Oral fluid/plasma cannabinoid ratios following controlled oral THC and smoked cannabis administration

Oral fluid (OF) is a valuable biological alternative for clinical and forensic drug testing. Evaluating OF to plasma (OF/P) cannabinoid ratios provides important pharmacokinetic data on the disposition of drug and factors influencing partition between matrices. Eleven chronic cannabis smokers resided on a closed research unit for 51 days. There were four 5-day sessions of 0, 30, 60, and 120 mg oral ?⁹-tetrahydrocannabinol (THC)/day followed by a five-puff smoked cannabis challenge on Day 5. Each session was separated by 9 days ad libitum cannabis smoking. OF and plasma specimens were analyzed for THC and metabolites. During ad libitum smoking, OF/P THC ratios were high (median, 6.1; range, 0.2–348.5) within 1 h after last smoking, decreasing to 0.1–20.7 (median, 2.1) by 13.0–17.1 h. OF/P THC ratios also decreased during 5-days oral THC dosing, and after the smoked cannabis challenge, median OF/P THC ratios decreased from 1.4 to 5.5 (0.04–245.6) at 0.25 h to 0.12 to 0.17 (0.04–5.1) at 10.5 h post-smoking. In other studies, longer exposure to more potent cannabis smoke and oromucosal cannabis spray was associated with increased OF/P THC peak ratios. Median OF/P 11-nor-9-carboxy-THC (THCCOOH) ratios were 0.3–2.5 (range, 0.1–14.7) ng/μg, much more consistent in various dosing conditions over time. OF/P THC, but not THCCOOH, ratios were significantly influenced by oral cavity contamination after smoking or oromucosal spray of cannabinoid products, followed by time-dependent decreases. Establishing relationships between OF and plasma cannabinoid concentrations is essential for making inferences of impairment or other clinical outcomes from OF concentrations.     

Dynamic behavior in diplatinum metalloreceptors

Diplatinum metalloreceptors anti-4a and anti-4b exhibit dynamic behavior in solution that is modified by anion binding. An X-ray crystal structure determination of anti-4a supports its proposed solution structure.     

A rare ether-bridged cobalt complex which gives rise to an unusual 'serpentine' metal-ligand binding motif

An unusual metal-ligand binding motif is found in dimeric cobalt(II) complexes coordinated by diamidoether ligands that bridge the metals in a 'serpentine' fashion through the ether donors of the ligand backbone rather than the amido groups.     

The preparation and crystal structure of bis(bis(diphenyl-phosphino)ethane)carbonylformylosmium(II) hexafluoroantimonatedichloromethane (1/1)

Reaction of trans[Os(CO)₂(dppe)₂]²⁺ with [KHB(OPrⁱ)₃] gives the formyl complex trans[Os(CHO)(CO)(dppe)₂][SbF₆] which is thermally very stable; the crystal structure shows it to have trans stereochemistry and a long Os-C bond.     

Chlorosulfonic acid-mediated cyclization of 4-phenyl-3-isocoumarincarboxylic acids and 4-phenyl-3-isoquinolinonecarboxylic acids: an efficient synthesis of 3-oxoindeno[2,1-c]isocoumarins and 3-oxoindeno[2,1-c]isoquinolinones

A highly efficient and clean method has been developed for the synthesis of 3-oxoindeno[2,1-c]isocoumarins and 3-oxoindeno[2,1-c]isoquinolinones from 4-phenyl-3-isocoumarincarboxylic acids and 4-phenyl-3-isoquinolinonecarboxylic acids, respectively.     

β‐Diketiminate‐Stabilized Magnesium(I) Dimers and Magnesium(II) Hydride Complexes: Synthesis,Characterization, Adduct Formation,and Reactivity Studies

The preparation and characterization of a series of magnesium(II) iodide complexes incorporating β‐diketiminate ligands of varying steric bulk and denticity, namely, [(ArNCMe)₂CH]^? (Ar=phenyl, (^PhNacnac), mesityl (^MesNacnac), or 2,6‐diisopropylphenyl (Dipp, ^DippNacnac)), [(DippNCtBu)₂CH]^? (^tBuNacnac), and [(DippNCMe)(Me₂NCH₂CH₂NCMe)CH]^? (^DmedaNacnac) are reported. The complexes [(^PhNacnac)MgI(OEt₂)], [(^MesNacnac)MgI(OEt₂)], [(^DmedaNacnac)MgI(OEt₂)], [(^MesNacnac)MgI(thf)], [(^DippNacnac)MgI(thf)], [(^tBuNacnac)MgI], and [(^tBuNacnac)MgI(DMAP)] (DMAP=4‐dimethylaminopyridine) were shown to be monomeric by X‐ray crystallography. In addition, the related β‐diketiminato beryllium and calcium iodide complexes, [(^MesNacnac)BeI] and [{(^DippNacnac)CaI(OEt₂)}₂] were prepared and crystallographically characterized. The reductions of all metal(II) iodide complexes by using various reagents were attempted. In two cases these reactions led to the magnesium(I) dimers, [(^MesNacnac)MgMg(^MesNacnac)] and [(^tBuNacnac)MgMg(^tBuNacnac)]. The reduction of a 1:1 mixture of [(^DippNacnac)MgI(OEt₂)] and [(^MesNacnac)MgI(OEt₂)] with potassium gave a low yield of the crystallographically characterized complex [(^DippNacnac)Mg(μ‐H)(μ‐I)Mg(^MesNacnac)]. All attempts to form beryllium(I) or calcium(I) dimers by reductions of [(^MesNacnac)BeI], [{(^DippNacnac)CaI(OEt₂)}₂], or [{(^tBuNacnac)CaI(thf)}₂] have so far been unsuccessful. The further reactivity of the magnesium(I) complexes [(^MesNacnac)MgMg(^MesNacnac)] and [(^tBuNacnac)MgMg(^tBuNacnac)] towards a variety of Lewis bases and unsaturated organic substrates was explored. These studies led to the complexes [(^MesNacnac)Mg(L)Mg(L)(^MesNacnac)] (L=THF or DMAP), [(^MesNacnac)Mg(μ‐AdN₆Ad)Mg(^MesNacnac)] (Ad=1‐adamantyl), [(^tBuNacnac)Mg(μ‐AdN₆Ad)Mg(^tBuNacnac)], and [(^MesNacnac)Mg(μ‐tBu₂N₂C₂O₂)Mg(^MesNacnac)] and revealed that, in general, the reactivity of the magnesium(I) dimers is inversely proportional to their steric bulk. The preparation and characterization of [(^tBuNacnac)Mg(μ‐H)₂Mg(^tBuNacnac)] has shown the compound to have different structural and physical properties to [(^tBuNacnac)MgMg(^tBuNacnac)]. Treatment of the former with DMAP has given [(^tBuNacnac)Mg(H)(DMAP)], the X‐ray crystal structure of which disclosed it to be the first structurally authenticated terminal magnesium hydride complex. Although attempts to prepare [(^MesNacnac)Mg(μ‐H)₂Mg(^MesNacnac)] were not successful, a neutron diffraction study of the corresponding magnesium(I) complex, [(^MesNacnac)MgMg(^MesNacnac)] confirmed that the compound is devoid of hydride ligands.     

Imaging mesoscopic nuclear spin noise with a diamond magnetometer

Magnetic resonance imaging can characterize and discriminate among tissues using their diverse physical and biochemical properties. Unfortunately, submicrometer screening of biological specimens is presently not possible, mainly due to lack of detection sensitivity. Here we analyze the use of a nitrogen-vacancy center in diamond as a magnetic sensor for nanoscale nuclear spin imaging and spectroscopy. We examine the ability of such a sensor to probe the fluctuations of the "classical" dipolar field due to a large number of neighboring nuclear spins in a densely protonated sample. We identify detection protocols that appropriately take into account the quantum character of the sensor and find a signal-to-noise ratio compatible with realistic experimental parameters. Through various example calculations we illustrate different kinds of image contrast. In particular, we show how to exploit the comparatively long nuclear spin correlation times to reconstruct a local, high-resolution sample spectrum.     

Highly efficient on-DNA amide couplings promoted by micelle forming surfactants for the synthesis of DNA encoded libraries

DNA encoded libraries (DELs) represent powerful new technology for finding small molecule ligands for proteins and are increasingly being applied to hit finding in medicinal chemistry. Crucial to the synthesis of high quality DELs is the identification of chemical reactions for their assembly that proceed with very high conversion across a range of different substrates, under conditions compatible with DNA-tagged substrates. Many current chemistries used in DEL synthesis do not meet this requirement, resulting in libraries of low fidelity. Amide couplings are the most commonly used reaction in synthesis of screening libraries and also in DELs. The ability to carry out highly efficient, widely applicable amide couplings in DEL synthesis would therefore be highly desirable. We report a method for amide coupling using micelle forming surfactants, promoted by a modified linker, that is broadly applicable across a wide range of substrates. Most significantly, this works exceptionally well for coupling of DNA-conjugated carboxylic acids (N-to-C) with amines in solution, a procedure that is currently very inefficient. The optimisation of separate procedures for coupling of DNA-conjugated acids and amines by reagent screening and statistically driven optimisation is described. The generality of the method is illustrated by the application to a wide range of examples with unprecedented levels of conversion. The utility of the (N-to-C) coupling of DNA-conjugated acids in DEL synthesis is illustrated by the three cycle synthesis of a fully DNA-encoded compound by two cycles of coupling of an aminoester, with intermediate ester hydrolysis, followed by capping with an amine. This methodology will be of great utility in the synthesis of high fidelity DELs.

Highly efficient forward and reverse on-DNA amide couplings were developed exploiting hydrophobic linkers in combination with the micelle forming surfactant TPGS-750M. The method is highly effective for a wide range of substrates in the synthesis of DNA-encoded libraries.