Characterization of Dendrimers

Dendrimers have been characterized by a variety of general techniques of analytical chemistry, and also by some specialized techniques that are particularly suitable for dendrimers. The following sections describe these techniques as they have been applied to dendrimers. For more details, the reader is referred to the books fisted in Further Reading section. 

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Mass spectroscopy is a useful technique for the characterization of dendrimers because it can be used to determine relative molar mass. Also, from the fragmentation pattern, the details of the monomer assembly in the branches can be confirmed. A variety of mass spectroscopic techniques have been used for this, including electron impact, fast atom bombardment and matrix-assisted laser desorption ionization (MALDI) mass spectroscopy. 

M. C. Rogers, B. Adisa, and D. A. Bruce, Synthesis and characterization of dendrimer-templated mesoporous oxidation catalysts, Catal Lett. 98,29-36 (2004). 

G. Lafaye, C. T. Williams, and M. D. Amiridis, Synthesis and microscopic characterization of dendrimer-derived Ru/A1203 catalysts, Catal. Lett. 96, 43-47 (2004). 

Synthesis and Characterization of Dendrimer-Encapsulated Metal Nanoparticles... 

A recently developed technique that has found extensive use in the characterization of dendrimers, specifically in determining the purity and monodispersity of these novel materials, has been matrix-assisted laser desorption/ionization (MALDI) mass spectrometry [16,17]. For dendrimers grown by the divergent strategy, incomplete functionalization of the periphery can lead to subsequent failure sequences and loss of strict dendritic growth. Observation and quantification of these defects is extremely difficult by other techniques, however MALDI mass spectrometry has been successfully employed by a variety of authors to... 

Abstract. The synthesis and study of dendrimers has been truly dramatic in the last ten years. This review gives a brief introduction to some of the key concepts and main synthetic strategies in dendrimer chemistry. The focus of the chapter is a survey of modern analytical techniques and physical characterization of dendrimers. Results of model calculations and experiments probing the dimensions and conformation of dendrimers are reviewed. In the final sections the experimental work on dendrimer-polymer hybrids is highlighted. The dense spherical conformation of dendrimers has been combined with the loose random-coil conformation of ordinary polymers to form new hybrids with potentially interesting new properties. 

Rajca and Utamapanya have further expanded 20 their iterative procedures to include the unprecedented synthesis (Scheme 5.3) and characterization of dendrimers possessing 15 and 31 centers of unpaired electrons. The convergent synthesis of these unique materi-... 

In this chapter we introduce structures and physicochemical properties of dendrimers. Then synthesis and characterization of dendrimer-nanoparticles are discussed. 

Sub-stoichiometric yttrium complexes of Starburst PAMAMs with N(CH2CH2COf)2 surface groups displayed intramolecular exchange reactions as determined by 13C-NMR spectroscopy and 90Y tracer experiments [166]. These and other complexation properties may serve as useful probes for the systematic characterization of dendrimer surfaces. 

Many studies have been carried out on the electrochemical characterization of dendrimers. In general, the observed electrochemical behavior depends on the position occupied by the active unit(s) in the molecular structure. 

Milhem, O.M. Mobedi, H. Day, N. McKeown, N.B. Attwood, D. D Emanuele, A. Development and characterization of dendrimer conjugates derivatives for drug delivery. Proc. Int. Symp. Control. Release Bioact. Mater. 2001, 28, 329-330. 

MALDI can be used to follow dendrimer growth. Some papers report the characterization of dendrimers grown on a star-shaped nucleus made of and of some aromatic polyester dendrimers. Figure 10.37 shows the MALDI-TOF mass spectra of a dendrimer which grows on a star-shaped nucleus made of PEG, at various stages of its growth. Initially, the molar mass is around 25000, then it changes to 28000 and to 33000, and eventually it reaches 39000. 

The structures of precursors to Fr6chet-type dendrimers have been proven by high field 2D-NMR at 750 MHz. These techniques can be very useful for the characterization of dendrimers, and to obtain the unambiguous chemical shift assignments of their NMR resonances. 

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