Monitoring Intermolecular and Intramolecular Interactions by NMR Spectroscopy

Insights into the formulation properties, biocompatibility, and permeability of poorly water-soluble methoxyflavones with PEG400 and propylene glycol

“…Also, the lack of vibrational signals from the methoxyflavones whilst in solution could be interpreted as an inference of the extensive solvation effects of the glycols on the drug compounds. It is expected that successful molecular interactions between any two chemical species will alter the chemical environment of the compounds, which in turn would be reflected in their NMR fingerprint (35). In this work, minor shifts in the position of the proton signal from the PEG400 ethylene oxide extending unit were observed.…”

Design, Synthesis, and Application of Fluorescent Ligands Targeting the Intracellular Allosteric Binding Site of the CXC Chemokine Receptor 2

“…Subsequently, to obtain structural information, we employed rotating-frame nuclear Overhauser effect spectroscopy (ROESY) (Figures S20 and S21). This technique, used to establish through-space correlation between nuclei physically near to each other, , allowed us to visualize the interactions of the protons in the molecule that are close in space even if they are not bonded or coupling to each other. Interestingly, compounds 6a and 6b differ particularly in their phenolic OH signal.…”

Quantitative Evaluation of Noncovalent Interactions between 3,4-Dimethyl-1H-pyrazole and Dissolved Humic Substances by NMR Spectroscopy

“…Proton spin− lattice (T 1 ) and spin−spin (T 2 ) relaxation times are NMRderived physical−chemical parameters that reflect the changes in the chemical environment experienced by the hydrogen nuclei of a compound, including the formation of complexes with other compounds. 39,40 It is thus conceivable that, when humic molecules interact with DMPP by forming complexes, these associations may limit DMPP motility, thereby increasing the release to the lattice of the energy acquired during a NMR experiment and resulting in a faster DMPP relaxation and concomitant shortening of its T 1 values.…”

“…Moreover, the formation of complexes also causes a progressive broadening of the pyrazole 1 H signals as a function of FA concentration, which appears as a decrease in signal intensity (Figure A) and represents further evidence for the establishment of weak DMPP–FA interactions. In fact, since the amplitude at half-height of NMR signals is inversely proportional to the Brownian motions of a molecule, a decrease in compound motility due to interactions determines an increase in the amplitude of its NMR signals. , We can infer that the formation of humo–DMPP adducts occurs through a host–guest formation. In fact, such a hypothesis is attributed to the large affinity of DMPP with the hydrophobic domains of the fulvic material represented by alkyl, aromatic, and phenolic moieties (Figure S1), which are associated with flexible supramolecular structures potentially capable of hosting DMPP by forming multiple weak interactions, , with consequent reduction of its spatial motility and enhancement of the relative NMR signal amplitude.…”