Regulating room temperature phosphorescence of carbazole quaternization
pyridine in polymer through Hofmeister effect
Abstract
Hofmeister effect is a famous physical chemistry phenomenon that was
reported a hundred years ago, which firstly refers to the action of
certain salts to decrease the solubility of proteins while others
increase. The Hofmeister effect on the luminescent properties of
cationic organic fluorophore is still obscure, especially for their room
temperature phosphorescence (RTP). Herein, hydrophilic groups
(quaternization pyridine) were introduced into carbazole molecules to
obtain a series of carbazole derivatives (named CZ-Py
+) with different counter anions in the Hofmeister
series. These carbazole derivatives displayed tunable fluorescent color
from cyan to yellow in the solid state following the Hofmeister sequence
and anti-Hofmeister behavior in aqueous solution. Moreover, RTP material
with tunable emission color and lifetime was achieved by doping CZ-Py
+ with Hofmeister series anion in polymethyl
methacrylate (PMMA) and polyvinyl alcohol (PVA), which displayed good
performance in time getting information encryption and
anti-counterfeiting.