Avoiding Steric Congestion in Dendrimer Growth through Proportionate Branching: A Twist on da Vinci’s Rule of Tree Branching

• Published in: Journal of organic chemistry 2012-10, Vol.77 (20), p.8879-8887
• Main Authors: Yue, Xuyi, Taraban, Marc B, Hyland, Laura L, Yu, Yihua Bruce
• Format: Article
• Language: English
• Subjects: Applied sciences; Dendrimers - chemical synthesis; Dendrimers - chemistry; Exact sciences and technology; Fluorocarbons - chemical synthesis; Fluorocarbons - chemistry; Molecular Structure; Organic polymers; Physicochemistry of polymers; Polymers with particular structures; Preparation, kinetics, thermodynamics, mechanism and catalysts; Propionates - chemical synthesis; Propionates - chemistry
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo301718y

Making defect-free macromolecules is a challenging issue in chemical synthesis. This challenge is especially pronounced in dendrimer synthesis where exponential growth quickly leads to steric congestion. To overcome this difficulty, proportionate branching in dendrimer growth is proposed. In proportionate branching, both the number and the length of branches increase exponentially but in opposite directions to mimic tree growth. The effectiveness of this strategy is demonstrated through the synthesis of a fluorocarbon dendron containing 243 chemically identical fluorine atoms with a MW of 9082 Da. Monodispersity is confirmed by nuclear magnetic resonance spectroscopy, mass spectrometry, and small-angle X-ray scattering. Growing different parts proportionately, as nature does, could be a general strategy to achieve defect-free synthesis of macromolecules.