{"id":6455,"date":"2012-04-02T20:35:44","date_gmt":"2012-04-02T19:35:44","guid":{"rendered":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=6455"},"modified":"2019-12-21T07:34:51","modified_gmt":"2019-12-21T07:34:51","slug":"a-golden-age-for-computational-spectroscopy","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455","title":{"rendered":"A golden age for (computational) spectroscopy."},"content":{"rendered":"<div class=\"kcite-section\" kcite-section-id=\"6455\">\n<p>I mentioned in my <a href=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/?p=6438\" target=\"_blank\" rel=\"noopener noreferrer\">last post<\/a> an unjustly neglected <a href=\"http:\/\/dx.doi.org\/10.1063\/1.1700491\" target=\"_blank\" rel=\"noopener noreferrer\">paper<\/a> from that golden age of 1951-1953 by Kirkwood and co. They had shown that Fischer&#8217;s <a href=\"https:\/\/webspace.yale.edu\/chem125\/125\/history99\/6Stereochemistry\/Fischer\/FischerGlucosePrf.pdf\" target=\"_blank\" title=\"Berichte der deutschen chemischen Gesellschaft 24, 1836 (1891)\" rel=\"noopener noreferrer\">famous guess<\/a> for the absolute configurations of organic chiral molecules was correct. The two molecules used to infer this are shown below.<\/p>\n<p><a href=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/04\/kirkwood.svg\"><img decoding=\"async\" class=\"aligncenter size-full wp-image-6456\" title=\"kirkwood\" src=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/04\/kirkwood.svg\" alt=\"\" \/><\/a><br \/> Using the theory Kirkwood had developed, the prediction for the optical rotation at the sodium D line for the (R,R) enantiomer of epoxybutene (Kirkwood did not use this R,R notation, which was still in the future) was +43\u00b0. The measured value was [\u03b1]D +59\u00b0. The (R,R) enantiomer did indeed correspond to Fischer notation.<\/p>\n<p>QED.<\/p>\n<p>A postscript is that a modern equivalent of Kirkwood&#8217;s result, using the \u03c9B97XD\/6-311+G(d,p) method gives +67\u00b0 for the <a href=\"http:\/\/hdl.handle.net\/10042\/to-13883\" target=\"_blank\" rel=\"noopener noreferrer\">gas phase<\/a> and +57\u00b0 for <a href=\"http:\/\/hdl.handle.net\/10042\/to-13884\" target=\"_blank\" rel=\"noopener noreferrer\">solution<\/a> (in CCl<sub>4<\/sub>). The experimental value relates to the pure liquid. In fact, Kirkwood had been very aware that solvation can influence the measured value of an optical rotation, and so even today, a match between experiment and calculation of \u00b1 16 \u00b0 is considered a good fit.<\/p>\n<p>But when it comes to the second molecule, (R)-1,2-dichloropropane, we are in a different ball park. In fact, most of Kirkwood&#8217;s article is devoted to unravelling this second system. This is because it was realised that it is conformationally flexible. Two conformations (this term was then often used interchangeably with configuration, which might confuse a modern audience) called <em>trans<\/em> and <em>skew<\/em> (now called <em>anti<\/em> and <em>gauche<\/em>) were considered and it was realised that the relative populations would be influenced by temperature and particularly, the solvent. I quote here the final conclusion: <em>We have assigned the absolute configuration of Fig. 2\u00a0to the dextrorotatory isomer of 1,2-dichloropropane. This\u00a0was done without any experimental data concerning the\u00a0optically active forms of the molecule, using only the\u00a0calculated dependence of the rotatory power on conformation\u00a0(Table II) and the information about the\u00a0potential of internal conformation obtained from the\u00a0electron diffraction and dipole moment measurements<\/em>.<\/p>\n<p>Non trivial then! Perhaps this is why these techniques were not immediately picked up by synthetic chemists to verify the absolute configuration of their own molecules. But my point is that the use of such techniques now seems to be growing exponentially, which is why this post is headed the golden age of computational spectroscopy. So what of such a modern take on\u00a0\u00a0(R)-1,2-dichloropropane (in heptane, which corresponds to the measured value of +20 to +30, and -21\u00b0 for the (S) enantiomer). Well, there are in fact three viable conformations, not two as Kirkwood supposed. He did not know that the <em>gauche<\/em> stereoelectronic effect favoured two of them despite the greater steric encumbrance. The calculated rotations are\u00a0<a href=\"http:\/\/hdl.handle.net\/10042\/to-13885\" target=\"_blank\" rel=\"noopener noreferrer\">+53<\/a> (<em>anti<\/em>), <a href=\"http:\/\/hdl.handle.net\/10042\/to-13886\" target=\"_blank\" rel=\"noopener noreferrer\">+96<\/a> (<em>gauche<\/em>) and <a href=\"http:\/\/hdl.handle.net\/10042\/to-13887\" target=\"_blank\" rel=\"noopener noreferrer\">-182\u00b0<\/a> (second <em>gauche<\/em> conformer). Such dependence on conformation is sadly not unusual, and it means you have to know the Boltzmann population very accurately indeed to infer an observed value. This might in part explain the rather circuitous argument used by \u00a0Kirkwood for dichloropropane!<\/p>\n<p>Fortunately, nowadays optical rotation (more accurately referred to as optical rotatory power, or ORP) is just one of a growing armoury of spectroscopic measurements that can be computed to the accuracy required to draw firm conclusions. These include ORD (optical rotatory dispersion, or variation with the frequency of the polarised light used), ECD (electronic circular dichroism) and VCD (vibrational circular dichroism). It is still not absolutely routine, but these techniques are now found in an increasing number of synthetic chemists&#8217; toolkits.<\/p>\n<p>And my final reflection is to ponder that the golden age of pharmaceutical synthesis (lets say \u00a01950 &#8211; 2000, but \u00a0I know I may get dissent), in which certainty about the separate physiological effects of both enantiomers of chiral drugs became mandatory, would not have been possible without Kirkwood&#8217;s pioneering article, along of course with <a href=\"http:\/\/dx.doi.org\/10.1038\/168271a0\" target=\"_blank\" rel=\"noopener noreferrer\">Bijvoet&#8217;s<\/a> independent result.<\/p>\n<!-- kcite active, but no citations found -->\n<\/div> <!-- kcite-section 6455 -->","protected":false},"excerpt":{"rendered":"<p>I mentioned in my last post an unjustly neglected paper from that golden age of 1951-1953 by Kirkwood and co. They had shown that Fischer&#8217;s famous guess for the absolute configurations of organic chiral molecules was correct. The two molecules used to infer this are shown below. Using the theory Kirkwood had developed, the prediction [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"activitypub_content_warning":"","activitypub_content_visibility":"","activitypub_max_image_attachments":5,"activitypub_interaction_policy_quote":"anyone","activitypub_status":"","footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[2644,565],"tags":[812,813,145,2651,820,392,821,33],"ppma_author":[2661],"class_list":["post-6455","post","type-post","status-publish","format-standard","hentry","category-chiroptics","category-historical","tag-dichloropropane","tag-epoxybutene","tag-gas-phase","tag-historical","tag-kirkwood-and-co","tag-optical-rotation","tag-pharmaceutical-synthesis","tag-spectroscopy"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>A golden age for (computational) spectroscopy. - Henry Rzepa&#039;s Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"A golden age for (computational) spectroscopy. - Henry Rzepa&#039;s Blog\" \/>\n<meta property=\"og:description\" content=\"I mentioned in my last post an unjustly neglected paper from that golden age of 1951-1953 by Kirkwood and co. They had shown that Fischer&#8217;s famous guess for the absolute configurations of organic chiral molecules was correct. The two molecules used to infer this are shown below. Using the theory Kirkwood had developed, the prediction [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa&#039;s Blog\" \/>\n<meta property=\"article:published_time\" content=\"2012-04-02T19:35:44+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2019-12-21T07:34:51+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/04\/kirkwood.svg\" \/>\n<meta name=\"author\" content=\"Henry Rzepa\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Henry Rzepa\" \/>\n\t<meta name=\"twitter:label2\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"A golden age for (computational) spectroscopy. - Henry Rzepa&#039;s Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455","og_locale":"en_GB","og_type":"article","og_title":"A golden age for (computational) spectroscopy. - Henry Rzepa&#039;s Blog","og_description":"I mentioned in my last post an unjustly neglected paper from that golden age of 1951-1953 by Kirkwood and co. 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Using the theory Kirkwood had developed, the prediction [&hellip;]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455","og_site_name":"Henry Rzepa&#039;s Blog","article_published_time":"2012-04-02T19:35:44+00:00","article_modified_time":"2019-12-21T07:34:51+00:00","og_image":[{"url":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/04\/kirkwood.svg","type":"","width":"","height":""}],"author":"Henry Rzepa","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Henry Rzepa","Estimated reading time":"3 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"A golden age for (computational) spectroscopy.","datePublished":"2012-04-02T19:35:44+00:00","dateModified":"2019-12-21T07:34:51+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455"},"wordCount":638,"commentCount":0,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455#primaryimage"},"thumbnailUrl":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/04\/kirkwood.svg","keywords":["dichloropropane","epoxybutene","gas phase","Historical","Kirkwood and co.","optical rotation","pharmaceutical synthesis","spectroscopy"],"articleSection":["Chiroptics","Historical"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455","name":"A golden age for (computational) spectroscopy. - Henry Rzepa&#039;s Blog","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455#primaryimage"},"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455#primaryimage"},"thumbnailUrl":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/04\/kirkwood.svg","datePublished":"2012-04-02T19:35:44+00:00","dateModified":"2019-12-21T07:34:51+00:00","author":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"breadcrumb":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455#primaryimage","url":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/04\/kirkwood.svg","contentUrl":"http:\/\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2012\/04\/kirkwood.svg"},{"@type":"BreadcrumbList","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6455#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog"},{"@type":"ListItem","position":2,"name":"A golden age for (computational) spectroscopy."}]},{"@type":"WebSite","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#website","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/","name":"Henry Rzepa&#039;s Blog","description":"Chemistry with a twist","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-GB"},{"@type":"Person","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281","name":"Henry Rzepa","image":{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g370be3a7397865e4fd161aefeb0a5a85","url":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","caption":"Henry Rzepa"},"description":"Henry Rzepa is Emeritus Professor of Computational Chemistry at Imperial College London.","sameAs":["https:\/\/orcid.org\/0000-0002-8635-8390"],"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?author=1"}]}},"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/pDef7-1G7","jetpack-related-posts":[{"id":21499,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=21499","url_meta":{"origin":6455,"position":0},"title":"Prediction preceding experiment in chemistry &#8211; how unlucky was John Kirkwood?","author":"Henry Rzepa","date":"November 30, 2019","format":false,"excerpt":"Some areas of science progressed via very famous predictions that were subsequently verified by experiments. Think of Einstein and gravitational waves or of Dirac and the positron. There are fewer well-known examples in chemistry; perhaps Watson and Crick's prediction of the structure of DNA, albeit based on the interpretation of\u2026","rel":"","context":"In &quot;Chiroptics&quot;","block_context":{"text":"Chiroptics","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2644"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2019\/12\/butan-2-ol-ORP-1024x312.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":21592,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=21592","url_meta":{"origin":6455,"position":1},"title":"Sign inversions in optical rotation as a function of wavelength (ORD spectra)","author":"Henry Rzepa","date":"December 9, 2019","format":false,"excerpt":"I have been discussing some historical aspects of the absolute configuration of molecules and how it was connected to their optical rotations. The nomenclature for certain types of molecules such as sugars and less commonly amino acids includes the notation (+) to indicate that the specific optical rotation of the\u2026","rel":"","context":"In &quot;Chiroptics&quot;","block_context":{"text":"Chiroptics","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2644"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":6438,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=6438","url_meta":{"origin":6455,"position":2},"title":"Confirming the Fischer convention as a structurally correct representation of absolute configuration.","author":"Henry Rzepa","date":"March 13, 2012","format":false,"excerpt":"I wrote in an earlier post\u00a0how Pauling's\u00a0Nobel prize-winning suggestion in February 1951 of a (left-handed)\u00a0\u03b1-helical structure for proteins was based on the wrong absolute configuration of the amino acids (hence his helix should really have been the right-handed enantiomer). This was most famously established a few months later by Bijvoet's\u2026","rel":"","context":"In &quot;Chiroptics&quot;","block_context":{"text":"Chiroptics","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2644"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":21546,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=21546","url_meta":{"origin":6455,"position":3},"title":"The (+) in D-(+)-glyceraldehyde means it has a positive optical rotation? Wrong!","author":"Henry Rzepa","date":"December 6, 2019","format":false,"excerpt":"Text books often show the following diagram, famously consolidated over many years by Emil Fischer from 1891 onwards. At the top sits D-(+)-glyceraldehyde, to which all the monosaccharides below are connected by painstaking chemical transformations. In this notation, D (for all these structures) indicates the absolute configuration of the series,\u2026","rel":"","context":"In &quot;Chiroptics&quot;","block_context":{"text":"Chiroptics","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=2644"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2019\/12\/glyceraldehyde-concentrations-1024x481.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":20120,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=20120","url_meta":{"origin":6455,"position":4},"title":"Organocatalytic cyclopropanation of an enal: (computational)  assignment of absolute configurations.","author":"Henry Rzepa","date":"September 1, 2018","format":false,"excerpt":"I am exploring the fascinating diverse facets of a recently published laboratory experiment for undergraduate students. Previously I looked at a possible mechanistic route for the reaction between an enal (a conjugated aldehyde-alkene) and benzyl chloride catalysed by base and a chiral amine, followed by the use of NMR coupling\u2026","rel":"","context":"In &quot;Interesting chemistry&quot;","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":399,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=399","url_meta":{"origin":6455,"position":5},"title":"The Chirality of Lemniscular Octaphyrins","author":"Henry Rzepa","date":"April 28, 2009","format":false,"excerpt":"In the previous post, \u00a0it was noted that \u00a0M\u00f6bius annulenes are intrinsically chiral, and should therefore in principle be capable of resolution into enantiomers. The synthesis of such an annulene by Herges and co-workers was a racemic one; no attempt was reported at any resolution into such enantiomers. Here theory\u2026","rel":"","context":"In &quot;Interesting chemistry&quot;","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"A 34-Octaphyrin. Click to see molecule","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2009\/04\/qarfar.jpg?resize=350%2C200","width":350,"height":200},"classes":[]}],"jetpack_likes_enabled":false,"authors":[{"term_id":2661,"user_id":1,"is_guest":0,"slug":"admin","display_name":"Henry Rzepa","avatar_url":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","0":null,"1":"","2":"","3":"","4":"","5":"","6":"","7":"","8":""}],"_links":{"self":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6455","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6455"}],"version-history":[{"count":12,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6455\/revisions"}],"predecessor-version":[{"id":21719,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/6455\/revisions\/21719"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6455"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6455"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6455"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=6455"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}