Spatially resolved NMR spectroscopy of heterogeneous gas phase hydrogenation of 1,3-butadiene with para-hydrogen
Svyatova, Alexandra, Elizaveta S. Kononenko, Kirill V. Kovtunov, Dmitry Lebedev, Evgeniy Yu. Gerasimov, Andrey V. Bukhtiyarov, Igor P. Prosvirin, et al. “Spatially Resolved NMR Spectroscopy of Heterogeneous Gas Phase Hydrogenation of 1,3-Butadiene with Para-Hydrogen.” Catalysis Science & Technology 10, no. 1 (2020): 99–104.
Magnetic resonance-based methods such as nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are widely used to provide in situ/operando information of chemical reactions. However, the low spin density and magnetic field inhomogeneities associated with heterogeneous catalytic systems containing gaseous reactants complicate such studies. Hyperpolarization techniques, in particular parahydrogen-induced polarization (PHIP), increase significantly the NMR signal intensity. In this study, we test 16 glass tube reactors containing Pd, Pt, Rh or Ir nanoparticles dispersed on a thin layer of TiO2, CeO2, SiO2 or Al2O3 for the hydrogenation of 1,3-butadiene using parahydrogen. The catalytic coatings of Ir and Rh gave hydrogenation products with the highest nuclear spin polarization while the coatings of Pd are the most selective ones for the semihydrogenation of 1,3-butadiene to 1- and 2-butenes. Spatially resolved NMR spectroscopy of the reagent and the product distribution along the reactor axis provided further mechanistic insight into the catalytic function of these reactive coatings under operando conditions.
Schmidt, Andreas B., Jakob Wörner, Andrey Pravdivtsev, Stephan Knecht, Harald Scherer, Stefan Weber, Jürgen Hennig, Dominik Elverfeldt, and Jan‐Bernd Hövener. “Lifetime of Para-Hydrogen in Aqueous Solutions and Human Blood.” ChemPhysChem 20, no. 19 (October 2, 2019): 2408–12.
Molecular hydrogen has unique nuclear spin properties. Its nuclear spin isomer, parahydrogen (pH2), was instrumental in the early days of quantum mechanics and allows to boost the NMR signal by several orders of magnitude. pH2-induced polarization (PHIP) is based on the survival of pH2 spin order in solution, yet its lifetime has not been investigated in aqueous or biological media required for in vivo applications. Herein, we report longitudinal relaxation times (T1) and lifetimes of pH2 ( tPOC) in methanol and water, with or without O2, NaCl, rhodiumcatalyst or human blood. Furthermore, we present a relaxation model that uses T1 and tPOC for more precise theoretical predictions of the H2 spin state in PHIP experiments. All measured T1 values were in the range of 1.4–2 s and tPOC values were of the order of 10–300 minutes. These relatively long lifetimes hold great promise for emerging in vivo implementations and applications of PHIP.
Open-Source Automated Parahydrogen Hyperpolarizer for Molecular Imaging Using 13C Metabolic Contrast Agents
Coffey, Aaron M., Roman V. Shchepin, Milton L. Truong, Ken Wilkens, Wellington Pham, and Eduard Y. Chekmenev. “Open-Source Automated Parahydrogen Hyperpolarizer for Molecular Imaging Using 13 C Metabolic Contrast Agents.” Analytical Chemistry 88, no. 16 (August 16, 2016): 8279–88.
An open-source hyperpolarizer producing 13C hyperpolarized contrast agents using parahydrogen induced polarization (PHIP) for biomedical and other applications is presented. This PHIP hyperpolarizer utilizes an Arduino microcontroller in conjunction with a readily modiﬁed graphical user interface written in the open-source processing software environment to completely control the PHIP hyperpolarization process including remotely triggering an NMR spectrometer for eﬃcient production of payloads of hyperpolarized contrast agent and in situ quality assurance of the produced hyperpolarization. Key advantages of this hyperpolarizer include: (i) use of opensource software and hardware seamlessly allowing for replication and further improvement as well as readily customizable integration with other NMR spectrometers or MRI scanners (i.e., this is a multiplatform design), (ii) relatively low cost and robustness, and (iii) in situ detection capability and complete automation. The device performance is demonstrated by production of a dose (∼2−3 mL) of hyperpolarized 13C-succinate with %P13C ∼ 28% and 30 mM concentration and 13C-phospholactate at %P13C ∼ 15% and 25 mM concentration in aqueous medium. These contrast agents are used for ultrafast molecular imaging and spectroscopy at 4.7 and 0.0475 T. In particular, the conversion of hyperpolarized 13C-phospholactate to 13C-lactate in vivo is used here to demonstrate the feasibility of ultrafast multislice 13C MRI after tail vein injection of hyperpolarized 13C-phospholactate in mice.
See also the application link: https://rekry.saima.fi/certiahome/open_job_view.html?did=5600&jc=1&id=00007645&lang=en
Postdoctoral researcher, Parahydrogen biosensors for hypersensitive NMR analysis
The University of Oulu in Northern Finland, with approximately 15000 students and 3000 employees, is an international, multidisciplinary research university with a rich pool of creative and intellectual talent. The strengths of the University are broad, multidisciplinary research interests, a modern research and study environment, and wide cooperation with international research and educational institutes (http://www.oulu.fi/english).
The postdoctoral position is in the field of nuclear magnetic resonance (NMR), in the following specific topic: Development of metal-free catalytic systems for parahydrogen-based NMR hyperpolarization techniques.
The position is located at the NMR Research Unit (http://cc.oulu.fi/~nmrwww), in the Faculty of Science. We are an internationally established, combined experimental and theoretical team of about 20 people, of which 50% with a PhD degree. We develop experimental, theoretical and computational research methods based on magnetic resonance phenomena and apply those methods to topical problems in molecular and materials sciences. Our particular strength is in the tight connection between state-of-the-art measurements and calculations. We have an open and encouraging working atmosphere and have a substantial track record in successful funding applications both at the Academy of Finland and in EU programmes. We are a key user of the NMR laboratory facility of the University of Oulu, furnished with six spectrometers (300-600 MHz) suited for an unusually broad variety of studies (wide range of nuclei, gas/liquid/solid, different sample sizes, imaging capabilities, diffusion probe, micro CryoProbe, remote detection, spin-exchange optical pumping/parahydrogen-induced/SABRE hyperpolarization), two low-field, mobile NMR spectrometers as well as nuclear magneto-optic instrumentation. CPU-intensive computational research is carried out mainly using the facilities of the national supercomputer centre (2300 TFlop/s total capacity). Local linux clusters belonging to the Finnish Grid and Cloud Infrastructure are used for high-throughput production calculations.
Subject field and description of the position
The position is a part of Academy Project “Parahydrogen biosensors for hypersensitive NMR analysis” provided by the Academy of Finland.
The research direction of the position is briefly described in the following: The project aims at development of metal-free activators of H2 molecules capable of producing nuclear spin hyperpolarization upon activation of parahydrogen, increasing NMR sensitivity by orders of magnitude. Typically, metal-containing activators/catalysts are used in parahydrogen-based hyperpolarization techniques. We develop more biogenic metal-free catalytic systems that can be used to create hypersensitive NMR biosensors for biomolecular monitoring.
The length of the position is two years. The starting date of the position is September 16, 2019, or as soon as possible thereafter.
A six-month trial period will be effective in the beginning of the two-year contract.
Required Qualifications and assessment
The successful applicant must have a completed PhD in physics, chemistry, materials science, or a related field. The applicants must show a visible scientific profile. Significant experience in experimental NMR spectroscopy and other physical methods of analysis are to be documented for this position. Strong skills in synthetic and experimental organic chemistry are valuable to the project. Experience in the application of computational methods for studies of chemical reactivity is considered as an advantage. The project requires computer experience in data analysis (Excel, Origin, Matlab).
Fluent English, good communication skills and good teamwork skills are required. Further, demonstrated potential in acquiring supplementary (extramural) funding, and teaching experience will be taken as a merit when choosing the scientist. When assessing the applicant’s qualifications, issues to be considered will include scientific publications, thesis supervision, activity in the scientific community, practical familiarity with the field in question, scientific work abroad, and other international activities.
As part of the NMR Research Unit, the duties also include supervising scientific research of BSc, MSc and PhD students as well participation in important research activities of the group. Participation in teaching within the physics curriculum and acquiring research funding are naturally expected.
The salary will be based on the levels 5-6 of the demand level chart for university–level teaching and research staff of Finnish universities. In addition, a salary component based on personal work performance will be paid (maximum of 50 % of the job-specific component). The salary is thus in practice roughly 3400–4000 € per month, depending on the appointee’s qualifications, experience and the progress in the research.
The following documents must be attached to the application:
1) Brief curriculum vitae in English
2) List of publications in international peer-reviewed journals
3) Brief description of research merits
4) Brief (1-2 pages) research and action plan in English
5) Contact information of two persons whom may be asked to give a statement of the candidate
Applications, together with all relevant enclosures, should be submitted using electronic application form by September 1, 2019 23:59 (Finnish local time).
The top candidates for the posts may be interviewed and asked to present their plans for running the post successfully.
For further information regarding the filling of this post:
Dr. Vladimir Zhivonitko, NMR Research Unit, University of Oulu, tel. +358-41-495 7904, email: vladimir.zhivonitko(at)oulu.fi
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NMR web database:
Bussandri, S., L. Buljubasich, and R.H. Acosta. “Combination of OPSY and PhD-PHIP Results in Enhanced Sensitivity in PHIP.” Journal of Magnetic Resonance 299 (February 2019): 28–32.
Despite the large degree of polarization in PHIP experiments compared to the Boltzmann factor, the presence of a large amount of non-reacted molecules with thermal polarization is an important obstacle when dealing with very diluted samples. The feasibility of enhancing both sensitivity and resolution in a single experiment by combining two well established pulse sequences, OPSY and PHD-PHIP is presented. OPSY is used as a block for ﬁltering the signals originated from thermally polarized protons. PhD-PHIP, on the other hand, is used as an acquisition block, increasing the resolution and further improving the sensitivity by preventing signal canceling in the presence of magnetic ﬁeld inhomogeneities. Experiments in a complex sample with very low hyperpolarization levels are presented showing the excellent performance of the method.