title: Stoichiometric control of DNA-grafted colloid self-assembly.
abstract: 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.
authors.affiliation: Department of Chemical Engineering, Columbia University, New York, NY 10027;
authors.forename: Thi
authors.initials: T
authors.lastname: Vo
authors.affiliation: Department of Chemical Engineering, Columbia University, New York, NY 10027;
authors.forename: Venkat
authors.identifier: http://orcid.org/0000-0002-4923-0582
authors.initials: V
authors.lastname: Venkatasubramanian
authors.affiliation: Department of Chemical Engineering, Columbia University, New York, NY 10027; sk2794@columbia.edu.
authors.forename: Sanat
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Gandhinagar 382424, India; and.
authors.forename: Babji
authors.initials: B
authors.lastname: Srinivasan
authors.affiliation: Department of Chemical Engineering, Columbia University, New York, NY 10027; Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973.
authors.forename: Suchetan
authors.initials: S
authors.lastname: Pal
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973.
authors.forename: Yugang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973.
authors.forename: Oleg
authors.initials: O
authors.lastname: Gang
mesh_terms: D003102:Colloids / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D008962:Models, Theoretical; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D003102:Colloids; D004247:DNA
keywords: colloidal interactions; functional particle; modeling; molecular design; superlattice engineering
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