Colloids with valence and specific directional bonding

Abstract

The ability to design and assemble 3-dimensional structures from colloidal particles is limited by the absence of specific directional bonds. As a result, complex or low-coordination structures, common in atomic and molecular systems, are rare in the colloidal domain. Here we demonstrate a general method for creating the colloidal analogues of atoms with valence: colloidal particles with chemically functionalized patches that can form highly directional bonds.These "colloidal atoms" possess all the common symmetries-and some uncommon ones-characteristic of hybridized atomic orbitals, including sp, sp 2 , sp 3 , sp 3 d, sp 3 d 2 , and sp 3 d 3 . Functionalizing the patches with DNA with single-stranded sticky ends makes the interactions between patches on different particles programmable, specific, and reversible, thus facilitating the self-assembly of particles into "colloidal molecules," including "molecules" with triangular, tetrahedral, and other bonding symmetries. Because colloidal dynamics are slow, the kinetics of molecule formation can be followed directly by optical microscopy. These new colloidal atoms should enable the assembly of a rich variety of new micro-structured materials. 2 IntroductionThe past decade has seen an explosion in the kinds of colloidal particles that can be synthesized 1,2 , with many new shapes, such as cubes 3 , clusters of spheres 4-6 and dimpled particles 7,8 reported. Because the self-assembly of these particles is largely controlled by their geometry, only a few relatively simple crystals have been made: face-centered and body-centered cubic crystals and variants 9 . Colloidal alloys increase the diversity of structures [10][11][12] , but many structures remain difficult or impossible to make. For example, the diamond lattice, predicted more than 20 years ago to have a full 3-dimensional photonic band gap 13 , still cannot be made by colloidal self-assembly because it requires 4-fold coordination. Without directional bonds, such low-coordination states are unstable.

A colloidoscope of colloid-based porous materials and their uses

“…32,33 The composition can later be tailored as desired, as discussed below and described in Figure 2. With the focus on the assembly of simple, spherical particles, this review does not cover the synthesis and self-assembly of more complex colloidal building blocks, such as Janus particles, 34,35 patchy particles, [36][37][38][39] core-shell particles, [40][41][42] particles with more complex internal structures, [43][44][45] anisotropic particles, 46 or non-spherical nanocrystals. [47][48][49][50] Complex properties and highly functional materials can emerge solely by controlling the structure of the material or by providing a template to generate patterns in another material.…”

Directing Assembly of DNA-Coated Colloids with Magnetic Fields To Generate Rigid, Semiflexible, and Flexible Chains

“…[1][2][3] As synthesis techniques have increased in sophistication, colloids have also been used as mimics for more complicated molecular systems. [4][5][6] Recently, the development of colloidal polymers (long chains of linked nano or micron-sized particles that are analogous to linear polymer molecules) has generated interest. [7][8][9][10] Colloidal polymer systems have multiple advantages, including being small enough to be influenced by Brownian forces yet large enough to enable studies with 'single molecules' using ordinary light microscopy.…”

Electroneutrality breakdown and specific ion effects in nanoconfined aqueous electrolytes observed by NMR

“…E lectric double layer near the interface is of fundamental importance in various applications ranging from electrochemistry 1 and electrophoresis 2 , to colloidal particles assembly 3 and nanofluidics 4 . The neutrality of the total charge is an important condition in deriving the ion distribution near the interface in the electric double layer theory.…”