Dissection of bicapped octahedral copper hydride cluster to form two chiral tetrahedral copper hydride cluster series exhibiting auto deracemization and photoluminescence.

Three series of copper hydride clusters [Cu8H6L6]2+ (1), [Cu4HX2L4]+ where X- = Cl- (2a), Br- (2b), I- (2c), N3- (2d) and SCN- (2e), and [Cu4HX3L3] where X- = Br- (3b) and I- (3c) (L = 2-(diphenylphosphino)pyridine, dppy) were synthesized and characterized by single-crystal X-Ray crystallography and standard spectroscopic techniques. The metal core of 1, Cu8, can be described as a bicapped octahedron, while those of 2 and 3 series adopt tetrahedral structures. The hydride positions were deduced from difference electron density maps and corroborated by NMR and DFT calculations. For 1, there are two µ4-H-, one each in the two tetrahedral cavities of the two capping atoms and four µ3-H- on the six triangular faces around the waist of the octahedron. For [Cu4HX2L4]+ and [Cu4HX3L3] series, the single µ4-H- resides in the center of the Cu4 tetrahedron. It was found that these three series of copper clusters are intimately connected and can convert from one to another under specific reaction conditions. Their transformation pathways were investigated in detail. Spontaneous resolution to form optically pure enantiomeric single crystals was observed for [Cu4H(SCN)2L4]+ (2e) and [Cu4HBr3L3] (3b). Photoluminescence was observed for [Cu4HX2L4]+, as well as [Cu4HX3L3] with strong emissions from green to yellow regions.

Synthesis, Structures, and Photoluminescence of Elongated Face-Centered-Cubic Ag14 Clusters Containing Lipoic Acid and Its Amide Analogue.

Three face-centered-cubic (fcc) silver clusters-namely, [Ag14(LA)2(HLA)4(PPh3)8]2- (1), [Ag14(HLA)6(PPh3)8] (2), and [Ag14(NLA)6(PPh3)8] (3)-that are coprotected by lipoic acid (or its amide derivative) and phosphine ligands have been synthesized and structurally characterized (HLA = (±)-α-lipoic acid, LA = (±)-α-lipoate, and NLA = d,l-6,8-thioctamide). These clusters possess two superatomic electrons (the Jellium model), in harmony with a bonding octahedral Ag6 core capped with 8 Ag atoms. Alternatively, the metal framework of 1-3 can be described as adopting a face-centered cubic (fcc) structure elongated along one of the 3-fold axes. The 12 S atoms from the six bioligands bridge the 12 edges of the (fcc) cube, forming a distorted icosahedron. The counterions, solvent or guest molecules play an important role in dictating the crystal lattices of the products. This is the first report of atom-precise structures of Ag-lipoic acid (or its derivatives) clusters, paving the way for further study of structure-property relationships of these bioligand protected metal nanoclusters. Photoluminescence was observed for cluster 3 with complex temperature-dependent emission patterns and efficiencies.

Extensive Lepromatous Lymphadenitis Preceding Lesions on the Face and Earlobes: An Unusual Presentation of Leprosy in Singapore.

Leprosy is also known as Hansen disease, as in some countries the diagnosis of leprosy carries a negative stigma and patients fear being shunned as outcasts. Presently, leprosy is primarily limited to specific geographical regions in resource-poor countries. As a result, there is increased difficulty for the younger generation of physicians today to correctly identify leprosy due to a lack of exposure and a low-index of suspicion, particularly in developed countries. In this case, the indurated lesions over the face demonstrated a preference for the outer lateral aspects over the maxillary areas, the nose bridge, and the pinna of the ears consistent with the organism's preference for cooler regions of the body. This was also evident in the other skin lesions affecting the more acral regions of the limbs in the early stage of disease progression. There is a need to keep this infective condition as an alternate diagnosis to all unusual cutaneous lesions.

Crystal structure of poly[(N,N-di-methyl-acetamide-κO)(µ4-5-methyl-isophthalato-κ(5) O:O,O':O'':O''')manganese(II)].

The title compound, poly[(N,N-di-methyl-acetamide-κO)(µ4-5-methyl-isophthalato-κ(5) O,O':O',O'':O'')manganese(II)], [Mn(C9H6O4)(C3H7NO)] n , was obtained from a mixture containing MnCl2·4H2O and 5-methyl-isophthalic acid in N,N-di-methyl-acetamide solution. The Mn(2+) ion is coordinated by five O atoms from four bridging 5-methyl-isophthalate ligands and one O atom from one N,N-di-methyl-acetamide ligand, defining a considerably distorted coordination polyhedron with one very long Mn-O bond of 2.623 (2) Å. The Mn(2+) ions are joined by carboxyl-ate groups, forming rod-shaped secondary building units along the a axis. The rods are further connected by 5-methyl-isophthalate ligands to form the pcu (primitive cubic net) structure.

Crystallographic snapshots of the interplay between reactive guest and host molecules in a porous coordination polymer: stereochemical coupling and feedback mechanism of three photoactive centers triggered by UV-induced isomerization, dimerization, and polymerization reactions.

We carried out photopolymerization by [2 + 2] dimerization of a photoreactive guest molecule in the channels of a photoreactive porous coordination polymer. The photoreactions of the guest and two host ligands were monitored by single-crystal X-ray crystallography, providing snapshots of the interplay between the reactive centers. By correlating the structures of these three photocenters, a strong synergism was discovered among three reaction (quasi)equilibria and three types of photochemical reactions (isomerization, dimerization, and polymerization). This result indicates a strong coupling and feedback mechanism among the photocenters moderated by the coordination backbone.

Ring expansion of spiro-thiolactam in rhodamine scaffold: switching the recognition preference by adding one atom.

A new rhodamine spiro scaffold with a six-membered reactive ring was developed by inserting a nitrogen atom in the known probe rhodamine B spiro thiohydrazide, which switched the recognition preference of the probe from Hg(2+) to Cu(2+). This probe is shown to be an efficient "turn-on" fluorescent chemodosimeter for Cu(2+) in a neutral aqueous medium. Mechanism studies suggested that the probe opened its spiro-ring by a Cu(2+)-induced transformation of the cyclic thiosemicarbazide moiety to an isothiocyanate group.

A heptamethine cyanine-based colorimetric and ratiometric fluorescent chemosensor for the selective detection of Ag+ in an aqueous medium.

A highly selective and sensitive ratiometric fluorescent chemosensor for Ag(+) in aqueous solution was developed, in a linear range of 0.6 × 10(-7) to 50 × 10(-7) mol L(-1), based on a A-Ag(+)-A binding mode with a heptamethine cyanine motif containing one adenine moiety.

Diethyl 2-{4-diethyl-amino-2-[(dimethyl-carbamothio-yl)-oxy]benzyl-idene}malonate.

In the title compound, C(21)H(30)N(2)O(5)S, the plane of the dimeth-yl-thio-carbamic group makes a dihedral angle of 78.41 (7)° with the central benzene ring. One of the carbonyl groups in the α,ß-unsaturated malonate side chain makes a dihedral angle of 8.73 (10)° with the central benzene ring, while the other carbonyl group makes a dihedral angle of 81.52 (8)°.

Poly[tris-(2,5-dimethyl-benzene-1,4--dicarboxyl-ato)bis-(pyridine)trizinc(II)].

The asymmetric unit of the title polymeric compound, [Zn(3)(C(10)H(8)O(4))(3)(C(5)H(5)N)(2)](n) or [Zn(3)(dmbdc)(3)(py)(2)](n) (dmbdc = 2,5-dimethyl-benzene-dicarboxyl-ate; py = pyridine) contains two Zn(II) ions, one of which is located on an inversion centre, one and a half 2,5-dimethyl-benzene-dicarboxyl-ate ligands and one pyridine ligand. Each ZnO(6) octa-hedron is sandwiched between two ZnO(4)N square-pyramids, forming a trinuclear zinc secondary building unit (SBU); each SBU is further linked by six 2,5-dimethyl-benzene-dicarboxyl-ate ligands with six adjacent trinuclear zinc SBU's, forming a two-dimensional layer structure with a (3,6) net. One of the three zinc ions is octa-hedrally coordinated and the other two are square-pyramidally coordinated. The coordination modes for 2,5-dimethyl-benzene-dicarboxyl-ates are bis-(bidentate) or bidentate-tridentate.

Poly[[[aqua(2,2'-bipyridine-κN,N')zinc(II)]-µ-2-nitroterephthalato-κO:O] monohydrate].

In the title compound, {[Zn(C(8)H(3)NO(6))(C(10)H(8)N(2))(H(2)O)]·H(2)O}(n), the Zn(II) ion is square-pyramidally coordinated, and bridged by 2-nitro-terephthalate ligands, forming a chain running along [10]. Intra-molecular hydrogen bonds are formed between the coordinated water mol-ecules and the nitro O atoms. Adjacent chains are linked by hydrogen bonds between the coordinated water mol-ecules and the O atoms of the monodentate carboxyl groups.

10H-Phenothia-zine 5-oxide.

In the title compound, C(12)H(9)NOS, the sulfoxide O atom is disordered over two sites with occupancies of 0.907 (4) and 0.093 (4). The dihedral angle betweeen the two aromatic rings is 18.40 (14)°. Different types of supramolecular interactions including inter-molecular N-H⋯O hydrogen bonds and π-π contacts [centroid-centroid distances = 3.9096 (16) and 4.1423 (16) Å] between the aromatic rings of symmetry-related mol-ecules are observed in the crystal structure.

Topochemical limits for solid-state photoreactivity by fine tuning of the pi-pi interactions.

The limiting topochemical criteria for photodimerization were studied by modulation of the pi-pi stacking interactions between self-templating planar molecules with hydrogen bonding. The product yield and composition can be controlled predominantly by the distance between the reactive bonds.

Poly[(µ(2)-4,4'-bipyridine)bis-(µ(4)-5-tert-butyl-isophthalato)bis-(µ(3)-5-tert-butyl-isophthalato)di-µ(3)-hydroxido-penta-zinc(II)].

The asymmetric unit of the title compound, [Zn(5)(C(12)H(12)O(4))(4)(OH)(2)(C(10)H(8)N(2))](n), consists of three Zn(II) ions (one of which is located on a twofold rotation axis), two 5-tert-butyl-isophthalate ligands, one 4,4'-bipyridine ligand and one hydroxide group. The five Zn(II) ions form a penta-nuclear zinc cluster, which is further bridged by ten organic ligands, forming two-dimensional sheets. The central zinc ion of the cluster has site symmetry 2 and is octahedrally coordinated in a N(2)O(4) donor set, whereas the other four zinc atoms are tetrahedrally coordinated by four O atoms. The coordination modes for the 5-tert-butyl-isophthalates are bis-(bidentate) or bidentate-monodentate. Hydrogen bonds are formed between adjacent sheets through the hydroxide groups and the O atoms of the monodentate carboxyl-ate groups. The two tert-butyl groups are disordered over two positions with ratios of 0.64 (2):0.36 (2) and 0.85 (3):0.15 (3).

Fluorogenic and chromogenic rhodamine spirolactam based probe for nitric oxide by spiro ring opening reaction.

A new fluorogenic and chromogenic probe rhodamine B spirolactam (1) was developed that in aqueous solutions exhibited a highly selective and sensitive "turn-on" type spectral response toward NO detection following a NO-induced spiro-ring opening reaction in 1.

Bis[tetrakis(triphenylphosphine-kappaP)silver(I)] di-mutrifluoroacetato-kappa4O:O'-bis[bis(trifluoroacetato-kappaO)stannate(IV)].

The crystal structure of the title compound, [Ag(C18H15P)4]2[Sn2(CH3)4(CF3CO2)6], consists of discrete tetrahedral cations and trans-C2SnO4 octahedral dianions [C-Sn-C = 154.6 (2) degrees ]. The dianion lies about a center of inversion and the two Sn atoms are linked unevenly by the carboxylate unit [Sn-O = 2.291 (3) A and Sn <-- O = 2.818 (3) A].

Polymeric dihydroxydiphthalatotricobalt(II).

In the crystal structure of dihydroxydiphthalatotricobalt(II), [Co(3)(C(8)H(4)O(4))(2)(OH)(2)](n), two of the four independent Co atoms lie at special positions of site symmetry 2. The hydroxy groups link three Co atoms to form a pyramidal Co(3)O unit, and adjacent Co(3)O units are linked through the Co base atoms into a honeycomb layer motif. Each of the phthalate dianions uses the O atoms of one carboxyl group to bind to three Co atoms, the bonding mode giving rise to six-coordinate Co atoms.