Fig. 3: Stacking-induced intermolecular charge transfer of the DTBT-based planar D-A-D molecules.
From: Self-stacked small molecules for ultrasensitive, substrate-free Raman imaging in vivo
a,b, 2D-GIWAXS pattern of the thin films of DTBT (a) and BBT (b), respectively. qz and qr, the out-of-plane and in-plane directions, respectively. c,d, BFDH theoretical crystal morphology of DTBT simulated by Mercury 3.8 based on the single-crystal structure from the Cambridge Crystallographic Data Centre (CCDC; code: 1308377). The arrangement of DTBT in the in-plane direction (c) and out-of-plane direction (d). e–g, ESP maps (e), vibration mode (894 cm−1) (f) and Raman spectra (g) of single DTBT or DTBT-DTBT packed in the in-plane or out-of-plane direction calculated by Gaussian 09/B3LYP/6-31 G(d) based on their crystal geometries from the CCDC. Color bar indicates the ESP energy value between the highest (blue) and the lowest (red) values (e). Boxed area in the ESP maps, intermolecular charge-transfer. h,i, Absorption spectra (h) or fluorescence decay curves (i) of BBT in water/THF mixtures with water fraction from 0% to 95%. No fit, the fluorescence emission was completely quenched. j, Schematic diagram of three-dimensional charge-transfer interactions of DTBT, substantially increasing the extent to electron delocalization to conduce to the enhanced Raman scattering. Green cylinders, intermolecular D•••A change-transfer in the out-of-plane direction. Blue ellipses, intermolecular D•••A change-transfer in the in-plane direction.
