The Self-Assembled Dual-Band Room Temperature Phosphorescence Crystals with Grating Morphology Directed by Deoxycholate

9-Bromophenanthrene (9BrP) crystals with a grating morphology and different optical properties were assembled in aqueous medium with sodium deoxycholate (NaDC). The morphology of crystals in the presence of 10 and 2 mmol/L NaDC (named 9BrP−G10 and 9BrP−G2, respectively) is significantly different from that in the absence of NaDC (named 9BrP−NG). XRD, FT-IR, Raman, and 13C NMR spectra prove that NaDC just works as a directing agent in the self-assembly of 9BrP crystals, which makes the Br···Br and H···π distances between 9BrP molecules slightly closer. Host−guest interaction between NaDC aggregate and 9BrP modifies sequentially the crystal morphology in the crystallizing process. In addition, the luminescence colors of 9BrP−G10 and 9BrP−G2 crystals are significantly different from each other as well as from that of the 9BrP−NG crystal, suggesting the luminescent properties of organic molecules can also be modified by adjusting the interaction parameters and the physical morphology. This study highlights the potential of biosurfactant as a directing agent as well as a considerable flexible tool in preparation of tunable-color luminescent or other functional materials.