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Versatility of NMR Spectroscopy. NMR at Ruđer Bošković Institute

The first successful nuclear magnetic resonance experiment was performed on LiCl molecular beam by Isidor I. Rabi in 1938, which was acknowledged by Nobel prize in physics in 1944. Several years latter detection of proton NMR signal was achieved in condensed matter by Edward M. Purcell at MIT and Felix Bloch at Stanford, both honored by Nobel prizes in physics in 1952. These first spectra showed wide lines and low-resolution. At the begining of the fifties chemists also found interest in NMR because of discovery of chemical shifts (Proctor and Yu) and spin-spin couplings (Gutowsky et al., Hahn et. al.). Further technological advances opened new era of high-resolution NMR spectroscopy in liquide phase, establishing NMR as a pivotial tool for structural elucidation in all branches of chemistry, especially in organic chemistry and biochemistry. Nowadays, it is possible by NMR to determine the structure of proteins of 30 kD and in some cases even up to 100 kD. In 1971 Damadian observed the increase of proton relaxation times in tumourus tissues of mammals, while in 1972 Laterbur introduced NMR zeugmatography (latter developed as NMR tomography), which both initiated the use of NMR in biology and medicine. The first imaging of human was performed by Hinshaw in 1977, while the first clinical use of NMR for diagnostic purposes started in 1981. Since term nuclear sounded threatening to the patients, the nuclear magnetic resonance tomography changed its name to magnetic resonance imaging (MRI). Today MRI is the most promising and more versatile of diagnostic tools in medicine, because it is noninvasive, nonionizing, enables excellent contrasts of tissues and bones and possibility of all kind scaning slices. Functional fMRI gives opportunity of monitoring different processes, from blood flow in vessels to neuron transmission in brain. MRS (magnetic resonance spectroscopy) enables following of metabolitic pathways of sugars, fats, etc., as well as pharmacokinetics and pharmacodynamics of drugs. The LC-NMR is a modern chromatographic technique, which makes possible separation of complex liquid mixtures with detection into the nanogram range. Unprecedented development of NMR techniques for liquids gave urge for advances in NMR of solids. High-resolution solid state NMR spectra can be obtained by CP MAS or MAR (cross polarization magic angle spinning or rotation) technique, opening new dimension in material sciences. NMR studies of polymers including measuring of relataxation, spin diffusion and imaging give insight into their dynamics and morphology. One of new approaches is monitoring of 129Xe adsorbed in polymers using high pressure gas probes. NMR spectroscopy has a long tradition at Ruđer Bošković Institute. In 1957 the building of the first NMR spectrometer started. This home-made low-resolution (29 MHz) device was completed in 1959 and it was the first Croatian NMR spectrometer. The first commercial high-resolution NMR spectrometer (Varian A-60A) at RBI was purchased in 1967 and installed in Department of organic chemistry and biochemistry. In 1978 JEOL FX-100, in 1980 JEOL FQ-90 and in 1990 Varian Gemini 300 were installed in the same department as well. The NMR investigations performed in tat time were in the field of adamantane chemistry, sugars, nucleosides and nucleotide. In 2002. Bruker’ s AV-300 and AV-600 NMR spectrometers were installed at RBI and in July 2003 the NMR center was established. NMR center is performing research in organomettalic chemistry, fluoroquinolone chemistry, supramolecular and gel chemistry, as well as of isotope effects, collaborating in several projects or giving services. measurments. In addition NMR center have its own project supported by the Ministry of Science and Technology of the Republic of Croatia (Nuclear magnetic resonance and calculations of bioorganic molecules) and Austrian-Croatian bilateral project (Multi-dimensional nuclear magnetic resonance spectroscopy of biomolecules). Theoretical investigations of isotope effects and nuclear shielding are also conducting in NMR center. Recently, we have started NMR investigations of small peptides, for now up to 13 amino acids, which are pharmacologically interested as antimicrobial agents. In addition, NMR analysis of biofluids and natural products from fungi are underway too. NMR center collaborates with different faculties of University of Zagreb, Rijeka, Split and Osijek as well as with Pliva and Belupo pharmaceutical companies. Centar is also involved in undergraduate and graduate studies of Croatian Universities. It is worth to mentioned that twelve years ago NMR facility of RBI was participated in structural investigations of Pliva's new antibiotic azithromycine, today famous Summamed.

NMR spectroscopy; development

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