The spatial structure of dendritic macromolecules

Abstract

A low-resolution ab initio shape determination was performed from small-angle neutron and X-ray scattering (SANS and SAXS) curves from solutions of polycarbosilane dendrimers with the three-functional and the four-functional branching centre of the fourth, fifth, sixth, seventh and eighth generations. In all cases, anisometric dendrimer shapes were obtained. The overall shapes of the dendrimers with the three-and four-functional branching centres were oblate ellipsoids of revolution and triaxial ellipsoids, respectively. The restored bead models revealed a pronounced heterogeneity within the dendrimer structure. The density deficit was observed in the central part and close to the periphery of the dendrimers. The fraction of the overall volume of the dendrimers available for solvent penetration was about 0.2-0.3. These results may help in the design of new practical applications of dendrimer macromolecules.

Small-angle scattering studies of macromolecular solutions

“…DAMMIN has been actively used for practical shape determination by different groups (Aparicio et al, 2002;Arndt et al, 2003;Bugs et al, 2004;Dainese et al, 2005;Egea et al, 2001;Fujisawa et al, 2001;Hammel et al, 2004;Scott et al, 2002). Interestingly, the program also provided meaningful models for non-biological systems with moderate polydispersity (Ozerin et al, 2005;Shtykova et al, 2003). The executables of DAMMIN and of other programs developed at the EMBL and described below are freely available for academic users at http://www.embl-hamburg.de/ExternalInfo/Research/Sax/ software.html.…”

Formation of a Hollow Core in Dendrimers in Solvents

“…Only a few reports are available for other types of dendrimers when small‐angle scattering experiments were used for the investigation of the inner structure of dendrimers in solution: flexible dendrimers (carbosilane dendrimers) [ 163–166 ] and rigid dendrimers. [ 167,168 ]…”

“…Flexible polybutylcarbosilane dendrimers in solution were investigated. [ 163,164,166 ] SAXS and SANS methods were used to reconstruct the dendrimer shape and radial density profile, [ 166 ] which were interpreted as a justification of a hollow core. At the same time, a rather flexible carbosilane dendrimer is completely appropriate to compare with classical theory results presented in Section 2.1, which suggest that hollow core is not expected for this dendrimer particularly.…”

High-throughput SANS experiment on two-detector system of YuMO spectrometer

“…Two-detector system has no such disadvantage. The need of high resolution at the nearest position for the wide spectrum of samples (alconates [15], proteins [16][17][18][19], dendrimers [20][21][22][23][24][25], nanotubes [26], lipids [27][28][29]) leads to conducting the experiments at the nearest position of the well-collimated detector. Consequently the time of measurements range on the spectrometer YuMO is from 3 min [30,31] up to 12h [32,33].…”