(a) Absorption and (b) fluorescence spectra
of 1–4 in DMSO (2 μM). (c) Rates of decay
of DPBF (initial concentration
= 30 μM), as monitored spectroscopically at 417 nm, in the absence
and presence of 1 (4 μM), 2 (4 μM), 3 (12 μM), or 4 (12 μM) in DMSO upon
irradiation (λ = 400–700 nm). Change in (d) absorption
and (e) fluorescence spectra of 1 by changing the solvent
from DMSO to 1% DMSO in water. Change in (f) absorption and (g) fluorescence
spectra of 2 by changing the solvent from DMSO to 1%
DMSO in water. (h) TEM images of Milli-Q water solutions of 1 and 2 deposited over formvar/carbon, copper
grids after glow discharge treatment. (i) Hydrodynamic diameter distribution
of 1 and 2 in water.