porphyrin ligand (haematoporphyrin... 

As a new series of "open-chain cryptands", "multi-armed cyclams" were designed and employed in the cation transport experiments. Parent polyamine macrocycle (cyclam) is well known to show somewhat different cation binding properties from those of macrocyclic polyethers. It effectively bind ammoniiim cations via strong hydrogen bonding as well as transition metal cations via coordination interaction. Hence, new "multi-armed cyclams" are expected to exhibit unique cation transport abilities. Their cation transport results are summarized in Table 3. 

The overall basicities of polyazacycloalkanes are lower than those of their acyclic counterparts, because of greater gathering of positive charge occurring for the cyclic molecules upon successive protonation (Figure 5). Nevertheless, the parallelism between the variation of the overall basicities of macrocyclic and open-chain polyamines and the number of amine groups is consistent with similar protonation pattems. ... 

Figure 5 Overall basicity of [3fc]aneN t, [4 ]aneN/i, and open-chain analogs of [3 ]aneN< polyamines.

Table 6 Rate constants for the reaction of hydroxycuprate(ii) species with un-protonated cyclic and open-chain polyamines at 25 °C...

Lin, C.-T, Rorabacher, D.B., Cayley, G.R., and Margerum, D.W. (1975) Steric effects in the complexation kinetics of cyclic and open-chain polyamines with copper(II) in basic aqueous media. Inorg. Chem., 14, 919-925. 

Suzuki et al. [14] reported the Pd-catalyzed ring-opening polymerization of a cyclic carbamate in the presence of an initiator, which also acts as a core molecule, to afford a hyperbranched polyamine. The polymerization was proposed to be an in situ multibranching process, wherein the number of propagating chain ends increase with the progress of the polymerization. 

There are some useful techniques of extending the polyamine chain on one or both sides (Bradshaw et al., 1992). Nucleophilic ring opening of the azir-idine molecule is one of the most used methods to extend the chain. Most of... 

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