Molecular design and synthesis.
To enable the multi-dimensional regulation of H-bonds, DPI was
attached to a central HBT core to obtain the model ESIPT
chromophore HBT-DPI . Although both DPI and BTcontain unsaturated N atoms, endowing them with excellent H-bond
accepting capability, whereas the presence of sulfur atom in BTweakens its hydrogen accepting ability.49,50 Moreover,
the DPI group contains an extra H-bond donor (N-H) that can
form either an intramolecular H-bond with the oxygen of the phenol core
or an intermolecular H-bond with other molecules, which could extend the
possible molecular packing behaviors in the solid state. By such a
molecular design, the manipulation of multi-dimensional H-bonds (intra-
and intermolecular) would render the environment sensitive material with
a variety of photophysical properties. The ESIPT chromophoreHBT-DPI was synthesized by three-step reactions according to
Supplementary Scheme S1 and characterized using 1H
NMR, 13C NMR and high-resolution mass spectrometry
(Figures S20-22).