Electrospray Mass Spectrometry of Poly(propylene imine) Dendrimers—The Issue of Dendritic Purity or Polydispersity

Electrospray mass spectrometry (ESI-MS) is used to analyze in detail the structure of the first five generations of the poly(propylene imine) dendrimers with 4-64 end groups. Although the reaction sequence to prepare these dendrimers is highly optimized, an accumulation of statistical defects is observed at higher generations. A simple statistical simulation allows the assignment of all peaks in the deconvoluted spectrum and the determination of yields for each side reaction in the formation of each generation. The fifth generation of the poly(propylene imine) dendrimer containing amine end groups, which is formed after 248 consecutive reaction steps, possesses a dendritic purity of approx. 20%, which corresponds to a polydispersity of approximately 1.002. The defects in the divergent growth patterns of dendrimers are compared to those observed in the Merrifield synthesis of polypeptides.

[1]  Jean M. J. Fréchet,et al.  A “Branched-Monomer Approach” for the Rapid Synthesis of Dendimers† , 1994 .

[2]  J. V. Hest,et al.  Synthesis, characterization, and guest-host properties of inverted unimolecular dendritic micelles , 1996 .

[3]  D. Belder,et al.  Separation and Identification of Basic Dendrimers Using Capillary Electrophoresis On‐line Coupled to a Sector Mass Spectrometer , 1996 .

[4]  A. Dorsselaer,et al.  SYNTHESIS AND CHARACTERIZATION BY ELECTROSPRAY MASS SPECTROMETRY OF A NOVEL DENDRITIC HEPTANUCLEAR COMPLEX OF RUTHENIUM(II) , 1996 .

[5]  Richard D. Smith,et al.  Detection of high molecular weight starburst dendrimers by electrospray ionization mass spectometry , 1995 .

[6]  S. Yeates,et al.  Characterisation of aromatic polyester dendrimers by matrix-assisted laser desorption ionisation mass spectrometry , 1994 .

[7]  F. Vögtle,et al.  Dendrimers: From Generations and Functional Groups to Functions , 1995 .

[8]  E. W. Meijer,et al.  Poly(propylenimin)‐Dendrimere: Synthese in größerem Maßstab durch heterogen katalysierte Hydrierungen , 1993 .

[9]  R. Mülhaupt,et al.  Polynitril‐ und polyaminfunktionalisierte Poly(trimethylenimin)‐Dendrimere , 1993 .

[10]  Christopher L. Brown,et al.  A Convergent Synthesis of Carbohydrate‐Containing Dendrimers , 1996 .

[11]  J. Fréchet,et al.  Functional polymers and dendrimers: reactivity, molecular architecture, and interfacial energy. , 1994, Science.

[12]  George R. Newkome,et al.  Detection and Functionalization of Dendrimers Possessing Free Carboxylic Acid Moieties1 , 1997 .

[13]  G. Newkome,et al.  Chemistry of micelles series. 22. Cascade polymers: synthesis and characterization of four-directional spherical dendritic macromolecules based on adamantane , 1992 .

[14]  D. A. Tomalia,et al.  Starburst‐Dendrimere: Kontrolle von Größe, Gestalt, Oberflächenchemie, Topologie und Flexibilität beim Übergang von Atomen zu makroskopischer Materie , 1990 .

[15]  E. W. Meijer,et al.  Poly(propylene imine) Dendrimers: Large‐Scale Synthesis by Hetereogeneously Catalyzed Hydrogenations , 1993 .

[16]  Fritz Vögtle,et al.  Dendrimere: von Generationen zu Funktionalitäten und Funktionen , 1994 .

[17]  C. Wilkins,et al.  Analysis of hydrocarbon dendrimers by laser desorption time-of-flight and fourier transform mass spectrometry , 1994, Journal of the American Society for Mass Spectrometry.

[18]  Jean M. J. Fréchet,et al.  Hyperbranched macromolecules via a novel double-stage convergent growth approach , 1991 .

[19]  A. Beezer,et al.  An approach for the rapid synthesis of moderately sized dendritic macromolecules , 1994 .

[20]  J. Fréchet,et al.  Analysis of aromatic polyether dendrimers and dendrimer-linear block copolymers by matrix-assisted laser desorption ionization mass spectrometry , 1995 .

[21]  Charles L. Wilkins,et al.  Double Exponential Dendrimer Growth , 1995 .

[22]  Karen L. Wooley,et al.  Verzweigte Monomere als Quelle für einen schnelleren Zugang zu Dendrimeren , 1994 .