Cations, with ethylenediamine

Nanostructures containing cationized gelatin are able to protect pDNA and siRNA from nuclease degradation and transfect a variety of cell types and tissues, both in vitro and in vivo. After cationization with ethylenediamine or spermine, the levels of transfection efficiency achieved can be compared to those provided by classic transfection agents such as polyethyleneimine. Table 8.2 shows the most important results obtained with nanoparticles based on cationized gelatin for gene delivery. 

Apart from this mechanistic hypothesis, another scenario, with a ferrate complex as intermediate, may be possible. In 1928, Hieber discovered that Fe(CO)5 78 underwent a disproportionation in the presence of ethylenediamine 122 [97-101]. Depending on the reaction temperature, different ferrate complexes were formed that incorporated a [Fe(en)3] cation (en = ethylenediamine) and mono-, di- or trinuclear ferrate anions (Scheme 32) [102-107]. As the reaction discussed above is also performed with amines at high temperatures, these ferrates may well be involved in the catalytic cycle of the carbonylation discussed above. 

Exchange of complex cations. Complexation of transition metal cations with uncharged ligands such as with amines and with amino acids results in a selectivity enhancement compared to the selectivity of the aqueous metal cation (27, 65-72). Fig. 3 shows an example for the Cu(ethylenediamine) adsorption in montmorillonites of different charge density. Standard thermodynamic data for other cases are given in table IV. In all cases the free ligand concentration in equilibrium solution was... 

Reaction of the heated solution of this salt with ethylenediamine gives the parent dihydrodiazepinium cation in high yield without recourse to high dilution techniques and provides the most convenient method for its... 

Lithium halide complexes with ethylenediamine, en, LiXen2, provide a nice illustration of both chelation and bridging by this ligand (26), resulting in a tetrahedral environment for the cation with Li—N, 2.07 A. 

The preparation of salts containing the [Cr(en)3]3+ cation from anhydrous chromium sulfate has been described previously in Inorganic Syntheses,1 and the merits of this, and other, methods have been reviewed.9 A more rapid route to this cation involves refluxing CrCl3 6H20 in methanol with ethylenediamine and zinc metal, which allows the substitution to proceed by way of the kineti-cally labile chromium(II) species.10 All of these preparations yield hydrated salts the procedure described below leads to anhydrous [Cr(en)3] Br3. 

Earlier work (6) using this method yielded a second-order rate constant of 24.7 1.5 M""1 sec."1 for the reaction of dilute solutions of cesium with water in ethylenediamine. On the basis of optical absorption spectra (7) and other evidence (8, II), it was assumed that this reaction was that of the solvated electron as well as loosely bound electrostatic aggregates of electrons and cations with water. This permitted correlation with the results of aqueous radiation chemistry. 

Ethylenediamine, NH2C2H4NH2, is a base that can add one or two protons. The successive pKy values for the reaction of the neutral base and that of the monovalent (+1) cation with water are 3.288 and 6.436, respectively. In a 0.0100 M solution of ethylenediamine, what are the concentrations of the singly charged cation and of the doubly charged cation ... 

With ethylenediamine complexes of the formula Ln(en)3X3 and Ln(en)4X3, where X = C1 , Br , NO, CIOJ have been characterized. IR data indicate that the tris and tetrakis complexes of the fighter lanthanides La-Sm, contain both ionic and coordinated nitrate groups. By contrast tetrakis complexes of heavier lanthanides, Eu-Yb contain ionic nitrate. This is possibly due to steric factors resulting from decreasing cationic radius that force the nitrate out of the coordination sphere of the lanthanides. A coordination number of 8 for tris complexes and a number of 9 for fighter lanthanide tetrakis complexes appears reasonable [234]. The thermodynamic parameters obtained show enthalpy stabilization for... 

Fig. 3-149. Separation of divalent cations with direct conductivity detection. - Separator column surface-sulfonated cation exchanger (Benson Co., Reno, USA) eluent 0.0015 mol/L ethylenediamine + 0.002 mol/L tartaric acid, pH 4.0 flow rate 0.85 mL/min injection volume 100 pL solute concentrations 10.3 ppm Zn2+, 9.1 ppm Co2+, 16 ppm Mn2+, 16.1 ppm Cd2+, 17.1 ppm Ca2+, 16 ppm Pb2+, and 20.3 ppm Sr2+ (taken from [148]).

Table 5.8. Comparison of capacity factors (k) of various cations with cationic eluents. (Concentrations HCIO4, 0.250 M NaClOa, 0.100 M all others are 1.0 x 10 M, pH 2.5 t = 0.495 min. EnH j = ethylenediamine eluent PhenH 2 = oj-phenylenediamine eluent.

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