Selective turn-on fluorescent probes for imaging hydrogen sulfide in living cells.

Hydrogen sulfide (H(2)S) is an important biological messenger but few biologically-compatible methods are available for its detection. Here we report two bright fluorescent probes that are selective for H(2)S over cysteine, glutathione and other reactive sulfur, nitrogen, and oxygen species. Both probes are demonstrated to detect H(2)S in live cells.

Bis{1,2-bis-[bis-(3-meth-oxy-prop-yl)phosphan-yl]ethane-κP,P'}dichlorido-osmium(II).

In the centrosymmetric title compound, [OsCl(2)(C(18)H(40)O(4)P(2))(2)], the Os(II) atom adopts a trans-OsCl(2)P(4) geometry, arising from its coordination by two chelating diphosphane ligands and two chloride ions. One of the meth-oxy side chains of the ligand is disordered over two orientations in a 0.700 (6):0.

Generation of metal nanoparticles from silver and copper objects: nanoparticle dynamics on surfaces and potential sources of nanoparticles in the environment.

The use of silver nanoparticles (AgNPs) in antimicrobial applications, including a wide range of consumer goods and apparel, has attracted attention because of the unknown health and environmental risks associated with these emerging materials. Of particular concern is whether there are new risks that are a direct consequence of their nanoscale size. Identifying those risks associated with nanoscale structure has been difficult due to the fundamental challenge of detecting and monitoring nanoparticles in products or the environment.

Anion-dependent fluorescence in bis(anilinoethynyl)pyridine derivatives: switchable ON-OFF and OFF-ON responses.

Urea and sulfonamide derivatives of 1 exhibit ON-OFF and OFF-ON switchable fluorescent and colorimetric responses upon protonation. The magnitude of the fluorescence event is dictated by the anion, resulting in a rare, fully organic "turn-on" fluorescent sensor for chloride.

The unique molecular behavior of water at the chloroform-water interface.

The molecular bonding and orientation of water at the chloroform-water interface has been examined in this study using vibrational sum-frequency spectroscopy (VSFS). The results provide a key puzzle piece towards our understanding of the systematic changes in the interfacial bonding and orientation of water that occur with variations in the polarity of the organic phase, especially when compared with previous studies of different liquid-liquid interfacial systems. In these VSFS studies the OH spectral responses of interfacial water molecules are used to characterize the interactions between water and the organic phase.

Arylethynyl receptors for neutral molecules and anions: emerging applications in cellular imaging.

This critical review will focus on the application of shape-persistent receptors for anions that derive their rigidity and optoelectronic properties from the inclusion of arylethynyl linkages. It will highlight a few of the design strategies involved in engineering selective and sensitive fluorescent probes and how arylacetylenes can offer a design pathway to some of the more desirable properties of a selective sensor. Additionally, knowledge gained in the study of these receptors in organic media often leads to improved receptor design and the production of chromogenic and fluorogenic probes capable of detecting specific substrates among the multitude of ions present in biological systems.

2,2'-(Propane-2,2-di-yl)dibenzothia-zole.

The two symmetry-independent mol-ecules in the asymmetric unit of the title compound, C(17)H(14)N(2)S(2), have similar geometry; the dihedral angles between the least-squares planes of the benzothia-zole groups in the two mol-ecules are 83.93 (3) and 81.26 (3)°.

trans-Bis{1,2-bis-[bis-(2-methoxy-ethyl)phosphino]ethane}dichloridoiron(II).

The Fe atom in the title compound, [FeCl(2)(C(14)H(32)O(4)P(2))(2)], has a distorted octa-hedral coordination with four P atoms in equatorial positions and two Cl atoms in apical positions.

Bis{1,2-bis-[bis-(3-hydroxy-prop-yl)phosphino]ethane}dichloridoiron(II).

In the title compound, [FeCl(2)(C(14)H(32)O(4)P(2))(2)], the Fe(II) atom (site symmetry ) adopts a distorted trans-FeCl(2)P(4) octa-hedral geometry with two P,P'-bidentate ligands in the equatorial positions and two chloride ions in the axial positions. In the crystal, mol-ecules are linked by O-H⋯O and O-H⋯Cl hydrogen bonds, generating a three-dimensional network.

Taming the highly reactive oxonium ion.

'Onium rings: Incorporation of the trivalent oxygen atom as a structural element within the tricyclic core of 1-3 imparts unprecedented stability to this "extraordinary" class of tertiary oxonium ions. Cation 1 is the least reactive and can be refluxed in water for 72 hours with no noticeable decomposition.

Tetra-carbonyl-bis(η-cyclo-penta-dienyl)bis[(dec-9-en-1-yl)diphenyl-phosphine]dimolybdenum(0)(Mo-Mo) tetra-hydro-furan disolvate.

The asymmetric unit of the title compound, [Mo(2)(η(5)-C(5)H(5))(2)(C(22)H(29)P)(2)(CO)(4)]·2C(4)H(8)O, contains two half-mol-ecules of the organometallic species and two solvent mol-ecules. Both organometallic mol-ecules are completed by crystallographic inversion symmetry, yielding dimeric units with Mo-Mo single-bond lengths of 3.2703 (6) and 3.

Synthesis and structure-property relationships of donor/acceptor-functionalized bis(dehydrobenzo[18]annuleno)benzenes.

Seven new bis(dehydrobenzo[18]annuleno)benzenes (bis[18]DBAs) functionalized with electron-donating dibutylamino groups and/or accepting nitro groups at various positions along the peripheries of the chromophores have been prepared. The effects of varying the donor/acceptor charge transfer pathways, chromophore lengths and molecular symmetries upon the optical band gaps are studied using UV-visible spectroscopy, and structure-property correlations are identified. It is found that bis[18]DBAs possessing donor-pi-donor and acceptor-pi-acceptor pathways exhibit the smallest band gaps, especially when an acceptor-pi-acceptor pathway is situated along the longest chromophore length in the molecule.

Di-μ(3)-oxido-di-μ(2)-oxido-tetra-oxido-bis-(1,1,2,2-tetra-methyl-ethylenedicyclo-penta-dien-yl)-dimolyb-denum(IV)-dimolybdenum(VI) hexa-hydrate.

The title compound, [Mo(4)(C(16)H(20))(2)O(8)]·6H(2)O, is a centrosymmetric ansa-molybdocene complex in which two dinuclear [C(2)Me(4)(η(5)-C(5)H(4))(2)]Mo(μ(2)-O)(2)MoO(2) units dimerize by forming two μ(3)-O bridges between three Mo atoms. The ansa-molybdocene [C(2)Me(4)(η(5)-C(5)H(4))(2)]Mo unit has a typical bent-sandwich metallocene structure with an inter-ring angle of 127.98 (8)°.

Tetracarbon-ylbis(η-cyclo-penta-dien-yl)bis(diphenyl-phosphine)dimolybdenum(Mo-Mo) hexane solvate.

The title compound, [Mo(2)(C(5)H(5))(2)(C(12)H(11)P)(2)(CO)(4)]·C(6)H(14), is a centrosymmetric Mo complex in which two Mo atoms are connected by an Mo-Mo bond [3.2072 (12) Å]. Each Mo atom is coordinated by an η(5)-cyclo-penta-dienyl ligand, two carbonyl ligands and a diphenyl-phosphine ligand in a piano-stool fashion.

(Ethane-1,2-di-yl)bis-[bis-(3-methoxy-prop-yl)methyl-phospho-nium] bis-(tetra-phenyl-borate) diethyl ether solvate.

In the course of substitution studies on the iron dihydrogen complex trans-[Fe(DMeOPrPE)(2)(H(2))H](BPh(4)) {DMeOPrPE = 1,2-bis-[bis-(methoxy-prop-yl)phosphino]ethane}, we discovered an unexpected transformation of the diphosphine ligand to a diphospho-nium dication without the use of any typical methyl-ating reagent. The P atoms in the dication of the title compound, C(20)H(46)O(4)P(2) (2+)·2C(24)H(20)B(-)·C(4)H(10)O, have a distorted tetra-hedral coordination with P-C(Me) distances of 1.791 (2) and 1.

Triammonium hexa-hydroxidoocta-deca-oxidohexa-molybdogallate(III) hepta-hydrate.

The title compound, (NH(4))(3)[GaMo(6)(OH)(6)O(18)]·7H(2)O, contains two centrosymmetric GaMo(6) B-type Anderson cluster units consisting of central GaO(6) octa-hedra surrounded by a hexa-gonal assembly of MoO(6) edge-sharing octa-hedra. Like other B-type Anderson clusters, where the central Mo atom is substituted with a di- or trivalent metal ion, the central six μ(3)-oxido bridges are protonated. The average Ga-O bond length is 1.

Effects of atmospherically important solvated ions on organic acid adsorption at the surface of aqueous solutions.

The effects of salts on the solubility of amphiphilic organic molecules are of importance to numerous atmospheric, environmental, and biological systems. A detailed picture of the influence of dissolved atmospheric salts, NaCl and Na(2)SO(4), on the adsorption of hexanoic acid at the vapor/water interface is developed using vibrational sum-frequency spectroscopy and surface tension measurements as a function of time, organic concentration, and solution pH. We have found that for hexanoic acid adsorption at the vapor/water interface, a fast initial adsorption is followed by two considerably slower processes: a reorientation of the polar headgroup and a restructuring of the headgroup solvation shell.

Nonlinear vibrational spectroscopic studies of the adsorption and speciation of nitric acid at the vapor/acid solution interface.

Nitric acid plays an important role in the heterogeneous chemistry of the atmosphere. Reactions involving HNO(3) at aqueous interfaces in the stratosphere and troposphere depend on the state of nitric acid at these surfaces. The vapor/liquid interface of HNO(3)-H2O binary solutions and HNO(3)-H(2)SO(4)-H2O ternary solutions are examined here using vibrational sum frequency spectroscopy (VSFS).

Alkanephosphonates on hafnium-modified gold: a new class of self-assembled organic monolayers.

A new method for assembling organic monolayers on gold is reported that employs hafnium ions as linkers between a phosphonate headgroup and the gold surface. Monolayers of octadecylphosphonic acid (ODPA) formed on gold substrates that had been pretreated with hafnium oxychloride are representative of this new class of organic thin films. The monolayers are dense enough to completely block assembly of alkanethiols and resist displacement by alkanethiols.

Inorganic metallodielectric materials fabricated using two single-step methods based on the Tollen's process.

Two methods for preparing polycrystalline silver shells on colloidal silica spheres are reported. These do not include the use of organic ligands or metal seeding steps and are based on the Tollen's process for silvering glass. Reaction parameters such as temperature and reactant concentrations are adjusted to slow the reaction kinetics, which we find leads to preferential silver growth on the spheres.

Differing adsorption behavior of environmentally important cyanophenol isomers at the air-water interface.

Vibrational sum-frequency spectroscopy and surface tensiometry have been used to study the adsorption of m- and p-cyanophenol at the air-water interface. Spectra of the cyano (CN) group under different polarization schemes are utilized to determine its hydrogen bonding environment and orientation. For both isomers, it is found that the cyano group is hydrogen bonded at the interface but that the CN orientation is independent of surface density.

Whole-molecule approach for determining orientation at isotropic surfaces by nonlinear vibrational spectroscopy.

Nonlinear vibrational spectroscopies such as visible-infrared sum-frequency spectroscopy may serve as powerful probes of interfacial structure. Obtaining quantitative orientation information, however, has been limited by the required knowledge of the corresponding molecular-level nonlinear optical properties. We provide a general scheme for calculating the vibrational hyperpolarizability of any infrared- and Raman-active mode, regardless of the molecular symmetry or complexity of the structure.