2-hydroxychalcones are known to be converted to the colored flavylium form under UV irradiation. In this study, the photochemical conversion of two 2-hydroxychalcone derivatives (4'-dimethylamino-2-hydroxychalcone and 4'-methoxy-2-hydroxychalcone) has been carried out in the solid matrix by the intercalation into the layer of the clay, montmorillonite. The 2-hydroxychalcone has been adsorbed on the clay by modifying the clay interlayer with a cationic surfactant, dodecyltrimethylammonium chloride. The addition of an acidic compound (benzenesulfonic acid) has induced the successful coloring reaction of the 2-hydroxychalcone derivatives by the conversion to the flavylium under UV irradiation between the clay interlayer. A delayed coloration has been observed on the short time irradiation of 4'-methoxy-2-hydroxychalcone included in the clay layer.
The effect of gel–solution
interfaces on the femtosecond
laser-induced nucleation of proteins was investigated. Using hen egg
white lysozyme, we found that the nucleation efficiency could be modulated
by the distance between the laser focus and agarose gel surfaces (h) and the gel concentration (c). In particular,
laser irradiation near the soft gel surface (h =
50 μm, c = 0.5%) could induce nucleation at
very low supersaturation, where no nucleation could be induced in
the bulk solutions even with femtosecond laser irradiation. Such enhancement
of the nucleation was also confirmed for the membrane protein, acriflavine
resistance protein B (AcrB), and an organic compound, N-(4-hydroxyphenyl)acetamide
(paracetamol). To gain further insights into the role of gel–solution
interfaces, we conducted fast imaging of cavitation bubbles, which
are known to locally concentrate supersaturated solutions and thus
act as a trigger for laser-induced nucleation. We found that the cavitation
bubbles shrank asymmetrically near the soft gel surfaces and then
finally collapsed toward the solution side. This is in contrast to
the symmetric collapse in bulk solutions, which generates a large
amount heat and chemical decomposition at the focus. In addition,
cavitation bubbles generated near stiff gel surfaces (c ≥ 2%) caused an axial liquid jet toward the gel surfaces,
which would disturb the formation of locally concentrated regions.
These results suggest that gel–solution interfaces significantly
modulate cavitation bubble dynamics and can be cues to achieve effective
nucleation.
Crystalline ternary charge transfer (CT) complexes were constructed for tuning colors by a supramolecular approach. The complexes are composed of 4,4′-biphenyldisulfonic acid (BPDS, donor), tetracyanoquinodimethane (TCNQ, acceptor), and aliphatic amines. Four salts of BPDS with methyl-, ethyl-, isopropyl-, or t-butylamine underwent insertion of TCNQ between biphenyl moieties to yield the CT complexes with different colors in a range of deep red to light orange. Such a color change was interpreted on the basis of crystal structures of the complexes. BPDS salts produce layer structures which provide nanospaces for TCNQ and alkyl groups. Steric complementarity in the nanospaces explains the above-mentioned color change.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.