The Interplay of Strongly and Weakly Exchange-Coupled Triplet Pairs in Intramolecular Singlet Fission.

Singlet fission (SF) and triplet-triplet annihilation upconversion (TTA-UC) nominally enable the interconversion of higher-energy singlet states with two lower-energy triplet states and vice versa, with both processes having envisaged application for enhanced solar power devices. The mechanism of SF/TTA-UC involves a complex array of different multiexcitonic triplet-pair states that are coupled by the exchange interaction to varying extents. In this work a family of bounded intramolecular SF materials, based upon the chromophore 1,6-diphenyl-1,3,5-hexatriene, were designed and synthesized.

Structure-Property Relationships for Potential Inversion From Electron Acceptors Based on Thiophene-Fused Triptycene Quinones, 1,4-Diketones and Their Malononitrile Adducts.

The synthesis and properties of a series of 11,11,12,12-tetracyano-9,10-anthraquinodimethane (TCAQ) inspired electron acceptors based on thiophene-fused quinone and triptycene motifs is presented. This has yielded insights into structure-property relationships for establishing and modulating simultaneous two-electron reduction processes in TCAQ analogues. These new compounds were synthesised using a Friedel-Crafts acylation between triptycene and thiophene-3,4-dicarbonyl chloride.

Suppression of Dexter transfer by covalent encapsulation for efficient matrix-free narrowband deep blue hyperfluorescent OLEDs.

Hyperfluorescence shows great promise for the next generation of commercially feasible blue organic light-emitting diodes, for which eliminating the Dexter transfer to terminal emitter triplet states is key to efficiency and stability. Current devices rely on high-gap matrices to prevent Dexter transfer, which unfortunately leads to overly complex devices from a fabrication standpoint. Here we introduce a molecular design where ultranarrowband blue emitters are covalently encapsulated by insulating alkylene straps.

Synthesis and intramolecular singlet fission properties of -phenylene linked oligomers of diphenylhexatriene.

In molecular dimers that undergo intramolecular singlet fission (iSF), efficient iSF is typically accompanied by triplet pair annihilation at rates which prohibit effective triplet harvesting. Collisional triplet pair separation and intramolecular separation by hopping to additional sites in extended oligomers are both strategies that have been reported to be effective for acene based iSF materials in the literature. Herein, a family of highly soluble diphenylhexatriene (DPH) oligomers were synthesized and investigated using transient absorption spectroscopy to determine whether these approaches can be applied to the non-acene singlet fission chromophore, DPH.

A short-term comparison of wheat straw and poplar wood chips used as litter in tiestalls on hygiene, milk, and behavior of lactating dairy cows.

A short-term study was conducted to compare the effect of using poplar wood chips (PWC) instead of wheat straw (WS) litter in dairy cows. A total of 38 lactating Holstein cows (204 ± 119 days in milk, 26.9 ± 6.

Generating Long-Lived Triplet Excited States in Narrow Bandgap Conjugated Polymers.

Narrow bandgap conjugated polymers are a heavily studied class of organic semiconductors, but their excited states usually have a very short lifetime, limiting their scope for applications. One approach to overcome the short lifetime is to populate long-lived triplet states for which relaxation to the ground state is forbidden. However, the triplet lifetime of narrow bandgap polymer films is typically limited to a few microseconds.

Soluble Diphenylhexatriene Dimers for Intramolecular Singlet Fission with High Triplet Energy.

Intramolecular singlet fission (iSF) facilitates single-molecule exciton multiplication, converting an excited singlet state to a pair of triplet states within a single molecule. A critical parameter in determining the feasibility of SF-enhanced photovoltaic designs is the triplet energy; many existing iSF materials have triplet energies too low for efficient transfer to silicon via a photon multiplier scheme. In this work, a series of six novel dimers based upon the high-triplet-energy, SF-active chromophore, 1,6-diphenyl-1,3,5-hexatriene (DPH) [(T) ∼ 1.

Quantitative Singlet Fission in Solution-Processable Dithienohexatrienes.

Singlet fission (SF) is a promising strategy to overcome thermalization losses and enhance the efficiency of single junction photovoltaics (PVs). The development of this field has been strongly material-limited, with a paucity of materials able to undergo SF. Rarer still are examples that can produce excitons of sufficient energy to be coupled to silicon PVs (>1.

Conformational Dependence of Triplet Energies in Rotationally Hindered N- and S-Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials.

A series of four heterocyclic dimers has been synthesized, with twisted geometries imposed across the central linking bond by ortho-alkoxy chains. These include two isomeric bicarbazoles, a bis(dibenzothiophene-S,S-dioxide) and a bis(thioxanthene-S,S-dioxide). Spectroscopic and electrochemical methods, supported by density functional theory, have given detailed insights into how para- vs.

Implementation of Individual Placement and Support in Italy: The Reggio Emilia Experience.

Individual placement and support (IPS) is an evidence-based intervention helping people with mental illness to obtain competitive jobs. In the last decade, European mental health leaders were interested on its implementation. Aim of the study was to assess the IPS feasibility in Italian patients with moderate-to-severe mental illness.

Harnessing Applied Potential: Selective β-Hydrocarboxylation of Substituted Olefins.

The construction of carboxylic acid compounds in a selective fashion from low value materials such as alkenes remains a long-standing challenge to synthetic chemists. In particular, β-addition to styrenes is underdeveloped. Herein we report a new electrosynthetic approach to the selective hydrocarboxylation of alkenes that overcomes the limitations of current transition metal and photochemical approaches.

Individual placement and support in Italian young adults with mental disorder: Findings from the Reggio Emilia experience.

Aim: Individual placement and support (IPS) has a considerable body of evidence for its effectiveness in helping people with mental disorder to achieve and maintain competitive jobs. However, little data in young adult populations are currently available, especially in Europe. Aim of this study was to assess the effect of IPS in Italian young adults with moderate-to-severe mental illness, examining the main competitive employment outcomes and drop out rates during a 3-year follow-up period.

Red-shifted delayed fluorescence at the expense of photoluminescence quantum efficiency - an intramolecular charge-transfer molecule based on a benzodithiophene-4,8-dione acceptor.

Employing the thiophene based quinone, benzo[1,2-b:4,5-b']dithiophene-4,8-dione, as the electron-accepting moiety alongside N-phenylcarbazole donors to produce a donor-π-acceptor-π-donor (D-π-A-π-D) molecule has yielded a new red emitter displaying delayed fluorescence. This new molecule shows strongly (over 100 nm) red-shifted emission when compared to an anthraquinone based analogue. Cyclic voltammetry complemented by computational insights prove that this red-shift is due to the significantly stronger electron-accepting ability of the thiophene quinone compared to anthraquinone.

Synthesis of Tetracyclic 2,3-Dihydro-1,3-diazepines from a Dinitrodibenzothiophene Derivative.

Triply fused 1,3-diazepine derivatives have been obtained by acidic reduction of rotationally locked and sterically hindered nitro groups in the presence of an aldehyde or ketone. The nitro groups are sited on adjacent rings of a dicyanodibenzothiophene-5,5-dioxide, which also displays fully reversible two-electron-accepting behavior. The synthesis, crystallographically determined molecular structures, and aspects of the electronic properties of these new molecules are presented.

Studies on DNA interaction of organotin(IV) complexes of meso-tetra(4-sulfonatophenyl)porphine that show cellular activity.

The interaction of the diorgano- and triorganotin(IV) derivatives of meso-tetra-(4-sulfonatophenyl)porphine (MeSn)TPPS, (BuSn)TPPS, (MeSn)TPPS and (BuSn)TPPS to natural DNA was analysed (together with free meso-tetra-(4-sulfonatophenyl)porphine (TPPS) for comparison purposes). Particular attention was paid to (BuSn)TPPS, a species that shows significant cellular action. Preliminary tests were done on the solution properties of the organotin(IV) compounds (pK and possible self-aggregation).

A Puna Collection of Senecio punae, Main Source of a Versatile Eremophilane-type Ketone.

Senecio punae Cabrera (Asteraceae-Senecioneae) is an endemic species from Puna semi-desert region of Argentina.The major compound, 4p,5p-eremophil- 7(11)9-dien-8-one, also known as dehydrofukinone (D), was isolated from the diethyl ether extract (E) of the plant. The phytochemical constituents from S.

Natural sesquiterpene lactones enhance oxacillin and gentamicin effectiveness against pathogenic bacteria without antibacterial effects on beneficial lactobacilli.

This is a report on the synergistic interactions (SIs) between melampolide-type sesquiterpene lactones 1-8 from Acanthospermum hispidum DC., and oxacillin or gentamicin, against four pathogenic strains of Staphylococcus aureus and Enterococcus faecalis; two of them were multi-resistant strains obtained from chronic infectious processes. Our results showed that all associations of 1-8 with antibiotics (ATBs) are more effective than pure ATBs to control pathogenic strains of S.

Efficient C-H/C-N and C-H/C-CO-N conversion via decatungstate-photoinduced alkylation of diisopropyl azodicarboxylate.

Tetrabutylammonium decatungstate (TBADT) accelerated the addition of C-H bonds to the N═N double bond of diisopropyl azodicarboxylate (DIAD) under irradiation conditions. The photoinduced three-component coupling between cyclic alkanes, CO, and DIAD was also achieved to give the corresponding acyl hydrazides.

Decatungstate as photoredox catalyst: benzylation of electron-poor olefins.

Excited tetrabutylammonium decatungstate (TBADT), known to activate a variety of compounds via hydrogen atom transfer (HAT), has now been applied as a photoredox catalyst for the effective oxidative cleavage of benzyl silanes and radical benzylation of reducible olefins occurring in isolated yields from poor to excellent.

Investigation on the phototransformation of tadalafil in aqueous media. 6-Epimerization vs. solvent trapping reaction.

Irradiation of tadalafil at lambda > 290 nm in aqueous solutions leads to 6-epimer and/or water adducts depending on concentration and pH. A rationalization of the results involves the heterolytic cleavage of C6-N5 bond via a well-stabilized zwitterionic intermediate. The drug is stable in the dark except under strongly basic conditions where it undergoes C12a-epimerization.

Photonucleophilic addition of the epsilon-amino group of lysine to a triflusal metabolite as a mechanistic key to photoallergy mediated by the parent drug.

A mechanism for triflusal-induced photoallergy involving complexation of 2-hydroxy-4-trifluoromethylbenzoic acid with site I of human serum albumin and subsequent formation of a covalent adduct by photoreaction between a metabolite and a neighboring lysine residue is proposed. This is supported by the observed photobinding to poly-L-lysine. Thereby, a photoantigen is generated, which is a likely trigger of the immune response.

A mechanistic study on the phototoxicity of atorvastatin: singlet oxygen generation by a phenanthrene-like photoproduct.

Atorvastatin calcium (ATV) is one of the most frequently prescribed drugs worldwide. Among the adverse effects observed for this lipid-lowering agent, clinical cases of cutaneous adverse reactions have been reported and associated with photosensitivity disorders. Previous work dealing with ATV photochemistry has shown that exposure to natural sunlight in aqueous solution leads to photoproducts resulting from oxidation of the pyrrole ring and from cyclization to a phenanthrene derivative.

Bioactive plants from Argentina and Bolivia.

Antibacterial and molluscicidal activities of methanol and chloroform extracts of 16 plant species belonging to the families Compositae and Melastomataceae were evaluated. The chloroform extract of Vernonanthura tweediana and the methanol extract of Senecio santelisis resulted to be very toxic to brine shrimp nauplii (LC(50)=1 microg/ml). Chloroform extracts of S.