1-Phenyl-isatin.

In the title compound, C(14)H(9)NO(2), the phenyl ring makes a dihedral angle of 50.59 (5)° with the mean plane of the isatin fragment. In the crystal, mol-ecules are linked through weak inter-molecular C-H⋯O hydrogen bonds. The crystal structure also exhibits two slipped π-π inter-actions between the benzene rings of neighbouring mol-ecules [centroid-centroid distance = 3.968 (3) Å, inter-planar distance = 3.484 (3) Šand slippage = 1.899 (3) Å], and between the phenyl rings of neighbouring mol-ecules [centroid-centroid distance = 3.968 (3) Å, inter-planar distance = 3.638 (3) Šand slippage = 1.584 (3) Å].

Photophysical properties of the series fac- and mer-(1-phenylisoquinolinato-N∧C2')(x)(2-phenylpyridinato-N∧C2')(3-x)iridium(III) (x = 1-3).

The photophysical properties of tris-cyclometalated iridium(III) complexes have been probed by chemical and geometric variation through the series fac- and mer-Ir(piq)(x)(ppy)(3-x) (x = 1-3; piq = 1-phenylisoquinolinato-N(∧)C(2'), ppy = 2-phenylpyridinato-N(∧)C(2')). The phosphorescent decays were recorded in solution at 295 K and in polymer films from 2 to 295 K. In the heteroleptic complexes, emission occurs based solely on the piq ligand(s), at least by the nanosecond time scale, as its excited states are the lowest energy. Because fac-Ir(piq)(3) and fac-Ir(ppy)(3) possess practically the same oxidation potential, comparison of photophysical properties through the series fac-Ir(piq)(x)(ppy)(3-x) (x = 1-3) revealed the effects of having one, two, or three emissive piq ligands with no confounding effects from differences in electron withdrawing or donating properties between the spectator ppy ligands and the piq ligands. Effects of placement of piq ligands in different coordination geometries were elucidated by comparisons to the mer series.

Coumarin-based, electron-trapping iridium complexes as highly efficient and stable phosphorescent emitters for organic light-emitting diodes.

A new class of coumarin-based iridium tris-cyclometalated complexes has been developed. These complexes are highly emissive, with emission colors ranging from green to orange-red. Besides modification of ligand structures, color tuning was realized by incorporation of ligands with different electrochemical properties in a heteroleptic structure. The organic light-emitting diodes (OLEDs) using these compounds as emissive dopants are highly efficient and stable. Unlike other Ir(III) phosphorescent dopants, these coumarin-based Ir(III) dopants can effectively trap and transport electrons in the emissive layer.

Non-blinking semiconductor nanocrystals.

The photoluminescence from a variety of individual molecules and nanometre-sized crystallites is defined by large intensity fluctuations, known as 'blinking', whereby their photoluminescence turns 'on' and 'off' intermittently, even under continuous photoexcitation. For semiconductor nanocrystals, it was originally proposed that these 'off' periods corresponded to a nanocrystal with an extra charge. A charged nanocrystal could have its photoluminescence temporarily quenched owing to the high efficiency of non-radiative (for example, Auger) recombination processes between the extra charge and a subsequently excited electron-hole pair; photoluminescence would resume only after the nanocrystal becomes neutralized again. Despite over a decade of research, completely non-blinking nanocrystals have not been synthesized and an understanding of the blinking phenomenon remains elusive. Here we report ternary core/shell CdZnSe/ZnSe semiconductor nanocrystals that individually exhibit continuous, non-blinking photoluminescence. Unexpectedly, these nanocrystals strongly photoluminesce despite being charged, as indicated by a multi-peaked photoluminescence spectral shape and short lifetime. To model the unusual photoluminescence properties of the CdZnSe/ZnSe nanocrystals, we softened the abrupt confinement potential of a typical core/shell nanocrystal, suggesting that the structure is a radially graded alloy of CdZnSe into ZnSe. As photoluminescence blinking severely limits the usefulness of nanocrystals in applications requiring a continuous output of single photons, these non-blinking nanocrystals may enable substantial advances in fields ranging from single-molecule biological labelling to low-threshold lasers.

Structure and conformation of 1-beta-D-ribo furanosyl pyridin-2-one-5-carboxamide: an anti-inflammatory agent.

The pyrimidine nucleoside, 1-beta-D-ribofuranosyl pyridine-2-one-5-carboxamide, is an anti inflammatory agent used in the treatment of adjuvant-induced arthritis. It is the 2-one isomer of 1-beta-D-ribofuranosyl pyridine-4-one 5-carboxamide, an unusual nucleoside isolated from the urine of patients with chronic myelogenic leukemia and an important cancer marker. Crystals of 1-beta-D-ribofuranosyl pyridine-2-one-5-carboxamide are monoclinic, space group C2, with the cell dimensions a = 31.7920(13), b = 4.6872 (3), c = 16.1838(11), beta = 93.071(3) degrees , V = 2408.2(2) A(3), D(calc) = 1.496 mg/m(3) and Z = 8 (two molecules in the asymmetric unit). The structure was obtained by the application of direct methods to diffractometric data and refined to a final R value of 0.050 for 1669 reflections with I >or= 3sigma. The nucleoside exhibits an anti conformation across the glycosidic bond (chi(CN) = -15.5 degrees , -18.9 degrees ), a C3 '-endo C2 '-exo [(3)(2)T] ribose pucker and g(+) across the C(4 ')-C(5 ') exocyclic bond. The amino group of the carboxamide group is distal from the 2-one and lacks the intramolecular hydrogen bonding found in the related 2-one molecule. Nuclear magnetic resonance studies shows also an anti conformation across the glycosidic bond but the solution conformation of the furanose ring is not the same as that found in the solid state.

N,N'-Dicyclo-hexyl-naphthalene-1,8;4:5-dicarboximide.

The title compound, C(26)H(26)N(2)O(4), synthesized by the reaction of naphthalene-1,4,5,8-tetra-carboxylic acid anhydride and cyclo-hexyl-amine, exhibits good n-type semiconducting properties. Accordingly, thin-film transistor devices comprising this compound show n-type behavior with high field-effect electron moblity ca 6 cm(2)/Vs [Shukla, Nelson, Freeman, Rajeswaran, Ahearn, Meyer & Carey(2008 ▶). Chem. Mater. Submitted]. The asymmetric unit comprises one-quarter of the centrosymmetric mol-ecule in which all but two methyl-ene C atoms of the cyclo-hexane ring lie on a mirror plane; the point-group symmetry is 2/m. The naphthalene-diimide unit is strictly planar, and the cyclo-hexane rings adopt chair conformations with the diimide unit in an equatorial position on each ring.

N,N'-Bis(2,2,3,3,4,4,4-hepta-fluoro-butyl)naphthalene-1,4:5,8-tetra-carboximide.

The title mol-ecule, C(22)H(8)F(14)N(2)O(4), lies across a crystallographic inversion center with the naphthalene diimide core essentially planar (mean deviation from plane is 0.0583 Å). The CF(2) groups in the perfluorobutyl chains are in an energetically favorable all trans conformation. In the crystal structure, mol-ecules are packed in slightly displaced layers so that the side chains overlap the aromatic naphthalene diimide rings, thus minimizing any possible π-π overlap.

Highly efficient, selective, and general method for the preparation of meridional homo- and heteroleptic tris-cyclometalated iridium complexes.

A highly efficient and general method based on transmetalation with an organozinc reagent is developed for selective preparation of homo- and heteroleptic meridional tris-cyclometalated iridium complexes. The molecular structure of mer-Ir(1-piq)2(ppy) (2) has been determined by a single-crystal X-ray diffraction analysis. The emission properties of a series of meridional complexes are reported.

Crystal and molecular structure and absolute configuration of lincomycin hydrochloride monohydrate.

Lincomycin is a broad-spectrum antibiotic synthesized by Streptomyces lincolnensis that is particularly active against Gram-positive bacteria. It is widely used in human and veterinary applications. The crystal structure of lincomycin has been undertaken with a view to obtain the conformational and structural features of the drug in order to afford a comparison of its structural features with other aminoglycoside antibiotics. We report here the details of its structural and conformational features as determined by single-crystal X-ray crystallography. Crystals of lincomycin hydrochloride are orthorhombic, space group P2(1)2(1)2, with the cell dimensions a=18.5294(3) Angstroms, b=20.5980(4) Angstroms, c=6.17380(10) Angstroms, V=2356.35(7) Angstroms3. The structure was solved using X-ray diffraction data and refined to a final R-value of 0.0391 for 2321 reflections (I > or = 2sigma). The absolute configuration was established using the anomalous dispersion of the sulfur and chlorine atoms in the structure. The molecule consists of an amino acid linked by an amide group to a monosaccharide of galactose stereochemistry. A network of hydrogen-bonds stabilizes the crystal structure.

Three-dimensional structure determination of N-(p-Tolyl)-dodecylsulfonamide from powder diffraction data and validation of structure using solid-state NMR spectroscopy.

The three-dimensional structure, conformation, and packing of molecules in the solid state are crucial components used in the optimization of many technologically useful materials properties. Single-crystal X-ray diffraction is the traditional and most effective method of determining 3-D structures in the solid state. Obtaining single crystals that are sufficiently large and free of imperfections is often laborious, time-consuming, and, occasionally, impossible. The feasibility of an integrated approach to the determination and verification of a complete three-dimensional structure for a medium-sized organic molecule without using single crystals is demonstrated for the case of an organic stabilizer compound N-(p-tolyl)-dodecylsulfonamide. The approach uses a combination of powder XRD data, several computational packages involving Monte Carlo simulations and ab initio quantum mechanical calculations, and experimental solid-state NMR chemical shifts. Structure elucidation of N-(p-tolyl)-dodecylsulfonamide revealed that the Bravais lattice is monoclinic, with cell dimensions of a = 38.773 A, b = 5.507 A, c = 9.509 A, and beta = 86.35 degrees, and a space group of P21/c.