An integrated approach combining experimental, informatics and energetic methods for solid form derisking of PF-06282999.

The landscapes of observed and predicted three-dimensional crystal packing arrangements of small-molecule drug candidates can be complex. The possible appearance of a more thermodynamically stable solid form during drug development has led to the digital workflow of informatics-based risk assessments, named a Solid Form Health Check. Herein, we describe the use of a combined approach consisting of experiments, informatics together with energetic calculations in analysis of four competing polymorphs of PF-06282999, a myeloperoxidase (MPO) inhibitor with conformational flexibility and multiple plausible hydrogen bond networks.

Radical Dimerization in a Plastic Organic Crystal Leads to Structural and Magnetic Bistability with Wide Thermal Hysteresis.

The nitroxyl radical 1-methyl-2-azaadamantane -oxyl (Me-AZADO) exhibits magnetic bistability arising from a radical/dimer interconversion. The transition from the rotationally disordered paramagnetic plastic crystal, Me-AZADO, to the ordered diamagnetic crystalline phase, (Me-AZADO), has been conclusively demonstrated by crystal structure determination from high-resolution powder diffraction data and by solid-state NMR spectroscopy. The phase change is characterized by a wide thermal hysteresis with high sensitivity to even small applied pressures.

Antiferroelectric Phase Transition in a Proton-Transfer Salt of Squaric Acid and 2,3-Dimethylpyrazine.

A proton-transfer reaction between squaric acid (Hsq) and 2,3-dimethylpyrazine (2,3-Mepyz) results in crystallization of a new organic antiferroelectric (AFE), (2,3-MepyzH)(Hsq)·HO (), which possesses a layered structure. The structure of each layer can be described as partitioned into strips lined with methyl groups of the MepyzH cations and strips featuring extensive hydrogen bonding between the Hsq anions and water molecules. Variable-temperature dielectric measurements and crystal structures determined through a combination of single-crystal X-ray and neutron diffraction reveal an AFE ordering at 104 K.

From lithium to sodium: design of heterometallic molecular precursors for the NaMO cathode materials.

Based on the well-established model structure of LiM(tbaoac), the first series of heterometallic molecular precursors NaM(tbaoac)(THF) (M = Fe, Co, and Ni) have been designed and successfully utilized for the preparation of NaMO oxide cathode materials of sodium-ion batteries.

Crystal Structure Prediction via Deep Learning.

We demonstrate the application of deep neural networks as a machine-learning tool for the analysis of a large collection of crystallographic data contained in the crystal structure repositories. Using input data in the form of multiperspective atomic fingerprints, which describe coordination topology around unique crystallographic sites, we show that the neural-network model can be trained to effectively distinguish chemical elements based on the topology of their crystallographic environment. The model also identifies structurally similar atomic sites in the entire data set of ∼50000 crystal structures, essentially uncovering trends that reflect the periodic table of elements.

Power of Three: Incremental Increase in the Ligand Field Strength of N-Alkylated 2,2'-Biimidazoles Leads to Spin Crossover in Homoleptic Tris-Chelated Fe(II) Complexes.

Homoleptic complexes [Fe(L )]X (L = 1,1'-(α,α'- o-xylyl)-2,2'-biimidazole, L = 1,1'-(α,α'-3,4-dibromo- o-xylyl)-2,2'-biimidazole, L = 1,1'-(α,α'-2,5-dimethoxy- o-xylyl)-2,2'-biimidazole; X = BF or ClO) were synthesized by direct reactions of the Fe(II) precursor salts and bidentate ligands L, L, or L. All mononuclear complexes undergo gradual temperature-driven spin-crossover (SCO) between the high-spin (HS, S = 2) and low-spin (LS, S = 0) states. Complexes with ligands L and L synthesized in methanol exhibit complete SCO with the midpoint of the LS↔HS conversion varying from 233 to 313 K, while complexes with ligand L, crystallized from an ethanol/dichloromethane mixture, exhibit incomplete SCO with the residual HS/LS ratio of ∼1:4 for [Fe(L)](BF) and ∼1:1 for [Fe(L)](ClO).

Heteroleptic Fe(II) Complexes with NS Coordination as a Platform for Designing Spin-Crossover Materials.

Heteroleptic complexes [Fe(bpte)(bim)]X and [Fe(bpte)(xbim)]X (bpte = S,S'-bis(2-pyridylmethyl)-1,2-thioethane, bim = 2,2'-biimidazole, xbim = 1,1'-(α,α'-o-xylyl)-2,2'-biimidazole, X = ClO, BF, OTf) were prepared by reacting the corresponding Fe(II) salts with a 1:1 mixture of the ligands. All mononuclear complexes exhibit temperature-induced spin crossover (SCO) with the onset above room temperature. The SCO is rather gradual, due to low cooperativity of interactions between the cationic complexes, as revealed by crystal structure analyses.

Competitive coordination aggregation for V-shaped [Co3] and disc-like [Co7] complexes: synthesis, magnetic properties and catechol oxidase activity.

Unique dependence on the nature of metal salt and reaction conditions for coordination assembly reactions of varying architecture and nuclearity have been identified in V-shaped [Co3L4] and planar disc-like [Co7L6] compounds: [CoL2(μ-L)2(μ-OH2)2(CF3CO2)2] (1) and [Co(μ-L)6(μ-OMe)6]Cl2 (2) (HL = 2-{(3-ethoxypropylimino)methyl}-6-methoxyphenol). At room temperature varying reaction conditions, cobalt-ligand ratios and use of different bases allowed unique types of coordination self-assembly. The synthetic marvel lies in the nature of aggregation with respect to the two unrelated cores in 1 and 2.

Correction: Two types of nitrito support for μ4-oxido-bridged [Cu4] complexes: synthesis, crystal structures, magnetic properties and DFT analysis.

Correction for 'Two types of nitrito support for μ4-oxido-bridged [Cu4] complexes: synthesis, crystal structures, magnetic properties and DFT analysis' by Moumita Pait, et al., Dalton Trans., 2015, 44, 6107-6117.

Two types of nitrito support for μ₄-oxido-bridged [Cu₄] complexes: synthesis, crystal structures, magnetic properties and DFT analysis.

Novel nitrito supported and μ4-oxido bridged Cu(II) aggregates have been found in two tetranuclear complexes, [Cu4(μ4-O)L2(μ(1,3)-ONO)4] (1) and [Cu4(μ4-O)L2(μ(1,3)-OAc)2(μ1,2-NO2)2] (2), of the chiral Schiff base HL (HL = 4-methyl-2,6-bis-(1-phenyl-ethylimino)-methylphenol). The structures contain either in situ generated or externally added peripheral μ-nitrito groups, in κ(2)O/O and κ(2)N/O bridging modes. Four NO2(-) bridges in 1 and two AcO(-) co-ligands along with two NO2(-) bridges in 2 are essential for the stabilization of these tetranuclear aggregates.