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Hydrolyses of chalcogenopyrylium dyes 1−9 give product distributions that are both heteroatom and oxygen dependent. Under anaerobic or aerobic conditions at pH 8, hydrolyses of dyes 1−4, which each contain a pyrylium ring, give 2-pentene-1,5-diones 10−13, respectively, in >90% yield from addition of hydroxide to the 2-position of the pyrylium ring followed by ring opening and tautomerization. Telluropyrylium dye 8 under anaerobic conditions over the pH range 6.9−11.0 gives a 1:1 mixture of telluropyranylidene aldehyde 14 and tris(telluropyranylidenemethyl)methane 15 derived from addition of hydroxide to the central carbon of the trimethine bridge. Under aerobic conditions, tellurophene 30(Te,Te) and trace amounts of telluropyranone 29 were also produced via oxidative mechanisms with relative yields of 30(Te,Te) increasing with pH over the pH range 6.9−11.0 and with oxygen concentration. Thiopyrylium dye 9, seleno-/thiopyrylium dye 5, selenopyrylium dye 6, and seleno-/telluropyrylium dye 7 gave hydrolysis ...

Chalcogenopyrylium monomethine dyes were prepared via condensation of a 4-methylchalcogenopyrylium compound with a chalcogenopyran-4-one bearing a 4-(diethoxyphosphoryl)phenyl substituent (or the phosphonic acid derivative). The dyes have absorbance maxima of 603–697 nm in the window where the solar spectrum is most intense. The dyes formed H-aggregates on TiO2, increasing the light-harvesting efficiency of the dyes. Shortcircuit photocurrent action spectra were acquired to evaluate the influence of dye structure on the photoelectrochemical performance.

The isoselenazolone (ISA) efficiently promotes bromolactonization of alkenoic acids, oxidation of secondary alcohols, as well as bromoesterification of alkenes and alkynes.Both processes proceed with good to high regio- and stereoselectivity.

The effect of a series of xerogel coatings modified with aminoalkyl/fluorocarbon/hydrocarbon groups on the adhesion of a new test species, the filamentous brown alga Ectocarpus crouaniorum, has been explored, and compared with the green alga Ulva linza. The results showed that E. crouaniorum adhered weakly to the less polar, low wettability coatings in the series, but stronger adhesion was shown on polar, higher surface energy coatings containing aminoalkyl groups. The results from a separate series of coatings tuned to have similar surface energies and polarities after immersion in artificial seawater (ASW), but widely different surface charges, demonstrated that surface charge was more important than surface energy and polarity in determining the adhesion strength of both E. crouaniorum and U. linza on xerogel coatings. No correlation was found between adhesion and contact angle hysteresis. X-ray photoelectron spectroscopy analysis of samples after immersion in ASW confirmed the presence of charged ammonium groups on the surface of the aminoalkylated coatings.

Dibromodiarylselenium(IV) species were efficient sources of positive bromine for bromolactonization of 4-pentenoic acid, bromocyclization of 4-penten-1-ol and 2-buten-1-ol, bromination of 1,3,5-trimethoxybenzene, and bromination of trans-stilbene and cyclohexene. These reactions were much slower than brominations with elemental bromine, and product distributions were brominating-agent dependent. Comparable reactions with the diphenylselenide−iodine complex were kinetically indistinguishable from reactions with elemental iodine. Diiododiaryltellurium(IV) species were efficient sources of positive iodine for iodolactonization of 4-pentenoic acid and for the iodocyclization of 4-penten-1-ol. The rates of iodolactonization decreased with increasing electron donation from substituents on the aryl groups. Dibromodiaryltellurium(IV) derivatives gave trace quantities of bromination products in reactions with olefinic substrates. However, diaryl tellurides gave debromination of erythro-1,2-dibromo-1,2-diphenyletha...

Isoselenazolones were synthesized by a copper-catalyzed Se-N bond forming reaction between 2-halobenzamides and selenium powder. The catalytic activity of the various isoselenazolones was studied in the bromolactonization of pent-4-enoic acid. Isoselenazolone 9 was studied as a catalyst in several reactions: the bromolactonization of a series of alkenoic acids with bromine or N-bromosuccinimide (NBS) in the presence of potassium carbonate as base, the bromoesterification of a series of alkenes using NBS and a variety of carboxylic acids, and the oxidation of secondary alcohols to ketones using bromine as an oxidizing reagent. Mechanistic details of the isoselenazolone-catalyzed bromination reaction were revealed by (77)Se NMR spectroscopic and ES-MS studies. The oxidative addition of bromine to the isoselenazolone gives the isoselenazolone(IV) dibromide, which could be responsible for the activation of bromine under the reaction conditions. Steric effects from an N-phenylethyl group on the amide of the isoselenazolone and electron-withdrawing fluoro substituents on the benzo fused-ring of the isoselenazolone appear to enhance the stability of the isoselenazolone as a catalyst for the bromination reaction.

The P-glycoprotein (P-gp, ABCB1) drug pump protects us from toxic compounds and confers multidrug resistance. Each of the homologous halves of P-gp is composed of a transmembrane domain (TMD) with 6 TM segments followed by a nucleotide-binding domain (NBD). The predicted drug- and ATP-binding sites reside at the interface between the TMDs and NBDs, respectively. Crystal structures and EM projection images suggest that the two halves of P-gp are separated by a central cavity that closes upon binding of nucleotide. Binding of drug substrates may induce further structural rearrangements because they stimulate ATPase activity. Here, we used disulfide cross-linking with short (8 Å) or long (22 Å) cross-linkers to identify domain-domain interactions that activate ATPase activity. It was found that cross-linking of cysteines that lie close to the LSGGQ (P517C) and Walker A (I1050C) sites of NBD1 and NBD2, respectively, as well as the cytoplasmic extensions of TM segments 3 (D177C or L175C) and 9 (N820C) with a short cross-linker activated ATPase activity over 10-fold. A pyrylium compound that inhibits ATPase activity blocked cross-linking at these sites. Cross-linking between the NBDs was not inhibited by tariquidar, a drug transport inhibitor that stimulates P-gp ATPase activity but is not transported. Cross-linking between extracellular cysteines (T333C/L975C) predicted to lock P-gp into a conformation that prevents close NBD association inhibited ATPase activity. The results suggest that trapping P-gp in a conformation in which the NBDs are closely associated likely mimics the structural rearrangements caused by binding of drug substrates that stimulate ATPase activity.

Twenty-seven chalcogenopyrylium derivatives varying in the heteroatom of the pyrylium core and substituents at the 2-, 4-, and 6-positions were examined for their effect on human MRP1-mediated uptake of tritiated estradiol glucuronide into inside-out membrane vesicles, their affinity for and ability to stimulate the ATPase activity of purified human P-glycoprotein (P-gp)-His(10), and their ability to promote uptake of calcein AM and vinblastine in multidrug-resistant cells. Differences in their effects on MRP1 and P-gp activity were noted, and a second set of thiopyrylium compounds with systematic substituent changes was examined to refine these differences further. Derivatives with tert-butyl substituents in the 2- and 6-positions had the lowest inhibitory activity toward both transporters. Derivatives with thioamide functionality in the 4-position were more active against MRP1 than derivatives with amide functionality. Conversely, derivatives with amide functionality in the 4-position were more active in P-gp than derivatives with thioamide functionality.

Twelve thiorhodamine derivatives have been examined for their ability to stimulate the ATPase activity of purified human P-glycoprotein (P-gp)-His(10), to promote uptake of calcein AM and vinblastine into multidrug-resistant, P-gp-overexpressing MDCKII-MDR1 cells, and for their rates of transport in monolayers of multidrug-resistant, P-gp-overexpressing MDCKII-MDR1 cells. The thiorhodamine derivatives have structural diversity from amide and thioamide functionality (N,N-diethyl and N-piperidyl) at the 5-position of a 2-thienyl substituent on the thiorhodamine core and from diversity at the 3-amino substituent with N,N-dimethylamino, fused azadecalin (julolidyl), and fused N-methylcyclohexylamine (half-julolidyl) substituents. The julolidyl and half-julolidyl derivatives were more effective inhibitors of P-gp than the dimethylamino analogues. Amide-containing derivatives were transported much more rapidly than thioamide-containing derivatives.

Four-component xerogel films consisting of 1 mole-% n-octadecyltrimethoxysilane (C18) and 50 mole-% tetraethoxysilane (TEOS) in combination with 1–24 mole-% tridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane (TDF) and 25–48 mole-% n-octyltriethoxysilane (C8) and a 1:49:50 mole-% C18/TDF/TEOS were prepared. Settlement of barnacle cyprids and removal of juvenile barnacles, settlement of zoospores of the alga Ulva linza, and strength of attachment of 7-day sporelings (young plants) of Ulva were compared amongst the xerogel formulations. Several of the xerogel formulations were comparable to poly(dimethylsiloxane) elastomer with respect to removal of juvenile barnacles and removal of sporeling biomass. The 1:4:45:50 and 1:14:35:50 C18/TDF/C8/TEOS xerogels displayed some phase segregation by atomic force microscopy (AFM) pre- and post-immersion in water. Imaging reflectance infrared microscopy showed the formation of islands of alkane-rich and perfluoroalkane-rich regions in these same xerogels both pre- and post-immersion in water. Surface energies were unchanged upon immersion in water for 48 h amongst the TDF-containing xerogel coatings. AFM measurements demonstrated that surface roughness on the 1:4:45:50 and 1:14:35:50 C18/TDF/C8/TEOS xerogel coatings decreased upon immersion in water.

T lymphocytes play a central role in many human immunologic disorders including both autoimmune and alloimmune diseases. In hematopoietic stem cell transplant (HSCT), acute graft-versus-host-disease (GVHD) is caused by an attack on the recipient's tissues from donor allogeneic T cells. Ex vivo application of phototherapy to selectively deplete GVHD-causing cells prior to transplant may prevent GVHD. However, none of the photosensitive agents in use today have demonstrated selectivity without significant toxicity occurring in resting cells. We have designed the first-in-class, novel photosensitizer 2-Se-Cl with the ability to accumulate in pathogenic T cells in proportion to degree of oxidative phosphorylation (OXPHOS). Unique to 2-Se-Cl is the ability to potently stimulate P-glycoprotein (P-pg). Enhanced P-gp activity promotes the efficient removal of photosensitizer not sequestered in mitochondria, and protects resting lymphocytes essential for antipathogen and antitumor responses. To confirm that 2-Se-Cl selectively depletes antigen-specific immune responses, human lymphocytes were cultured with staphylococcal enterotoxin B (SEB) for 72 hours. Cells were then pulsed with 2-Se-Cl and exposed to 5 J/cm2 of light, which resulted in the impedance of OXPHOS and induction of apoptosis in stimulated T cells. After photodepletion (PD), resting cells remained intact with the ability to respond to stimulation by Toxic Shock Syndrome Toxin-1 (TSST-1) but not SEB. To evaluate the selective depletion of alloimmune responses, a well-established complete mHC antigen-mismatched murine model of HSCT was employed. To prepare the PD - treated primed splenocytes, donor C57BL/6 splenocytes were cocultured for 5 days with irradiated Balb/c splenocytes, and then photodepleted. In vitro analysis of PD - treated primed splenocytes demonstrated selective depletion of antihost immune responses by CFSE dilution, with complete retention of third-party responses (C3H/HeJ mice). On the day of HSCT, recipient Balb/c mice were irradiated with 900 cGy, and received 5x106 T cell-depleted bone marrow cells accompanied by 5x106 PD - treated (treatment group) or untreated (control group) primed splenocytes, and then monitored for signs of GVHD according to an established mouse GVHD grading system. Five animals underwent HSCT in each group in 3 independent experiments. All mice died of acute GVHD after the addition of 5x106 untreated primed C57BL/6 cells at a median of 25 days after HSCT. In contrast, > 90% of mice that received the same number of PD - treated cells survived > 60 days without evidence of GVHD (see figure). Additionally, third-party C3H/Hej mice that received the same number of PD-treated cells died of GVHD, confirming the selective depletion of the alloimmune response for BalB/c by 2-Se-Cl. The high selectivity of this novel photosensitizer may have broad applications, including targeting the bioenergetics in alloimmune, autoimmune, and malignant T cells to provide alternative treatment options and improve clinical outcomes for patients with diseases such as GVHD, systemic lupus erythematosus, or peripheral T cell lymphoma. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

Oxygen responsive sensor platforms were fabricated by pin printing tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) ([Ru(dpp)(3)](2+)) doped sols onto wavelength tuned reflective Bragg gratings. In an epi-luminescence configuration, these Bragg gratings (Gr) were designed to selectively reflect the O(2) responsive [Ru(dpp)(3)](2+) emission toward the detector to enhance the detected signal magnitude. The xerogel based sensors were formed onto (i) glass (XGl), (ii) directly on top of the grating (XGrGl), or (iii) on the glass substrate opposite the grating (XGlGr). The results show that all sensors exhibit linear, statistically equivalent O(2) sensitivities, and the XGrGl platform yields up to an 8-fold increase in relative detected analytical signal (RDAS) in comparison to the control (XGl) platform.

Biological and biochemical studies of inorganic and organic complexes of tellurium are reviewed. Subject areas include the biosequestration and bioincorporation of tellurite and other inorganic tellurium compounds as well as tellurite-resistant bacteria. The incorporation of tellurium into amino acids (tellurocysteine) and the formation of unnatural glutathione peroxidases and thioredoxin reductases incorporating tellurocysteine are also described. Low molecular weight organotellurium compounds that mimic glutathione peroxidase and the thioredoxin reductases are discussed as are inorganic and organic tellurium compounds that inhibit cysteine proteases and related enzymes. The interactions of P-glycoprotein with organotellurium compounds to give stimulators and inhibitors of ATPase activity in the enzyme are described. The role of tellurium-containing chromophores in the photodynamic therapy of cancer and the photodynamic inactivation of viral and bacterial pathogens is also reviewed. The binding modes of tellurium-containing chromophores to DNA are also described. Keywords: tellurite; organotellurides; diorgano ditellurides; inorganic tellurium complexes; glutathione peroxidase; thioredoxin reductase; tellurocysteine; P-glycoprotein; photodynamic therapy; anti-microbial activity

Mixtures of n-octadecyltrimethoxysilane (C18, 1-5 mole-%), n-octyltriethoxysilane (C8) and tetraethoxysilane (TEOS) gave xerogel surfaces of varying topography. The 1:49:50 C18/C8/TEOS xerogel formed 100-400-nm-wide, 2-7-nm deep pores by AFM while coatings with ≥3% C18 were free of such features. Segregation of the coating into alkane-rich and alkane-deficient regions in the 1:49:50 C18/C8/TEOS xerogel was observed by IR microscopy. Immersion in ASW for 48 h gave no statistical difference in surface energy for the 1:49:50 C18/C8/TEOS xerogel and a significant increase for the 50:50 C8/TEOS xerogel. Settlement of barnacle cyprids and removal of juvenile barnacles, settlement of zoospores of the alga Ulva linza, and strength of attachment of 7-day sporelings were compared amongst the xerogel formulations. Settlement of barnacle cyprids was significantly lower in comparison to glass and polystyrene standards. The 1:49:50 and 3:47:50 C18/C8/TEOS xerogels were comparable to PDMSE with respect to removal of juvenile barnacles and sporeling biomass, respectively.

Rhodamine photosensitizers (PSs) substituting S or Se for O in the xanthene ring give turnover numbers (TONs) as high as 9000 for the generation of hydrogen via the reduction of water using [Co(III)(dmgH)(2)(py)Cl] (where dmgH = dimethylglyoximate and py = pyridine) as the catalyst and triethanolamine as the sacrificial electron donor. The turnover frequencies were 0, 1700, and 5500 mol H(2)/mol PS/h for O, S, and Se derivatives, respectively (Φ(H(2)) = 0%, 12.2%, and 32.8%, respectively), which correlates well with relative triplet yields estimated from quantum yields for singlet oxygen generation. Phosphorescence from the excited PS was quenched by the sacrificial electron donor. Fluorescence lifetimes were similar for the O- and S-containing rhodamines (∼2.6 ns) and shorter for the Se analog (∼0.1 ns). These data suggest a reaction pathway involving reductive quenching of the triplet excited state of the PS giving the reduced PS(-) that then transfers an electron to the Co catalyst. The longer-lived triplet state is necessary for effective bimolecular electron transfer. While the cobalt/rhodamine/triethanolamine system gives unprecedented yields of hydrogen for the photoreduction of water, mechanistic insights regarding the overall reaction pathway as well as system degradation offer significant guidance to developing even more stable and efficient photocatalytic systems.

The large rate of intersystem crossing between singlet and triplet states of tellurapyrylium dyes leads to efficient generation of singlet oxygen in irradiated airsaturated aqueous solutions containing these dyes. One reaction of tellurapyrylium dyes with singlet oxygen and water is the formation of dihydroxy tellurane [tellurium(IV)] species. We have found that the photochemical generation of dihydroxy telluranes is reversible thermally. The tellurapyrylium dye is regenerated while a molecule of hydrogen peroxide is produced. The thermal generation of hydrogen peroxide coupled with a photochemical generation of singlet oxygen allows a catalytic cycle to be devised for the conversion of oxygen and water to hydrogen peroxide. The dihydroxy telluranes are efficient two-electron oxidizing agents and can be used as catalysts to accelerate reactions using hydrogen peroxide as a two-electron oxidizing agent. Examples of tellurapyrylium dye-mediated reactions of hydrogen peroxide include reactions of le...

Intramolecular acylation of Z-3-(3-hydroxyphenyltelluro)propenoic acids 9 with P2O5/CH3SO3H gave 4H-7-hydroxybenzo[b]tellurin-4-ones 10a−c in 42%, 25%, and 20% isolated yields, respectively. 4H-7-Hydroxybenzo[b]tellurin-4-ones 10a−d were also prepared by demethylation of 4H-7-methoxybenzo[b]tellurin-4-ones 11 with BBr3 in CH2Cl2 in 88%, 70%, 66%, and 78% isolated yields.

Asymmetric synthesis of (3S,4S)-3-phenylsulfonyl-4-phenylazetidin-2-ones in up to 46% ee from achiral amines and 2-phenylsulfonyl-3-phenylpropenoyl chloride was achieved with chiral Lewis-acid catalysis by salen-copper(II) complexes derived from (1R,2R)-(−)-1,2-diaminocyclohexane. The absolute configuration was assigned by single crystal, X-ray crystallographic analysis of enantiomerically pure (3S,4S)-(−)-3-phenylsulfonyl-4-phenylazetidin-2-one (7).

Enol ethers 9 are formed as a mixture of E- and Z-isomers from the addition of ethanol to 1,4-pentadiyn-3-ones 2 in sodium ethoxide/ethanol. The enol ethers react with disodium chalcogenides to give the corresponding 2,6-disubstituted chalcogenopyranones 1 bearing alkyl, aryl, or heteroaryl substituents in high yield as the only heterocyclic product of reaction. Diynones 2 react with disodium chalcogenides to give mixtures of products in which the chalcogenopyranones 1 are minor components and the dihydrochalcogenophenes 3 are the major products. The addition of hydrogen sulfide to diynone 2b in ethanol gives a product mixture nearly identical to that observed for the addition of disodium sulfide in sodium ethoxide in ethanol to 2b. Intermediates for the addition of hydrogen chalcogenides and disodium chalcogenides to both 2 and 9 are described, which lead to the heterocyclic products.

Novel rhodamine dyes were prepared from xanthone precursors in a 'one-pot' procedure via reaction of the xanthone with trifluoromethanesulfonic anhydride followed by Pd-mediated Suzuki coupling between the xanthone triflate and an arylboroxin. Rhodamines with 9-(3- or 4-carboxyphenyl) and 9-(3-nitrophenyl) substituents were prepared by this procedure. The procedure also works well with thio- and selenoxanthones, but not with telluroxanthones.

The large rate of intersystem crossing between singlet and triplet states of tellurapyrylium dyes leads to efficient generation of singlet oxygen in irradiated airsaturated aqueous solutions containing these dyes. One reaction of tellurapyrylium dyes with singlet oxygen and water is the formation of dihydroxy tellurane [tellurium(IV)] species. We have found that the photochemical generation of dihydroxy telluranes is reversible thermally. The tellurapyrylium dye is regenerated while a molecule of hydrogen peroxide is produced. The thermal generation of hydrogen peroxide coupled with a photochemical generation of singlet oxygen allows a catalytic cycle to be devised for the conversion of oxygen and water to hydrogen peroxide. The dihydroxy telluranes are efficient two-electron oxidizing agents and can be used as catalysts to accelerate reactions using hydrogen peroxide as a two-electron oxidizing agent. Examples of tellurapyrylium dye-mediated reactions of hydrogen peroxide include reactions of le...

Various 1-[[bis(1-methylethyl)amino]carbonyl]-2-(dibromo-n-alkylseleno)ferrocene derivatives reacted with 2 equiv of 4-pentenoic acid or 5-hexenoic acid to give the corresponding γ- or δ-lactones, respectively, from transfer of the alkyl group bound to selenium to the terminal alkene carbon. In the lactone cyclization, 1-[[bis(1-methylethyl)amino]carbonyl]-2-(bromoselenenyl)ferrocene (25) is formed and reacts with a second equivalent of the alkenoic acid to give either 5-[1-[[bis(1-methylethyl)amino]carbonyl]ferrocene-2-selenenylmethyl]tetrahydro-2-furanone (23) or 6-[1-[[bis(1-methylethyl)amino]carbonyl]ferrocene-2-selenenylmethyl]tetrahydro-2H-pyran-2-one (26) as a mixture of diastereomers in yields comparable to the corresponding γ- or δ-lactone. The addition of 1-[[bis(1-methylethyl)amino]carbonyl]-2-(dibromo-n-butylseleno)ferrocene to 3-butenoic acid gave alkyl transfer to the internal alkene carbon and formation of the γ-lactone. Density functional theory (DFT) geometry optimizations were performed ...