posted on 2023-08-23, 14:04authored byYong Wu, Dongdong Sun, Xie Han, Zhiyong Zhao, Feng Liang, Simin Liu
A series of naphthalimide derivatives
are synthesized
and their
binding behavior upon complexation with cucurbit[n]urils (CB[n]s) has been investigated. With a heavy
atom (bromine) on the naphthalimide core, 4-bromo-1,8-naphthalimide
derivatives 1–4 show short room-temperature
phosphorescence (RTP) lifetimes with low quantum yields. Their RTP
properties are significantly enhanced in the presence of CB[8] or
CB[10] both in aqueous solution and solid state owing to the efficient
suppression of nonradiative decay and isolation of quenching factors
by the rigid cavity of CB[n]. Without the bromine
atom, 1,8-naphthalimide derivatives 5 and 6 show strong excimer emission upon complexation with CB[10] accompanied
by fluorescence transition from blue to cyan. The fluorescence colors
of 4-(dimethylamino)-1,8-naphthalimide derivatives 7 and 8 change from blue to white to yellow with the addition of
CB[n]. This host–guest complexation strategy
to modulate the luminescence of the luminophore would further broaden
the application of luminescent materials.