One and two scandium ions (Sc3+) are bound strongly to nonheme manganese(IV)–oxo complexes, (N4Py)MnIV(O)2+ (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) and (Bn-TPEN)MnIV(O)2+ ...(Bn-TPEN = N-benzyl-N,N′,N′-tris(2-pyridylmethyl)-1,2-diaminoethane), to form MnIV(O)–(Sc3+)1 and MnIV(O)–(Sc3+)2 complexes, respectively. The binding of Sc3+ ions to the MnIV(O) complexes was examined by spectroscopic methods as well as by DFT calculations. The one-electron reduction potentials of the MnIV(O) complexes were markedly shifted to a positive direction by binding of Sc3+ ions. Accordingly, rates of the electron transfer reactions of the MnIV(O) complexes were enhanced as much as 107–fold by binding of two Sc3+ ions. The driving force dependence of electron transfer from various electron donors to the MnIV(O) and MnIV(O)–(Sc3+)2 complexes was examined and analyzed in light of the Marcus theory of electron transfer to determine the reorganization energies of electron transfer. The smaller reorganization energies and much more positive reduction potentials of the MnIV(O)–(Sc3+)2 complexes resulted in remarkable enhancement of the electron-transfer reactivity of the MnIV(O) complexes. Such a dramatic enhancement of the electron-transfer reactivity of the MnIV(O) complexes by binding of Sc3+ ions resulted in the change of mechanism in the sulfoxidation of thioanisoles by MnIV(O) complexes from a direct oxygen atom transfer pathway without metal ion binding to an electron-transfer pathway with binding of Sc3+ ions.
Triflic acid (HOTf)-bound nonheme Mn(IV)-oxo complexes, (L)Mn
(O)
-(HOTf)
(L = N4Py and Bn-TPEN; N4Py =
-bis(2-pyridylmethyl)-
-bis(2-pyridyl)methylamine) and Bn-TPEN =
-benzyl-
,
,
...-tris(2-pyridylmethyl)ethane-1,2-diamine), were synthesized by adding HOTf to the solutions of the (L)Mn
(O)
complexes and were characterized by various spectroscopies. The one-electron reduction potentials of the Mn
(O) complexes exhibited a significant positive shift upon binding of HOTf. The driving force dependence of electron transfer (ET) from electron donors to the Mn
(O) and Mn
(O)-(HOTf)
complexes were examined and evaluated in light of the Marcus theory of ET to determine the reorganization energies of ET. The smaller reorganization energies and much more positive reduction potentials of the (L)Mn
(O)
-(HOTf)
complexes resulted in much enhanced oxidation capacity towards one-electron reductants and
-X-substituted-thioanisoles. The reactivities of the Mn(IV)-oxo complexes were markedly enhanced by binding of HOTf, such as a 6.4 × 10
-fold increase in the oxygen atom transfer (OAT) reaction (i.e., sulfoxidation). Such a remarkable acceleration in the OAT reaction results from the enhancement of ET from
-X-substituted-thioanisoles to the Mn
(O) complexes as revealed by the unified ET driving force dependence of the rate constants of OAT and ET reactions of (L)Mn
(O)
-(HOTf)
. In contrast, deceleration was observed in the rate of H-atom transfer (HAT) reaction of (L)Mn
(O)
-(HOTf)
complexes with 1,4-cyclohexadiene as compared with those of the (L)Mn
(O)
complexes. Thus, the binding of two HOTf molecules to the Mn
(O) moiety resulted in remarkable acceleration of the ET rate when the ET is thermodynamically feasible. When the ET reaction is highly endergonic, the rate of the HAT reaction is decelerated due to the steric effect of the counter anion of HOTf.
Microplastic pollution in the ocean has a major impact on marine organisms, including digestive system damage and reduced growth and fertility. This study investigated the amount, size, color, type, ...and presence of heads and intestines of microplastics by size in Litopenaeus vannamei, a type of marine organism. Microplastic analysis was performed using FTIR and digital microscopy. The number of microplastics by the size of the shrimp ranged from 1.73 to 3.8 MPs per 10 g, and the microplastic size of less than 100 μm was 77–92%, with blue showing the highest ratio. As for the type of plastic, PE and PP showed the highest ratio, and PET, PS, nylon, and PVC were found. Microplastics were found to be 11.83 MPs/10 g for heads and intestines and 3.16 MPs/10 g for samples without heads and intestines. This study adds to evidence for the presence of high levels of microplastics in the intestines and heads of shrimp. It also enhances our understanding of the need for efficient plastic waste management in the ocean and the impact of microplastics on marine biota.
This study aims to select the radiated area for the wild grazing of Crested ibis(Nipponia Nippon) in 2017 and develop a best-fit models for the wild grazing candidate area and dispersed area based on ...the existing restoration center in Gyeongnam area. According to the restoration policy of the endangered species Crested ibis, the regions that have a high suitability index are selected. In order to increase genetic diversity and prevent massive bird flu outbreaks, designating protection area for Crested ibis is necessary and it is recommended to release them in a geographically dispersed manner. As a result, the data obtained from the Crested ibis releasing could be shared with other restoration centers and also used as a basic data for the conservation of other endangered species in the entire Korea Peninsula.
Direct oxygen atom transfer from a nonheme Mn(iv)-oxo complex, (Bn-TPEN)Mn
(O)
, to triphenylphosphine (Ph
P) derivatives occurs with a significant steric effect resulting from the ortho-substituents ...on the phenyl group of the Ph
P derivatives, whereas the phosphine oxygenation by a Mn(iv)-oxo complex in the presence of HOTf occurs via an electron transfer mechanism without the substrate-steric effect.
The Association between Suicide Attempts and Toxoplasma gondii Infection Bak, Jeongjae; Shim, Se-Hoon; Kwon, Young-Joon ...
Clinical psychopharmacology and neuroscience : the official scientific journal of the Korean College of Neuropsychopharmacology,
02/2018, Volume:
16, Issue:
1
Journal Article
Peer reviewed
Open access
Chronic 'latent' infection by
is common and most of the hosts have minimal symptoms or they are even asymptomatic. However, there are possible mechanisms by which
may affect human behavior and it may ...also cause humans to attempt suicide. This article aimed to investigate the potential pathophysiological relationship between suicide attempts and
infection in Korea.
One hundred fifty-five psychiatric patients with a history of suicide attempt and 135 healthy control individuals were examined with enzyme-linked immunoassays and fluorescent antibody technique for
seropositivity and antibody titers. The group of suicide attempters was interviewed regarding the history of suicide attempt during lifetime and evaluated using 17-item Korean version of Hamilton Depression Scale (HAMD), Columbia Suicide Severity Rating Scale (C-SSRS), State-Trait Anxiety Inventory (STAI) and Korean-Barratt Impulsiveness Scale (BIS).
Immunoglobulin G antibodies were found in 21 of the 155 suicide attempters and in 8 of the 135 controls (
=0.011). The Toxoplasma-seropositive suicide attempters had a higher HAMD score on the depressed mood and feeling of guilt subscales and a higher total score than the seronegative suicide attempters.
seropositive status was associated with higher C-SSRS in the severity and lethality subscales.
IgG seropositivity was significantly associated with higher STAI-X1 scores in the suicide attempters group.
Suicide attempters showed higher seroprevalence of
than healthy controls. Among the suicide attempters, the
seropositive and seronegative groups showed several differences in the aspects of suicide. These results suggested a significant association between
infection and psychiatric problems in suicidality.
Redox‐inactive metal ions play important roles in tuning chemical properties of metal–oxygen intermediates. Herein we report the effect of water molecules on the redox properties of a nonheme ...iron(III)–peroxo complex binding redox‐inactive metal ions. The coordination of two water molecules to a Zn2+ ion in (TMC)FeIII‐(O2)‐Zn(CF3SO3)2 (1‐Zn2+) decreases the Lewis acidity of the Zn2+ ion, resulting in the decrease of the one‐electron oxidation and reduction potentials of 1‐Zn2+. This further changes the reactivities of 1‐Zn2+ in oxidation and reduction reactions; no reaction occurred upon addition of an oxidant (e.g., cerium(IV) ammonium nitrate (CAN)) to 1‐Zn2+, whereas 1‐Zn2+ coordinating two water molecules, (TMC)FeIII‐(O2)‐Zn(CF3SO3)2‐(OH2)2 1‐Zn2+‐(OH2)2, releases the O2 unit in the oxidation reaction. In the reduction reactions, 1‐Zn2+ was converted to its corresponding iron(IV)–oxo species upon addition of a reductant (e.g., a ferrocene derivative), whereas such a reaction occurred at a much slower rate in the case of 1‐Zn2+‐(OH2)2. The present results provide the first biomimetic example showing that water molecules at the active sites of metalloenzymes may participate in tuning the redox properties of metal–oxygen intermediates.
Redox‐inactive metal ions play important roles in tuning chemical properties of metal‐oxygen intermediates. The effect of water molecules on the redox properties of nonheme iron(III)–peroxo complexes binding redox‐inactive metal ions is reported. The present results provide the first biomimetic example showing that water molecules at the active sites of metalloenzymes may participate in tuning the redox properties of metal–oxygen intermediates. CAN=cerium(IV)ammonium nitrate, TMC=transition‐metal complex.
Redox-inactive metal ions play pivotal roles in regulating the reactivities of high-valent metal–oxo species in a variety of enzymatic and chemical reactions. A mononuclear non-heme Mn(IV)–oxo ...complex bearing a pentadentate N5 ligand has been synthesized and used in the synthesis of a Mn(IV)–oxo complex binding scandium ions. The Mn(IV)–oxo complexes were characterized with various spectroscopic methods. The reactivities of the Mn(IV)–oxo complex are markedly influenced by binding of Sc3+ ions in oxidation reactions, such as a ∼2200-fold increase in the rate of oxidation of thioanisole (i.e., oxygen atom transfer) but a ∼180-fold decrease in the rate of C–H bond activation of 1,4-cyclohexadiene (i.e., hydrogen atom transfer). The present results provide the first example of a non-heme Mn(IV)–oxo complex binding redox-inactive metal ions that shows a contrasting effect of the redox-inactive metal ions on the reactivities of metal–oxo species in the oxygen atom transfer and hydrogen atom transfer reactions.
Direct oxygen atom transfer from a nonheme Mn(
iv
)-oxo complex, (Bn-TPEN)Mn
IV
(O)
2+
, to triphenylphosphine (Ph
3
P) derivatives occurs with a significant steric effect resulting from the
ortho
...-substituents on the phenyl group of the Ph
3
P derivatives, whereas the phosphine oxygenation by a Mn(
iv
)-oxo complex in the presence of HOTf occurs
via
an electron transfer mechanism without the substrate-steric effect.
Direct oxygen atom transfer from Mn(
iv
)-oxo to Ph
3
P occurs, exhibiting significant steric effects of the
ortho
-substitution of the phenyl group, whereas in the presence of HOTf, the mechanism is switched to electron transfer from Ph
3
P to Mn(
iv
)-oxo, exhibiting no steric effects.
The ring size effect of macrocyclic TMC ligands in nonheme iron(IV)-oxo complexes has been examined in hydrogen atom transfer (HAT) and oxygen atom transfer (OAT) reactions; an iron(IV)-oxo complex ...bearing a smaller TMC ligand is more reactive in both HAT and OAT reactions, resulting from its high Fe(IV/III) redox potential.
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