As a crystal approaches a few nm in size, atoms become nonequivalent, bonds vibrate, and quantum effects emerge. To study quantum dots (QDs) with structural control common in molecular science, we need atomic precision synthesis and analysis. We describe here the synthesis of QDs of lead bromide perovskite via self-organization of a lead malate chelate complex and PbBr3– under ambient conditions. Millisecond and angstrom resolution electron microscopic analysis revealed the structure and the dynamic behavior of individual QDs—structurally uniform cubes made of 64 lead atoms, where eight malate molecules are located on the eight corners of the cubes, and oleylamonium cations lipophilize and stabilize the edges and faces. Lacking translational symmetry, the cube is to be viewed as a molecule rather than a nanocrystal. The QD exhibits quantitative photoluminescence and stable electroluminescence at 460 nm with a narrow half-maximum linewidth of 15 nm, reflecting minimum structural defects. This controlled synthesis and precise analysis demonstrate the potential of cinematic chemistry for the characterization of nanomaterials beyond the conventional limit.