Zeolite-formation mechanisms have long been the subject of intensive study, with most work concentrating on hydrothermal mechanisms. However, non-traditional zeolite syntheses that do not rely crystallisation provided a number new routes to interesting and unexpected materials, but their formation remain poorly understood. Here, we show how simultaneous in situ liquid- solid-state 29Si NMR spectroscopy can reveal mechanism from layered silicate precursor. The study provides evidence for...

Highly reflective crystals of the nucleotide base guanine are widely distributed in animal coloration and visual systems. Organisms precisely control morphology organization to optimize different optical effects, but little is known about how this achieved. Here we examine a fundamental question that has remained unanswered after over 100 years research on guanine:

A whiter shade of PAl: The reaction LAlI with white phosphorus yields the first main-group complex [(LAl)2P4] (L=HC(CMeNAr)2, Ar=2,6-iPr2C6H3) containing {P4}4− moiety, in which two P–P edges P4 tetrahedron are opened and each is bridged by a LAl moiety (see structure). results supported quantum chemical calculations.

We report a strategy for structure determination of organic materials in which complete solid-state nuclear magnetic resonance (NMR) spectral data is utilized within the context from powder X-ray diffraction (XRD) data. Following crystal XRD data, first-principles density functional theory-based techniques GIPAW approach are exploited to calculate NMR structure, followed by careful scrutiny agreement with experimental The successful application this demonstrated 1:1 cocrystal indomethacin...

A multi-technique strategy reveals a new hydrogen-bonding motif for 2′-deoxyguanosine derivative.

Abstract During the last 75 years, crystal structures have been reported for 19 of 20 directly encoded proteinogenic amino acids in their natural (enantiomerically pure) form. The structure is now final member this set: L ‐lysine. As crystalline ‐lysine has a strong propensity to incorporate water under ambient atmospheric conditions form hydrate phase, pure (non‐hydrate) phase can be obtained only by dehydration rigorously anhydrous conditions, resulting microcrystalline powder sample. For...

A range of diazonium salts and their corresponding triazenes have been prepared in order to directly compare relative thermal stabilities (via initial decomposition temperature) from differential scanning calorimetry (DSC) data. structure–stability relationship has explored investigate trends stability, depending on the aromatic substituent structure secondary amine component triazenes. All investigated show significantly greater stability (many are stable above 200 °C) compared with salts,...

Highly reflective assemblies of purine, pteridine, and flavin crystals are used in the coloration visual systems many different animals. However, structure determination biogenic by single-crystal XRD is challenging due to submicrometer size beam sensitivity crystals, powder inhibited small volumes powders, crystalline impurity phases, significant preferred orientation. Consequently, crystal structures materials remain unknown. Herein, we demonstrate that 3D electron diffraction (3D ED)...

The nature of glycine--glycine interactions in aqueous solution has been studied using molecular dynamics simulations at four different concentrations and, each case, temperatures. Although evidence is found for formation small, transient hydrogen-bonded clusters glycine molecules, the main type interaction between molecules to be single NH...OC hydrogen bonds. Double-hydrogen-bonded "dimers", which have often cited as a significant species present solutions glycine, are only observed...

We report the crystal structure of L-arginine, one last remaining natural amino acids for which has never been determined; determination was carried out directly from powder X-ray diffraction (XRD) data, exploiting direct-space genetic algorithm technique solution followed by Rietveld refinement.

Given the importance of phenomenon polymorphism from both fundamental and applied perspectives, there is considerable interest in discovery new systems that exhibit abundant polymorphism. In present article, preparation strategies structural properties three polymorphs (denoted Forms III, IV, V) m-aminobenzoic acid (m-ABA) are reported, elevating this system to rare class polymorphic with at least five known polymorphs. The crystal structures have been determined directly powder X-ray...

Abstract A new in‐situ NMR strategy (termed CLASSIC NMR) for mapping the evolution of crystallization processes is reported, involving simultaneous measurement both liquid‐state and solid‐state spectra as a function time. This combined allows complementary information to be obtained on solid liquid phases during process. In particular, proceeds (monitored by NMR), solution state becomes more dilute, leading changes in solution‐state speciation modes molecular aggregation solution, which are...

We report the crystal structure of anhydrous phase cimetidine hydrochloride, determined directly from powder X-ray diffraction data. The material was prepared by dehydration readily obtained monohydrate form only for which a has previously been reported. As such, solid-state processes typically yield product as microcrystalline powder, and determination carried out data, using direct-space genetic algorithm technique solution followed Rietveld refinement. further validated calculating 13C...

We report the crystal structure of a new polymorph l-tyrosine (denoted β polymorph), prepared by crystallization from gas phase following vacuum sublimation. Structure determination was carried out combined analysis three-dimensional electron diffraction (3D-ED) data and powder X-ray (XRD) data. Specifically, 3D-ED were required for reliable unit cell space group assignment, with solution independently both XRD data, using direct-space strategy implemented genetic algorithm. refinement...

Hitherto, direct structural characterization of polycrystalline product phases obtained in solid state polymerization reactions has been limited by the lack appropriate experimental techniques for structure determination. This paper demonstrates opportunity to apply modern powder X-ray diffraction carrying out complete determination such cases, reporting properties polymer phase photopolymerization reaction 2,5-distyrylpyrazine. The phase, which solution was carried using direct-space...

We report a high-field in-situ solid-state NMR study of the hydration CaAl2O4 (the most important hydraulic phase in calcium aluminate cement), based on time-resolved measurements 27Al spectra during early stages reaction. A variant CLASSIC methodology, involving alternate recording direct-excitation and MQMAS spectra, was used to monitor species present both solid liquid phases as function time. Our results provide quantitative information changes relative amounts sites with tetrahedral...

H2/air fuel cell polymer electrolyte membranes, consisting of poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI) doped with phosphoric acid, have been studied by 1H and 31P magic-angle spinning (MAS) NMR to investigate the polymer−acid interaction unresolved question nature proton conductivity. The resonances fully assigned, giving a complete picture species present allowing study local motion these nuclear relaxation. These results compared conductivity measurements, enabling conclusions...

It is demonstrated that sequential resonance assignments can be obtained from (13C,13C) correlation spectroscopy on a uniformly labeled protein under magic angle spinning. The experiment relies weak (C′,Cα) coupling conditions using defined range of MAS rates and employed at arbitrary magnetic field strength.

"Aufgeschnitten" wird der P4-Tetraeder von weißem Phosphor bei Reaktion mit LAlI, und es entsteht erste Hauptgruppenmetallkomplex einer {P4}4−-Einheit: [(LAl)2P4] (L=HC(CMeNAr)2, Ar=2,6-iPr2C6H3). In ihm sind zwei P-P-Kanten des Tetraeders geöffnet jeweils durch eine LAl-Einheit überbrückt (siehe Struktur). Die Ergebnisse werden quantenchemische Rechnungen gestützt.

We are engaged in a multidisciplinary study of fundamental aspects the crystallization organic molecular materials from solution, focusing on polymorphic systems under recognition that such represent an ideal opportunity for obtaining systematic understanding competing pathways processes. The range techniques employed this work sensitive to structural properties different length scales and thus appropriate mapping changes occur at stages process, starting early aggregation events solution...