One-dimensional Magnetic Resonance Research Articles

New polyketides from the liquid culture of Diaporthebreyniae sp. nov. (Diaporthales, Diaporthaceae).

During the course of a study on the biodiversity of endophytes from Cameroon, a fungal strain was isolated. A multigene phylogenetic inference using five DNA loci revealed that this strain represents an undescribed species of Diaporthe, which is introduced here as D.breyniae. Investigation into the chemistry of this fungus led to the isolation of two previously undescribed secondary metabolites for which the trivial names fusaristatins G (7) and H (8) are proposed, together with eleven known compounds. The structures of all of the metabolites were established by using one-dimensional (1D) and two-dimensional (2D) Nuclear Magnetic Resonance (NMR) spectroscopic data in combination with High-Resolution ElectroSpray Ionization Mass Spectrometry (HR-ESIMS) data. The absolute configuration of phomopchalasin N (4), which was reported for the first time concurrently to the present publication, was determined by analysis of its Rotating frame Overhauser Effect SpectroscopY (ROESY) spectrum and by comparison of its Electronic Circular Dichroism (ECD) spectrum with that of related compounds. A selection of the isolated secondary metabolites were tested for antimicrobial and cytotoxic activities, and compounds 4 and 7 showed weak antifungal and antibacterial activity. On the other hand, compound 4 showed moderate cytotoxic activity against all tested cancer cell lines with IC50 values in the range of 5.8-45.9 µM. The latter was found to be less toxic than the other isolated cytochalasins (1-3) and gave hints in regards to the structure-activity relationship (SAR) of the studied cytochalasins. Fusaristatin H (8) also exhibited weak cytotoxicity against KB3.1 cell lines with an IC50 value of 30.3 µM. Graphical abstract.

Constituents from ripe figs of Ficus vallis-choudae Delile (Moraceae) with antiplasmodial activity.

Ripe figs, barks, and wood of Ficus vallis-choudae are used in traditional medicine against several conditions including nausea and malaria. However, its use is still to be scientifically documented and validated. Hence, the aim of the present work was to evaluate the antiplasmodial activity of the dichloromethane-methanol (DCM-MeOH (1:1)) crude extract, their hexane, dichloromethane, ethyl acetate, and methanoli fractions, as well as the isolated chemical constituents. The chemical study of the DCM-MeOH (1:1) crude extract of F. vallis-choudae figs led to the isolation of fifteen (15) known compounds identified based on their spectroscopic data [one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR), mass spectrometry] and by comparison of these data with those reported in the literature. Some of the isolated compounds were assessed in vitro for their antiplasmodial activity against Plasmodium falciparum chloroquine-sensitive 3D7 (Pf3D7) and multidrug-resistant Dd2 strains. The dichloromethane fraction exhibited very good antiplasmodial activity against both strains with IC50 values of 13.86 μg/mL and 8.18 μg/mL, respectively. Among the tested compounds, wighteone (2) was the most active against P. falciparum 3D7 (IC50 = 24.6 ± 1.5 μM) and Dd2 (IC50 = 11.9 ± 2.4 μM) strains. The obtained results could justify the traditional uses of F. vallis-choudae against malaria. Wighteone appears to be the most active ingredient. However, further consideration of this compound as starting point for antimalarial drug discovery will depend upon its selectivity of action towards Plasmodium parasites.Highlights• 15 (fifteen) compounds were isolated from the dichloromethane-methanol extract of Ficus vallis-choudae.• Their structures were determined on the basis of their spectroscopic data.• The dichloromethane fraction showed promising activities on the Pf3D7 and PfDd2 strains with IC50 values of 13.86 and 8.18 µg/mL, respectively.• Wighteone was the most active compound against PfDd2 (IC50 = 11.9 ± 2.4 μM).Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00436-022-07540-5.

Nematicidal activity of furanoeremophilenes against Meloidogyne incognita and Nacobbus aberrans.

While searching for novel small molecules for new organic pesticide agents against plant-parasitic nematodes, we found that the hexane extract from the roots of Senecio sinuatos and its main secondary metabolite, 3β-angeloyloxy-6β-hydroxyfuranoeremophil-1(10)-ene (1), possess nematicidal activity against the second stage juvenile (J2) of Meloidogyne incognita and Nacobbus aberrans. Both species reduce yield of various vegetable crops. These results encouraged us to synthesize esters 3-9 formed by diol 2, obtained by alkaline hydrolysis of 1 and acetic anhydride, benzoic acid, 2-nitrobenzoic acid, 2-bromobenzoic acid, 4-nitrobenzoic acid, 4-bromobenzoic acid, and 4-methoxybenzoic acid, respectively. The nematicidal activity of these esters was evaluated and compared with that of the free benzoic acids. Natural product 1 and derivatives 2-9 were obtained and characterized by their physical and spectroscopic properties, including one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) experiments; X-ray diffraction analysis established their absolute configuration. The nematicidal activity of compounds 1-9 was assessed in vitro against M. incognita and N. aberrans J2 and was compared to activity shown by benzoic acid, 2-nitrobenzoic acid, 2-bromobenzoic acid, 4-nitrobenzoic acid, 4-bromobenzoic acid, and 4-methoxybenzoic acid. The esters suppressed nematodes more than free benzoic acid. Nacobbus aberrans J2 were suppressed, with compounds 5, 6, and 8 being the most active. Esters formed by 3β,6β-dihydroxyfuranoeremophil-1(10)-ene and ortho- or para-substituted benzoic acids containing electron acceptor groups had nematicidal activity against N. aberrans. These compound can potentially serve as a model for the development of new organic nematicidal agents. © 2022 Society of Chemical Industry.

Extraction, isolation, structural characterization and prebiotic activity of cell wall polysaccharide from Kluyveromyces marxianus

In this study, three yeast α-mannans (LZ-MPS, MC-MPS, and G-MPS) were extracted from different sources of Kluyveromyces marxianus. The total sugar content of the three α-mannans ranged from 91.13–97.10%, whereas no proteins were detected. A structural arrangement was proposed using ultraviolet spectroscopy, Fourier-transform infrared spectroscopy, and one-dimensional and two-dimensional nuclear magnetic resonance. The main chain of the three yeast α-mannans was formed by a →6)-α-D-Manp-(1→ unit, which was slightly different from the repeating unit of the branch structure. The prebiotic potential of LZ-MPS, MC-MPS, and G-MPS was assessed using in vitro fermentation with pure and faecal cultures. The three yeast α-mannans could be utilised as substrates for the growth of Lactobacillus and Lactococcus strains. In addition, the three yeast α-mannans markedly regulated the intestinal microbiota composition by increasing the relative abundances of Bacteroides, Parabacteroides, and Phascolarctobacterium and decreasing the abundance of pathogenic bacteria.

Characterisation of four new triterpenoid saponins with nitric oxide inhibitory activity from aerial parts of Gouania leptostachya

Four new triterpenoid saponins (gouaniasides VII–IX [1–3] and joazeiroside C [4]) and one known triterpenoid (5) were isolated from the aerial parts of Gouania leptostachya DC. (Rhamnaceae). Their structures were elucidated via one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy, high-resolution electrospray ionisation–mass spectrometry, and analyses of hydrolytic cleavage results. The anti-inflammatory potential of compounds 1–3 was evaluated according to their ability to inhibit the production of nitric oxide (NO) by RAW 264.7 macrophages. All compounds at noncytotoxic concentrations significantly inhibited NO production by macrophages in a concentration-dependent manner.

Terminalin from African Mango (Irvingia gabonensis) Stimulates Glucose Uptake through Inhibition of Protein Tyrosine Phosphatases.

Protein tyrosine phosphatases (PTPs), along with protein tyrosine kinases, control signaling pathways involved in cell growth, metabolism, differentiation, proliferation, and survival. Several PTPs, such as PTPN1, PTPN2, PTPN9, PTPN11, PTPRS, and DUSP9, disrupt insulin signaling and trigger type 2 diabetes, indicating that PTPs are promising drug targets for the treatment or prevention of type 2 diabetes. As part of an ongoing study on the discovery of pharmacologically active bioactive natural products, we conducted a phytochemical investigation of African mango (Irvingia gabonensis) using liquid chromatography–mass spectrometry (LC/MS)-based analysis, which led to the isolation of terminalin as a major component from the extract of the seeds of I. gabonensis. The structure of terminalin was characterized by spectroscopic methods, including one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and high-resolution (HR) electrospray ionization (ESI) mass spectroscopy. Moreover, terminalin was evaluated for its antidiabetic property; terminalin inhibited the catalytic activity of PTPN1, PTPN9, PTPN11, and PTPRS in vitro and led to a significant increase in glucose uptake in differentiated C2C12 muscle cells, indicating that terminalin exhibits antidiabetic effect through the PTP inhibitory mechanism. These findings suggest that terminalin derived from African mango could be used as a functional food ingredient or pharmaceutical supplement for the prevention of type 2 diabetes.

Identification of synthetic cannabinoid methyl 2-{[1-(cyclohexylmethyl)-1H-indol-3-yl] formamido}-3-methylbutanoate using modern mass spectrometry and nuclear magnetic resonance techniques

Abstract The samples of plant material suspected to contain new psychoactive substances are very often the subject of chemical-toxicological analyses. Gas chromatography-mass spectrometry (MS), liquid chromatography-quadrupole time-of-flight-MS, and liquid chromatography-tandem MS were applied with the aim to identify synthetic cannabinoid, methyl 2-{[1-(cyclohexylmethyl)-1H-indol-3-yl] formamido}-3-methylbutanoate (MMB-CHMICA) without the analytical standard, which is very often the case when a new drug arrives. The structure of compound was also confirmed by one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy and conformational analysis. After identification, methanolic extract of plant material containing MMB-CHMICA was successfully used for developing a multiple reaction monitoring method on liquid chromatography-tandem MS instrument. The optimization procedure is shown in detail. The complete fragmentation pattern and also the optimization of the extraction procedure of MMB-CHMICA from plant material were shown. The obtained data are useful for forensic, toxicological, and clinical purposes.

Evaporation of Sessile Binary Mixture Droplets: Time Dependence of Droplet Shape and Concentration Profile from One-Dimensional Magnetic Resonance Microscopy.

Many technological applications like inkjet printing, coating, or cooling processes rely on the evaporation of sessile droplets. Regarding liquid mixtures, the understanding of the underlying physics is still incomplete and process optimization requires trial and error. Our main goal is to establish a novel method in this field, one-dimensional magnetic resonance microscopy, to investigate the evaporation of sessile binary mixture droplets in the microliter range. It allows us not only to determine the droplet volume and shape, including contact angle, but also to measure concentration profiles with a spatial resolution of a few micrometers. These capabilities are demonstrated for a mixture of 1-octanol (OCT) and pentadecafluoro-1-octanol (F-OCT) by combining spatially resolved 1H and 19F nuclear magnetic resonance measurements. We clearly observe three evaporation regimes for the OCT/F-OCT mixture. The first and second regimes are characterized by the predominant evaporation of F-OCT and are separated by a depinning event. The third regime starts when no F-OCT is left and, thus, features the evaporation of a pure OCT droplet. During all stages, concentration gradients perpendicular to the substrate are weak in the studied binary droplet.

Withasomniferol D, a New Anti-Adipogenic Withanolide from the Roots of Ashwagandha (Withania somnifera).

Withania somnifera (Solanaceae), well-known as ‘Indian ginseng’ or ‘Ashwagandha’, is a medicinal plant that is used in Ayurvedic practice to promote good health and longevity. As part of an ongoing investigation for bioactive natural products with novel structures, we performed a phytochemical examination of the roots of W. somnifera employed with liquid chromatography–mass spectrometry (LC/MS)-based analysis. The chemical analysis of the methanol extract of W. somnifera roots using repeated column chromatography and high-performance liquid chromatography under the guidance of an LC/MS-based analysis resulted in a new withanolide, withasomniferol D (1). The structure of the newly isolated compound was elucidated by spectroscopic methods, including one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and high-resolution (HR) electrospray ionization (ESI) mass spectroscopy, and its absolute configuration was established by electronic circular dichroism (ECD) calculations. The anti-adipogenic activities of withasomniferol D (1) were evaluated using 3T3-L1 preadipocytes with Oil Red O staining and quantitative real-time polymerase chain reaction (qPCR). We found that withasomniferol D (1) inhibited adipogenesis and suppressed the enlargement of lipid droplets compared to the control. Additionally, the mRNA expression levels of adipocyte markers Fabp4 and Adipsin decreased noticeably following treatment with 25 μM of withasomniferol D (1). Taken together, these findings provide experimental evidence that withasomniferol D (1), isolated from W. somnifera, exhibits anti-adipogenic activity, supporting the potential application of this compound in the treatment of obesity and related metabolic diseases.

A New Isoflavan From the Heartwood of Dalbergia cochinchinensis

A new isoflavan, named dalbergiacochan A (1), was isolated from the heartwood of Dalbergia cochinchinensis, along with two known isoflavans, namely mucronulatol (2) and 2′-O-methylsepiol (3). Their structures were elucidated based on extensive spectroscopic analyses, including one-dimensional (1D) and two-dimensional nuclear magnetic resonance (2D NMR), and mass spectroscopy (MS) data, and the absolute stereochemistry of compound 1 was determined as R-3′,6-dihydroxy-2′,4′,8-trimethoxyisoflavan from its circular dichroism spectrum. Compound 1 was inactive against Escherichia coli, Bacillus thuringiensis, and Shigella dysenteriae.

Structural implications of lipoarabinomannan glycans from global clinical isolates in diagnosis of Mycobacterium tuberculosis infection

In Mycobacterium tuberculosis (Mtb), surface-exposed Lipoarabinomannan (LAM) is a key determinant of immunogenicity, yet its intrinsic heterogeneity confounds typical structure–function analysis. Recently, LAM gained a strong foothold as a validated marker for active tuberculosis (TB) infection and has shown great potential in new diagnostic efforts. However, no efforts have yet been made to model or evaluate the impact of mixed polyclonal Mtb infections (infection with multiple strains) on TB diagnostic procedures other than antibiotic susceptibility testing. Here, we selected three TB clinical isolates (HN878, EAI, and IO) and purified LAM from these strains to present an integrated analytical approach of one-dimensional and two-dimensional Nuclear Magnetic Resonance (NMR) spectroscopy, as well as enzymatic digestion and site-specific mass spectrometry (MS) to probe LAM structure and behavior at multiple levels. Overall, we found that the glycan was similar in all LAM preparations, albeit with subtle variations. Succinates, lactates, hydroxybutyrate, acetate, and the hallmark of Mtb LAM-methylthioxylose (MTX), adorned the nonreducing terminal arabinan of these LAM species. Newly identified acetoxy/hydroxybutyrate was present only in LAM from EAI and IO Mtb strains. Notably, detailed LC/MS-MS unambiguously showed that all acyl modifications and the lactyl ether in LAM are at the 3-OH position of the 2-linked arabinofuranose adjacent to the terminal β-arabinofuranose. Finally, after sequential enzymatic deglycosylation of LAM, the residual glycan that has ∼50% of α−arabinofuranose -(1→5) linked did not bind to monoclonal antibody CS35. These data clearly indicate the importance of the arabinan termini arrangements for the antigenicity of LAM.

Chemical Constituents of the Folk Medicinal Plant Argyreia acuta Lour. and Their Anti-Inflammatory Activity

Phytochemical investigation of the folk medicinal plant Argyreia acuta Lour. has led to the isolation of a pair of new 3-alkylated coumarin enantiomers, (±)-acutamarin [(±)-1] and 3 known structurally related coumarins (2-4), along with 4 known flavonoids (5-8). The structures of these compounds were elucidated on the basis of extensive spectroscopic (including one-dimensional and two-dimensional nuclear magnetic resonance) analyses and by comparison of their spectral data with those reported in the literature. The absolute configurations of ( − )-1 and ( + )-1 were proposed by comparison of experimental and calculated electronic circular dichroism data. Compounds 5 and 7 exhibited in vitro anti-inflammatory activity by inhibiting the production of nitric oxide with IC50 values of 24.54 ± 0.36 μM and 10.60 ± 0.15 μM, respectively.

Secondary Metabolites of the Endophytic Fungus Chaetomium globosum Isolated From Coptis chinensis

A new steroid, chaetglotone (1), together with 3 known compounds (2-4), were isolated from Chaetomium globosum, which is an endophytic fungus isolated from the root of Coptis chinensis Franch . The new compound was characterized by one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy and high-resolution electrospray ionization mass spectrometer. The relative configuration and absolute configuration of 1 were further determined via the DP4 + and Early Childhood Development protocols, separately.

Conjugated Polyene Ketones From the Marine Sponge Clathria (Thalysias) Reinwardti (Vosmaer, 1880) and Their Cytotoxic Activity

Five conjugated polyene ketones (1-5) were isolated from the methanol extract of the marine sponge Clathria ( Thalysias) reinwardti (Vosmaer, 1880) living in the coastal waters of Vietnam. Their structures were determined to be 8-(2′,3′,4′-trimethylphenyl)-6-methyl-oct-3( E),5( E),7( E)-trien-2-one (1), 13-apoastaxanthinone (2), 9-apoastaxanthinone (3), 2,3-dehydro-4-oxo- β-ionone (4), and 4-(2′,3′,4′-trimethylphenyl)-but-3( E)-en-2-one (5), by extensive analysis of high-resolution electron spray ionization mass spectrum (HR-ESI-MS), one-dimensional, and two-dimensional (2D) nuclear magnetic resonance (NMR) spectra, as well as by comparison of the spectral data with those reported in the literature. Compound 1 was new, compounds 2 to 4 were isolated from nature for the first time, and the chemical structure as well as the NMR assignments, of 5 were indicated by 2D NMR for the first time. Additionally, compound 5 exhibited cytotoxic activity against the human cancer cells SK-LU-1, SK-Mel-2, MCF-7, and Hep-G2 with half-minimal inhibitory concentration (IC50) values of 15.12 ± 3.43, 17.41 ± 2.83, 33.12 ± 3.39, and 34.38 ± 3.52 µM, respectively, but displayed only a weak cytotoxic effect on the normal HEK-239A cells (IC50 64.67 ± 3.67 µM). Compound 5 also significantly increased Caspase-3 activity in SK-LU-1 cells at concentrations of 10, 15, and 20 µM.

Nuclear magnetic resonance-based chemical signature and nutritional discrimination of Macrotyloma uniflorum accessions from the alpine Himalayas.

Macrotyloma uniflorum (horsegram) is cultivated in the alpine Himalayas for its nutritional benefits. The chemical diversity of M. uniflorum has been explored by several research groups, but none has reported the chemical signature to monitor the identity and quality. To overcome quality control problems and provide more accurate chemotype information, proton nuclear magnetic resonance (1 H-NMR)-based chemical signature and tentative metabotype discrimination was studied. Metabolites were identified by characteristic chemical shifts and their correlations in one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) experiments. The identifications were confirmed by reference standards, with in-house databases, and with public databases. From the analysis of seed samples from eight locations, NMR detected 46 diversified metabolites, including 18 amino acids, nine carbohydrates, three vitamins, seven flavonoids, and nine miscellaneous molecules (fatty acids/choline/phenolics/organic acids/sterols). These metabolites generated a single snapshot chemical signature for M. uniflorum. Greater content of identified metabolites was found at high elevations of 1829 m (55.78 g kg-1 ) followed by 1000-1150 m (19.30-17.23 g kg-1 ) and 1150-1450 m (7.33-13.41 g kg-1 ). Principal component analysis of samples revealed that chemotypes grouped into three distinct clusters. 'Cluster-3' was positively correlated with metabolites and found the best nutritionally enriched chemotype. A proton nuclear magnetic resonance-based M. uniflorum chemical signature was generated for the first time. The environmental conditions of 1829 m were most suitable for obtaining nutritionally enriched M. uniflorum crops. Overall, this information could help in the conservation, quality control, product development, and agriculture inventions of M. uniflorum. © 2021 Society of Chemical Industry.

Microbial transformation of some simple isoquinoline and benzylisoquinoline alkaloids and in vitro studies of their metabolites

Simple isoquinoline alkaloids (heliamine, dehydroheliamine), a phthalide isoquinoline alkaloid noscapine, and an aporphine alkaloid boldine are biosynthetically derived from an amino acid tyrosine. These substrates and a simple synthetic isoquinoline alkaloid (2-acetyl-7-amino-1,2,3,4-tetrahydroisoquinoline) contain an isoquinoline nucleus. The biotransformation of these substrates via reduction, oxidation, hydroxylation, and N-oxidation reactions with different microorganism produced nine metabolites, namely: N-(2-acetyl-1,2,3,4-tetrahydroisoquinolin-7-yl) acetamide (Metabolite 1), heliamine N-oxide (Metabolite 2), 6,7-dimethoxyisoquinoline (Metabolite 3), 3,4-dihydro-6,7-dimethoxy isoquinolin-1-one (Metabolite 4), heliamine (Metabolite 5), dehydroheliamine N-oxide (Metabolite 6), cotarnine (Metabolite 7), 5-hydroxy cotarnine (Metabolite 8), and boldine N-oxide (Metabolite 9). Primarily, the metabolites are structurally elucidated by one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) analyses, and high-resolution electrospray ionization mass spectrometry (HR-ESIMS). Furthermore, the substrates and their isolated metabolites are evaluated in vitro for their anti-inflammatory, antimicrobial, cytotoxicity, and anticancer activities. The in vitro studies reveal that some of the isolated compounds are potential as anti-inflammatory, antitumor, and antimicrobial leads.

Two dimensional 1H magnetic resonance relaxometry-based analyses of Argonne premium coals

1H magnetic resonance (MR) is a useful technique for determining molecular structure of coals. Most previous MR studies were based on one-dimensional 1H magnetic resonance relaxometry. Two-dimensional (2D) 1H magnetic resonance relaxation correlation methods, T1–T2* and T1ρ–T2*, were used to evaluate Argonne premium coals, including Beulah-Zap (BZ), Wyodak-Anderson (WA), Pittsburgh #8 (PIT), Upper Freeport (UF), and Pochontas #3 (POC) coals as received. Samples were also measured after oxidization at low temperature (110 and 210 °C). From the 2D relaxation correlations, various hydrogen-containing components were distinguished and characterized. The change of hydrogen during low temperature oxidation was analyzed, and the hydrogen content estimated. The technique captured significant differences between low rank coals (BZ and WA) and high rank coals (PIT, UF, and POC). The order of T1/T2* ratios is aliphatic hydrogen > aromatic hydrogen > hydrogen- and oxygen-containing functional groups > moisture in BZ and WA coals. The PIT, UF, and POC coals mainly contain aromatic hydrogens. The T1–T2* and T1ρ–T2* spectra of BZ and WA coals change significantly during low temperature oxidation. Our new MR method provides new insight into coal behaviour.

Alpha-Glucosidase Inhibitory Diterpenes from Euphorbia antiquorum Growing in Vietnam

Bioactive-guided phytochemical investigation of Euphorbia antiquorum L. growing in Vietnam led to the isolation of five ent-atisanes, one seco-ent-atisane, and one lathyrane (ingol-type). The structures were elucidated as ent-1α,3α,16β,17-tetrahydroxyatisane (1), ethyl ent-3,4-seco-4,16β,17-trihydroxyatisane-3-carboxylate (2), ent-atisane-3-oxo-16β,17-acetonide (3), ent-3α-acetoxy-16β,17-dihydroxyatisane (4), ent-16β,17-dihydroxyatisane-3-one (5), calliterpenone (6), and ingol 12-acetate (7). Their chemical structures were unambiguously determined by analysis of one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and high resolution mass spectrometry, as well as by comparison with literature data. Among them, 1 is a new compound while 2 is an ethylated artifact of ent-3,4-seco-4,16β,17-trihydroxyatisane-3-carboxylic acid, a new compound. Isolates were evaluated for alpha-glucosidase inhibition. Compound 3 showed the most significant inhibitory activity against alpha-glucosidase with an IC50 value of 69.62 µM. Further study on mechanism underlying yeast alpha-glucosidase inhibition indicated that 3 could retard the enzyme function by noncompetitive.

Fully Conjugated Pyrene-BODIPY and Pyrene-BODIPY-Ferrocene Dyads and Triads: Synthesis, Characterization, and Selective Noncovalent Interactions with Nanocarbon Materials.

Several pyrene-boron-dipyrromethene (BODIPY) and pyrene-BODIPY-ferrocene derivatives with a fully conjugated pyrene fragment appended to the α-position(s) of the BODIPY core have been prepared by Knoevenagel condensation reaction and characterized by one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR), UV-vis, fluorescence spectroscopy, high-resolution mass spectrometry as well as X-ray crystallography. The redox properties of new donor-acceptor BODIPY dyads and triads were studied by electrochemical (cyclic voltammetry (CV) and differential pulse voltammetry (DPV)) and spectroelectrochemical approaches. Formation of weakly bonded noncovalent complexes between the new pyrene-BODIPYs and nanocarbon materials (C60, C70, single-walled carbon nanotube (SWCNT), and graphene) was studied by UV-vis, steady-state fluorescent, and time-resolved transient absorption spectroscopy. UV-vis and fluorescent spectroscopy are indicative of the much stronger and selective interaction between new dyes and (6,5)-SWCNT as well as graphene compared to that of C60 and C70 fullerenes. In agreement with these data, transient absorption spectroscopy provided no evidence for any significant change in excited-state lifetime or photoinduced charge transfer between pyrene-BODIPYs and C60 or C70 fullerenes when the pyrene-BODIPY chromophores were excited into the lowest-energy singlet excited state. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations suggest that the pyrene fragments are fully conjugated into the π-system of BODIPY core, which correlates well with the experimental data.

Computer Assisted Structure Elucidation (CASE): Current and future perspectives.

The first efforts for the development of methods for Computer-Assisted Structure Elucidation (CASE) were published more than 50years ago. CASE expert systems based on one-dimensional (1D) and two-dimensional (2D) Nuclear Magnetic Resonance (NMR) data have matured considerably by now. The structures of a great number of complex natural products have been elucidated and/or revised using such programs. In this article, we discuss the most likely directions in which CASE will evolve. We act on the premise that a synergistic interaction exists between CASE, new NMR experiments, and methods of computational chemistry, which are continuously being improved. The new developments in NMR experiments (long-range correlation experiments, pure-shift methods, coupling constants measurement and prediction, residual dipolar couplings [RDCs]), and residual chemical shift anisotropies [RCSAs], evolution of density functional theory (DFT), and machine learning algorithms will have an influence on CASE systems and vice versa. This is true also for new techniques for chemical analysis (Atomic Force Microscopy [AFM], "crystalline sponge" X-ray analysis, and micro-Electron Diffraction [micro-ED]), which will be used in combination with expert systems. We foresee that CASE will be utilized widely and become a routine tool for NMR spectroscopists and analysts in academic and industrial laboratories. We believe that the "golden age" of CASE is still in the future.