Antimonene, a novel group 15 two‐dimensional material, is functionalized with a tailormade perylene bisimide through strong van der Waals interactions. The functionalization process leads to a significant quenching of the perylene fluorescence, and surpasses that observed for either graphene or black phosphorus, thus allowing straightforward characterization of the flakes by scanning Raman microscopy. Furthermore, scanning photoelectron microscopy studies and theoretical calculations reveal a remarkable charge‐transfer behavior, being twice that of black phosphorus. Moreover, the excellent stability under environmental conditions of pristine antimonene has been tackled, thus pointing towards the spontaneous formation of a sub‐nanometric oxide passivation layer. DFT calculations revealed that the noncovalent functionalization of antimonene results in a charge‐transfer band gap of 1.1 eV.
The model reaction of photoinduced donor-acceptor interaction in linked systems (dyads) has been used to study the comparative reactivity of a well-known antiinflammatory drug,
(S)-naproxen (NPX) and its (R)-isomer. (R)-or (S)-NPX in these dyads is linked to (S)-N-methylpyrrolidine (Pyr) using a linear or cyclic amino acid bridge (AA or CyAA), to give (R)-/(S)-NPX-AA-(S)-Pyr flexible and (R)-/(S)-NPX-CyAA-(S)-Pyr rigid dyads. The donor-acceptor interaction is reminiscent of the binding (partial charge transfer, CT) and electron transfer (ET) processes involved in the extensively studied inhibition of the cyclooxygenase enzymes (COXs) by the NPX enantiomers. Besides that, both optical isomers undergo oxidative metabolism by enzymes from the P450 family, which also includes ET. The scheme proposed for the excitation quenching of the (R)-and (S)-NPX excited state in these dyads is based on the joint analysis of the chemically induced dynamic nuclear polarization (CIDNP) and fluorescence data. The 1 H CIDNP effects in this system appear in the back electron transfer in the biradical-zwitterion (BZ), which is formed via dyad photoirradiation. The rate constants of individual steps in the proposed scheme and the fluorescence quantum yields of the local excited (LE) states and exciplexes show stereoselectivity. It depends on the bridge's length, structure and solvent polarity. The CIDNP effects (experimental and calculated) also demonstrate stereodifferentiation. The exciplex quantum yields and the rates of formation are larger for the dyads containing (R)-NPX, which let us suggest a higher contribution from the CT processes with the (R)-optical isomer.
The two enantiomers of the nonsteroidal antiinflammatory drug naproxen and of its methyl ester have been selected as representative probes with markedly different hydrophobicity to assess the potential of cholic acid aggregates as drug carriers by means of photophysical techniques. The different distribution of the probes between bulk solution and aggregates has been assessed by quenching of their singlet and triplet excited states by iodide and nitrite anions, respectively. This straightforward photophysical methodology can, in principle, be extended to a variety of drugs containing a photoactive chromophore.
We report a straightforward chemical methodology for controlling the thickness of black phosphorus flakes down to the monolayer limit by layer-by-layer oxidation and thinning, using water as solubilizing agent.
Cyclophanes of different ring sizes featuring perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) linked by flexible malonates were designed, synthesized, and investigated with respect to their structural, chemical and photo-physical properties. It is...
Single-walled carbon nanotubes (SWCNT) have been covalently cross-linked via a reductive functionalization pathway, utilizing negatively charged carbon nanotubides (KC). We have compared the use of difunctional linkers acting as molecular pillars between the nanotubes, namely, p-diiodobenzene, p-diiodobiphenyl, benzene-4,4'-bis(diazonium), and 1,1'-biphenyl-4,4'-bis(diazonium) salts as electrophiles. We have employed statistical Raman spectroscopy (SRS), a forefront characterization tool consisting of thermogravimetric analysis coupled with gas chromatography and mass spectrometry (TG-GC-MS) and aberration-corrected high-resolution transmission electron microscopy imaging series at 80 kV to unambiguously demonstrate the covalent binding of the molecular linkers. The present study shows that the SWCNT functionalization using iodide derivatives leads to the best results in terms of bulk functionalization homogeneity ( H) and degree of addition. Phenylene linkers yield the highest degree of functionalization, whereas biphenylene units induce a higher surface area with an increase in the thermal stability and an improved electrochemical performance in the oxygen reduction reaction (ORR). This work illustrates the importance of molecular engineering in the design of novel functional materials and provides important insights into the understanding of basic principles of reductive cross-linking of carbon nanotubes.
Fluoroquinolones (FQs) are photoreactive drugs, but it is not known whether laboratory light exposure can influence the induction of photoproducts and modify in vitro test results. The basophil activation test (BAT) has proven to be useful for evaluating immunoglobulin E (IgE)-mediated hypersensitivity to FQs, with a higher percentage of positive responders with ciprofloxacin (CIP) than with moxifloxacin (MOX). We studied the effect of laboratory light on CIP and MOX degradation, and drug-protein conjugate formation, and its influence on the BAT for evaluating IgE-mediated hypersensitivity to FQs. The results showed an important decrease in fluorescence emission intensity under light compared to dark conditions for MOX, and that BAT positivity was lower in light (17.9%) than in dark (35.7%) conditions. No changes were found for CIP in either fluorescence emission intensity or BAT results (46.4% in both conditions). We can conclude that light exposure is a critical factor in BAT results when photolabile drugs like MOX are used. Therefore, light is important when interpreting in vitro results.
New photoactive dyads have been synthesized by derivatization of cholic acid (CA) or cholesterol (Ch). These compounds have proven to be efficient tools to monitor incorporation of CA and Ch to mixed micelles (MM) and to probe the microenvironment experienced inside these entities. The outstanding capability of MM to solubilize Ch has been demonstrated.
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