An Autonomous Chemical Robot Discovers the Rules of Inorganic Coordination Chemistry without Prior Knowledge

We present a chemical discovery robot for the efficient and reliable discovery of supramolecular architectures through the exploration of a huge reaction space exceeding ten billion combinations. The system was designed to search for areas of reactivity found through autonomous selection of the reagent types, amounts, and reaction conditions aiming for combinations that are reactive. The process consists of two parts where reagents are mixed together, choosing from one type of aldehyde, one amine and one azide (from a possible family of two amines, two aldehydes and four azides) with different volumes, ratios, reaction times, and temperatures, whereby the reagents are passed through a copper coil reactor. Next, either cobalt or iron is added, again from a large number of possible quantities. The reactivity was determined by evaluating differences in pH, UV‐Vis, and mass spectra before and after the search was started. The algorithm was focused on the exploration of interesting regions, as defined by the outputs from the sensors, and this led to the discovery of a range of 1‐benzyl‐(1,2,3‐triazol‐4‐yl)‐N‐alkyl‐(2‐pyridinemethanimine) ligands and new complexes: [Fe(L¹)₂](ClO₄)₂ ( 1 ); [Fe(L²)₂](ClO₄)₂ ( 2 ); [Co₂(L³)₂](ClO₄)₄ ( 3 ); [Fe₂(L³)₂](ClO₄)₄ ( 4 ), which were crystallised and their structure confirmed by single‐crystal X‐ray diffraction determination, as well as a range of new supramolecular clusters discovered in solution using high‐resolution mass spectrometry.     

New 19F NMR methodology reveals structures of molecules in complex mixtures of fluorinated compounds

Although the number of natural fluorinated compounds is very small, fluorinated pharmaceuticals and agrochemicals are numerous. ¹⁹F NMR spectroscopy has a great potential for the structure elucidation of fluorinated organic molecules, starting with their production by chemical or chemoenzymatic reactions, through monitoring their structural integrity, to their biotic and abiotic transformation and ultimate degradation in the environment. Additionally, choosing to incorporate ¹⁹F into any organic molecule opens a convenient route to study reaction mechanisms and kinetics. Addressing limitations of the existing ¹⁹F NMR techniques, we have developed methodology that uses ¹⁹F as a powerful spectroscopic spy to study mixtures of fluorinated molecules. The proposed ¹⁹F-centred NMR analysis utilises the substantial resolution and sensitivity of ¹⁹F to obtain a large number of NMR parameters, which enable structure determination of fluorinated compounds without the need for their separation or the use of standards. Here we illustrate the ¹⁹F-centred structure determination process and demonstrate its power by successfully elucidating the structures of chloramination disinfectant by-products of a single mono-fluorinated phenolic compound, which would have been impossible otherwise. This novel NMR approach for the structure elucidation of molecules in complex mixtures represents a major contribution towards the analysis of chemical and biological processes involving fluorinated compounds.

¹⁹F-centred NMR structure determination protocol alleviates the need for compound separation. Disinfection byproducts of chloramination were unraveled by analyzing the reaction pathways of a single fluorinated molecule.     

Line Intensity of R(0) and R(3) of the CH4 2ν3 Band from Diode Laser Spectroscopy

We have determined the spectroscopic parameters that are necessary to describe accurately the R(0) line profile of the CH₄ 2ν₃ band from about 1 Torr to a few hundred Torr of pure CH₄. The intensities determined at each pressure are in overall agreement to better than 0.7%. The R(3) manifold of the same band has also been investigated. Relative positions and absolute intensities of the three transitions composing the triplet have been determined. The intensity distribution inside the triplet is in fair agreement with recent theoretical predictions.     

Search for new heavy particles in the WZ0 final state in pp collisions at square root[s] = 1.8 TeV

We present the first general search for new heavy particles, X, which decay via X --> WZ0 --> e(nu)+jj as a function of M(X) and Gamma(X) in pp collisions at square root[s] = 1.8 TeV. No evidence is found for production of X in 110 pb(-1) of data collected by the Collider Detector at Fermilab. General cross section limits are set at the 95% C.L. as a function of mass and width of the new particle. The results are further interpreted as mass limits on the production of new heavy charged vector bosons which decay via W' --> WZ0 in an extended gauge model as a function of the width, Gamma(W'), and mixing factor between the W' and the standard model W bosons.     

Some comments on the parameter choices for S.C.M.O. calculations on five membered heteroatomic π-electron systems

It has been reported [1] that the usual semi-empirical S.C.M.O. treatments of heteroatomic -electron systems yield unexpected dependencies of charge distribution on the _core terms involving the heteroatoms. Other workers [2] have claimed that the most usual choices of parameters yield chemically unreasonable charge densities in furan and pyrrole. It is shown here that the first effect is related to the relative magnitudes of the diagonal elements of the Fock matrix and that the second depends very strongly on the nonnearest neighbor F matrix elements but can be overcome with certain parameter choices by the inclusion of non-nearest neighbor _core terms in the calculations.

---

Zusammenfassung Bei den üblichen semiempirischen SCMO-Rechnungen an Heteroaromaten ergeben sich unerwartete Abhängigkeiten der Ladungsverteilung von den _Rumpf-Termen [1]. Die gebräuchlichste Parameterwahl führt zu chemisch unverständlichen Ladungsverteilungen bei Furan und Pyrrol [2]. Es wird gezeigt, daß der erste Effekt mit der relativen Größe der Diagonalelemente der Fockmatrix zusammenhängt; der zweite Effekt hängt sehr stark von den Nichtnachbarelementen ab: Bei Einschluß von Nichtnachbar- _Rumpf-Termen und entsprechender Parameterwahl erhält man befriedigende Ladungsverteilungen.

---

Résumé Il a été indiqué [1] que le traitement semi-empirique S.C.M.O. habituel des systèmes d'électrons dans les hétérocycles comporte des relations in attendues entre la distribution de charge et les termes _coeur impliquant les hétéroatomes. D'autres chercheurs [2] ont affirmé que les choix les plus communs de paramètres fournissent des densités de charge dans le furane et le pyrrole déraisonnables sur le plan chimique. On montre ici que le premier effet est lié aux grandeurs relatives des éléments diagonaux de la matrice de Fock et que le second effet dépend fortement des éléments non immédiatement voisins de cette matrice, mais peut être annulé avec certains choix de paramètres par introduction des termes non voisins _coeur dans les calculs.