Drug–Drug Interactions within Protein Cavities Probed by Triplet–Triplet Energy Transfer

A new direct and noninvasive methodology based on transient absorption spectroscopy has been developed to probe the feasibility of drug–drug interactions within a common protein binding site. The simultaneous presence of (<i>R</i>)-cinacalcet (CIN) and (<i>S</i>)-propranolol (PPN) within human or bovine α₁-acid glycoproteins (AAGs) is revealed by detection of ³CIN* as the only transient species after laser flash photolysis of CIN/PPN/AAG mixtures at 308 nm. This is the result of triplet–triplet energy transfer from ³PPN* to CIN, which requires close contact between the two drugs within the same biological compartment. Similar results are obtained with nabumetone and CIN as donor/acceptor partners. This new methodology can, in principle, be extended to a variety of drug/drug/biomolecule combinations

Photophysical Probes To Assess the Potential of Cholic Acid Aggregates as Drug Carriers

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

Fundamental Insights into the Reductive Covalent Cross-Linking of Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWCNT) have been covalently cross-linked via a reductive functionalization pathway, utilizing negatively charged carbon nanotubides (KC₄). We have compared the use of difunctional linkers acting as molecular pillars between the nanotubes, namely, <i>p</i>-diiodobenzene, <i>p</i>-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 (<i>H</i>_bulk) 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

Fundamental Insights into the Reductive Covalent Cross-Linking of Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWCNT) have been covalently cross-linked via a reductive functionalization pathway, utilizing negatively charged carbon nanotubides (KC₄). We have compared the use of difunctional linkers acting as molecular pillars between the nanotubes, namely, <i>p</i>-diiodobenzene, <i>p</i>-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 (<i>H</i>_bulk) 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

Fundamental Insights into the Reductive Covalent Cross-Linking of Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWCNT) have been covalently cross-linked via a reductive functionalization pathway, utilizing negatively charged carbon nanotubides (KC₄). We have compared the use of difunctional linkers acting as molecular pillars between the nanotubes, namely, <i>p</i>-diiodobenzene, <i>p</i>-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 (<i>H</i>_bulk) 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