Exploring the structure and dynamics of soft and hard cuticle of Bombyx mori using solid-state NMR techniques.

This study conducts a comprehensive analysis and comparison of Bombyx mori cuticles across different developmental stages, ranging from larval to adult, utilizing advanced solid-state NMR techniques. The primary objective is to elucidate the underlying reasons for the contrasting hardness of adult cuticles and softness of larval cuticles. Notably, PXRD analysis reveals a prominent broad peak at 19.

Analyzing atomic scale structural details and nuclear spin dynamics of four macrolide antibiotics: erythromycin, clarithromycin, azithromycin, and roxithromycin.

The current investigation centers on elucidating the intricate molecular architecture and dynamic behavior of four macrolide antibiotics, specifically erythromycin, clarithromycin, azithromycin, and roxithromycin, through the application of sophisticated solid-state nuclear magnetic resonance (SSNMR) methodologies. We have measured the principal components of chemical shift anisotropy (CSA) parameters, and the site-specific spin-lattice relaxation time at carbon nuclei sites. To extract the principal components of CSA parameters, we have employed C 2DPASS CP-MAS SSNMR experiments at two different values of magic angle spinning (MAS) frequencies, namely 2 kHz and 600 Hz.

Functionality Modulation Toward Thianthrene-based Metal-Free Electrocatalysts for Water Splitting.

The development of metal-free bifunctional electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) is significant but rarely demonstrated. Porous organic polymers (POPs) with well-defined electroactive functionalities show superior performance in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Precise control of the active sites' local environment requires careful modulation of linkers through the judicious selection of building units.

Atomic-Scale Resolution Insights into Structural and Dynamic Differences between Ofloxacin and Levofloxacin.

This study employs advanced solid-state NMR techniques to investigate the atomic-level structure and dynamics of two enantiomers: ofloxacin and levofloxacin. The investigation focuses on critical attributes, such as the principal components of the chemical shift anisotropy (CSA) tensor, the spatial proximity of H and C nuclei, and site-specific C spin-lattice relaxation time, to reveal the local electronic environment surrounding specific nuclei. Levofloxacin, the levo-isomer of ofloxacin, exhibits higher antibiotic efficacy than its counterpart, and the dissimilarities in the CSA parameters indicate significant differences in the local electronic configuration and nuclear spin dynamics between the two enantiomers.

Investigation of the Influence of Various Functional Groups on the Dynamics of Glucocorticoids.

The basic configuration of glucocorticoid consists of four-fused rings associated with one cyclohexadienone ring, two cyclohexane rings, and one cyclopentane ring. The ways the structure and dynamics of five glucocorticoids (prednisone, prednisolone, prednisolone acetate, methylprednisolone, and methylprednisolone acetate) are altered because of the substitution of various functional groups with these four-fused rings are studied thoroughly by applying sophisticated solid-state nuclear magnetic resonance (NMR) methodologies. The biological activities of these glucocorticoids are also changed because of the attachment of various functional groups with these four-fused rings.

Study of the Variation of the Electronic Distribution and Motional Dynamics of Two Independent Molecules of an Asymmetric Unit of Atorvastatin Calcium by Solid-State NMR Measurements.

Significant changes in the spin-lattice time and chemical shift anisotropy (CSA) parameters are observed in two independent molecules of an asymmetric unit of atorvastatin calcium (ATC-I) (which is referred to as "a"- and "b"-type molecules by following Wang et al.). The longitudinal magnetization decay curve is fitted by two exponentials-one with longer relaxation time and another with shorter relaxation time for most of the carbon nuclei sites.

Study of the structure and dynamics at various parts of the antibacterial drug molecule cefpodoxime proxetil.

The structure and dynamics of cefpodoxime proxetil are elucidated by measuring chemical shift anisotropy (CSA) tensor, spin-lattice relaxation time, and local correlation time at twenty-one crystallographically different C nuclei sites. The principal components of CSA tensor of cefpodoxime proxetil are extracted by the two-dimensional phase adjusted sinning sideband (2DPASS) cross-polarization magic angle spinning (CP-MAS) solid-state NMR experiment, and the spin-lattice relaxation time is measured by the method outlined by Torchia(T1CP). The local correlation time is calculated by bearing in mind that the spin-lattice relaxation mechanism of C nuclei is mainly governed by the CSA interaction and the heteronuclear dipole-dipole interaction.

Structure and dynamics of sodium alginate as elucidated by chemical shift anisotropy and site-specific spin-lattice relaxation time measurements.

The biocompatible, biodegradable, linear copolymer sodium alginate is fabricated from [Formula: see text] linked [Formula: see text]-D-mannuronic acid (M block) and [Formula: see text]-L-guluronic acid (G-block). It has wide applications in drug delivery, cell encapsulation, and commercial application in the textile, cosmetics, paper, food, biomedical, and pharmaceutical industries. The structure and dynamics of sodium alginate were here investigated by measuring chemical shift anisotropy (CSA) parameters, spin-lattice relaxation time, and molecular correlation time.

Probing Atomistic Behavior To Unravel Dielectric Phenomena in Charge Transfer Cocrystals.

Six new binary charge-transfer (CT) cocrystals have been synthesized by solvent drop-assisted mechanochemical grinding method, and all of them exhibited remarkable color changes during the grinding process. Crystal structure analysis reveals the donor (D) and acceptor (A) molecules have assembled primarily via cofacial π···π stacking interactions displaying mixed D-A-D-A stacked columns. Interestingly these cocrystals exhibited very diverse dielectric response in the presence of an alternating current (ac) external electric field, and their dielectric behavior can be explained from the nature and strength of CT interactions in the cocrystal assembly.

Investigation of the Structure and Dynamics of Antiviral Drug Adefovir Dipivoxil by Site-Specific Spin-Lattice Relaxation Time Measurements and Chemical Shift Anisotropy Tensor Measurements.

Adefovir is regarded as a potential antiviral agent. However, it cannot be considered as a valuable drug candidate due to its high polarity that limits its permeability across the human intestinal mucosa. When the ribose phosphate group of adefovir is replaced by the isopolar phosphonomethyl ether functionality, it neutralizes the negative charge of the drug.

Understanding the structure and dynamics of anti-inflammatory corticosteroid dexamethasone by solid state NMR spectroscopy.

For decades corticosteroid dexamethasone has been applied as an anti-inflammatory, immunosuppressant, and decongestant, in the prevention of postoperative nausea and vomiting (PONV), and for auto-immune diseases, allergic reactions, total hip arthroplasty (THA), and cancer. Recently studies suggested that it may be beneficial to deal with the COVID-19 pandemic. This important drug molecule was investigated by solid state NMR measurements to provide more complete features of its structure and dynamics at atomic scale resolution.

An atomic resolution description of folic acid using solid state NMR measurements.

The chemical shift anisotropy tensor and site-specific spin-lattice relaxation time of folic acid were determined by a C 2DPASS CP-MAS NMR experiment and Torchia CP experiment respectively. The molecular correlation time at various carbon nuclei sites of folic acid was evaluated by assuming that the C spin-lattice relaxation mechanism is mainly governed by chemical shift anisotropy interaction and hetero-nuclear dipole-dipole coupling. CSA parameters are larger for the carbon nuclei residing at the heteroaromatic ring and aromatic ring, and those attached to double-bonded electronegative oxygen atoms.

Understanding the correlation between structure and dynamics of clocortolone pivalate by solid state NMR measurement.

Structural characteristics of clocortolone pivalate are unique in the topical corticosteroid field having high penetration power through the stratum corneum of skin as well as low corticosteroid-related adverse effects. The molecule was thoroughly studied by C 2DPASS CP MAS NMR and spin-lattice relaxation time measurements. Molecular correlation time at different carbon nuclei positions was calculated by assuming that the chemical shift anisotropy interaction and heteronuclear dipole-dipole interaction play vital roles in the C spin-lattice relaxation mechanism.

Investigation of the Detailed Internal Structure and Dynamics of Itraconazole by Solid-State NMR Measurements.

The structure and dynamics of itraconazole were investigated by C 2DPASS MAS SSNMR and spin-lattice relaxation time measurement to get an insight into its multiple biological activities, e.g., antifungal, antiviral, anticancer activities, etc.

Investigation of the internal structure and dynamics of cellulose by C-NMR relaxometry and 2DPASS-MAS-NMR measurements.

Internal structure and dynamics of commercial and natural cellulose were studied by measuring chemical shift anisotropy (CSA) parameters, and spin-lattice relaxation rate (1/T) at each and every chemically different carbon nuclear site. CSA parameters were measured by C two-dimensional phase adjusted spinning sideband (2DPASS) cross-polarization magic angle spinning (CP-MAS) NMR experiment. Site specific spin-lattice relaxation time was measured by Torchia-CP method.

A comprehensive and comparative study of the internal structure and dynamics of natural β-keratin and regeneratedβ-keratin by solid state NMR spectroscopy.

Structure and dynamics of natural and regenerated chicken feather β-keratin were investigated by C cross-polarization (CP) magic angle spinning (MAS) solid state nuclear magnetic resonance (SSNMR) spectral analysis, C and H spin-lattice relaxation time measurements, and C two dimensional phase adjusted spinning sidebands (2DPASS) MAS SSNMR measurements. Chemical shift anisotropy (CSA) parameters of both natural and regenerated chicken feather β-keratin were extracted by using 2DPASS MAS SSNMR experiment. The beauty of 2DPASS MAS SSNMR experiment is it can correlate the isotropic and anisotropic dimension with the help of shearing transformation and two dimensional Fourier Transformation.

Elucidating the internal structure and dynamics of α-chitin by 2DPASS-MAS-NMR and spin-lattice relaxation measurements.

The structure and dynamics of the second most abundant biopolymer α-chitin were studied by high resolution solid state C cross-polarization magic angle spinning nuclear magnetic resonance (CP-MAS-NMR) spectral analysis, C relaxation measurements at eight chemically different carbon sites and chemical shift anisotropy measurement by two-dimensional phase-adjusted spinning sidebands (2DPASS) magic angle spinning (MAS) solid state NMR method.C spin-lattice relaxation time was measured by high resolution Torchia CP method. Spin-lattice relaxation rate (1/T) of side chain carbon nuclei were remarkably high, because those nuclei possess higher degree of motional freedom.

"Perfect echo" HMQC: sensitivity and resolution enhancement by broadband homonuclear decoupling.

Homonuclear (1)H-(1)H J-modulation leads to J-multiplets in F1 dimension of 2D (1)H-(13)C HMQC spectra. This hampers unambiguous signal assignment for overcrowded (13)C spectra. Broadband homonuclear decoupling has been achieved in the indirect t1 evolution period by incorporating blocks of perfect echo.

Use of spatial encoding in NMR photography.

NMR photography has gained significant attention as a method of storing and retrieving information using NMR spectroscopy. Among the commonly practiced methods the most important is the frequency encoding by use of a multi-frequency pulse on a liquid crystal molecule. We propose and demonstrate another robust method which relies on spatial encoding.