Competitive pi-stacking and H-bond piling increase solubility of heterocyclic redoxmers

Yuyue Zhao, Erik S. Sarnello, Lily A. Robertson, Jingjing Zhang, Zhangxing Shi, Zhou Yu, Sambasiva R. Bheemireddy, Y Z, Tao Li, Rajeev S. Assary, Lei Cheng, Zhengcheng Zhang, Lu Zhang, Ilya A. Shkrob

Research output: Contribution to journalArticlepeer-review


Redoxmers are organic molecules that carry electric charge in flow batteries. In many instances, they consist of heteroaromatic moieties modified with appended groups to prevent stacking of the planar cores and increase solubility in liquid electrolytes. This higher solubility is desired as it potentially allows achieving greater energy density in the battery. However, the present synthetic strategies often yield bulky molecules with low molarity even when they are neat and still lower molarity in liquid solutions. Fortunately, there are exceptions to this rule. Here, we examine one well-studied redoxmer, 2,1,3-benzothiadiazole, which has solubility ∼5.7 M in acetonitrile at 25 °C. We show computationally and prove experimentally that the competition between two packing motifs, face-to-face π-stacking and random N−H bond piling, introduces frustration that confounds nucleation in crowded solutions. Our findings and examples from related systems suggest a complementary strategy for the molecular design of redoxmers for high energy density redox flow cells.

Original languageEnglish (US)
Pages (from-to)10409-10418
Number of pages10
JournalJournal of Physical Chemistry B
Issue number46
StatePublished - Nov 19 2020

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry


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