Fig. 1: Au₃₂-NC self-assembly into microcrystals.

a Structural drawing of the Au₃₂(ⁿBu₃P)₁₂Cl₈-NCs. The different colors represent the Au- (gold), Cl- (green), P- (purple), and C- (gray) atoms, while hydrogens are omitted for clarity. The Au core has a diameter of ~0.9 nm, while the size of the entire NC is about 1.3 nm. Scale bar: 0.4 nm. b–d Schematic illustration of the assembly process. An Au₃₂-NC solution is injected onto the liquid subphase within a Teflon chamber. The Au₃₂-NCs self-assemble into microcrystals and sink down through the subphase onto the immersed substrate. Details are given in the “Methods” section. e Optical micrograph of self-assembled Au₃₂-NC microcrystals on a Si/SiO_x substrate. The crystals are µm-sized and exhibit a parallelogram shape. Different sizes and thicknesses (color) can be observed. Scale bar: 15 µm. f SEM micrograph of a microcrystal with indicated long axis A, short axis B, and angle Δ. Scale bar: 2 µm. g Distribution of long and short axis revealing typical crystal sizes of A = 17.4 ± 4.2 µm, B = 10.6 ± 2.5 µm (dispersity of Đ = 1.07, see Supplementary Information for details).