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| '''Johannes Martin Bijvoet''' [[ForMemRS]]<ref name="frs">{{cite doi|10.1098/rsbm.1983.0002}}</ref> (23 January 1892, [[Amsterdam]] – 4 March 1980, [[Winterswijk]]) was a Dutch [[chemist]] and [[crystallography|crystallographer]] at the van 't Hoff Laboratory at [[Utrecht University]]. He is famous for devising a method of establishing the [[absolute configuration]] of [[molecules]].<ref>{{cite doi|10.1038/134849a0}}</ref><ref>{{cite doi|10.1038/162771a0}}</ref><ref>{{cite doi|10.1038/168271a0}}</ref><ref>{{cite doi|10.1038/169949a0}}</ref><ref>{{cite doi|10.1038/173888a0}}</ref><ref>Bijvoet, J. M. ''Proc. Acad. Sci. Amst.'' '''52''', ''1949'', 313.</ref><ref>Peerdeman, A. F., van Bommel, A. J., Bijvoet, J. M. ''Proc. Acad. Sci. Amst.'' '''54''', ''1951'', 16.</ref> | | The author's name is Christy Brookins. [http://alles-herunterladen.de/excellent-advice-for-picking-the-ideal-hobby/ psychic readings online] I am really fond of to go to karaoke but I've been using on new things recently. Her family life in Ohio but her husband desires them to move. My working day job is a journey agent.<br><br>Have a look at my web site - phone [http://www.weddingwall.com.au/groups/easy-advice-for-successful-personal-development-today/ telephone psychic] readings; [http://www.010-5260-5333.com/index.php?document_srl=1880&mid=board_ALMP66 Test by click the "Remove Empty Lines" button and watch these blank lines between this text disappear.], |
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| The concept of [[tetrahedron|tetrahedrally]] bound [[carbon]] in [[organic compound]]s stems back to the work by [[Jacobus Henricus van 't Hoff|van 't Hoff]] and [[Joseph Achille Le Bel|Le Bel]] in 1874. At this time, it was impossible to assign the absolute configuration of a molecule by means other than referring to the projection formula established by [[Hermann Emil Fischer|Fischer]], who had used [[glyceraldehyde]] as the prototype and assigned randomly its absolute configuration.
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| In 1949 Bijvoet outlined his principle, which relies on the [[anomalous dispersion]] of [[X-ray]] [[electromagnetic radiation|radiation]]. Instead of the normally observed [[elastic scattering]] of X-rays when they hit an [[atom]], which generates a scattered wave of the same energy but with a shift in phase, X-ray radiation near the [[absorption (electromagnetic radiation)|absorption]] edge of an atom creates a partial [[ionisation]] process. Some new X-ray radiation is generated from the inner [[electron shell]]s of the atoms. The X-ray radiation already being scattered is interfered with by the new radiation, both [[amplitude]] and [[phase (waves)|phase]] being altered. These additional contributions to the scattering may be written as a real part <math>\Delta</math>''f''' and an imaginary one, <math>\Delta</math>''f''". Whereas the real part is either positive or negative, the imaginary is always positive, resulting in an addition to the [[phase angle]].
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| In 1951, using an X-ray tube with a [[zirconium]] target, Bijvoet and his coworkers Peerdeman and van Bommel achieved the first experimental determination of the absolute configuration of sodium rubidium [[tartrate]]. In this compound, [[rubidium]] atoms were the ones close to the absorption edge. In their later publication in [[Nature (journal)|''Nature'']], entitled ''Determination of the absolute configuration of optically active compounds by means of X-rays'', the authors conclude that
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| "The result is that Emil Fisher's ''convention'', which assigned the configuration of FIG. 2 to the dextrorotatory acid ''appears to answer the reality''."
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| The determination of absolute configuration is nowadays achieved using "soft" X-ray radiation, most often generated with a [[copper]] target (which generates X-rays with a characteristic wavelength of 154 pm). Shorter wavelengths make the observable differences in measured intensities smaller, thereby making the distinction of absolute configuration more difficult. The measurement of absolute configuration is also facilitated by the presence of atoms heavier than oxygen.
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| X-ray diffraction is still considered the ultimate proof of absolute structure, but other techniques such as [[circular dichroism]] spectroscopy are often used as faster alternatives.
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| ==Bijvoet Center==
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| {{main|Bijvoet Center for Biomolecular Research}}
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| The Bijvoet Center for Biomolecular Research at Utrecht University, which was founded in 1988, was named after him.<ref name="CC_Apr_1988">{{Cite news
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| |title=SON en RUU in Bijvoet Centrum
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| |author=Joop Kessels
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| |newspaper=Chemische Courant
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| |date=April 7, 1988
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| |language=Dutch
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| }}</ref> The Bijvoet Center performs research on the relation between the structure and function of biomolecules, including [[proteins]] and [[lipids]], which play a role in biological processes such as regulation, interaction and recognition.<ref name="DUB_1">{{Cite news
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| |title=Bijvoet Centrum (1): ziektes bestrijden op atomair niveau
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| |newspaper=DUB
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| |author=Erik Hardeman
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| |date=October 30, 2012
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| |language=Dutch
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| |URL=http://www.dub.uu.nl/artikel/achtergrond/bijvoet-centrum-1-ziektes-bestrijden-op-atomair-niveau.html
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| }}</ref> The Bijvoet Center maintains advanced infrastructures for the analysis of proteins using [[NMR]], [[electron microscopy]], [[X-ray crystallography]] and [[mass spectrometry]].<ref name="MERIL">{{cite web
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| |title=Bijvoet Center - Bijvoet Center for Biomolecular Research
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| |website=MERIL - Mapping fo the European Research Infrastructure Landscape
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| |url=http://portal.meril.eu/converis-esf/publicweb/research_infrastructure/2362
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| |accessdate=May 2, 2013
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| |language=English}}</ref>
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| ==References==
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| {{reflist}}
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| ==External links==
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| * The [http://www.uu.nl/science/bijvoet Bijvoet Center] at Utrecht University
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| {{Authority control|VIAF=108202618}}
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| {{Persondata <!-- Metadata: see [[Wikipedia:Persondata]]. -->
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| | NAME = Bijvoet, Johannes Martin
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| | ALTERNATIVE NAMES =
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| | SHORT DESCRIPTION = Dutch crystallographer
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| | DATE OF BIRTH = 23 January 1892
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| | PLACE OF BIRTH =
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| | DATE OF DEATH = 4 March 1980
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| | PLACE OF DEATH =
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| }}
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| {{DEFAULTSORT:Bijvoet, Johannes Martin}}
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| [[Category:1892 births]]
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| [[Category:1980 deaths]]
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| [[Category:Crystallography]]
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| [[Category:Dutch chemists]]
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| [[Category:Utrecht University faculty]]
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| [[Category:People from Amsterdam]]
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| [[Category:Foreign Members of the Royal Society]]
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