Chlorine reactivity

Dibromoacetic acid (DBA), a by-product of disinfection, develops in drinking water during chlorination or ozonation processes. Water intake is the main source of DBA exposure in humans, which is potentially neurotoxic. The present study investigated the neurotoxic effects of DBA by assessing the behavioral and biochemical characteristics of Sprague Dawley rats intragastrically treated with DBA at concentrations of 20, 50 and 125 mg kg(-1) body weight for 28 consecutive days. The results indicated that animal weight gain and food consumption were not significantly affected by DBA...

A major problem with many promising nano-sized biotherapeutics including macromolecules is that owing to their size they are subject to cellular uptake via endocytosis, and become entrapped and then degraded within endolysosomes, which can significantly impair their therapeutic efficacy. Photochemical internalisation (PCI) is a technique for inducing cytosolic release of the entrapped agents that harnesses sub-lethal photodynamic therapy (PDT) using a photosensitiser that localises in endolysosomal membranes...

BACKGROUND: Photodynamic therapy (PDT) has been established in several countries as an alternative therapy for the treatment of various malignancies. This therapy involves the incorporation of a photosensitizer (PS) that is activated by visible light and form reactive oxygen species leading to target cell death by apoptosis or necrosis. Previously, our group has demonstrated that CHL-T (semi-synthesized from chlorophyll a and containing a linked solubilizing group TRISMA(®)) presented a pronounced potential to induce death in HeLa cell line after PDT...

We report here a highly facile one-pot synthesis of a new series of fully π-conjugated unsymmetric chlorin-porphyrin heterodimers with quantitative yields by utilizing intermacrocyclic interactions. One-electron oxidations of dicopper(II) and dipalladium(II) porphyrin dimers using mild oxidants such as iodine at room temperature resulted in the formation of a strongly interacting cofacial mixed-valent π-cation radical dimers. The radical being highly reactive drives spontaneous and rapid transformation involving a new N=C bond formation, 1,2-ethyl migration and the generation of a new indolizinium ring that bridges between the two macrocycles...

Water reuse is receiving unprecedented attention, as many areas around the globe attempt to better manage their fresh water resources. Wastewaters in coastal regions may contain elevated levels of bromide (Br-) and iodide (I-) from seawater intrusion or a high mineral content in the source waters. Disinfection of such wastewater is essential to prevent the spread of pathogens, however, little is known about the toxicity of the treated wastewater. In this study, we evaluated the genotoxicity to Chinese Hamster Ovary (CHO) cells induced by municipal secondary wastewater effluent amended with elevated Br-/I- after disinfection by chlorine, chloramines, or ozone...

A laterally π-extended dithia[6]helicene 1, representing an interesting saddle-helix hybrid molecule containing an unusual heptagon, has been synthesized by MoCl5-mediated oxidative stitching of tetrakis(thienylphenyl)naphthalene precursor 2 involving reactive-site capping by chlorination, and subsequent Pd-mediated dechlorination of tetrachlorinated intermediate 1-Cl4. Highly distorted, wide helical structures of dithia[6]helicenes (1 and 1-Cl4) were clarified by single crystal X-ray diffraction analyses, where heterochiral slipped π-π stacking was displayed in one-dimensional fashion...

Intramolecular halogen atom coordinated H transfer reaction in the gas phase dissociation of protonated dichlorvos derivatives has been explored by electrospray ionization tandem mass spectrometry. Upon collisional activation, protonated dichlorvos underwent dissociation reaction via cleavage of the P-O bond to give reactive ion-neutral complex (INC) intermediate, [dimethoxylphosphinoylium + dichloroacetaldehyde]. Besides direct dissociation of the complex, intramolecular chlorine atom coordinated H transfer reaction within the complex takes place, leading to the formation of protonated dimethyl chlorophosphate...

Municipal solid waste incineration (MSWI) fly ash has been classified as hazardous waste and needs treatment in an environmentally safe manner. Mechanochemical (MC) treatment is such a detoxification method, since it destroys dioxins and solidifies heavy metals. Milling, however, also introduces supplemental metals (Fe, Ni, Cr, Mn…), following wear of both steel balls and housing. Milling moreover reduces the particle size of fly ash and disperses catalytic metal, potentially rising the reactivity of fly ash to form and destroy 'dioxins', i...

A combined experimental and theoretical study of the high-temperature reaction of SiCl4 and elemental silicon is presented. The nature and reactivity of the product formed upon rapid cooling of the gaseous reaction mixture is investigated by comparison with defined model compounds, i.e. cyclo-Si5Cl10, n-Si5Cl12 and n-Si4Cl10. A DFT assessment provides mechanistic insight into the oligosilane formation. Experimental 29Si NMR investigations, supported by quantum-chemical 29Si NMR calculations, consistently show that the reaction product is composed of discrete molecular perchlorinated oligosilanes...

The development of selective functionalization strategies of white phosphorus (P4) is important to avoid the current chlorinated intermediates. The use of transition metals (TMs) could lead to catalytic procedures, but these are severely hampered by the high reactivity and unpredictable nature of the tetrahedron. Herein, we report selective first steps by reacting P4 with a metal anion [Cp*Fe(CO)2](-) (Cp*=C5(CH3)5), which, in the presence of bulky Lewis acids (LA; B(C6F5)3 or BPh3), leads to unique TM-substituted LA-stabilized bicyclo[1...

The competition between bimolecular nucleophilic substitution and base-induced elimination is of fundamental importance for the synthesis of pure samples in organic chemistry. Many factors that influence this competition have been identified over the years, but the underlying atomistic dynamics have remained difficult to observe. We present product velocity distributions for a series of reactive collisions of the type X(-) + RY with X and Y denoting the halogen atoms fluorine, chlorine and iodine. By increasing the size of the residue R from methyl to tert-butyl in several steps, we find that the dynamics drastically change from backward to dominant forward scattering of the leaving ion relative to the reactant RY velocity...

The development of methods for the generation of site-selective interstrand crosslinks (ICLs) in synthetic oligonucleotides provides a platform for the study of ICL repair mechanisms and the stabilisation of DNA-based materials. Our group has previously reported on the use of a furan moiety as a masked reactive functionality for ICL generation and recently introduced the use of (1)O2 as an efficient light-induced oxidant. Here, the use of porphyrin-based photosensitizers (PSs) has been explored for ICL generation...

The degradation kinetics, pathways and disinfection by-products (DBPs) formation of iopamidol by chlorine and chloramines were investigated in this paper. The chlorination kinetics can be well described by a second-order model. The apparent second-order rate constants of iopamidol chlorination significantly increased with solution pH. The rate constants of iopamidol with HOCl and OCl(-) were calculated as (1.66 ± 0.09) × 10(-3) M(-1) s(-1) and (0.45± 0.02) M(-1) s(-1), respectively. However, the chloramination of iopamidol fitted well with third-order kinetics and the maximum of the apparent rate constant occurred at pH 7...

Photodynamic therapy (PDT) is a non-invasive antitumor treatment that uses the combination of a photosensitizer, tissue oxygen, and visible light irradiation to produce cytotoxic reactive oxygen species, predominantly singlet oxygen. Currently, first-generation PDT using porfimer sodium with an excimer dye laser, and second-generation PDT using talaporfin sodium PDT with a semiconductor laser are approved by health insurance for use in Japan. However, the cancer cell specificity and selectivity of these treatments are inadequate...

Macrophage-derived foam cells are a major component of atherosclerotic plaques and have an important role in the progression of atherosclerotic plaques, thus posing a great threat to human health. Photodynamic therapy (PDT) has emerged as a therapeutic strategy for atherosclerosis. Here, we investigated the effect of PDT mediated by upconversion fluorescent nanoparticles encapsulating chlorin e6 (UCNPs-Ce6) on the cholesterol efflux of THP-1 macrophage-derived foam cells and explored the possible mechanism of this effect...

Dichloroacetonitrile (DCAN), one of the disinfection byproducts of water chlorination, induces cell proliferation and apoptosis, however, the detailed mechanism remains unclear. Oxidative stress participates in various biological processes, including DNA damage and cytotoxicity. To explore whether oxidative stress mediated DCAN-induced cell proliferation and apoptosis, we assessed the effect of redox imbalance and apoptosis in LO2 cells. We observed increase of reactive oxygen species and malondialdehyde and increased apoptosis by 13...

When a bromide-containing water is treated by the ultraviolet (UV)/chlorine process, hydroxyl radicals (HO) and halogen radicals such as Cl or Br are formed due to the UV photolysis of free halogens. These reactive species may induce the formation of bromate, which is a probable human carcinogen. Bromate formation in the UV/chlorine process using low pressure (LP) and medium pressure (MP) lamps in the presence of bromide was investigated in the present study. The UV/chlorine process significantly enhanced bromate formation as compared to dark chlorination...

MauG is a diheme enzyme that utilizes two covalently bound c-type heme centers. We report here step-wise oxidations of a synthetic analog of MauG in which two heme centers are bridged covalently via flexible linker containing a pyrrole moiety. One- and two-electron oxidations produce monocation radical and dication diradical intermediates, respectively, which, being highly reactive, undergo spontaneous intramolecular rearrangement involving the pyrrole bridge itself to form indolizinium-fused chlorin-porphyrin and spiro-porphyrinato heterodimers...

Apart from their well-known culinary use, gastropod species such as Helix, which have a hydrogel-like mucus, are increasingly being exploited for cosmetic, bioengineering and medical applications. However, not only are the origin and composition of these "sticky" secretions far from being fully characterized, the number and morphology of the mucus glands involved is also uncertain. This study aims to characterize in detail the cutaneous glands of the Helix pomatia foot on morphological, histochemical and immunohistochemical levels...

In this study we designed a claudin 4-directed dual photodynamic and photothermal system, in which a 30-amino acid claudin 4-binding peptide, Clostridium perfringens enterotoxin (CPE), was linked to a photodynamic agent chlorin e6 (Ce6) through a polyethylene glycol spacer (CPC) and anchored onto reduced graphene oxide (rGO) nanosheets to form CPC/rGO nanosheets. For comparison, a conjugate of polyethylene glycol and Ce6 (PC) was anchored onto the rGO nanosheets to generate PC/rGO. Both PC and CPC generated reactive oxygen species upon irradiation at 660 nm...