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Heterocyclic building blocks incorporating quinoline and morpholine units are central to the synthesis of a wide range of biologically active molecules, where conformational preferences and solid-state organization can directly influence the reactivity and functional performance. In this study, the molecular structure of 2-(morpholin-4-yl)quinoline-3-carbaldehyde (abbreviated as MQ3CA), a key intermediate for quinoline-, morpholine-, and piperazine-based drug scaffolds, is examined using a synergistic combination of solution and solid-state NMR spectroscopy, complemented by single-crystal X-ray diffraction (SC-XRD) and density functional theory (DFT) calculations. Complete resonance assignments, including chemical shifts, scalar coupling constants, and through-bond and through-space correlations, were achieved using 2D J-resolved, COSY, NOESY, HSQC, and HMBC experiments, enabling an unambiguous description of molecular connectivity and conformation in solution. Solid-state 13C CPMAS-TOSS and two-dimensional 1H-13C HETCOR NMR measurements provided atomic-level insight into the solid-state organization of MQ3CA. The observed differences between the solid- and solution-state 13C chemical shifts indicate the influence of crystal packing and weak intermolecular interactions, consistent with the crystallographic analysis. PXRD analysis further confirmed the absence of polymorphic phases in the investigated sample. The SC-XRD information supports that the morpholine ring adopts a chair conformation with the quinoline ring positioned in the equatorial plane, whereas C-H···O hydrogen bonds and π···π interactions dominate the crystal packing. DFT-derived electronic descriptors further support the experimentally observed structural stability. This work demonstrates the effectiveness of integrated magnetic resonance approaches for resolving structure-packing relationships in pharmaceutically relevant intermediates.
Understanding chemical reactions is central to pharmaceutical and chemical development, and nuclear magnetic resonance (NMR) spectroscopy is increasingly attractive for reaction analysis because it provides direct structural insight and quantitative information without dependence on response factors. However, conventional high-field NMR instruments are rarely located in chemistry laboratories due to demanding infrastructure requirements and reliance on liquid cryogens. Recent advances in cryogen-free magnet technologies address this limitation and enable practical deployment of NMR directly in laboratory and manufacturing environments. This work evaluates cryogen-free NMR as a process analytical technology (PAT) by comparing a 400-MHz high-temperature superconducting (HTS) magnet NMR system with an 80-MHz benchtop NMR instrument. Two representative reactions were studied: a ring-closing metathesis reaction and the transesterification of a pinacol arylboronic ester to an aryl triolborate. The comparison focuses on data quality, the ability to extract kinetic and speciation information, and the strengths and limitations of each platform for complex reaction monitoring. Results demonstrate that both cryogen-free systems can deliver meaningful reaction insights, including in cases with overlapping NMR signals, while offering distinct technical advantages. The higher-field HTS system provides improved resolution and analytical capability, whereas the benchtop instrument offers simplicity, accessibility, and ease of integration. Overall, cryogen-free NMR instruments lower barriers to adoption, eliminate liquid-cryogen's requirements, and expand the use of NMR for routine reaction monitoring. These technologies enable broader application of NMR-based PAT, and support more informed decision-making in chemistry laboratories and manufacturing settings across diverse reaction types and operational scales worldwide.
Heterogeneously catalyzed hydrogenations are pivotal in the chemical industry. Studying these reactions often demands significant experimental effort due to safety requirements, elevated pressures and temperatures, and the operational modes of traditional laboratory reactors. To address these challenges, we propose an automated, efficient, and cost-effective method for characterizing such reactions within a kinetic laboratory setting. Utilizing benchtop NMR as a noninvasive, automatable analytical tool offers advantages in terms of space and cost over high-frequency NMR, though its limited spectral resolution may restrict applicability to certain reaction systems. In this study, we investigate the hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE) as a model reaction. While literature provides extensive data on the main components, the formation of side products remains inadequately explained. Conducting the reaction in a batch reactor, we assess the detection and quantification of side products. Samples withdrawn during hydrogenation are analyzed using benchtop NMR coupled with a quantum-mechanical Bayesian quantitative NMR analysis, employing component knowledge to quantify mixtures through mathematical modeling. We collect kinetic data, gaining both qualitative and quantitative insights into the reaction network at temperatures up to 80°C and a pressure of 10 bar. Our findings demonstrate that the reaction mixture's composition can be quantitatively monitored in real-time, facilitating the derivation of kinetic parameters. Despite the minor formation of various side products, we successfully quantify dimeric reaction products and evaluate process parameters influencing their formation. The integration of a reactor, online benchtop NMR, and advanced qNMR data analysis yields high-quality results essential for process optimization.
Diffusion-NMR, including diffusion-ordered spectroscopy (DOSY), is a powerful technique for measuring self-diffusion and inferring molecular size, shape, aggregation, and intermolecular interactions in solution. Its noninvasive nature and ability to separate components in complex mixtures have made DOSY widely used across chemistry, biochemistry, and materials science. However, accurate and reproducible diffusion measurements depend not only on careful experimental design but also on robust, transparent, and consistent data processing. Despite the growing adoption of diffusion-NMR, widely adopted protocols, practical tutorials, and broadly accepted guidelines for DOSY data analysis remain limited, contributing to variability in reported diffusion coefficients and reduced comparability between studies. The General NMR Analysis Toolbox (GNAT) is a free, open-source platform for visualizing and analyzing diffusion-NMR data. In this article, we present a clear, step-by-step guide to processing diffusion-NMR data with GNAT, emphasizing best practices, quality control, and common pitfalls. The workflow covers data import, preprocessing (including baseline/phase considerations and signal selection), diffusion fitting and model choice, validation of results, and recommendations for reporting key parameters and uncertainty. Although written with new users in mind, this guide also serves as a reference for experienced practitioners seeking greater consistency and rigor in DOSY analysis. By promoting standardized, reproducible workflows and encouraging the use of open-source tools, this work aims to improve the transparency, quality, and comparability of diffusion-NMR studies.
The presence of radicals in fluids can significantly influence the 1H longitudinal nuclear magnetic resonance relaxation processes. The field-cycling nuclear magnetic relaxometry technique provides a unique approach to study these interactions within a broad Larmor frequency range. The situation is quite common in fluid systems subjected to oxidative stress, such as lubricants in internal combustion engines. Our previous studies in lubricant degradation did not consider in detail specific effects of radicals on the 1H longitudinal relaxation. In the present work, we focus on a simplified system in which TEMPOL radicals are introduced in controlled concentrations into ethylene glycol samples. The system's behavior is evaluated at different radical concentrations to elucidate the influence of the paramagnetic species on the relaxation dispersion profile. We propose the inclusion of an additional relaxation term to account for intermolecular proton-electron interactions. We observe that, for radical concentrations exceeding approximately 2 × 1017 radicals/cm3, paramagnetic interactions dominate the relaxation dispersion at Larmor frequencies below 1 MHz. Moreover, we show that both the diffusion constants of ethylene glycol and TEMPOL molecules can be estimated from a single experiment. The consistency of our results with existing literature suggests an in-depth analysis of the paramagnetic contribution in the relaxometric characterization of degraded lubricants.
NMR and MRI provide a variety of customizable methods for process monitoring. A selection was applied to monitor structural and compositional changes in hazelnuts during thermal treatment, with particular focus on the roasting and aging behavior of hazelnut oil. Hazelnuts contain a high oil fraction stored in subcellular oleosomes, whose stability is crucial for product quality and shelf life. Thermal stress can alter these microscopic oil-containing structures, affecting oil mobility and oxidative stability. In situ MRI measurements were combined with pulsed field gradient stimulated echo (PFG-STE) NMR diffusion experiments to investigate structural changes across multiple length scales. MRI detected mesostructural alterations in the hazelnut matrix from ~50 μm to several millimeters, corresponding to features above the cellular level. At roasting temperatures below 150°C, only minor structural changes occurred, whereas at 200°C, pronounced void formation and cellular collapse were observed. A dedicated experimental setup enabled in situ measurements during roasting under controlled temperature, allowing spatially resolved monitoring of oil redistribution in coarse nut structure. Complementary PFG-STE NMR diffusion measurements provided insight into the microstructure (100 nm-10 μm), revealing subcellular structural changes and oil mobility. These results showed that oleosomes were largely destroyed already at 100°C. Furthermore, NMR spectroscopy demonstrated temperature-dependent oxidation kinetics of unsaturated fatty acids in hazelnut oil on a molecular level, with clear formation of oxidation products upon heating, whereas ambient storage caused only minor chemical changes. The combined use of MRI and NMR enables quasi-nondestructive, in situ monitoring of molecular, microstructural, and mesostructural transformations in hazelnuts and their oil under controlled thermal processing conditions.
NMR relaxation of liquids in the presence of solid interfaces, such as silica gel or porous glass, is affected by slowed-down and anisotropic molecular reorientations compared to the bulk, but also by the presence of spins as potential relaxation partners on or close to the surface. The latter contribution is predominantly considered as unpaired electrons in metal centers or surface radicals, but dipolar interactions with spin-bearing nuclei such as 29Si or 1H may also contribute to relaxation of adsorbed species. In this study, an attempt is made at identifying the most relevant relaxation contributions by either adding or removing relaxation sinks: While immobilized stable radicals (TEMPO) on the surface shorten relaxation times of adsorbed liquids, the replacement of 1H nuclei by 2H in hydroxyl groups is expected to remove the dominating part of nuclear dipolar spin-spin relaxation. In both cases, it is assumed that surface chemistry, which is the decisive parameter for spin relaxation mechanisms at interfaces, remains unchanged. Longitudinal and transverse relaxation, 2d T1-T2 maps, and frequency-dependent relaxation measurements of a number of homogeneous liquid phases as well as binary mixtures in the pore space of silica gel and porous glass are discussed in terms of the presence of radicals, whereas the replacement of OH by OD is observed to reduce relaxation rates in the systems under study.
Nuclear magnetic resonance (NMR) is a powerful analytical tool for wine analysis to identify and quantify a metabolite composition. However, a limiting factor of 1D 1H NMR spectroscopy is the overlap of signals in complex mixtures. While conventional 2D NMR methods disperse the signals over two dimensions, they are associated with long experiment times. In the case of wine, interesting metabolites are also often masked by the large water and ethanol peaks. To improve wine analysis by NMR, a method that uses the advantages of 2D NMR while suppressing solvent signals and being within the timeframe of 1D NMR is highly desirable. Interleaved ultrafast COSY (iuf-COSY) offers a possibility for fast acquisition of a 2D spectrum and has been demonstrated as a powerful tool in metabolomics studies, as a complement to 1D NMR methods. Here, the iuf-COSY experiment has been adapted to suppress water and ethanol signals by using a shaped pulse and a NOESY block. This approach efficiently suppresses solvent signals and gives a 2D COSY spectrum of wine in approximately 20 min. Important metabolites that originally were covered by solvent signals could be annotated, while minimal interleaving artefacts were observed. This is an efficient method to acquire a COSY spectrum of a wine sample, which can aid with the identification and discrimination of metabolites in future wine studies through additional cross peaks, while working within a high-throughput time scale. This might be particularly interesting in the field of wine metabolomics, quality control, authenticity and fraud.
Metabolomics is a powerful tool for assessing drug safety and understanding the biochemical effects of pharmaceutical compounds. Favipiravir, a drug widely used during the COVID-19 pandemic, has been associated with damage to various organs, including the heart. However, a comprehensive analysis of its metabolic impact on cardiac tissue has not yet been performed. This study utilized high-resolution 1H NMR-based metabolomics to investigate metabolic alterations in rat heart tissue following favipiravir treatment. For this purpose, 60 male Wistar Albino rats were randomly assigned to three groups: control, low-dose favipiravir (200 mg/kg), and high-dose favipiravir (300 mg/kg), with 20 rats in each group. Treatments were administered via oral gavage, and heart tissue samples were collected for 1H NMR analysis after the treatment period. Bioinformatics analysis results showed significant dose-dependent changes in key metabolites in the favipiravir-treated groups. Decreased levels of ATP, citrate, and valine accompanied by increased levels of lactate and AMP suggest a disruption in mitochondrial energy production and a shift towards anaerobic glycolysis. At the higher dose, more pronounced disruptions were noted, including decreases in glutamate, glutamine, aspartate, tyrosine, 3-methylhistidine, and asparagine, suggesting a broader metabolic dysfunction. These findings offer valuable insights into the cardiotoxic effects of favipiravir and highlight the utility of NMR metabolomics in identifying drug-induced metabolic disturbances.
Pyridines are a crucial class of heterocycles with widespread applications in natural products, pharmaceuticals, and fluorescent organic materials. In this manuscript, we report the results from a kinetic and mechanistic investigation of an inverse-electron-demand Diels-Alder (IEDDA) cycloaddition involving an oxazole-type diene synthesized via an Ugi-Zhu multicomponent reaction (UZ-3CR). This heterodiene reacts efficiently with various dienophiles such as E-4-oxopentenoic acid, fumaric acid, and monoethyl maleate, yielding highly substituted pyridines in good to excellent yields. Reaction conditions were optimized, and the influence of solvent polarity on regioselectivity was evaluated. The necessity of protonation for successful cycloadditions was probed using structurally diverse dienophiles, revealing the essential role of the carboxylic acid group in triggering the reactions. Mechanistic insights were supported by a comprehensive NMR study (1H, 13C, and 15N), which provided indirect evidence of in situ protonation of the oxazole ring. Notably, 15N NMR revealed significant downfield shifts of the oxazole nitrogen, consistent with its protonation, and the emergence of new nitrogen signals corresponding to pyridine products. This study demonstrates the synthetic utility of Ugi-Zhu-derived 5-aminooxazoles in IEDDA cycloadditions and highlights the critical role of acid-promoted activation in enabling efficient pyridine synthesis. We report the results from a kinetic and mechanistic investigation of an IEDDA cycloaddition involving an oxazole-type diene synthesized via an UZ-3CR.
In this study, we examine the influence of homogeneous and highly inhomogeneous electric fields (HIEFs) on NMR parameters such as isotropic spin-spin couplings and nuclear magnetic shieldings. The model compounds imidazole and pyrrole were chosen because of their distinct symmetries with respect to the applied fields. Calculations were performed at the CAM-B3LYP and second-order polarization propagator approximation (SOPPA) levels using the aug-cc-pVTZ-J basis set. The results show that the influence of the external HIEF is comparable in magnitude with that produced by solvation in water. The coupling constants exhibit angular dependence that partially resembles Karplus-type relationships, with a slight asymmetry, with nitrogen nuclei showing the most pronounced responses. One-bond couplings are mainly governed by their Fermi contact contributions, so that the isotropic coupling is almost indistinguishable from the Fermi contact term. In contrast, the two-bond couplings display a clear separation between the Fermi contact and the isotropic values, influenced by paramagnetic spin-orbit or spin-dipolar contributions. The nuclear shieldings, in turn, exhibit a more harmonic dependence, following the variations of the applied field.
Drug development is a risky endeavour with a high failure rate, often caused by the limited ability to predict the efficacy and interactions of candidate drugs in a native cellular environment. In this context, in-cell NMR spectroscopy is a promising tool for assessing drug-target binding directly in living cells, thereby improving the screening and development of new molecules. In this study, we used real-time in-cell 19F NMR spectroscopy in a flow bioreactor to observe competitive binding of fluorinated benzenesulfonamide derivatives to three cytosolic isoforms of carbonic anhydrase. Quantitative measurement of the dissociation constants relative to a spy ligand allowed an accurate ranking of the compounds based on their intracellular affinities for each isoform. The use of two fluorinated ligands allowed simultaneous observation of spy ligand displacement and test ligand binding, as well as estimation of the effective ratio of free ligand concentrations under poor solubility conditions. We also show that signal saturation caused by short repetition times, which can significantly impact the analysis, can be easily corrected a posteriori. Overall, we show that real-time in-cell 19F NMR spectroscopy can reliably quantify drug-target binding in the cellular environment, paving the way for future applications in drug discovery.
Analyzing nuclear magnetic relaxation dispersion (NMRD) profiles to determine parameters of atomic/molecular motion in complex systems is a challenging task that involves the fitting of these profiles. The choice of the theoretical model, the constraint on parameters, and their reliability are key factors for a realistic description of systems. Herein, strategies for fitting proton NMRD profiles in smectite clay aqueous suspensions are evaluated, with the aim of providing the most realistic description of water molecules dynamics at clay surfaces. Profiles are adjusted with a combination of Jean-Pierre Korb (JPK) and Solomon-Bloembergen-Morgan (SBM) model. Due to the large number of parameters involved, rigorous methodology is implemented to achieve a unique and reliable solution. Two approaches are tested. In a one-step approach, the overall theoretical model (JPK + SBM) is adjusted to experimental profile at once. In a two-step approach, the frequency ranges where JPK and SBM models prevail, and an initial set of parameters obtained from the one-step approach serve as starting point for a segmented regression procedure. Below a frequency ω I , l i m chosen as the breakpoint, profiles are fitted with the JPK model (first step) and the resulting optimized parameters injected and kept constant in the global model (second step), to optimize the SBM parameters. The study is applied to montmorillonite and beidellite clay suspensions. While, for the former, both approaches lead to fairly similar and conclusive results, for the later, only the two-step approach provides a reasonable description of the system.
Rehydration of texturized vegetable proteins (TVPs) is decisive for their functional properties, but little is known in relation to how rehydration conditions impact their ability to absorb and retain water. The present study aimed to investigate how rehydration dynamics and intrinsic water mobility of texturized soy protein are affected by temperature, pH, and ionic strength under dynamic or equilibrium conditions. Low-field NMR T2 relaxation measurements were conducted dynamically on soy TVP during rehydration under different combinations of pH (5.4, 6.2, or 7.0), ionic strength (0.29, 0.46, or 0.71 M), and temperature (15, 25, or 35°C). Rehydration could be tracked from a decrease in the T2 relaxation time constant, reflecting a reduced mobility of water protons when water molecules were immobilized in intrinsic structures. Kinetic modeling revealed a significant effect of temperature on the rate of rehydration, whereas pH and ionic strength did not affect the rate of rehydration. To evaluate equilibrium conditions, 24 h soaking experiments were conducted, which revealed significant effects of pH on the rehydration capacity and NMR T2 relaxation. Increasing pH increased the rehydration capacity and T2 relaxation time constants, indicating that water compartmentalization in TVPs can be modulated through pH effects on electrostatic repulsion. In conclusion, NMR relaxometry enables kinetic studies of soy TVP rehydration, and this study demonstrates that rehydration kinetics and equilibrium rehydration capacity can be decoupled. Temperature primarily governed the rate of water uptake, whereas pH influenced final rehydration capacity, while ionic strength in the range applied here did not affect rehydration capacity.
Understanding how drugs interact with metal ions is essential for predicting their stability, how well they are absorbed in the body, and possible side effects. Pravastatin is a commonly used statin to prevent cardiovascular heart disease and has several functional groups that can bind metal ions, but its interactions with transition metals and lanthanides are not well studied. This work examines the complexation process of pravastatin with transition metal ions zinc (Zn2+), nickel (Ni2+) and lanthanide gadolinium (Gd3+) using high-resolution NMR spectroscopy. It was found that the presence of ions (Ni2+, Gd3+) in an aqueous solution of pravastatin causes broadening of 1H NMR signals, leading to a change in signal intensity in the HMQC spectra and disappearance of the correlation between the 1H and 13C signals in the HMBC spectra. No significant changes were observed in the NMR spectra of similar experiments of pravastatin with zinc salt. The DOSY NMR spectrum of pravastatin in the presence of ions (Gd3+, Ni2+, and Zn2+) revealed a change in self-diffusion coefficients compared to the parent structure. An assumption about the possible centers of localization of Gd3+ and Ni2+ ions near the pravastatin molecule has been made.
Propolis from Apis mellifera and cerumen from Tetragonula carbonaria are complex mixtures of beeswax, plant resins, and bee secretions whose composition varies with geography and species. Understanding these differences is important for exploring their bioactive potential. This study employs untargeted quantitative 1H NMR metabolomics to characterize A. mellifera propolis from Scandinavia (Denmark and Norway) and Australia, as well as cerumen from T. carbonaria in Australia. Hydrophilic and hydrophobic extracts were analyzed to assess compositional differences across geographical origin and bee species, and to link specific metabolites to radical scavenging activity (RSA). Principal component analysis (PCA) of the 1H NMR spectra showed a marked separation between Scandinavian and Australian propolis. Hydrophilic extracts showed that Scandinavian propolis contains higher levels of aromatic compounds, whereas Australian propolis is richer in carbohydrates. In contrast, cerumen from T. carbonaria exhibits higher amounts of terpenoids. Hydrophobic extracts revealed that Australian propolis has the highest wax content, with shorter chains and more free fatty acids, while Scandinavian propolis samples display uniform wax structures and the highest aromatic content. Multivariate regression using recursive weighted partial least squares (rPLS) to RSA prediction highlighted signals attributable to ferulic acid and p-coumaric acid, which were confirmed by statistical total correlation spectroscopy (STOCSY). These findings demonstrate the utility of quantitative 1H NMR metabolomics for distinguishing botanical and geographic chemotypes of propolis and cerumen. The findings further show that Scandinavian propolis is more consistent with respect to metabolite composition compared to Australian samples, presumably reflecting differences in resin sources for foraging.
Solid-state NMR experiments provide valuable insights into the structure of pharmaceutical compounds, many of which contain nitrogen. Recent literature indicates that the indirect detection of 14N offers significant advantages for structural analysis, particularly when using two-dimensional 1H-14N HMQC experiments. The advantage of these experiments is that they allow us to rapidly collect information about the hydrogen bonding interaction with a minimal amount of the compound. In our study, we have carried out 1H-14N HMQC experiments on structurally similar pharmaceutical compounds sorafenib and regorafenib monohydrate to explore the hydrogen bonding interactions and differentiate different nitrogen signals which are difficult to obtain using 15N solid-state NMR experiments on unlabeled compounds. Our findings enable us to distinguish between intramolecular and intermolecular hydrogen bonding interactions and identify different nitrogen atoms in their structures. Thus, our results show that the 1H-14N HQMC experiments provide a rapid and effective method for distinguishing different hydrogen bonding interactions.
Biochar is a multifunctional soil amendment that improves soil structure, enhances water-holding capacity, and contributes to carbon sequestration. However, the dose-response relationship between biochar addition and soil behavior remains underexplored, particularly at high application rates. In this study, fifteen soil-biochar mixtures were prepared with biochar mass fractions from 0 to 1 (fBC = 0-1) to evaluate in detail the changes induced in a Sicilian clay soil. The mixtures were investigated for pH, electrical conductivity, bulk density, water-holding capacity, and water activity (Aw). Biochar addition caused pronounced increases in alkalinity, porosity, and water retention, following nonlinear dose-response trends with clear thresholds beyond fBC ≈ 0.3-0.5. FT-IR spectroscopy revealed the progressive appearance of oxygenated and aromatic functional groups, accompanied by a reduction in signals from adsorbed water and native soil polar groups. Fast Field-Cycling NMR relaxometry provided molecular-scale insight into soil-water interactions. At high biochar contents, water proton T1 relaxation times were markedly lengthened, indicating a reduced overall efficiency of surface-driven relaxation. Correlation-time (τc) analysis further revealed the emergence of water populations with longer correlation times and a redistribution of relaxation pathways toward outer-sphere dominated mechanisms. Overall, the results indicate that biochar improves soil water retention not by strong surface adsorption but through effective pore-space storage, keeping water available for biological use. The combined spectroscopic and relaxometric approach establishes a direct link between molecular-level water dynamics and macroscopic soil properties, highlighting the value of FFC-NMR as a powerful tool for studying natural porous systems.
Trandolapril, an angiotensin-converting enzyme (ACE) inhibitor, undergoes two-state exchange in organic solvents arising from cis-trans isomerization around a N-C bond. A previous NMR study reported different equilibrium constants depending on which 1H nuclei were used for analysis. Such variations have been attributed to experimental error but require experimental resolution. In this study, we developed a new method for measuring cross-peak volumes based on a projection technique and applied the method to a series of two-dimensional 1H-13C HSQC spectra of trandolapril, acquired using the time-zero HSQC (HSQC0) scheme. The Proj-Vol method yielded consistent equilibrium constant values across multiple 1H nuclei, demonstrating that trandolapril has a single equilibrium constant, consistent with its single exchange mechanism. The Proj-Vol method is based on constructing 1D 13C projections of narrow rectangular regions around the cross-peaks. The use of 1D projection provides several advantages, including fewer fitting parameters and the elimination of the need to consider peak splitting due to 1H homonuclear J-couplings. It also offers other useful benefits, such as a narrower projection box size to reduce the contributions of other diagonally overlapping cross-peaks in 2D HSQC spectra, the improved signal-to-noise ratio of projection spectra by slice summation, and the cancellation of dispersion components caused by spectral misphasing in the 1H dimension. These advantages and benefits increase the accuracy of cross-peak volume determination in 2D HSQC spectra, compared with existing methods that directly fit 2D cross-peak shapes.
Quantitative analysis of solid-state NMR data, based on magic-angle spinning with cross-polarization experiments (CP-MAS), often requires extensive signal processing, from the transformation of raw time-domain data (FIDs) to the extraction of quantitative data and the modelling of signal intensity kinetics. Many current workflows rely on semi-manual peak fitting and heterogeneous tools across laboratories for intensity curve modelling, limiting reproducibility and throughput. In this work, we propose a fully reproducible and open workflow combining two key methodological approaches: (1) an adaptive bucketing approach, extraction of relevant variables for analysis (ERVA), implemented in NMRProcFlow application, to automatically segment 13C spectra into chemically relevant spectral regions; and (2) an online modelling platform that allows users to fit intensity curves over contact time with multiple models, guided by objective indicators including fit quality scores and parameter sensitivity metrics. This integrated approach provides a fast, user-friendly and transparent path from FIDs to kinetic model parameters, opening new perspectives for reproducible quantitative solid-state NMR.