Institute for Chemical Research

Sevilla, Spain

Institute for Chemical Research

Sevilla, Spain
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To understand the fundamental mechanism behind acid dissolution, Zhang et al. from the Institute for Chemical Research at Kyoto University encapsulated HF, as well as HF•H O and H O within a C fullerene. They found that in order to force the molecules into the open fullerene cavity, the molecules required "pushing from the outside" using high pressure conditions, and "pulling from the inside" via molecular interactions between HF and H O. They were able to identify how hydrogen bonding occurred between these two molecules. Their work appears in Science Advances. Prior work by Zhang et al. showed that the C fullerene could be opened in a three-step process that involved the addition of a pyridazine derivative either to the alpha or beta bonds on the C . This created a 13-member ring opening that formed slightly different compounds, denoted by α-13mem and β-13mem. Dehydration of both compounds resulted in a 16-member ring opening. The ring could be closed again via hydrolysis and a two-step process. β-16mem was large enough to capture H O, but α-16mem was not. Given these results from previous studies, for the current study, Zhang et al. used α-16mem to try to encapsulate HF. Instead, they found three different possibilities within the fullerenes: HF@C , (HF•H O)@C , and H O@C . Their reaction conditions required high pressure (9000 atm) to "push" the guest molecule into the α-16mem cavity. Time-dependent studies showed that HF filled the cavity first, followed by H O•HF, and then H O. Notably, the open cage did not entrap H O when HF was not present, indicating that the interaction between H O and HF prompted H O encapsulation. Further studies showed that HF is "pulling" H O into the cavity while the high pressure environment "pushes" it into the cavity. This process allowed the authors to study the interaction between H O and HF within a confined environment using 1H NMR. NMR analysis showed that that the (H O•HF)@C was down-shifted from H O@C and HF@C , which indicated hydrogen bonding. Furthermore, shift and coupling values indicated that oxygen was acting as the hydrogen-bond acceptor. Using single-crystal x-ray diffraction, Zhang et al. demonstrated the structure of the (HF•H O)@C , and report the first x-ray structure for doubly encapsulated C . These analyses and experimental studies confirmed that the H+ ion in HF forms a linear hydrogen bond with the O in H O. Additionally, compared to theoretical calculations of free H O and HF, the studies of the encapsulated molecules revealed close contact with hydrogen and oxygen that may be characteristic of H3O+•F-. The C fullerene derivative provides an excellent nanoenvironment for studying isolated chemical species, something that has not been available to chemists in the past. This isolated environment allowed the authors to investigate the interactions of two compounds without interference from the surrounding environment and provided important insights into a ubiquitous chemical process. More information: Rui Zhang et al. Isolation of the simplest hydrated acid, Science Advances (2017). DOI: 10.1126/sciadv.1602833 Abstract Dissociation of an acid molecule in aqueous media is one of the most fundamental solvation processes but its details remain poorly understood at the distinct molecular level. Conducting high-pressure treatments of an open-cage fullerene C70 derivative with hydrogen fluoride (HF) in the presence of H2O, we achieved an unprecedented encapsulation of H2O·HF and H2O. Restoration of the opening yielded the endohedral C70s, that is, (H2O·HF)@C70, H2O@C70, and HF@C70 in macroscopic scales. Putting an H2O·HF complex into the fullerene cage was a crucial step, and it would proceed by the synergistic effects of "pushing from outside" and "pulling from inside." The structure of the H2O·HF was unambiguously determined by single crystal x-ray diffraction analysis. The nuclear magnetic resonance measurements revealed the formation of a hydrogen bond between the H2O and HF molecules without proton transfer even at 140°C.

Pais V.F.,University of Huelva | Lassaletta J.M.,Institute for Chemical Research | Fernandez R.,University of Seville | El-Sheshtawy H.S.,South Valley University | And 2 more authors.
Chemistry - A European Journal | Year: 2014

Borylated arylisoquinolines with redshifted internal charge-transfer (ICT) emission were prepared and characterized. Upon heating, significant fluorescence quenching was observed, which forms the basis for a molecular thermometer. In the investigated temperature range (283-323 K) an average sensitivity of -1.2 to -1.8 % K-1 was found for the variations in fluorescence quantum yield and lifetime. In the physiological temperature window (298-318 K) the average sensitivity even reaches values of up to -2.4 % K-1. The thermometer function is interpreted as the interplay between excited ICT states of different geometry. In addition, the formation of an intramolecular Lewis pair can be followed by 11B NMR spectroscopy. This provides a handle to monitor temperature-dependent ground-state geometry changes of the dyes. The role of steric hindrance is addressed by the inclusion of a derivative that lacks the Lewis pair formation. Getting warmer: A series of molecular fluorescent thermometers with good to very good sensitivity is reported. Borylated arylisoquinolines show pronounced fluorescence quenching upon heating (see figure), which can be reverted by cooling. The analysis of kinetic parameters revealed the involvement of a thermally activated nonradiative excited-state decay channel. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Home > Press > Electron partitioning process in graphene observed, a world first: Toward the realization of electron interferometer devices which utilize the wave nature of electrons Abstract: Graphene, a single atomic layer of graphite with a carbon-layered structure, has been drawing much attention because of its abundant electronic properties and the possibilities of application due to its unique electronic structure. Andre Geim and Konstantin Novoselov extracted single-atom-thick crystallites from bulk graphite in 2004 for the first time. This results earned them the Nobel Prize in physics 2010. A group of researchers from Osaka University, the University of Tokyo, Kyoto University, and the National Institute for Materials Science precisely examined current-fluctuation ("shot noise") in the graphene p-n junction in the Quantum Hall (QH) regime and succeeded in observing electron partitioning taking place on the region along the p-n junction as current fluctuation. (See upper-left of Figure 1. Electron Partition Process.) In addition, this group also clarified that electron partitioning did not take place under the absence of the p-n junction even in the QH regime. It is expected that this group's achievement will lead to the clarification of the electron partition process in the graphene p-n junction in the QH regime because of its spin freedom and valley freedom and the realization of electron interference devices using the graphene p-n junction in the QH regime. Kensuke Kobayashi (Professor, Graduate School of Science, Osaka University) and Sadashige Matsuo (Assistant Professor, Graduate School of Engineering, The University of Tokyo), in cooperation with research groups led by Teruo Ono (Professor, Institute for Chemical Research, Kyoto University) and Kazuhito Tsukagoshi (Research Fellow, International Center for Materials Nanoarchitectonics, National Institute for Materials Science), produced graphene samples capable of forming p-n junctions by combining gate electrodes and performed precise measurements of current-fluctuation ("shot noise") in the graphene p-n junction in the QH regime in the strong magnetic fields and at low temperatures. As shown by Figure 1, this group clarified that while shot noise took place in the graphene p-n junction in the QH regime, shot noise did not take place in the absence of the graphene p-n junction. This group also verified that the quantity of the observed shot noise was nearly consistent with theoretical predictions. These results directly demonstrated for the first time in the world that electron partitioning took place in the p-n junction in the QH regime, and microscopic characteristics of electron partitioning taking place in the graphene p-n junction were quantitatively established for the first time. This research was published in the electronic version of Nature Communications (UK) on September 4, 2015. Furthermore, results closely related to this group's research results were simultaneously published in the Nature Communications by a joint group of researchers from Nippon Telegraph and Telephone Corporation (NTT) and French research institutes. The latter research was performed totally independently from the former research, thus, it is noteworthy that the world's first research results were simultaneously announced from the two separate Japanese research teams. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Larrinaga G.,University of the Basque Country | Perez I.,University of the Basque Country | Sanz B.,University of the Basque Country | Blanco L.,University of the Basque Country | And 6 more authors.
Regulatory Peptides | Year: 2010

The angiotensin-converting enzymes (ACE and ACE2) are highly expressed in renal tubules and play an important role in the regulation of renal function by the intrarenal renin-angiotensin system (iRAS). Dysregulation of these cell-surface peptidases has been associated with renal injury. Most of these studies, however, have focused on non-neoplastic kidney diseases. In the present study, ACE and ACE2 activity and protein and mRNA expression were analysed in a subset of clear-cell (CCRCC) and chromophobe (ChRCC) renal cell carcinomas, and in renal oncocytoma (RO). Enzyme activity was measured by spectrofluorometric (ACE2) and spectrophotometric assays (ACE), and protein and mRNA expression were determined by immunohistochemistry and qRT-PCR assays, respectively. The enzyme activities and immunohistochemistry showed that both enzymes are mainly downregulated in these neoplasms. qRT-PCR studies in CCRCC showed no positive correlation between ACE and ACE2 activity/protein expression and mRNA levels, whereas downregulation of ACE2 mRNA levels was observed in tumors from the distal nephron (ChRCC and RO). These findings suggest a metabolic imbalance in iRAS and a role of this system in renal neoplastic diseases, and point to ACE and ACE2 as potential prognostic/diagnostic markers. © 2010 Elsevier B.V.

Larrinaga G.,University of the Basque Country | Varona A.,University of the Basque Country | Perez I.,University of the Basque Country | Sanz B.,University of the Basque Country | And 5 more authors.
Histology and Histopathology | Year: 2010

The presence of CB1 and CB2 cannabinoid receptors and their physiological role in the kidney has been described in animal models but not in humans. Our aim in this study was to evaluate the presence of these receptors in human kidney, adult and fetal. For this purpose, RT-PCR, western-blot and immunohistochemical assays were performed. RT-PCR confirmed the presence of CB1 receptor mRNA receptor and the absence of the CB2 receptor mRNA in adult and fetal kidney. Western-blot and immunohistochemical assays revealed the presence of the CB1 cannabinoid receptor protein, which displayed a similar distribution in fetal and adult kidneys. Proximal and distal convoluted tubule cells and intercalated cells in the collecting ducts showed marked positivity. Conversely, the CB2 cannabinoid receptor protein was consistently negative in all cases. Our data suggest a possible implication of the endocannabinoid system in the physiology and development of the human kidney.

Larrinaga G.,University of the Basque Country | Sanz B.,University of the Basque Country | Blanco L.,University of the Basque Country | Perez I.,University of the Basque Country | And 5 more authors.
Clinical Biochemistry | Year: 2013

Objective: To analyze the mRNA and protein expression of cannabinoid receptors CB1 and CB2 in chromophobe renal cell carcinoma (ChRCC) and renal oncocytoma (RO). Design and methods: Fresh and formalin-fixed tissue samples of ChRCC and RO were analyzed by using real-time quantitative RT-PCR and immunohistochemical techniques (n. = 40). Results: Quantitative RT-PCR analysis showed that CB1 mRNA was underexpressed by 12-fold in ChRCC and had a variable expression in RO. CB1 protein showed intense positive immunostaining in both neoplasms. Both CB2 mRNA and protein were not expressed in tumor and non tumor renal tissue. Conclusion: This distinct immunoprofile may eventually be used as an additional tool with practical interest in the differential diagnosis of renal tumors. © 2013 The Canadian Society of Clinical Chemists.

Larrinaga G.,University of the Basque Country | Sanz B.,University of the Basque Country | Perez I.,University of the Basque Country | Blanco L.,University of the Basque Country | And 4 more authors.
Journal of Histochemistry and Cytochemistry | Year: 2010

Several studies in cell cultures and in animal models have demonstrated that cannabinoids have important antitumoral properties. Because many of these effects are mediated through cannabinoid (CB) receptors CB1 and CB2, the study of their expression in human neoplasms has become of great interest in recent years. Fresh and formalin-fixed tissue samples of 20 consecutive clear cell renal cell carcinomas (CCRCCs) were collected prospectively and analyzed for the expression of both CB receptors by using RT-PCR, Western blot (WB), and immunohistochemical techniques. RT-PCR assays demonstrated the expression of mRNA encoding the CB1 in tumor tissue and in adjacent non-neoplastic kidney. Conversely, WB and IHC revealed a marked downregulation of CB1 protein in tumor tissue; CB2 was not expressed. The obtained data suggest a possible implication of the endocannabinoid system in renal carcinogenesis. A posttranscriptional downregulation of CB1 and the absence of expression of CB2 characterize CCRCC. © 2010 Larrinaga et al.

Varona A.,University of the Basque Country | Blanco L.,University of the Basque Country | Perez I.,University of the Basque Country | Gil J.,University of the Basque Country | And 5 more authors.
BMC Cancer | Year: 2010

Background: Cell-surface glycoproteins play critical roles in cell-to-cell recognition, signal transduction and regulation, thus being crucial in cell proliferation and cancer etiogenesis and development. DPP IV and NEP are ubiquitous glycopeptidases closely linked to tumor pathogenesis and development, and they are used as markers in some cancers. In the present study, the activity and protein and mRNA expression of these glycoproteins were analysed in a subset of clear-cell (CCRCC) and chromophobe (ChRCC) renal cell carcinomas, and in renal oncocytomas (RO).Methods: Peptidase activities were measured by conventional enzymatic assays with fluorogen-derived substrates. Gene expression was quantitatively determined by qRT-PCR and membrane-bound protein expression and distribution analysis was performed by specific immunostaining.Results: The activity of both glycoproteins was sharply decreased in the three histological types of renal tumors. Protein and mRNA expression was strongly downregulated in tumors from distal nephron (ChRCC and RO). Moreover, soluble DPP IV activity positively correlated with the aggressiveness of CCRCCs (higher activities in high grade tumors).Conclusions: These results support the pivotal role for DPP IV and NEP in the malignant transformation pathways and point to these peptidases as potential diagnostic markers. © 2010 Varona et al; licensee BioMed Central Ltd.

Hatakeyama T.,Institute for Chemical Research | Hashimoto S.,Institute for Chemical Research | Nakamura M.,Institute for Chemical Research
Organic Letters | Year: 2011

The tandem phospha-Friedel-Crafts reaction transforms dichloro(m-teraryl) phosphine to the corresponding triarylphosphine derivatives containing curved π-conjugated frameworks with a phosphorus ring junction. The rigid molecular frameworks enable these unprecedented phosphine compounds to hold an extended π-conjugation spread over the whole molecule. © 2011 American Chemical Society.

Sivakumar M.,Japan National Institute of Advanced Industrial Science and Technology | Sivakumar M.,University of Nottingham Malaysia Campus | Towata A.,Japan National Institute of Advanced Industrial Science and Technology | Yasui K.,Japan National Institute of Advanced Industrial Science and Technology | And 5 more authors.
Ultrasonics Sonochemistry | Year: 2010

Fine particles of rutile TiO2 supporting nanosized particles of Pt were prepared by a simultaneous in situ sonochemical reduction and deposition method using a standing wave sonochemical reactor (SWSR). The mean diameter of sonochemically obtained Pt particles are of 2 nm. Following this sonochemical technique, rutile TiO2 was also deposited with different weight percentages of Pt. Catalytic function of the prepared composite catalysts were tested by the oxidation of CO to CO2. From the catalytic activity results, it has been found out that the catalysts prepared by the sonochemical method exhibited higher catalytic activity for CO oxidation, probably attributed to the higher Pt particle distribution achieved under sonication. Transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), and diffuse reflectance spectroscopy (DRS) were employed to characterize the resulting material. © 2009 Elsevier B.V. All rights reserved.

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