title: Average relaxation time of internal spectrum for carbosilane dendrimers: nuclear magnetic resonance studies.
abstract: A new theoretical description of the interior mobility of carbosilane dendrimers has been tested. Experiments were conducted using measurements of the (1)H NMR spin-lattice relaxation time, T(1H), of two-, three- and four-generation carbosilane dendrimers with three different types of terminal groups in dilute chloroform solutions. Temperature dependences of the NMR relaxation rate, 1/T(1H), were obtained for the internal CH(2)-groups of the dendrimers in the range of 1/T(1H) maximum, allowing us to directly evaluate the average time of the internal spectrum for each dendrimer. It was found that the temperature of 1/T(1H) maximum is practically independent of the number of generations, G; therefore, the theoretical prediction was confirmed experimentally. In addition, the average time of the internal spectrum of carbosilane dendrimers was found to be near 0.2 ns at room temperature, and this value correlates well with the values previously obtained for other dendrimer structures using other experimental techniques.
authors.affiliation: Laboratory of Physics, Lappeenranta University of Technology, Box 20, 53851 Lappeenranta, Finland. markeloved@gmail.com
authors.forename: Denis A
authors.initials: DA
authors.lastname: Markelov
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Matveev
authors.forename: Petri
authors.initials: P
authors.lastname: Ingman
authors.forename: Erkki
authors.initials: E
authors.lastname: Lähderanta
authors.forename: Natalia I
authors.initials: NI
authors.lastname: Boiko
mesh_terms: D050091:Dendrimers / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D012821:Silanes / Q000138:chemical synthesis / Q000737:chemistry*; D013997:Time Factors
chemical_list: D050091:Dendrimers; D012821:Silanes; C504072:carbosilane