90 research outputs found
Social Protection and Child Protection: Two Sides of the Same Coin?
There is widespread recognition that children are a particularly vulnerable group; they have different basic needs than adults do, they are dependent on others for the fulfilment of their needs and the denial of those needs can have far-reaching and long-term adverse consequences (Roelen and Sabates-Wheeler 2012, White, Leavy, and Masters 2003, Sabates-Wheeler, Devereux, and Hodges 2009). The policy areas of social protection and child protection are part and parcel of the response to children and their vulnerabilities. Nevertheless, both policy areas have largely developed in silos (Roelen, Long, and Edstrom 2012). This holds in both academic and policy terms. Whilst issues of child protection are mostly dealt with in disciplines of child psychology and childhood studies, social protection is largely appropriated by economists and social scientists. Similarly, national governments, international organisations and NGOs often deal with issues of child protection and social protection in different departments and through distinct sectoral policies. It is increasingly recognised that this dichotomy is artificial (Shibuya and Taylor 2013), and that it compromises the effectiveness of the response to the wide set of needs of vulnerable children
pH and Auxiliary Ligand Influence on the Structural Variations of 5Â(2′-Carboxylphenyl) Nicotate Coordination Polymers
A ligand 5-(2′-carboxylphenyl) nicotic acid (H<sub>2</sub>cpna) has been successfully applied to construct a series
of coordination
complexes {[CdÂ(Hcpna)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]·3H<sub>2</sub>O}<sub><i>n</i></sub> (<b>1</b>), [CdÂ(cpna)Â(H<sub>2</sub>O)]<sub><i>n</i></sub> (<b>2</b>), [MÂ(cpna)Â(2,2′-bipy)Â(H<sub>2</sub>O)]<sub><i>n</i></sub> (M = Cd (<b>3</b>),
Co (<b>4</b>), and Mn (<b>5</b>)), [CoÂ(cpna)Â(phen)Â(H<sub>2</sub>O)]<sub><i>n</i></sub> (<b>6</b>), [MnÂ(cpna)Â(phen)Â(H<sub>2</sub>O)]<sub><i>n</i></sub> (<b>7</b>), {[NdÂ(Hcpna)Â(cpna)Â(H<sub>2</sub>O)<sub>2</sub>]·3H<sub>2</sub>O}<sub><i>n</i></sub> (<b>8</b>), and {[LnÂ(Hcpna)Â(cpna)Â(phen)]·2H<sub>2</sub>O}<sub><i>n</i></sub> (Ln = Pr (<b>9</b>),
Nd (<b>10</b>), Eu (<b>11</b>), and Gd (<b>12</b>), 2,2′-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline)
under hydrothermal conditions. By adjusting the reaction pH, H<sub>2</sub>cpna ligand is partially deprotonated to form Hcpna<sup>–</sup> in <b>1</b> and completely deprotonated to create cpna<sup>2–</sup> in <b>2</b>–<b>7</b>, and both
forms are observed in <b>8</b>–<b>12</b>. Complexes <b>1</b>–<b>5</b> and <b>8</b> possess two-dimensional
(2D) layered structures, which are further extended into 3D metal–organic
supramolecular frameworks by C–H···O hydrogen
bond and/or π–π stacking interactions. Complexes <b>6</b>, <b>7</b>, and <b>9</b>–<b>12</b> exhibit one-dimensional (1D) chain structures, which further build
three-dimensional (3D) supramolecular architecture via C–H···O
hydrogen-bonding and/or π–π stacking interactions.
The results revealed that the pH value of the reaction system and
auxiliary ligand play an important role in determining the structures
of the complexes. Magnetic susceptibility measurements indicate that
compounds <b>4</b>–<b>10</b> and <b>12</b> have dominating antiferromagnetic couplings between metal centers.
Furthermore, thermal stabilities for <b>1</b>–<b>12</b> and luminescent properties for <b>1</b>–<b>3</b>, and <b>11</b> are also discussed in detail
pH and Auxiliary Ligand Influence on the Structural Variations of 5Â(2′-Carboxylphenyl) Nicotate Coordination Polymers
A ligand 5-(2′-carboxylphenyl) nicotic acid (H<sub>2</sub>cpna) has been successfully applied to construct a series
of coordination
complexes {[CdÂ(Hcpna)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]·3H<sub>2</sub>O}<sub><i>n</i></sub> (<b>1</b>), [CdÂ(cpna)Â(H<sub>2</sub>O)]<sub><i>n</i></sub> (<b>2</b>), [MÂ(cpna)Â(2,2′-bipy)Â(H<sub>2</sub>O)]<sub><i>n</i></sub> (M = Cd (<b>3</b>),
Co (<b>4</b>), and Mn (<b>5</b>)), [CoÂ(cpna)Â(phen)Â(H<sub>2</sub>O)]<sub><i>n</i></sub> (<b>6</b>), [MnÂ(cpna)Â(phen)Â(H<sub>2</sub>O)]<sub><i>n</i></sub> (<b>7</b>), {[NdÂ(Hcpna)Â(cpna)Â(H<sub>2</sub>O)<sub>2</sub>]·3H<sub>2</sub>O}<sub><i>n</i></sub> (<b>8</b>), and {[LnÂ(Hcpna)Â(cpna)Â(phen)]·2H<sub>2</sub>O}<sub><i>n</i></sub> (Ln = Pr (<b>9</b>),
Nd (<b>10</b>), Eu (<b>11</b>), and Gd (<b>12</b>), 2,2′-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline)
under hydrothermal conditions. By adjusting the reaction pH, H<sub>2</sub>cpna ligand is partially deprotonated to form Hcpna<sup>–</sup> in <b>1</b> and completely deprotonated to create cpna<sup>2–</sup> in <b>2</b>–<b>7</b>, and both
forms are observed in <b>8</b>–<b>12</b>. Complexes <b>1</b>–<b>5</b> and <b>8</b> possess two-dimensional
(2D) layered structures, which are further extended into 3D metal–organic
supramolecular frameworks by C–H···O hydrogen
bond and/or π–π stacking interactions. Complexes <b>6</b>, <b>7</b>, and <b>9</b>–<b>12</b> exhibit one-dimensional (1D) chain structures, which further build
three-dimensional (3D) supramolecular architecture via C–H···O
hydrogen-bonding and/or π–π stacking interactions.
The results revealed that the pH value of the reaction system and
auxiliary ligand play an important role in determining the structures
of the complexes. Magnetic susceptibility measurements indicate that
compounds <b>4</b>–<b>10</b> and <b>12</b> have dominating antiferromagnetic couplings between metal centers.
Furthermore, thermal stabilities for <b>1</b>–<b>12</b> and luminescent properties for <b>1</b>–<b>3</b>, and <b>11</b> are also discussed in detail
Total Syntheses of (±)-Rhodonoids A and B and C12-<i>epi</i>-Rhodonoid B
Total
syntheses of (±)-rhodonoids A and B and C12-<i>epi</i>-rhodonoid B are described here. A unified strategy employed
in these syntheses is an intramolecular <i>oxa</i>-[3 +
3] annulation for accessing the chromene unit. A FeÂ(OTf)<sub>3</sub>-promoted diastereoselective cationic [2 + 2] cycloaddition and a
photochemical [2 + 2] cycloaddition were featured to construct the
cyclobutane core of (±)-rhodonoids A and B and C12-<i>epi</i>-rhodonoid B, respectively. FeÂ(OTf)<sub>3</sub> also leads to an
interesting bridged tetracycle, which was unambiguously confirmed
by single crystal X-ray analysis
Total Syntheses of (±)-Rhodonoids C, D, E, F, and G and Ranhuadujuanine B
Here
we describe the divergent, biosynthetically inspired syntheses
of (±)-rhodonoids C–G and (±)-ranhuadujuanine B.
The key steps of the syntheses include the construction of the chromene
unit through a formal oxa-[3 + 3] annulation and a biomimetic acid-catalyzed
ring cyclization. Cationic [2 + 2] cycloaddition is accomplished to
form the cyclobutane core of (±)-rhodonoids E and F
Transition Metal-Free Visible Light-Driven Photoredox Oxidative Annulation of Arylamidines
A fast catalytic synthesis of multisubstituted
quinazolines from
readily available amidines via visible light-mediated oxidative CÂ(sp<sup>3</sup>)-CÂ(sp<sup>2</sup>) bond formation has been established. This
reaction is a metal-free oxidative coupling catalyzed by a photoredox
organocatalyst. The protocol features low catalyst loading (1 mol
%)
Capillary-Driven Boiling Heat Transfer on Superwetting Microgrooves
Boiling can transfer a vast amount of heat and thereby
is widely
used for cooling advanced systems with high power density. However,
the capillary force of most existing wicks is insufficient to surpass
the liquid replenishing resistance for high-efficient boiling. Herein,
we report a new microgroove wick on high-conductive copper substrates
that was constructed via ultraviolet nanosecond pulsed laser milling.
The phase explosion, combined with melting and resolidification effects
of laser milling induces dense microcavities with sizes around several
micrometers on the microgroove surface. The hierarchical microstructures
significantly improve the wettability of the microgroove wicks to
obtain strong capillary and meanwhile provide abundant effective nucleation
sites. The boiling heat transfer in a visualized flat heat pipe shows
that the new wicks enable sustainable liquid replenishing even under
antigravity conditions, thus resulting in maximum 33-fold improvement
of equivalent thermal conductivity when compared with the copper base.
This research provides both scientific and technical bases for the
design and manufacture of high-performance phase change cooling devices
Continuous Modification of Perovskite Film by a Eu Complex to Fabricate the Thermal and UV-Light-Stable Solar Cells
Perovskite solar cells (PSCs) with
simple and low-cost processability
have shown promising photovoltaic performances. However, internal
defects, external UV light, and heat sensitivity are principal obstacles
on their way toward commercialization. Herein, we prepare an Eu complex
and directly dope it into the perovskite precursor as a UV filter
to decrease the photodegradation of PSCs. The formation of hydrogen
bonds between the organic cation of perovskite and the −CF3 in the Eu complex could restrain the escape of organic cations
under heating. The Eu complex acts as a redox shuttle to reduce metallic
lead (Pb0) and iodine (I0) defects when the
PSCs have a long-time operation. Additionally, the ligand-containing
aromatic rings could reduce the trace amount of I0 existing
as electronic defects in perovskites and together with the long alkyl
chain retard the moisture immersion into the PSCs. The best efficiency
of PSCs modified by the Eu complex improves up to 20.9%. The excellent
thermal stability and UV-light resistance are also realized. This
strategy provides a method to design a passivator which continuously
modifies the imperfections and inhibits the chemical chain reactions
in perovskite film, thereby enhancing the performance and stability
of PSCs
Mechanistic Insights into the Gold(I)-Catalyzed Activation of Glycosyl <i>ortho</i>-Alkynylbenzoates for Glycosidation
Anomerization, which involves cleavage
and formation of the anomeric
C–O bond, is of fundamental importance in the carbohydrate
chemistry. Herein, the unexpected goldÂ(I)-catalyzed anomerization
of glycosyl <i>ortho</i>-alkynylbenzoates has been studied
in detail. Especially, crossover experiments in the presence of an
exogenous isochromen-4-yl goldÂ(I) complex confirm that the anomerization
proceeds via the exocleavage mechanism, involving (surprisingly) the
addition of the isochromen-4-yl goldÂ(I) complex onto a sugar oxocarbenium
(or dioxolenium) and an elimination of LAu<sup>+</sup> from the vinyl
goldÂ(I) complex. The inhibitory effect of the exogenous isochromen-4-yl
goldÂ(I) complex when in stoichiometric amount on the anomerization
has guided us to disclose an isochromen-4-yl <i>gem</i>-goldÂ(I)
complex, which is inactive in catalysis but in equilibrium with the
monogoldÂ(I) complex and the LAu<sup>+</sup> catalyst. The proposed
key intermediate in the anomerization, a transient glycosyloxypyrylium
species, is successfully trapped via a cycloaddition reaction with <i>n</i>-butyl vinyl ether as a dienophile. S<sub>N</sub>2-like
substitution of the initially formed glycosyloxypyrylium intermediate
has then been achieved to a large extent via charging with acceptors
in an excess amount to lead to the corresponding glycosides in a stereoselective
manner
Total Syntheses of Cannabicyclol, Clusiacyclol A and B, Iso-Eriobrucinol A and B, and Eriobrucinol
Total syntheses of a series of chromane natural products that contain a cyclobutane ring are described. A unified theme in the strategy employed for all these syntheses is an <i>oxa</i>-[3 + 3] annulation for constructing the chromane nucleus and a stepwise cationic [2 + 2] cycloaddition for the cyclobutane formation. More importantly, the two reactions could be rendered in tandem, thereby providing an expeditious approach to this family of natural products
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