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Background: In patients with end-stage heart failure, durable Left Ventricular Assist Devices (LVADs) can be used as a bridge to transplant or destination therapy. LVADs have been shown to improve survival for patients with heart failure (HF). HF is associated with electrolyte abnormalities and the development of sustained arrhythmias. However, data on the influence of arrhythmias and electrolyte imbalances on inpatient outcomes in LVAD patients are lacking. Furthermore, previous works assessing inpatient outcomes focused mainly on the role of chronic comorbidities in those outcomes. Methods: In this cross-sectional study, we used discharge data from the National Inpatient Sample from 2019 to 2020 to assess the influence of acute arrhythmias on inpatient mortality in patients with LVADs. We also investigated the relationship between acute medical conditions and mortality. Results: There were 9418 (not survey-adjusted) hospitalizations with LVAD, among which 2539 (27%) died during the hospitalization. Univariate analysis of arrhythmias showed that ventricular arrhythmias (VAs)—ventricular fibrillation/flutter and ventricular tachycardia—as well as complete heart block were associated with significantly higher odds of mortality. Follow-up multivariable logistic analysis showed that these arrhythmias retain their increased association with death. Hyperkalemia and acidosis had increased adjusted odds of death (1.54 (95% confidence interval: 1.28–1.85) (p < 0.001) and 2.44 (CI: 2.14–2.77) (p < 0.001), respectively). Conclusions: VAs, complete heart block, hyperkalemia, and acidosis were associated with increased odds of all-cause mortality. Females had higher odds of inpatient mortality. These findings suggest that electrolyte management, maintenance of optimal acid–base balance, and interventions to treat sustained ventricular arrhythmias may be suitable therapeutic targets to reduce mortality in hospitalized patients with LVADs.

The concept of variable stoichiometry cocrystallization is explored in halogen-bonded systems. Three novel cocrystals of 1,4-diiodotetrafluorobenzene and 3-nitropyridine with molar ratios of 1:1, 2:1, and 1:2, respectively, are prepared by slow evaporation methods. Single-crystal X-ray diffraction analysis reveals key differences between each of the nominally similar cocrystals. For instance, the 1:1 cocrystal crystallizes in the [P2.sub.1]/n space group and features a single chemically and crystallographically unique halogen bond between iodine and the pyridyl nitrogen. The 2:1 cocrystal crystallizes in the P1 space group and features a halogen bond between iodine and one of the nitro oxygens in addition to an iodine--nitrogen halogen bond. The 1:2 cocrystal crystallizes with a large unit cell (V = 9896 [A.sup.3]) in the Cc space group and features 10 crystallographically distinct iodine-nitrogen halogen bonds. Powder X-ray diffraction experiments carried out on the 1:1 and 2:1 cocrystals confirm that gentle grinding does not alter the crystal forms. [.sup.1]H [right arrow] [.sup.13]C and [.sup.19]F [right arrow] [.sup.13]C cross-polarization magic angle spinning (CP/MAS) NMR experiments performed on powdered samples of the 1:1 and 2:1 cocrystals are used as spectral editing tools to select for either the halogen bond acceptor or donor, respectively. Carbon-13 chemical shifts in the cocrystals are shown to change only very subtly relative to pure solid 1,4-diiodotetrafluorobenzene, but the shift of the carbon directly bonded to iodine nevertheless increases, consistent with halogen bond formation (e.g., a shift of +1.6 ppm for the 2:1 cocrystal). This work contributes new examples to the field of variable stoichiometry cocrystal engineering with halogen bonds. Key words: solid-state NMR, X-ray diffraction, halogen bond, cocrystal, polymorphism, stoichiometry, stoichiomorphism. Nous avons etudie le concept de cocristallisation a stoechiometrie variable dans des systemes a liaison halogene. Nous avons prepare par evaporation lente trois nouveaux cocristaux de 1,4-diiodotetrafluorobenzene et de 3-nitropyridine avec des rapports molaires de 1:1, de 2:1 et de 1:2, respectivement. L'analyse par diffraction des rayons X sur monocristal revele des differences importantes entre les cocristaux theoriquement similaires. Par exemple, le cocrystal 1:1 cristallise selon le groupe d'espace [P2.sub.1]/n et presente une seule liaison halogene, sur les plans chimique et cristallographique, entre l'iode et l'azote du groupe pyridyle. Le cocrystal 2:1 cristallise selon le groupe d'espace P1 et presente une liaison halogene entre l'iode et l'un des oxygenes du groupe nitro, en plus de la liaison halogene iode-azote. Le cocristal 1:2 cristallise en formant une grande cellule unitaire (V = 9896 [A.sup.3]) selon le groupe d'espace Cc et presente 10 liaisons halogene iode-azote distinctes sur le plan cristallographique. Des experiences de diffraction des rayons X sur poudre realisees sur les cocristaux 1:1 et 2:1 confirment qu'un broyage leger ne modifie pas les formes cristallines. Nous avons utilise des experiences de RMN [.sup.1]H [right arrow] [.sup.13]C et [.sup.19]F [right arrow] [.sup.13]C a polarisation croisee en rotation a l'angle magique (CP/MAS, cross-polarization/magic angle spinning), realisees sur des echantillons de cocristaux 1:1 et 2:1 sous forme de poudre, comme outils d'edition spectrale pour selectionner l'accepteur ou le donneur de liaison halogene, respectivement. Les deplacements chimiques du carbone-13 dans les cocris-taux ne changent que de facon tres subtile par rapport au 1,4-diiodotetrafluorobenzene solide pur, mais le deplacement du carbone directement lie a l'iode augmente neanmoins, ce qui concorde avec la formation de liaisons halogene (p. ex., un deplacement de +1,6 ppm dans le cas du cocrystal 2:1). Ces travaux apportent de nouveaux exemples au domaine de l'ingenierie des cocristaux a stoechiometrie variable comportant des liaisons halogene. [Traduit par la Redaction] Mots-cles : RMN a l'etat solide, diffraction des rayons X, liaison halogene, cocristal, polymorphisme, stoechiometrie, stoechiomorphisme., Introduction Molecular and ionic solids can adopt a range of forms depending on how they are prepared. (1,2) Such forms include pure crystalline or amorphous phases, hydrates, or solvates. In [...]

Background: Depression and anxiety occur more frequently in women and are associated with an increased risk of cardiovascular disease. Objectives: Data on the association between these psychiatric conditions and the incidence of acute heart failure (HF) and how they influence heart failure outcomes in women are lacking. We investigated this potential relationship using data from the National Inpatient Sample. Methods: We used ICD-10 codes to extract encounters for acute heart failure and/or the acute exacerbation of chronic heart failure, anxiety, and depression from the discharge data of the NIS from 2019 to 2020. We compared baseline characteristics and length of stay (LOS), cost of care (COC) and acute HF by depression/anxiety status for males and females and employed regression models to assess the influence of these psychiatric conditions on the outcomes. Results: There were 6,394,136 encounters involving females, which represented 56.6% of the sample. The prevalence of depression and anxiety were 15.7% and 16.8%, respectively. Among females, the occurrence of acute CHF did not differ by depression or anxiety status. However, Takostubo cardiomyopathy was more prevalent in those with depression (0.3% vs. 0.2%, p = 0.003) and anxiety (0.3% vs. 0.2%, p = 0.03) compared to those without these conditions. Among those with depression, LOS was significantly longer (3 days IQR: 2–6, vs. 3 days IQR:2–5 days, p < 0.001). The COC was USD 1481 more in patients with depression. On the contrary, LOS and COC were significantly lower in those without anxiety. Conclusions: Depression was associated with an increased LOS among both men and women and an increased cost of care among women. Anxiety was associated with a decreased LOS and cost of care among women, which may be related to an increased rate of against medical advice (AMA) discharges among this population. Further research is necessary to identify optimal management strategies for depression and anxiety among patients hospitalized with HF.

Cerebral artery aneurysms are present in up to 10% of ischemic stroke patients, often within or adjacent to the occluded vessel. In some cases, the approach to intervention may need to be modified based on the size and location of the aneurysm. We describe a 99-year-old female with a known history of cerebral aneurysm who underwent successfully mechanical thrombectomy of a right middle cerebral artery thrombus; an 8-mm aneurysm involving the right M1 bifurcation was identified only on post-procedural digital subtraction angiography. In addition, we discuss strategies to reduce the risk of iatrogenic aneurysm rupture in the setting of endovascular thrombectomy.

A pair of novel polymorphic ionic cocrystals of 3,4‐dicyanotelluradiazole and tetraphenylphosphonium bromide are synthesized and are characterized by single‐crystal XRD. Strong and directional non‐covalent chalcogen bonds (ChB) between Te and Br are analyzed via solid‐state NMR to reveal large and anisotropic J(125Te,79/81Br) coupling tensors, providing unequivocal evidence for non‐Fermi contact contributions across ChBs. Along with large 79/81Br quadrupolar couplings for the Br− anions, these data provide new tools to characterize chalcogen bonds and to differentiate between ChB polymorphs. [ABSTRACT FROM AUTHOR]

Users of the microbond test assume that a microbond resin droplet’s properties are equivalent to a macroscale specimen. However, there is currently no standardised methodology for determining the cure state of droplet specimens used in the microbond test. In this paper, we present a technique for microbond test users to better understand the properties of thermoset droplet specimens. Utilising a conventional benchtop spectrometer, a novel sample preparation technique involving curing epoxy droplets on thin-steel filaments allowed for high-throughput determination of the microbond droplet cure state. The parity between steel filament and glass fibre microbond samples was confirmed by infrared microspectroscopy. It is shown that cure schedules used in manufacturing composite parts produced microbond droplets with degrees of cure lower than that of bulk matrix specimens subjected to an identical thermal history. Testable microbond droplets could only be prepared for commercial resin systems when introducing a room temperature pre-curing time of at least 2 h. It is concluded that microbond testing should be supported by some droplet cure state characterisation methods to ensure that interfacial effects are not artefacts of droplet sample preparation. [ABSTRACT FROM AUTHOR]

Abstract Diffuse large B‐cell lymphoma often presents with extranodal manifestations involving the musculoskeletal system. Shoulder pain is particularly worrisome for malignancy. Individuals presenting with refractory upper extremity complaints should undergo a prompt and thorough evaluation for cancer, as a delay in diagnosis can result in an unfavorable outcome.

Background: In patients with end-stage heart failure, durable Left Ventricular Assist Devices (LVADs) can be used as a bridge to transplant or destination therapy. LVADs have been shown to improve survival for patients with heart failure (HF). HF is associated with electrolyte abnormalities and the development of sustained arrhythmias. However, data on the influence of arrhythmias and electrolyte imbalances on inpatient outcomes in LVAD patients are lacking. Furthermore, previous works assessing inpatient outcomes focused mainly on the role of chronic comorbidities in those outcomes. Methods: In this cross-sectional study, we used discharge data from the National Inpatient Sample from 2019 to 2020 to assess the influence of acute arrhythmias on inpatient mortality in patients with LVADs. We also investigated the relationship between acute medical conditions and mortality. Results: There were 9418 (not survey-adjusted) hospitalizations with LVAD, among which 2539 (27%) died during the hospitalization. Univariate analysis of arrhythmias showed that ventricular arrhythmias (VAs)—ventricular fibrillation/flutter and ventricular tachycardia—as well as complete heart block were associated with significantly higher odds of mortality. Follow-up multivariable logistic analysis showed that these arrhythmias retain their increased association with death. Hyperkalemia and acidosis had increased adjusted odds of death (1.54 (95% confidence interval: 1.28–1.85) (p < 0.001) and 2.44 (CI: 2.14–2.77) (p < 0.001), respectively). Conclusions: VAs, complete heart block, hyperkalemia, and acidosis were associated with increased odds of all-cause mortality. Females had higher odds of inpatient mortality. These findings suggest that electrolyte management, maintenance of optimal acid–base balance, and interventions to treat sustained ventricular arrhythmias may be suitable therapeutic targets to reduce mortality in hospitalized patients with LVADs. [ABSTRACT FROM AUTHOR]

Lithium salts continue to find pharmaceutical applications, particularly as psychiatric medications. As with any active pharmaceutical ingredient, structural polymorphism is an important concern for lithium-based medications that can influence solubility and other physicochemical properties. Here we report a 13C, 1H, and 7Li magic-angle spinning solid-state nuclear magnetic resonance (MAS SSNMR) study of two 1:1 polymorphic ionic cocrystals of lithium 4-methoxybenzoate and L-proline (L4MPRO(α) and L4MPRO(β)). One-dimensional 13C cross-polarization MAS and two-dimensional heteronuclear correlation NMR spectra hint at differential mobilities of the proline and benzoate moieties for the two polymorphs. Five key resonances differ in 13C chemical shift by more than 1 ppm between the two polymorphs, clearly distinguishing between them. Gauge-including projector-augmented-wave density functional theory calculations of 13C and 1H magnetic shielding constants correlate strongly with the experimental chemical shifts for both polymorphs. R2 and root-mean-square deviation metrics are shown to be insufficient in the case of 13C, but sufficient in the case of 1H, for differentiating between the polymorphs. 7Li satellite-transition MAS NMR of both polymorphs are identical, as are the computed lithium magnetic shielding constants, demonstrating the insensitivity of 7Li NMR to polymorphism in these samples. This work highlights the utility of solid-state NMR spectroscopy for examining ionic salt cocrystals and also highlights some caveats in this regard. [ABSTRACT FROM AUTHOR]

This recommendation proposes a definition for the term "pnictogen bond"; the term pnictogen bond designates a subset of the attractive interactions between an electrophilic region on a pnictogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. [ABSTRACT FROM AUTHOR]

Matere bonds (MaB) to rhenium in a set of organic perrhenates are probed via185/187Re solid-state NMR in applied magnetic fields of up to 35.2 T, and via185/187Re NQR. 185/187Re quadrupolar couplings distinguish between MaB samples and control samples, and their precise values are governed by shear strain of the ReO4− anions. [ABSTRACT FROM AUTHOR]

Macrocycle formation that relies upon trans metal coordination of appropriately placed pyridine ligands within an arylene ethynylene construct provides rapid and reliable access to molecular rotators encapsulated within macrocyclic stators. Showing no significant close contacts to the central rotators, X‐ray crystallography of AgI‐coordinated macrocycles provides plausibility for unobstructed rotation or wobbling of rotators within the central cavity. Solid‐state 13C NMR of PdII‐coordinated macrocycles supports the notion of unobstructed movement of simple arenes in the crystal lattice. Solution 1H NMR studies indicate complete and immediate macrocycle formation upon the introduction of PdII to the pyridyl‐based ligand at room temperature. Moreover, the formed macrocycle is stable in solution; a lack of significant changes in the 1H NMR spectrum upon cooling to −50 °C is consistent with the absence of dynamic behavior. The synthetic route to these macrocycles is expedient and modular, providing access to rather complex constructs in four simple steps involving Sonogashira coupling and deprotection reactions. [ABSTRACT FROM AUTHOR]

The first example of a binary cocrystal, comprised of SnPh3Cl and PPh3, whose components are organized via short and directional tetrel bonds (TtB) between tin and phosphorus, is described. DFT elucidates, for the first time, the factors influencing the strength of TtBs involving heavy pnictogens. A CSD survey reveals that such TtBs are also present and determinative in single component molecular systems, highlighting their significant potential as tuneable structure-directing elements. [ABSTRACT FROM AUTHOR]

[sup.17]O solid-state NMR studies of waters of hydration in crystalline solids are presented. The [sup.17]O quadrupolar coupling and chemical shift (CS) tensors, and their relative orientations, are measured experimentally at room temperature for a-oxalic acid dihydrate, barium chlorate monohydrate, lithium sulfate monohydrate, potassium oxalate monohydrate, and sodium perchlorate monohydrate. The [sup.17]O quadrupolar coupling constants ([C.sub.Q]) range from 6.6 to 7.35 MHz and the isotropic chemical shifts range from -17 to 19.7 ppm. The oxygen CS tensor spans vary from 25 to 78 ppm. These represent the first complete CS and electric field gradient tensor measurements for water coordinated to metals in the solid state. Gauge-including projector-augmented wave density functional theory calculations overestimate the values of [C.sub.Q], likely due to librational dynamics of the water molecules. Computed CS tensors only qualitatively match the experimental data. The lack of strong correlations between the experimental and computed data, and between these data and any single structural feature, is attributed to motion of the water molecules and to the relatively small overall range in the NMR parameters relative to their measurement precision. Nevertheless, the isotropic chemical shift, quadrupolar coupling constant, and CS tensor span clearly differentiate between the samples studied and establish a 'fingerprint' [sup.17]O spectral region for water coordinated to metals in solids. Key words: nuclear magnetic resonance, water, quadrupolar coupling, hydrogen bonding, chemical shifts, density functional theory, [sup.17]O solid-state NMR. Nous presentons les resultats d'etudes de RMN de l'[sup.17]O a l'etat solide portant sur les molecules d'eau d'hydratation dans des solides cristallins. Nous avons mesure experimentalement a temperature ambiante le couplage quadripolaire de l'[sup.17]O et les tenseurs de deplacement chimique (DC) ainsi que leurs orientations relatives de l'acide a-oxalique dihydrate, du chlorate de baryum monohydrate, du sulfate de lithium monohydrate, de l'oxalate de potassium monohydrate et du perchlorate de sodium monohydrate. Les constantes de couplage quadripolaires ([C.sub.Q]) de l'[sup.17]O varient de 6,6 a 7,35 MHz et les deplacements chimiques isotropes de -17 a 19,7 ppm. L'envergure du tenseur de DC de l'oxygene varie de 25 a 78 ppm. Ces resultats representent les premieres mesures completes de DC et de tenseur de gradient de champ electrique effectuees sur des molecules d'eau coordonnees a des metaux en phase solide. Nous avons observe que les calculs de la theorie de la fonctionnelle de la densite par la methode<>surestiment les valeurs de [C.sub.Q], probablement a cause de la dynamique de libration des molecules d'eau. Les valeurs calculees des tenseurs de DC correspondent aux valeurs experimentales seulement sur le plan qualitatif. L'absence de fortes correlations entre les donnees experimentales et calculees, et entre ces donnees et toute caracteristique structurale, s'explique par le mouvement des molecules d'eau et la variation globale relativement faible des parametres de RMN par rapport a la precision de mesure de ceux-ci. Quoi qu'il en soit, le deplacement chimique isotrope, la constante de couplage quadripolaire et l'envergure des tenseurs de DC permettent de distinguer clairement les echantillons etudies les uns des autres et d'etablir une <> dans la region spectrale de l'[sup.17]O correspondant aux molecules d'eau coordonnees aux metaux dans les solides. [Traduit par la Redaction] Mots-cles: resonance magnetique nucleaire, eau, couplage quadripolaire, liaison hydrogene, deplacements chimiques, theorie de la fonctionnelle de la densite, [sup.17]O RMN a l'etat solide., Introduction Water is essential to life, innumerable biochemical and inorganic processes, chemical reactions, and the structure and properties of various materials. (1,2) Water molecules play key structural roles in organic, [...]

A thorough investigation of solid-state NMR signal enhancement schemes and high-resolution techniques for application to the spin-7/2 [sup.43]Ca nuclide are presented. Signal enhancement experiments employing double frequency sweeps, hyperbolic secant pulses, and rotor-assisted population transfer, which manipulate the satellite transitions of half-integer quadrupolar nuclei to polarize the central transition (m = +1/2 [left and right arrow] -1/2), are carried out on four well-characterized [sup.43]Ca isotopically enriched calcium salts: Ca[(N[O.sub.3]).sub.2], Ca[(OD).sub.2], CaS[O.sub.4] x 2[H.sub.2]O, and Ca[(OAc).sub.2] x [H.sub.2]O. These results, in conjunction with numerical simulations of [sup.43]Ca NMR spectra under magic-angle spinning conditions, are used to identify the technique that provides the most uniform (or quantitative) polarization enhancement as well as the largest signal enhancement factors independent of size of the [sup.43]Ca quadrupolar coupling constant, which is the most significant source of resonance broadening in [sup.43]Ca NMR spectra. These samples are further investigated using [sup.43]Ca double-rotation NMR spectroscopy to yield isotropic, or solution-like, NMR spectra with exquisite resolution. In addition, three unique calcium sites are resolved for the hemihydrated form of calcium acetate (unknown structure), Ca[(OAc).sub.2] x 0.5[H.sub.2]O, with double-rotation NMR, whereas the more common, but more time-consuming, multiple quantum magic-angle spinning technique only clearly resolves two calcium sites. The results shown herein will be useful for other NMR spectroscopists attempting to acquire [sup.43]Ca solid-state NMR data for unknown and more complex materials with a higher degree of both sensitivity and resolution. Key words: [sup.43]Ca solid-state NMR spectroscopy, double-rotation NMR, signal enhancement, high-resolution quadrupolar NMR, calcium acetate hemihydrate, crystallography. Nous presentons un examen approfondi des schemas d'amplification du signal RMN a l'etat solide et des techniques de RMN du solide en haute resolution en vue de les appliquer au nucleide [sup.43]Ca, de spin 7/2. Quatre sels de calcium enrichis en isotope [sup.43]Ca et bien caracterises, soit le Ca[(N[O.sub.3]).sub.2], le Ca[(OD).sub.2], le CaS[O.sub.4] x 2[H.sub.2]O et le Ca[(OAc).sub.2] x [H.sub.2]O, ont ete soumis a des experiences d'amplification du signal au moyen de balayages a double frequence, d'impulsions de forme secante hyperbolique et de transfert de population assiste par rotor, qui permettent de manipuler les transitions satellites des noyaux quadripolaires de spin demi-entier afin de polariser la transition centrale (m = +1/2 [left and right arrow] 1/2). Nous avons utilise ces resultats, combines aux simulations numeriques de spectres RMN du [sup.43]Ca en conditions de rotation a l'angle magique, pour determiner la technique produisant l'amplification de polarisation la plus uniforme (ou la plus quantitative) et les facteurs d'amplification du signal les plus importants, et ce, sans egard a la valeur de la constante de couplage quadripolaire du [sup.43]Ca, qui est la principale source d'elargissement du a la resonnance dans les spectres RMN du [sup.43]Ca. Nous avons soumis ces echantillons a des analyses plus poussees au moyen de la spectroscopie RMN a double rotation afin d'obtenir des spectres RMN isotropes (ou semblables a des spectres en solution) d'une resolution exceptionnelle. En outre, par spectroscopie RMN a double rotation, on distingue trois positions uniques des atomes de calcium de Facetate de calcium dans sa forme semi-hydratee (Ca[(OAc).sub.2] x 0.5[H.sub.2]O) (dont la structure est inconnue), tandis que la spectroscopie de correlation multiquanta en rotation a l'angle magique, qui est une technique plus courante que la precedente, mais qui requiert plus de temps, ne permet de distinguer clairement que deux positions des atomes de calcium. Les resultats presentes dans le present article sauront etre utiles a d'autres chercheurs en spectroscopie RMN qui tentent d'accumuler des donnees de RMN du [sup.43]Ca a l'etat solide a partir de materiaux inconnus ou plus complexes, et ce, avec une meilleure sensibilite et une meilleure resolution. [Traduit par la Redaction] Mots-cles: spectroscopie RMN du [sup.43]Ca a l'etat solide, RMN a double rotation, amplification du signal, RMN quadripolaire a haute resolution, acetate de calcium semi-hydrate, cristallographie., Introduction Due to the availability of superconducting magnets with large fields (e.g., ≥ 18.8 T), nuclear magnetic resonance (NMR) studies on nuclides whose observation was thought to be too impractical [...]

This article describes some highlights of the research which has been carried out in my laboratory at the University of Ottawa over the period covering 2005 to 2014. My research is in the general areas of solid-state NMR, applications of quantum chemistry, and biomolecular NMR. The format will follow that of my 2014 Canadian Society for Chemistry Keith Laidler Award presentation given in Vancouver in June 2014 at the 97th Canadian Chemistry Conference and Exhibition. Following a brief introduction, I will present some of our most interesting and exciting recent advances according to the following six themes: 1. Fundamental solid-state NMR. 2. Materials characterization and NMR crystallography. 3. Pharmaceuticals and polymorphism. 4. Non-covalent interactions: Halogen bonds. 5. Biomolecular NMR. 6. Software development. Key words: NMR, solid-state NMR, materials, biomolecules, non-covalent interactions. Le present article decrit certains points saillants des travaux de recherche menes dans mon laboratoire de l'Universite d'Ottawa au cours de la periode de 2005 a 2014. Mes recherches portent sur les domaines generaux de la RMN biomoleculaire et du solide, etdes applications de lachimie quantique. La forme de cet article est analogue acelle de l'expose quej'aipresente dans le cadre du prix Keith Laidler 2014 de la Societe canadienne de chimie, lors du 97e congres canadien de chimie et exposition qui s'est tenu a Vancouver en juin 2014. Apres une breve introduction, je presenterai quelques-unes de nos recentes avancees les plus interessantes et les plus passionnantes, classees selon les six sujets suivants: 1. Recherche fondamentale en RMN du solide; 2. Caracterisation des materiaux par cristallographie et RMN; 3. Agents pharmaceutiques et polymorphisme; 4. Interactions non covalentes: liaisons halogenes; 5. RMN biomoleculaire; 6. Developpement de logiciels. [Traduit par la Redaction] Mots-cles: RMN, RMN du solide, materiaux, biomolecules, interactions non covalentes., Introduction Canada has a strong research tradition in the field of NMR spectroscopy, (1,2,3,4,5,6,7) and following my doctoral work with Rod Wasylishen at Dalhousie University and at the University of [...]

Phenomena such as anticooperativity and competition among non‐covalent bond donors and acceptors are key considerations when exploring the polymorphic and stoichiomorphic landscapes of binary and higher‐order cocrystalline architectures. We describe the preparation of four cocrystals of 1,3,5‐trifluoro‐2,4,6‐triiodobenzene with N‐heterocyclic compounds, namely acridine, 3‐aminopyridine, 4‐methylaminopyridine, and 1,2‐di(4‐pyridyl)ethane. The cocrystals, which are characterized by single‐crystal and powder X‐ray diffraction experiments, all show moderately strong and directional iodine⋅⋅⋅nitrogen halogen bonds with reduced distance parameters ranging from 0.79 to 0.92 and carbon‐iodine⋅⋅⋅nitrogen bond angles ranging from 165.4(3) to 175.31(7)°. The cocrystal comprising 1,3,5‐trifluoro‐2,4,6‐triiodobenzene and acridine provides a relatively rare example where all three halogen bond donor sites form halogen bonds with three acceptor molecules, overcoming an anticooperative effect. This effect manifests itself through the lengthening of non‐halogen‐bonded C−I bonds, weakening their potential to form halogen bonds. The effect is only observed once two halogen bonds have been formed to 1,3,5‐trifluoro‐2,4,6‐triiodobenzene; one such bond does not appear to be adequate. Among the four cocrystals studied, competition between the pyridyl nitrogen atoms and the amine nitrogen atoms suggests that the former are the preferred halogen bond acceptors. Analysis by Hirshfeld fingerprint plots and 13C and 19F magic‐angle spinning solid‐state nuclear magnetic resonance (NMR) spectroscopy provides additional insights into the prevalence of various short contacts in the crystal structures and into the spectral response to halogen‐bond‐induced cocrystallization. [ABSTRACT FROM AUTHOR]

Ameloblastic carcinoma is a locally aggressive odontogenic tumor that most commonly affects young and middle-aged adults. Metastatic disease may develop insidiously and manifest months or years after the initial diagnosis. Herein, we describe the clinical, imaging, and pathologic findings of a 31-year-old male who presented to the emergency department with headache and vision loss of 3 months duration and was subsequently found to have ameloblastic carcinoma with hepatic metastases. Initial computed tomography (CT) and magnetic resonance imaging revealed a multilocular cystic mass with avidly-enhancing nodular soft-tissue components associated with the right temporal fossa. Histologic examination of a tissue sample showed findings consistent with ameloblastic carcinoma. An initial staging CT scan showed several small hepatic cystic lesions. Follow-up surveillance imaging showed interval growth. A subsequent biopsy of a hepatic lesion showed findings compatible with metastatic ameloblastic carcinoma. The patient was started on systemic chemotherapy with evidence of disease progression at 1-year follow-up. [ABSTRACT FROM AUTHOR]

Three novel chalcogen‐bonded cocrystals featuring 3,4‐dicyano‐1,2,5‐selenodiazole (C4N4Se) or 3,4‐dicyano‐1,2,5‐tellurodiazole (C4N4Te) as chalcogen‐bond donors and hydroquinone (C6H6O2), tetraphenylphosphonium chloride (C24H20P+·Cl−) or tetraethylphosphonium chloride (C8H20P+·Cl−) as chalcogen‐bond acceptors have been prepared and characterized by single‐crystal X‐ray diffraction (XRD), powder X‐ray diffraction and 77Se/125Te magic‐angle spinning solid‐state NMR spectroscopy. The single‐crystal XRD results show that the chalcogenodiazole molecules interact with the electron donors through two σ‐holes on each of the chalcogen atoms, which results in highly directional and moderately strong chalcogen bonds. Powder XRD confirms that the crystalline phases are preserved upon moderate grinding of the samples for solid‐state NMR experiments. Measurement of 77Se and 125Te chemical shift tensors via magic‐angle spinning solid‐state NMR spectroscopy confirms the number of magnetically unique chalcogen sites in each asymmetric unit and reveals the impact of chalcogen‐bond formation on the local electronic structure. These NMR data are further assessed in the context of analogous data for a wider range of crystalline chalcogen‐bonded systems. [ABSTRACT FROM AUTHOR]

Halogen bonding to phosphorus atoms remains uncommon, with relatively few examples reported in the literature. Here, the preparation and investigation of the cocrystal bis(dicyclohexylphenylphosphine)(1,6-diiodoperfluorohexane) by X-ray crystallography and solid-state multinuclear magnetic resonance spectroscopy is described. The crystal structure features two crystallographically unique C--I...P halogen bonds [dI...P = 3.090 (5) A, 3.264 (5) A ] and crystallographic disorder of one of the 1,6-diiodoperfluorohexane molecules. The first of these is the shortest and most linear I...P halogen bond reported to date. 13C, 19F, and 31P magic angle spinning solid-state NMR spectra are reported. A 31P chemical shift change of -7.0 p.p.m. in the cocrystal relative to pure dicyclohexylphenylphosphine, consistent with halogen bond formation, is noted. This work establishes iodoperfluoroalkanes as viable halogen bond donors when paired with phosphorus acceptors, and also shows that dicyclohexylphenylphosphine can act as a practical halogen bond acceptor. [ABSTRACT FROM AUTHOR]

Halogen bonding to phosphorus atoms remains uncommon, with relatively few examples reported in the literature. Here, the preparation and investigation of the cocrystal bis(dicyclohexylphenylphosphine)(1,6‐diiodoperfluorohexane) by X‐ray crystallography and solid‐state multinuclear magnetic resonance spectroscopy is described. The crystal structure features two crystallographically unique C—I…P halogen bonds [dI…P = 3.090 (5) Å, 3.264 (5) Å] and crystallographic disorder of one of the 1,6‐diiodoperfluorohexane molecules. The first of these is the shortest and most linear I…P halogen bond reported to date. 13C, 19F, and 31P magic angle spinning solid‐state NMR spectra are reported. A 31P chemical shift change of −7.0 p.p.m. in the cocrystal relative to pure dicyclohexylphenylphosphine, consistent with halogen bond formation, is noted. This work establishes iodoperfluoroalkanes as viable halogen bond donors when paired with phosphorus acceptors, and also shows that dicyclohexylphenylphosphine can act as a practical halogen bond acceptor.The halogen‐bonded cocrystal bis(dicyclohexylphenylphosphine)(1,6‐diiodoperfluorohexane) is prepared mechanochemically and investigated by X‐ray crystallography and solid‐state NMR spectroscopy, revealing the presence of a rare C—I…P halogen bond. [ABSTRACT FROM AUTHOR]

Field‐stepped NMR spectroscopy at up to 36 T using the series‐connected hybrid (SCH) magnet at the U.S. National High Magnetic Field Laboratory is demonstrated for acquiring ultra‐wideline powder spectra of nuclei with very large quadrupolar interactions. Historically, NMR evolved from the continuous‐wave (cw) field‐swept method in the early days to the pulsed Fourier‐transform method in the modern era. Spectra acquired using field sweeping are generally considered to be equivalent to those acquired using the pulsed method. Here, it is shown that field‐stepped wideline spectra of half‐integer spin quadrupolar nuclei acquired using WURST/CPMG methods can be significantly different from those acquired with the frequency‐stepped method commonly used with superconducting magnets. The inequivalence arises from magnetic field‐dependent NMR interactions such as the anisotropic chemical shift and second‐order quadrupolar interactions; the latter is often the main interaction leading to ultra‐wideline powder patterns of half‐integer spin quadrupolar nuclei. This inequivalence needs be taken into account to accurately and correctly determine the quadrupolar coupling and chemical shift parameters. A simulation protocol is developed for spectral fitting to facilitate analysis of field‐stepped ultra‐wideline NMR spectra acquired using powered magnets. A MATLAB program which implements this protocol is available on request. [ABSTRACT FROM AUTHOR]

Chalcogen bonds (ChB) are moderately strong, directional, and specific non‐covalent interactions that have garnered substantial interest over the last decades. Specifically, the presence of two σ‐holes offers great potential for crystal engineering, catalysis, biochemistry, and molecular sensing. However, ChB applications are currently hampered by a lack of methods to characterize and control chalcogen bonds. Here, we report on the influence of various substituents (halogens, cyano, and methyl groups) on the observed self‐complementary ChB networks of 2,1,3‐benzoselenadiazoles. From molecular electrostatic potential calculations, we show that the electrostatic surface potentials (ESP) of the σ‐holes on selenium are largely influenced by the electron‐withdrawing character of these substituents. Structural analyses via X‐ray diffraction reveal a variety of ChB geometries and binding modes that are rationalized via the computed ESP maps, although the structure of 5,6‐dimethyl‐2,1,3‐benzoselenadiazole also demonstrates the influence of steric interactions. 77Se solid‐state magic‐angle spinning NMR spectroscopy, in particular the analysis of the selenium chemical shift tensors, is found to be an effective probe able to characterize both structural and electrostatic features of these self‐complementary ChB systems. We find a positive correlation between the value of the ESP maxima at the σ‐holes and the experimentally measured 77Se isotropic chemical shift, while the skew of the chemical shift tensor is established as a metric which is reflective of the ChB binding motif. [ABSTRACT FROM AUTHOR]

We present herein an in‐depth study of complexes in which a molecule containing a boron‐boron triple bond is bound to tellurate cations. The analysis allows the description of these salts as true π complexes between the B−B triple bond and the tellurium center. These complexes thus extend the well‐known Dewar‐Chatt‐Duncanson model of bonding to compounds made up solely of p block elements. Structural, spectroscopic and computational evidence is offered to argue that a set of recently reported heterocycles consisting of phenyltellurium cations complexed to diborynes bear all the hallmarks of π‐complexes in the π‐complex/metallacycle continuum envisioned by Joseph Chatt. Described as such, these compounds are unique in representing the extreme of a metal‐free continuum with conventional unsaturated three‐membered rings (cyclopropenes, azirenes, borirenes) occupying the opposite end. [ABSTRACT FROM AUTHOR]

Group 16 chalcogens potentially provide Lewis‐acidic σ‐holes, which are able to form attractive supramolecular interactions with electron rich partners through chalcogen bonds. Here, a multifaceted experimental and computational study of a large series of novel chalcogen‐bonded cocrystals, prepared using the principles of crystal engineering, is presented. Single‐crystal X‐ray diffraction studies reveal that dicyanoselenadiazole and dicyanotelluradiazole derivatives work as promising supramolecular synthons with the ability to form double chalcogen bonds with a wide range of electron donors including halides and oxygen‐ and nitrogen‐containing heterocycles. Extensive 77Se and 125Te solid‐state nuclear magnetic resonance spectroscopic investigations of cocrystals establish correlations between the NMR parameters of selenium and tellurium and the local chalcogen bonding geometry. The relationships between the electronic environment of the chalcogen bond and the 77Se and 125Te chemical shift tensors were elucidated through a natural localized molecular orbital density functional theory analysis. This systematic study of chalcogen‐bond‐based crystal engineering lays the foundations for the preparation of the various multicomponent systems and establishes solid‐state NMR protocols to detect these interactions in powdered materials. [ABSTRACT FROM AUTHOR]

We report a multifaceted experimental and computational study of three self-complementary chalcogen-bond donors as well as a series of seven chalcogen bonded cocrystals. Bis(selenocyanatomethyl)benzene derivatives were cocrystallized with various halide salts (Bu4NCl, Bu4NBr, Bu4NI) and nitrogen-containing Lewis bases (4,4′-bipyridine and 1,2-di(4-pyridyl)ethylene). Three new single-crystal X-ray structures are reported. 77Se solid-state nuclear magnetic resonance spectroscopic study of a series of cocrystals establishes correlations between the NMR parameters of selenium and the local ChB geometry. For example, the 77Se isotropic chemical shift generally decreases on cocrystal formation. Diagnostic 13C chemical shifts are also described. In addition, all the chalcogen bonded cocrystals and pure tectons are investigated by Raman and IR spectroscopy techniques. Characteristic red shifts of the NC–Se stretching band upon cocrystal formation on the order of 10 to 20 cm−1 are observed, which provides a distinct signature of the chalcogen bond involving selenocyanates. The 125Te chemical shift tensor and X-ray structure of chalcogen-bonded tellurocyanatomethylbenzene are also reported. Insights into the connection between the electronic structure of the chalcogen bond and the experimentally measured 77Se chemical shift tensors are afforded through a natural localized molecular orbital density functional theory analysis. For the systems studied here, the lack of a very strong a correlation between experimental and DFT-computed 77Se chemical shift tensors leads to the conclusion that many structural features likely influence their ultimate values; however, computations on model systems reveal that the ChB alone produces consistent and predictable effects (e.g., the chalcogen chemical shift decreases as the chalcogen bond is shortened). [ABSTRACT FROM AUTHOR]

Diffuse large B‐cell lymphoma often presents with extranodal manifestations involving the musculoskeletal system. Shoulder pain is particularly worrisome for malignancy. Individuals presenting with refractory upper extremity complaints should undergo a prompt and thorough evaluation for cancer, as a delay in diagnosis can result in an unfavorable outcome. [ABSTRACT FROM AUTHOR]

This recommendation proposes a definition for the term "chalcogen bond"; it is recommended the term is used to designate the specific subset of inter- and intramolecular interactions formed by chalcogen atoms wherein the Group 16 element is the electrophilic site. [ABSTRACT FROM AUTHOR]

The halogen bond has previously been explored as a versatile tool in crystal engineering and anion coordination chemistry, with mechanochemical synthetic techniques having been shown to provide convenient routes towards cocrystals. In an effort to expand our knowledge on the role of halogen bonding in anion coordination, here we explore a series of cocrystals formed between 3‐iodoethynylpyridine and 3‐iodoethynylbenzoic acid with halide salts. In total, we report the single‐crystal X‐ray structures of six new cocrystals prepared by mechanochemical ball milling, with all structures exhibiting C≡C−I⋅⋅⋅X− (X=Cl, Br) halogen bonds. Whereas cocrystals featuring a pyridine group favoured the formation of discrete entities, cocrystals featuring a benzoic acid group yielded an alternation of halogen and hydrogen bonds. The compounds studied herein were further characterized by 13C and 31P solid‐state nuclear magnetic resonance, with the chemical shifts offering a clear and convenient method of identifying the occurrence of halogen bonding, using the crude product obtained directly from the mechanochemical ball milling. Whereas the 31P chemical shifts were quickly able to identify the occurrence of cocrystallization, 13C solid‐state NMR was diagnostic of both the occurrence of halogen bonding and of hydrogen bonding. [ABSTRACT FROM AUTHOR]