Shape of the amine

The alumino and gallophosphates were formed [7] in the systems amine-Al(Ga)203—P205—H20 using the same way of the synthesis and the same range of temperatures and pressure. However, the introduction of phosphoric acid in the synthesis lowered the pH of the solutions to a neutral or weakly acidic medium which favours higher coordinations for aluminium and gallium ions. The combined effect of pH and of the shape of the amines lead to ca two hundred structure types. 

Beside the effect of pH, the difference between ULM-3 and ULM-4 showed that the volume of the amine also plays a role on the nature of the observed solids. Consequently, a careful analysis of the structural evolution in the system using different amines was required. Two parameters are important the shape of the amine (either spherical or linear) and its correlated ability to be protonated. Indeed, there is a relation between their shape and their acidobasic characteristics. Their acidity constants are very different and, if the pKa of aliphatic diamines lies in the 7-10 range, for spherical amines, it is only in the range 4-6. That means that both the volume, the anisotropy and the charge will influence the structure of the solid and therefore the shape of the cavities. 

Recorded kinetic curves were fitted to the five-parameter Equation (1). The parameters pj with their errors and the standard deviation of regressions are summarized in Tables 1-6. Comparison of the data confirm the previously reported (refs. 8,12) similarity in the behavior of the two isomers in the presence of strong bases in spite of the different shape of the kinetic curves. The relatively good agreement of exponents p2, P4 computed for the diastereomers at the same temperature and amine concentration demonstrates the validity of the model used. From comparison of Equations (4) and (7) it follows that both reaction must give the same exponent. 

The nanorods obtained are well cylindrically shaped and well crystalline (Fig. 4), although disorder is probably present at the surface as shown by HRTEM image (see Fig. 4), probably due to the strong bonding of the amine which cover the entire surface. This is demonstrated also from the fact that the nanorods display very different solubilities at different pH values in aqueous solutions due to the amphiphilic behavior of the amine group. In an acidic medium (pH < 3), the amine group is protonated, and the nanorods cannot be precipitated because they form a stable suspension.164 When the pH is increased to basic conditions (pH > 9), the nanorods precipitated within a few minutes. This could be another interesting way to develop... 

Corresponding electron-transport materials have been made by replacing the amino substituents in the first shell by oxadiazole groups (29) [70, 61] or phenyl-quinoxalines (30) [60]. As in the case of the amines, dendrimer-shaped structures are obtained by repeating the substitution pattern in a second shell (31) [76], The Tg was increased from 142°C in 29 to 222° C in 31. 

Functional groups attached to the carbonyl group naturally alter the shape of the energy surface to some extent. Rode and Preuss 212> studied the interaction of Li+ with formamide. As a result of the amine substituent the mobility... 

The shape of the asymmetric S-O bands in the Ci4AO/SDS difference spectra change with composition. The higher frequency shoulder increases in relative intensity as the SDS content decreases. This change indicates that the dilution of SDS in C14AO results in a replacement of the sulfonate-sodium ion interactions with sulfate-amine oxide interactions, since the exact frequency and shape of the complex S-O band depends on the size and location of the hydrated counterion of the sulfate group (4). A weak band due to amine oxide is known to occur near 1200 cm"1. The influence of this band on the vm S-O bandshape can only be observed at the highest amine oxide concentration (mass fraction SDS = 1%) where a low frequency shoulder near 1200 cm"1 is observed in the difference spectra. 

The tweezer-shaped Troger s bases 18a,b were prepared by cyclization of the amines 306a,b, which were heated with formaldehyde in the presence of concentrated HC1. Amine 306a afforded, in a 63% yield, a 4 1 mixture of stereoisomers syn and anti of 18a. Amine 306b, instead, under the same reaction conditions, afforded a complex mixture from which a significant quantity of 306b was recovered and the anti stereoisomer of 18b was obtained in very low yield (6%)... 

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