Multi-dimensional Hydrogen Bonds Regulated Emissions of Single Molecule
Enabling Hydrophobicity/Hydrophilicity Mapping
Abstract
Constructing multi-dimensional hydrogen bond (H-bond) regulated
single-molecule systems with multi-emission remains a challenge. Herein,
we report an excited-excited intramolecular transfer (ESIPT) featured
chromophore (HBT-DPI) that shows flexible emission tunability via the
multi-dimensional regulation of intra- and intermolecular H-bonds. The
feature of switchable intramolecular H-bonds is induced via
incorporating two hydrogen bond acceptors into a single-molecule system,
HBT-DPI, allowing the “turn on/off” of ESIPT process by forming
isomers with distinct intramolecular H-bonds. In response to different
solvent environments, the obtained four types of crystal/cocrystals vary
in the contents of isomers and the molecular packing modes, which are
mainly guided by the intermolecular H-bonds, exhibiting non-emissive
features or emissions ranging from green to orange. Moreover, we
demonstrate the practical utility of this fluorescent material for
visualizing hydrophobic/hydrophilic areas on large-scale heterogeneous
surfaces of modified PVDF membranes and quantitatively estimate the
surface hydrophobicity, providing a new approach for
hydrophobicity/hydrophilicity monitoring and measurement.