Two mononuclear ruthenium complexes [(bpy)RuL/L](ClO) ([1]/[2]) (bpy-2,2' bipyridine, L = 2,3-di(pyridin-2-yl)pyrazino[2,3-f][1,10]phenanthroline) and L = 2,3-di(thiophen-2-yl)pyrazino[2,3-f][1,10]phenanthroline have been synthesized. The complexes have been characterized using various analytical techniques. The complex [1] has further been characterized by its single crystal X-ray structure suggesting ruthenium is coordinating through the N donors of phenanthroline end. Theoretical investigation suggests that the HOMOs of both complexes are composed of pyridine and pyrazine unit of ligands L and L whereas the LUMOs are formed by the contribution of bipyridine units. The low energy bands at ∼480 nm of the complexes can be assigned as MLCT with partial contribution from ligand transitions, whereas the rest are ligand centered. The complexes have shown Ru/Ru oxidation couples at E at 1.26 (70 mV) V and 1.28 (62 mV) V for [1] and [2] vs Ag/AgCl, respectively, suggesting no significant role of distal thiophene or pyridine units of the ligands. The complexes are emissive and display solvent dependent emission properties. Both complexes have shown highest emission quantum yield and lifetime in DMSO (ϕ = 0.05 and τ = 460 ns and λ at 620 nm for [1]; ϕ = 0.043 and τ = 425 ns and λ at 635 nm for [2]). Further, the long luminescent lifetime of these complexes has been utilized to generate reactive oxygen species for efficient azo dye decomposition.
Polymeric
nanocomposite films are used as promising transdermal
drug carriers because of the improved patient compliance, easy application
on skin, and noninvasiveness. A thermoresponsive polymeric composite
film has been developed here through the deposition of carbon quantum
dots (CQDs) on functionalized β-cyclodextrin (β-CD). The
composite has been developed by grafting of poly(N-vinyl caprolactam) on β-CD, followed by cross-linking of diethylene
glycol dimethacrylate and subsequent deposition of CQDs. CQDs have
been prepared from waste pomegranate peels via a hydrothermal method.
To enlighten the thermoresponsive nature of the composite film, lower
critical solution temperature, as well as temperature-dependent swelling
behavior, has been studied. The composite demonstrates excellent rheological
features. The developed polymeric composite film is nontoxic toward
NIH 3T3 fibroblast cell lines. On the deposition of CQDs on the copolymer,
the penetration power and fluorescent property have been improved,
which help to track the cells in vitro. This film
is worthy to be applied to the skin. It can efficiently load lidocaine
hydrochloride monohydrate (LHM). In vitro and ex vivo skin permeation profiles reveal the sustained release
behavior of loaded LHM at average skin temperature and pH.
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