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We used 1H, 13C HRMAS and genomic analysis to investigate regionally the transition from oxidative to glycolytic phenotype and its relationship with altered gene expression in adjacent biopsies through the brain of rats bearing C6 gliomas. Tumor-bearing animals were anesthetized and infused with a solution of [1-13C]-glucose, and small adjacent biopsies were obtained spanning transversally from the contralateral hemisphere (regions I and II), the right and left peritumoral areas (regions III and V, respectively), and the tumor core (region IV). These biopsies were analyzed by 1H, 13C HRMAS and by quantitative gene expression techniques. Glycolytic metabolism, as reflected by the [3-13C]-lactate content, increased clearly from regions I to IV, recovering partially to physiological levels in region V. In contrast, oxidative metabolism, as reflected by the [4-13C]-glutamate labeling, decreased in regions I-IV, recovering partially in region V. This metabolic shift from normal to malignant metabolic phenotype paralleled changes in the expression of HIF1α, HIF2α, HIF3α genes, downstream transporters, and regulatory glycolytic, oxidative, and anaplerotic genes in the same regions. Together, our results indicate that genetic and metabolic alterations occurring in the brain of rats bearing C6 gliomas colocalize in situ and the profile of genetic alterations in every region can be inferred from the metabolomic profiles observed in situ by multinuclear HRMAS., The present work was supported by grants SAF2014-53739-R, SAF2017-83043-R, and B2017/BMD-3688 from the Ministry of Economy and Competitiveness and from the Community of Madrid to PL-L and SC, Acciones Integradas IH-HI2006-0101 from the Ministry of Science and Technology to L.S. and S.C. The authors are indebted to Mr. Javier Pérez CSIC for careful drafting of the illustrations and to Mrs. Teresa Navarro CSIC for granting access to the Biomedical NMR Services of the Institute of Biomedical Research “Alberto Sols” CSIC.

A combination of van der Waals and electrostatic interactions was used to integrate SWNT and a suitably functionalized polythiophene into nanostructured ITO electrodes. In the resulting electron donor/acceptor nanocomposites, polythiophene represents the light-harvesting chromophore that readily donates an excited-state electron to the ground-state electron-accepting SWNT. Upon illumination, monochromatic incident photoconversion efficiencies between 1.2 and 9.3% were determined for single and eight-sandwiched layers, respectively.

This study describes for the first time the use of high-resolution nuclear magnetic resonance (NMR) on Klamath (Aphanizomenon flos-aquae, AFA) blue-green algae directly on powder suspension. These algae are considered to be a “superfood”, due to their complete nutritional profile that has proved to have important therapeutic effects. The main advantage of NMR spectroscopy is that it permits the detection of a number of metabolites all at once. The Klamath alga metabolome was revealed to be quite complex, and the most peculiar phytochemicals that can be detected directly on algae by NMR are mycosporine-like amino acids (porphyra-334, P334; shinorine, Shi) and low molecular weight glycosides (glyceryl β-d-galactopyranoside, GalpG; glyceryl 6-amino-6-deoxy-α-d-glucopyranoside, ADG), all compounds with a high nutraceutical value. The presence of cis-3,4-DhLys was revealed for the first time. This molecule could be involved in the anticancer properties ascribed to AFA.

Plant regeneration is a critical step in most in vitro breeding techniques. This paper studies the effects of a low-molecular-weight humic acid (HA) on morphogenesis from pear and quince leaf explants. Variable HA amounts [0 (control), 1, 5, 10, and 20 mg C L(-1)] were added to the regeneration media. A dose-response effect was observed in pear for root and shoot production; it was improved at HA 1 mg C L(-1) and considerably reduced at the highest amounts. HA was, instead, ineffective in quince. The (1)H HR-MAS NMR analyses of calli in the induction phase showed more evident metabolite (asparagine, alanine, and γ-aminobutyric acid) signals in quince than in pear. The assignment of overlapped signals in both genotypes was supported by the 2D NMR analyses. Spectroscopic characterization suggested also an enhancement of asparagine contents in morphogenic calli of pear with respect to the control and higher HA amount treatments.

A regioregular head-to-head/ tail-to-tail poly(beta,beta'-disubstituted bithiophene) P1 was synthesised by chemical and electrochemical polymerisation of 2,2'-bithiophene that bears (S)-2-methylbutylsulfanyl chains in the beta and beta'-positions. The polymer was characterised by GPC, NMR and UV/Vis spectroscopy, CD, AFM and by electrochemical and conductivity measurements. The CD spectra of P1 in solutions in which poor solvents are present show interesting features and allow the presence of different optically active species to be distinguished. Upon varying the casting conditions of P1, different relative amounts of grainy and homogeneous aggregated phases were observed in AFM micrographies of films and corresponding negative or positive first Cotton effects were found in the CD spectra. AFM, CD and UV/Vis characterisations were also performed on an electrogenerated optically active polymer PE1, in order to make a comparison with the chemically synthesised one. The interesting, small band gap of P1 allows for easy p- and n-electrochemical doping.

The reaction of ferric chloride and β-diketones (HL) in alkaline methanol solution represents a good synthetic route to hexairon(III) clusters [MFe6-(OCH3)12(L)6]+ (M = Na, Li), which exhibit an unusual sixfold molecular symmetry. Single-crystal X-ray diffraction showed that the six octahedrally coordinated iron(III) ions define a ring and are linked by twelve bridging methoxide ligands. The resulting [Fe6(OCH3)12] skeleton has the remarkable property of acting as a host for an alkali-metal ion both in the solid state and in organic solution, as demonstrated by 23Na and 7Li NMR experiments. The magnetic behavior of these systems is consistent with the presence of a nonmagnetic S = 0 ground state and of antiferromagnetic exchange interactions between the high-spin ferric ions. The energy of the excited states was studied in detail by high-field DC and pulsed-field differential magnetization experiments at 0.7 and 1.5 K. Single-crystal susceptibility measurements at variable temperature revealed a sizeable magnetic anisotropy, which has been successfully analyzed in terms of single-ion and dipolar contributions. The results are relevant to research into the origin of superparamagnetic-type behavior in transition-metal clusters.

The interaction of two biliar acids (chenodeoxycholic acid and cholic acid) with 2-hydroxypropyl-β-cyclodextrin (HPβCD) in solution and in the solid state was studied using different techniques. The formation of an inclusion complex with a 1:1 stoichiometry was suggested by the phase solubility studies. Both differential scanning calorimetry and X-ray diffractometry exhibited the amorphous state of the complex. The inclusion of both biliar acids into the HPβCD cavity was confirmed by the13C-NMR studies. Cholic acid showed a weaker affinity with respect to chenodeoxycholic acid probably owing to the presence of a hydroxyl group onC(12) (12α) close to the complexation site.

The 1H and 13C signals of the hexyl chains of the title compounds were fully assigned. The regiochemical features of the aliphatic region of proton and carbon spectra were analysed in dimers and trimers. Dimers and trimers proved to be reliable model compounds in the regiochemical assignment of poly(3-hexylthiophene) even when the aliphatic region of proton and carbon spectra was involved. The chemical shifts of the protons of CH2(α)s and of the hexyl chain as a whole and those of the first three aliphatic carbons appear to be the most significant.

The configurational and conformational properties of six 4-trimethylammoniummethyl 2,2-disubstituted 1,3-dioxolanes were studied using NOE experiments and vicinal coupling constants. Selective 1D NOE experiments proved to be effective tools in the configurational assignment of C-2 relative to C-4. The preferred conformation of the dioxolane ring and the exocyclic group at C-4 was obtained by employing vicinal coupling constants and NOE results. The 1H and 13C NMR chemical shifts show stereochemically dependent trends. Quantitative analysis of conformer populations was performed using Haasnoot et al's equation. The N+(CH3)3 group was found to be synclinal with respect to the heterocyclic O-3 atom and points outside the ring. When a phenyl group is present at C-2, the 4-CH2N+— group in a trans relationship to the 2-phenyl ring was found to occur prevalently in a pseudo-axial orientation, whereas it was established to be prevalently pseudo-equatorial when cis with respect to the phenyl ring.

The metabolic profile of human healthy and neoplastic colorectal tissues was obtained using ex vivo High-Resolution Magic Angle Spinning (HR-MAS) NMR spectroscopy. Principal Components Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA) were applied to NMR data in order to highlight the biochemical differences between healthy and neoplastic colorectal tissues. The synergic combination of ex vivo HR-MAS NMR spectroscopy with Multivariate Data Analysis enables discrimination between healthy and tumoral colorectal tissues and identification of the increase of taurine, acetate, lactate, and lipids, and the decrease of polyols and sugars as tumoral characteristics. Moreover, it was found that macroscopically/histologically normal colorectal tissues, collected at least 15 cm from the adenocarcinoma, are characterized by a metabolic pattern quite similar to that typical of tumoral lesions. It was shown that ex vivo HR-MAS NMR spectroscopy, performed on intact specimens, may be of great potentiality in the clinical evaluation of human neoplastic colorectal tissues and that the biochemical data represent the molecular basis for an accurate and noninvasive clinical applications of in vivo NMR spectroscopy.

In this work we report how the plasma treatment of electrophoretically deposited single-walled carbon nanotubes (e-SWCNTs) enabled us to obtain semi-transparent thin films used as anodes for the development of organic solar cells. Combining plasma treated e-SWCNT network with a conducting polymer (poly[7-(thien-3-ylsulfanyl)heptanoic acid]-co-thiophene), an increase of the open-circuit voltage and of the short-circuit current density was observed. We attribute this effect to an enhanced hole collection by the nanotube electrode due to their short aspect ratio permitting a better interpenetration of the polymer.

The preferred conformations of the methylsulphinyl group in a number of phenyl methyl sulphoxides substituted in the phenyl ring with one, two or three fluorine atoms have been studied by employing a multinuclear NMR approach. From the 1H, 13C and 17O chemical shifts of the methylsulphinyl group, and the torsional angles obtained either from MO calculations or experimental determinations for a number of the compounds, empirical correlations have been derived which enabled us to extract the preferred orientation of the SO bond or of the methyl group relative to the phenyl ring in all the molecules examined. For a limited number of the compounds, the structure of the preferred conformer is satisfactorily close to the solid-state structure found in an independent study carried out with x-ray diffraction. The twist of the SO bond relative to the phenyl ring changes as a function of the number of ortho substituents, being highest when two substituents are present. The lowest twist, torsional angle nearly zero, was found in ortho-monosubstituted compounds and the SO bond is oriented towards the opposite side with respect to the substituent. Analyses were also carried out of the conformational dependence of long-range nJ(HF) and nJ(CF) coupling constants, where the first nucleus in the parentheses refers to the methylsulphinyl group. The behaviour of these coupling constants as a function of internal rotation around the exocyclic CS bond was derived from semi-empirical INDO MO FPT calculations, and scaled interpolating equations were derived in order to reproduce the experimental results. It thus emerges that 5J(HF), 4J(CF), 5J(CF) and 6J(CF) are conformationally dependent and show, experimentally, significant changes. These parameters can be usefully employed for the conformational analysis of methyl phenyl sulphoxides.

The formation and geometry of the hyodeoxycholic acid (HDCA)/2-hydroxypropyl-β-cyclodextrin (HPβCD) complex in methanol-d4 solution was determined through a rotating frame nuclear Overhauser (ROESY) experiment. The reported results confirmed those independently and previously obtained though the use of 13C complexation shifts in the same solvent. The 13C approach, which needs shorter experimental times and is currently used in the study of HPβCD/bile acid systems, was then substantiated.

Interpenetrating networks of polythiophenes and fullerene derivatives give rise to charge transfer after irradiation with visible light. The resulting radical ion pairs have been studied by time-resolved EPR spectroscopy. At low temperatures (20 K), the radical pairs are spin correlated and locked at a distance of 27.1 A, whereas an increase of temperature causes the electron and the hole to move further away from each other.

The interaction of diclofenac sodium salt (DCFNa) and two cyclodextrins, β-cyclodextrin (βCD) and 2-hydroxypropyl-β-cyclodextrin (HPβCD), studied in D2O solution with different NMR techniques (1H, 13C NMR, ROESY experiments, NMR titrations), shows the existence of multiple equilibria involving 1:1 and 2:1 guest–host complexes.

Poly[3-(butylthio)thiophene] was obtained from 2,5-dibromo-3-(butylthio)thiophene according to the method of Kobayashi. The polymer was characterized as having regioregular head-to-tail (HT) connections with significant extended conjugation length and optical properties, such as solvatochromism and photoluminescence. The polymer is soluble in common organic solvents and can easily form films.

We studied the light dependent conduction of gold–oligothiophene–gold molecular junctions as a fully–customized platform. The flexibility and novelty of the platform relies on its plug-and-play connection to an external electronic board to perform eight parallel nanogap fabrications by Electromigration Induced Break Junction (EIBJ) and molecular electrical characterization. In addition, the octithiophene molecules are synthesized ad-hoc to efficiently self-assembly and selectively bridge the nanogap electrodes upon deposition, which can be carried out directly and in parallel on the 8 nanogap array platforms. The high portability of the platform is well suited for in–situ microscopic and spectroscopic analyses. In particular, we tested the electrical functionality of the octithiophene molecular junctions by coupling electrical current–voltage (I–V) characterization with fluorescence and Raman spectroscopies. In addition, surface-enhanced Raman spectroscopy (SERS) was used for the first time to precisely correlate the position of the molecule with the conductance of the junction. Modulation of the electrical conductance can also be achieved by varying the light excitation wavelength. Such electrical transduction of the junction revealed a peak in molecule conduction around the light excitation wavelength of 450 nm, with a photoresponsive modulation of the current at low bias voltage up to 120% with respect to the initial value at 300 nm. The proposed ad-hoc platform design makes molecular junctions real working blocks, which can be interfaced with external circuitries to serve the function of electronic components or sensors and overcome the limitations of usability, cost and portability of traditional molecular contacting methods, such as Mechanically Controlled Break Junction (MCBJ) or scanning probe microscopy. We thus demonstrate that the optoelectronic properties of oligothiophenes can be exploited in the form of molecular junctions to fabricate optoelectronic devices for molecular electronics.

The interaction of diclofenac sodium salt (DCFNa) and two cyclodextrins, β-cyclodextrin (βCD) and 2-hydroxypropyl-β-cyclodextrin (HPβCD), studied in D2O solution with different NMR techniques (1H, 13C NMR, ROESY experiments, NMR titrations), shows the existence of multiple equilibria involving 1:1 and 2:1 guest–host complexes.

The 1H NMR spectra of imidazo [1,2-a]pyrimidine derivatives have been analysed to study the aromatic character and protonation behaviour of this system. By employing the ‘ring currentn’ model and calculations based on the coupled Hartree-Fock method it can be deduced that a large π-electron delocalisation exists in this heterocyclic system and affects the screening constant of the protons. Charge density schemes obtained by SCF techniques agree with the reactivity behaviour of these molecules. A detailed study of protonation carried out by following the 1H NMR spectra both in trifluoroacetic acid and in aqueous hydrochloric acid shows that the most probable site of protonation is N-1, but leaves open the possibility of a rapid exchange of one proton between N-1 and N-8.

Long-range coupling constants, nJ(C, H), involving the formyl proton or carbon and the carbons or protons of the heterocyclc ring, were measured in the two isomeric formyl-furans and -thiophenes by employing coupled 13C NMR spectra. In furan-2-carboxaldehyde these coupling constants, obtained in solutions of different polarity, show conformational dependence and quantitatively reproduce the trend of conformer populations obtained from proton-proton coupling constants. Even in thiophene-2-carboxaldehyde, 3J(C, H), where H is the formyl proton, shows that the very biased equilibrium is further shifted toward the S,O-cis form in polar media. For the 3-formyl derivatives the changes of nJ(C, H) in different solvents are small, at the limit of experimental error; even so, comparison with the values measured for 4-iodofuran- and 4-iodothiophene-3-carboxaldehyde, which show an equilibrium significantly dependent on solvent polarity, enables one to verify that in these derivatives the X,O-trans form, prevailing in the equilibrium mixture, increases with increasing solvent polarity. From a least-squares analysis of the experimental values, the conformer populations in the different solvents and the coupling constants of the separate conformers were estimated. The coupling constants obtained show the effectiveness of each nJ(C, H) in the conformational analysis of these compounds. Larger changes, as a function of conformer populations, are expected for 3J(C, H) relative to the formyl proton, and this proves to be the observable quantity which best demonstrates small changes in the conformational equilibrium. The thermodynamic aspects of the equilibrium for the 3-formyl derivatives are discussed and, by employing classical reaction-field theory, it is tentatively shown that the increase of the less polar X,O-trans form in polar media should be due to the fact that quadrupolar contributions prevail over dipolar effects.

The NMR spectra of a number of 2,4-disubstituted 1,3-dioxolanes have been recorded and the proton chemical shifts and coupling constants derived from complete spectral analysis. Vicinal coupling constants were found to be dependent on the substituent at C-4 and this effect is more pronounced for J(trans) of the C-4-C-5 fragment. These coupling constants also indicate a homogeneous behaviour within a series with either a cis or trans configuration, although the cis behaviour differs from that of trans isomers. This has been interpreted in terms of definite ring conformations in substituted derivatives, while the unsubstituted 1,3-dioxolane undergoes free pesudorotation. Calculations of coupling constants were performed by semi-empirical MO methods, both for unsubstituted 1,3-dioxolane and for C-4 substituted derivatives in a large number of conformations, in order to compare calculated and experimental values; the correct order of J(cis) and J(trans) for 1,3-dioxolane is obtained only by employing energies from ab-initio MO calculations averaged over the pseudorotation circuit. For the C-4 substituted compounds calculated coupling constants were employed in a ‘trial and error’ process for the identification of the preferred conformations of these compounds; a set of two torsional angles for each compound was derived which allows a tentative description of the geometry of each molecule. A criticism of these geometries is given according to the evidence available on the structure of substituted 1,3-dioxolanes.

1H chemical shifts of quinoline, quinoline N-oxide and the quinolinium ion were obtained by complete analysis of their NMR spectra and interpreted critically in an attempt to quantify the possible different effects acting on the shielding constant of protons in these systems. Semi-empirical SCF calculations of electron charge densities and ring current contributions were also performed. It was found that the same effects that act on the shielding of protons directly bonded to the heterocyclic system also act, in an attenuated form, on the proton chemical shift of methyl groups in monomethyl derivatives. Vicinal coupling constants were rationalised in terms of π-electron bond order and electro-negativity of neighbouring atoms.

The new 9-methyladenine (made) complexes cis-[{Pt(PMe3)2(made)2][NO3]2 and cis-[{Pt(PMe3)2(made – H)}2][NO3]2 have been prepared and characterized. They are formed by treating stoichiometric amounts of the nucleobase with an aqueous solution of cis-[Pt(PMe3)2(NO3)2] at autogenous and neutral pH, respectively. A detailed multinuclear (1H, 31P, 195Pt, 13C and 15N at natural abundance) NMR investigation in (CD3)2SO indicated that in the mononuclear complex the adenine ligands are N(1)-co-ordinated and that rotation around the metal–nitrogen bonds is slow on the NMR time-scale leading to the presence of two conformers with a relative abundance of ca. 2 : 1. In the dinuclear complex the NH2-deprotonated adenine acts as a bridging ligand through the N(1) and N(6) atoms. The sites of metal binding are clearly evidenced in the 15N NMR spectra by the remarkable shifts shown by the co-ordinated nitrogens (60 ppm upfield for the endocyclic atom and 25 ppm downfield for the exocyclic one, with respect to the unco-ordinated nucleobase) and their coupling with the 31P nucleus of the ligand in mutual trans position (2JNPca. 60 Hz).

FeCl3 converts, in high yield, 3-butylsulfanyl-2,2′-bithiophene into a tris(butylsulfanyl)sexithiophene, which shows interesting optical properties and forms a stable radical cation and dication.

A full 1H and 1C NMR study through the use of one- and two-dimensional techniques (HMQC, HMBC, TOCSY and NOE-difference spectroscopy) was carried out on poly[3-(6-methoxyhexyl)-2,2́-bithiophene]. Inter-ring correlations detected in the HMBC spectra proved to be a valuable tool in the assignment of regiochemistry. NMR data can be interpreted on the basis of a four-triad model. Copyright © 1999 John Wiley & Sons, Ltd.

The 1H NMR spectra of the 2-trifluoroacetyl derivatives of benzo[b]furan and benzo[b]thiophene were recorded at 200MHz in two solvents, chloroform and acetone. A long-range coupling constant, 5J(HF), between the fluorine nuclei of the trifluoroacetyl group and H-3, of a value higher than 1 Hz, was measured. From the comparison of the 1H chemical shifts of, and the solvent effects on, the trifluoroacetyl compounds and those of the corresponding 2-acetyl derivatives, and on the basis of an empirical interpretation of the 5J(HF) coupling constant, a predominant Z conformation was tentatively assigned to these derivatives.

The 1H NMR parameters for a number of cis-arylmethyl oxiranes are reported and discussed in comparison with those of trans derivatives and styrene oxides substituted in the phenyl ring. While the macroscopic behaviour of the results is in agreement with a perturbative mechanism through the oxirane ring that is mainly electrostatic in character, a small contribution due to conjugative interaction is not excluded. It seems likely that the effect of substituents in the phenyl ring is mainly transmitted through bonds rather than through space, and that the different polarisation of the CH bonds in the oxirane ring is mainly responsible for the different behaviour of the protons in cis- and trans- arylmethyl oxiranes towards the effect of substituents.