Surface energy-driven growth of crystalline PbS octahedra and dendrites in the presence of cyclodextrin–surfactant supramolecular complexes

PbS crystals of cubic, octahedral, and dendritic shapes are synthesized in an aqueous solution that contains supramolecular complexes of β-cyclodextrin (CD) and hexadecyltrimethylammonium bromide (CTAB). The morphology of the PbS crystals depends on the concentration of CD or CTAB in the reaction solution; for example, the branched dendritic structures evolve with an appropriate molar ratio of CD/CTAB supramolecular complexes and reaction time. Regardless of the CD/CTAB molar ratios, octahedral PbS crystals are observed at all compositions of CD/CTAB for the reaction times of 1–5 h, while self-assembled branched/dendritic structures are obtained only for CD/CTAB molar ratios of 0.5, 1, and 2 after a prolonged reaction, e.g., for 24–48 h. Systematic investigation reveals that both reaction time and CD/CTAB molar ratio are responsible for self-assembled branched/dendritic structures of octahedral crystals.