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Title: Stoichiometric control of DNA-grafted colloid self-assembly

In this study, there has been considerable interest in understanding the self-assembly of DNA-grafted nanoparticles into different crystal structures, e.g., CsCl, AlB₂, and Cr₃Si. Although there are important exceptions, a generally accepted view is that the right stoichiometry of the two building block colloids needs to be mixed to form the desired crystal structure. To incisively probe this issue, we combine experiments and theory on a series of DNA-grafted nanoparticles at varying stoichiometries, including noninteger values. We show that stoichiometry can couple with the geometries of the building blocks to tune the resulting equilibrium crystal morphology. As a concrete example, a stoichiometric ratio of 3:1 typically results in the Cr₃Si structure. However, AlB₂ can form when appropriate building blocks are used so that the AlB₂ standard-state free energy is low enough to overcome the entropic preference for Cr₃Si. These situations can also lead to an undesirable phase coexistence between crystal polymorphs. Thus, whereas stoichiometry can be a powerful handle for direct control of lattice formation, care must be taken in its design and selection to avoid polymorph coexistence.
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  1. Columbia Univ., New York, NY (United States)
  2. Indian Inst. of Technology (IIT), Gandhinagar (India)
  3. Columbia Univ., New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
  4. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0027-8424; KC0403020
Grant/Contract Number:
SC00112704; FG02-12ER46909; AC02-98CH10886
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 16; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; colloidal interactions; functional particle; superlattice engineering; molecular design; modeling
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1188276