Photoluminescence Wavelength Control of Fluorene Derivatives through H-bonding and Protonation

A fluorene monomer, which comprised 4-pyridylcyanovinyl groups (FL-CNPy), was synthesized, and the photoluminescence (PL) properties of FL-CNPy combined with various (di)acids were evaluated. Due to hydrogen (H)-bonding or protonation between the pyridine end groups and acids, the PL emission maxima varied from 460 to 557nm according to the acidity (pK(a)) and type of (di)acid. Additionally, adjusting the ratio of FL-CNPy/(di)acid tuned the PL emission wavelength without modifying the materials.