Structural and supramolecular interactions of 2-aminothiazolium 3,5-dinitrobenzoate monohydrate.

The hydrated salt 2-aminothiazolium 3,5-dinitrobenzoate monohydrate, CHNS·CHNO·HO, was synthesized and its structure characterized with single-crystal X-ray diffraction and Hirshfeld surface analysis. In the crystal structure, proton transfer from the carboxylic acid group of the 3,5-dinitrobenzoic acid (DNBA) molecule to the thiazole N atom of the 2-aminothiazole (AT) molecule results in salt formation. The protonation is supported by a widened C-N(H)-C ring bond angle.

Xylylethynyl Titanocene with a Microsecond Emission Lifetime Photosensitizes Singlet-Oxygen Formation and Photon Upconversion.

Coordination complexes containing d metals with long-lived ligand-to-metal charge transfer (LMCT) excited states are promising candidates for use as photosensitizers. Previously, Cp*Ti(CPh)CuBr (where Cp* = pentamethylcyclopentadienyl and CPh = phenylethynyl) was reported to be emissive in THF solution at room temperature (RT) from an excited state with significant Cp*-to-Ti LMCT character (λ = 693 nm, τ = 0.18 μs).

Assessment of the structure-activity relationship of analogs of the enolase inhibitor HEX.

The pathogenic free-living amoeba causes primary amoebic meningoencephalitis (PAM), a highly fatal disease with limited treatment options, underscoring the urgent need for new therapeutics. Our previous studies identified (1-hydroxy-2-oxopiperidin-3-yl)phosphonic acid (HEX), an inhibitor of human enolase 2 (ENO2) involved in glucose metabolism, as a potent inhibitor of enolase (ENO) with potent amoebicidal activity. In this study, we explored the structure-activity relationship (SAR) of HEX by modifying its hydroxamate and phosphonate functional groups, as well as introducing steric alterations to generate new analogs.

Crystal engineering of a 1:1 5-fluoro-cytosine-4-hy-droxy-benzaldehyde cocrystal: insights from X-ray crystallography and Hirshfeld analysis.

The 1:1 cocrystal of 5-fluoro-cytosine (5FC) and 4-hy-droxy-benzaldehyde (4HB), CHFNO·CHO has been synthesized and its structure characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis. The compound crystallizes in the monoclinic 2/ space group. A robust supra-molecular architecture is stabilized by N-H⋯O, N-H⋯N, C-H⋯O and C-H⋯F hydrogen bonds, forming (8), (22), (32), and (34) ring motifs.

Diazacyclobutenes as Reactive Intermediates: The Cascade Cyclization of Thiolated Ene-ynes and Azodicarboxylates to Provide Tetrahydroindoles.

We describe a new one-pot synthesis to access richly functionalized tetrahydroindoles and related fused pyrroles. The key to this transformation is a robust cascade cyclization between ene-yne sulfides and azodicarboxylates involving diazacyclobutene formation primed for rapid electrocyclic ring opening to an α-iminothioimidate intermediate, followed by cyclization and aromatization to yield the -heterocycles in good yields. This tactic represents a significant departure from conventional approaches to the tetrahydroindole motif, which typically involve either staging the 140-year-old Paal-Knorr cyclization or leveraging transition metal catalysis.

Lanthanide-Germanate Adelite, Co(GeO)(OH) ( = La-Sm), with Edge-Sharing Octahedral Chains of Co Ions: Spin Frustration Expected to Form Cycloids.

A new series of 222 adelite-type Co(GeO)(OH) ( = La-Sm) single crystals were grown by a high-temperature, high-pressure hydrothermal method (650 °C and 100 MPa). Single-crystal diffraction refinements yielded chiral one-dimensional (1D) chains of Co along the axis with an average 2.98 Å separation between Co centers in the [CoO(OH)] ribbon chains.

Room Temperature Regioselective Debenzylative Cycloetherification Reaction.

A regio- and stereoselective debenzylative cycloetherification (DBCE) reaction of protected hexoses to form stereodefined hydroxylated tetrahydrofurans of synthetic utility has been investigated under very mild room temperature reaction conditions. This study revealed the potential application of the DBCE reaction of simple, abundant starting materials to access stereochemically rich tetrahydrofuran compounds under mild reaction conditions.

Facile interconversion of mesitylcopper into a CuMes-Cubis(amidinate) triangle and a tetracuprous Möbius strip.

A new flexible bis(amidine) ligand featuring two additional N-donor groups incorporates a defined [CuMesCu] fragment from mesitylcopper into a triangular cluster with a reactive organometallic coordination site. Subtle changes to the reaction protocol result in the formation of an intertwined tetracuprous arrangement that adopts the shape of a Möbius strip.

Synthesis, Structures, and Magnetic Investigations of Nickel Phosphates: Ni(PO)(OH), Ni(PO)(HPO)(OH), and NaNiPO Including Potential Haldane Behavior.

Three novel nickel-phosphate structures are reported, Ni(PO)(OH) (), Ni(PO)(HPO)(OH) (), and NaNiPO (). Each new system was prepared via a high-temperature hydrothermal synthesis at 600-650 °C. All three compounds are built of quasi-one-dimensional (quasi-1-D) Ni containing chains with varying phosphate bridging modes and were characterized by single crystal X-ray diffraction and magnetic susceptibility.

Cycloaddition of Phenyltriazolinedione with Carbazole-Alkynes and Yne-Carbamates to Access Diazacyclobutenes.

Previously, we described the synthesis of stable, bicyclic examples of the rather rare diazacyclobutene (DCB) motif by means of a cycloaddition between triazolinediones and electron-rich thiolated alkynes. Here, we report the investigation of the cycloaddition of triazolinediones with related electron-rich yne-carbamates and carbazole-alkynes. Bicyclic DCBs arising from yne-carbamates were isolated in 8-65% yield, while those arising from carbazole-alkynes were isolated in 28-59% yield.

Hydrogen-bonding interactions in 5-fluorocytosine-urea (2/1), 5-fluorocytosine-5-fluorocytosinium 3,5-dinitrosalicylate-water (2/1/1) and 2-amino-4-chloro-6-methylpyrimidine-6-chloronicotinic acid (1/1).

Three new compounds, namely, 5-fluorocytosine-urea (2/1), 2CHFNO·CHNO, (I), 5-fluorocytosine-5-fluorocytosinium 3,5-dinitrosalicylate-water (2/1/1), 2CHFNO·CHFNO·CHNO·HO, (II), and 2-amino-4-chloro-6-methylpyrimidine-6-chloronicotinic acid (1/1), CHClNO·CHClN, (III), have been synthesized and characterized by single-crystal X-ray diffraction. In compound (I), 5-fluorocytosine (5FC) molecules A and B form two different homosynthons [R(8) ring motif], one formed via N-H..

New Fluorine-Containing Diamine Monomers for Potentially Improved Polyimides.

Two new fluorine-containing diamine monomers were designed with the goal of reducing charge transfer complex (CTC) interactions between neighboring chains in polyimides (i.e., high transparency/low color) while hopefully maintaining the well-known thermal stability and flexibility generally associated with polyimides.

Design Strategies for Luminescent Titanocenes: Improving the Photoluminescence and Photostability of Arylethynyltitanocenes.

Complexes that undergo ligand-to-metal charge transfer (LMCT) to d metals are of interest as possible photocatalysts. CpTi(CPh) (where CPh = phenylethynyl) was reported to be weakly emissive in room-temperature (RT) fluid solution from its phenylethynyl-to-Ti LMCT state but readily photodecomposes. Coordination of CuX between the alkyne ligands to give CpTi(CPh)CuX (X = Cl, Br) has been shown to significantly increase the photostability, but such complexes are not emissive in RT solution.

Supramolecular interactions in some organic hydrated 2,4,6-triaminopyrimidinium carboxylate and sulfate salts.

Four salts, namely, 2,4,6-triaminopyrimidinium 6-chloronicotinate dihydrate, CHN·CHClNO·2HO, (I), 2,4,6-triaminopyrimidinediium pyridine-2,6-dicarboxylate dihydrate, CHN·CHNO·2HO, (II), 2,4,6-triaminopyrimidinediium sulfate monohydrate, CHN·SO·HO, (III), and 2,4,6-triaminopyrimidinium 3,5-dinitrobenzoate dihydrate, CHN·CHNO·2HO, (IV), were synthesized and characterized by X-ray diffraction techniques. Proton transfer from the corresponding acid to the pyrimidine base has occurred in all four crystal structures. Of the four salts, two [(I) and (IV)] exist as monoprotonated bases and two [(II) and (III)] exist as diprotonated bases.

Supramolecular interactions in salts/cocrystals involving pyrimidine derivatives of sulfonate/carboxylic acid.

The crystal structures of three compounds involving aminopyrimidine derivatives are reported, namely, 5-fluorocytosinium sulfanilate-5-fluorocytosine-4-azaniumylbenzene-1-sulfonate (1/1/1), CHFNO·CHNOS·CHFNO·CHNOS, I, 5-fluorocytosine-indole-3-propionic acid (1/1), CHFNO·CHNO, II, and 2,4,6-triaminopyrimidinium 3-nitrobenzoate, CHN·CHNO, III, which have been synthesized and characterized by single-crystal X-ray diffraction. In I, there are two 5-fluorocytosine (5FC) molecules (5FC-A and 5FC-B) in the asymmetric unit, with one of the protons disordered between them. 5FC-A and 5FC-B are linked by triple hydrogen bonds, generating two fused rings [two R(8) ring motifs].

A New Motif in Halogen Bonding: Cooperative Intermolecular S-Br⋅⋅⋅O, O⋅⋅⋅F, and F⋅⋅⋅F Associations in the Crystal Packing of α,ω-Di(sulfonyl bromide) Perfluoroalkanes.

We recently reported the first examples of S-Cl⋅⋅⋅O halogen bonding complemented by short F⋅⋅⋅F contacts between neighboring chains that resulted in stabilized crystals of ClSO (CF ) SO Cl and ClSO (CF ) SO Cl. More recently, other researchers studied our crystallographic data further using an Independent Gradient Model (IGM), and they suggested if one goes beyond IUPAC's proposed 'less than the sum of the van der Waals radii' criterion that even more noncovalent interactions between fluorine atoms on neighboring chains as well as Cl⋅⋅⋅Cl, Cl⋅⋅⋅S, O⋅⋅⋅F, and O⋅⋅⋅S attractive interactions can be found. With that said, we have prepared samples of the related BrSO (CF ) SO Br derivatives (where n=4, 6, 8, and others), which give rise to even stronger S-Br⋅⋅⋅O halogen bonding interactions complemented minimally by O⋅⋅⋅F and F⋅⋅⋅F intermolecular interactions as shown by X-ray crystallography and computational chemistry using IGM isosurface plots.

Halogen, chalcogen, and hydrogen bonding in organoiodine cocrystals of heterocyclic thiones: imidazolidine-2-thione, 2-mercaptobenzimidazole, 2-mercapto-5-methylbenzimidazole, 2-mercaptobenzoxazole, and 2-mercaptobenzothiazole.

Through the combination of heterocyclic thiones with variation in the identity of the heterocyclic elements, namely, imidazolidine-2-thione, 2-mercaptobenzimidazole, 2-mercapto-5-methylbenzimidazole, 2-mercaptobenzoxazole, and 2-mercaptobenzothiazole with the common halogen-bond donors 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene, 1,3,5-trifluorotriiodobenzene, and tetraiodoethylene, a series of 18 new crystalline structures were characterized. In most cases, N-H..

-(2,3,5,6-Tetrafluoropyridin-4-yl)formamide.

The title compound, CHFNO, displays amide bond lengths of 1.218 (3) Å and 1.366 (3) Å for the C=O and C-N bonds, respectively.

Bis[3,5-di-fluoro-2-(pyridin-2-yl)phen-yl](4,4'-di-meth-oxy-2,2'-bi-pyridine)-iridium(III) hexa-fluorido-phosphate.

The title cyclo-metalated distorted octa-hedral iridium complex, [Ir(CHFN)(CHNO)]PF, exhibits elongated Ir-N bonds to the dimeth-oxy bi-pyridine ligand [2.128 (3) and 2.136 (3) Å] where these nitro-gen atoms are to the Ir-C bonds of the two cyclo-metalating di-fluoro-phenyl-pyridine ligands.

Ln (SeO ) (SO )(H O) (Ln=Sm, Dy, Yb): A Mixed-Ligand Pathway to New Lanthanide(III) Multifunctional Materials Featuring Nonlinear Optical and Magnetic Anisotropy Properties.

Bottom-up assembly of optically nonlinear and magnetically anisotropic lanthanide materials involving precisely placed spin carriers and optimized metal-ligand coordination offers a potential route to developing electronic architectures for coherent radiation generation and spin-based technologies, but the chemical design historically has been extremely hard to achieve. To address this, we developed a worthwhile avenue for creating new noncentrosymmetric chiral Ln materials Ln (SeO ) (SO )(H O) (Ln=Sm, Dy, Yb) by mixed-ligand design. The materials exhibit phase-matching nonlinear optical responses, elucidating the feasibility of the heteroanionic strategy.

Role of the Trifluoropropynyl Ligand in Blue-Shifting Charge-Transfer States in Emissive Pt Diimine Complexes and an Investigation into the PMMA-Imposed Rigidoluminescence and Rigidochromism.

Square-planar Pt complexes are of interest as dopants for the emissive layer of organic light-emitting diodes. Herein, the photophysics of three Pt bipyridyl complexes with the strongly e withdrawing, high-field, 3,3,3-trifluoropropynyl ligand has been investigated. One complex, (phbpy)PtCCF (phbpy = 6-phenyl-2,2'-dipyridyl), has also been characterized by single-crystal X-ray diffraction.

Photochemistry and Photophysics of Charge-Transfer Excited States in Emissive / Heterobimetallic Titanocene Tweezer Complexes.

Transition-metal complexes that undergo ligand-to-metal charge transfer (LMCT) to metals are of interest as possible photocatalysts due to the lack of deactivating d-d states. Herein, the synthesis and characterization of nine titanocene complexes of the formula CpTi(CAr)·MX (where Ar = phenyl, dimethylaniline, or triphenylamine; and MX = CuCl, CuBr, or AgCl) are presented. Solid-state structural characterization demonstrates that MX coordinates to the alkyne tweezers and CuX coordination has a greater structural impact than AgCl.

The reaction of thiourea and 1,3-dimethylthiourea towards organoiodines: oxidative bond formation and halogen bonding.

By varying the halogen-bond-donor molecule, 11 new halogen-bonding cocrystals involving thiourea or 1,3-dimethylthiourea were obtained, namely, 1,3-dimethylthiourea-1,2-diiodo-3,4,5,6-tetrafluorobenzene (1/1), CFI·CHNS, 1, thiourea-1,3-diiodo-2,4,5,6-tetrafluorobenzene (1/1), CFI·CHNS, 2, 1,3-dimethylthiourea-1,3-diiodo-2,4,5,6-tetrafluorobenzene (1/1), CFI·CHNS, 3, 1,3-dimethylthiourea-1,3-diiodo-2,4,5,6-tetrafluorobenzene-methanol (1/1/1), CFI·CHNS·CHO, 4, 1,3-dimethylthiourea-1,3-diiodo-2,4,5,6-tetrafluorobenzene-ethanol (1/1/1), CFI·CHNS·CHO, 5, 1,3-dimethylthiourea-1,4-diiodo-2,3,5,6-tetrafluorobenzene (1/1), CFI·CHNS, 6, 1,3-dimethylthiourea-1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), CFI·CHNS, 7, 1,3-dimethylthiourea-1,1,2,2-tetraiodoethene (1/1), CHNS·CI, 8, [(dimethylamino)methylidene](1,2,2-triiodoethenyl)sulfonium iodide-1,1,2,2-tetraiodoethene-acetone (1/1/1), CHINS·I·CHO·CI, 9, 2-amino-4-methyl-1,3-thiazol-3-ium iodide-1,1,2,2-tetraiodoethene (2/3), 2CHNS·2I·3CI, 10, and 4,4-dimethyl-4H-1,3,5-thiadiazine-3,5-diium diiodide-1,1,2,2-tetraiodoethene (2/3), 2CHNS·4I·3CI, 11. When utilizing the common halogen-bond-donor molecules 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene, as well as 1,3,5-trifluoro-2,4,6-triiodobenzene, bifurcated I..