Showing papers in "Chemistry-an Asian Journal in 2014"
TL;DR: Recent efforts in metal-catalyzed C-S bond cross-coupling reactions are summarized, focusing especially on the coupling of thiols with aryl- and vinyl halides based on different metals.
Abstract: Sulfur-containing molecules such as thioethers are commonly found in chemical biology, organic synthesis, and materials chemistry. While many reliable methods have been developed for preparing these compounds, harsh reaction conditions are usually required in the traditional methods. The transition metals have been applied in this field, and the palladium-catalyzed coupling of thiols with aryl halides and pseudo halides is one of the most important methods in the synthesis of thioethers. Other metals have also been used for the same purpose. Here, we summarize recent efforts in metal-catalyzed C-S bond cross-coupling reactions, focusing especially on the coupling of thiols with aryl- and vinyl halides based on different metals.
351 citations
TL;DR: In this Focus Review, recent developments of hypervalent iodine-catalyzed reactions are described including some asymmetric variants.
Abstract: Hypervalent iodine chemistry is now a well-established area of organic chemistry. Novel hypervalent iodine reagents have been introduced in many different transformations owing to their mild reaction conditions and environmentally friendly nature. Recently, these reagents have received particular attention because of their applications in catalysis. Numerous hypervalent iodine-catalyzed oxidative functionalizations such as oxidations of various alcohols and phenols, α-functionalizations of carbonyl compounds, cyclizations, and rearrangements have been developed successfully. In these catalytic reactions stoichiometric oxidants such as mCPBA or oxone play a crucial role to generate the iodine(III) or iodine(V) species in situ. In this Focus Review, recent developments of hypervalent iodine-catalyzed reactions are described including some asymmetric variants. Catalytic reactions using recyclable hypervalent iodine catalysts are also covered.
258 citations
TL;DR: Recent advances in the palladium-catalyzed CDC reactions of C(sp(2) )-H bond are summarized, with a focus on the period from 2011 to early 2013.
Abstract: The catalytic cross-dehydrogenative coupling (CDC) reaction has received intense attention in recent years. The attractive feature of this coupling process is the formation of a C-C bond from two C-H moieties under oxidative conditions. In this Focus Review, recent advances in the palladium-catalyzed CDC reactions of C(sp(2) )-H bond are summarized, with a focus on the period from 2011 to early 2013.
238 citations
TL;DR: In this work, chiral non-racemic hypervalent iodine(III) reagents and catalysts have emerged as versatile tools for the realization of important enantioselective transformations in alkene difunctionalization reactions.
Abstract: Hypervalent iodine(III) reagents have been known for over a century, and their reaction profile is still actively investigated. Recent years have seen impressive improvements in the area of alkene difunctionalization reactions, where new methodologies have become available. Especially chiral non-racemic hypervalent iodine(III) reagents and catalysts have emerged as versatile tools for the realization of important enantioselective transformations.
237 citations
TL;DR: This Focus Review highlights recent significant advances in microporous MOFs for gas separation with high porosities with optimized gas separation selectivity and capacity.
Abstract: Microporous metal-organic frameworks (MOFs) are comparatively new porous materials. Because the pores within such MOFs can be readily tuned through the interplay of both metal-containing clusters and organic linkers to induce their size-selective sieving effects, while the pore surfaces can be straightforwardly functionalized to enforce their different interactions with gas molecules, MOF materials are very promising for gas separation. Furthermore, the high porosities of such materials can enable microporous MOFs with optimized gas separation selectivity and capacity to be targeted. This Focus Review highlights recent significant advances in microporous MOFs for gas separation.
180 citations
TL;DR: The improved electrochemical performance for reversible sodium-ion storage could be ascribed to the synergistic effects of the SnS2 nanoplatelet/graphene nanosheets as an integrated hybrid nanoarchitecture, in which the graphene nanOSheets provide electronic conductivity and cushion for the active SnS 2 nanoplatelets during Na-ion insertion and extraction processes.
Abstract: Na-ion batteries have been attracting intensive investigations as a possible alternative to Li-ion batteries. Herein, we report the synthesis of SnS2 nanoplatelet@graphene nanocomposites by using a morphology-controlled hydrothermal method. The as-prepared SnS2/graphene nanocomposites present a unique two-dimensional platelet-on-sheet nanoarchitecture, which has been identified by scanning and transmission electron microscopy. When applied as the anode material for Na-ion batteries, the SnS2/graphene nanosheets achieved a high reversible specific sodium-ion storage capacity of 725 mA h g(-1), stable cyclability, and an enhanced high-rate capability. The improved electrochemical performance for reversible sodium-ion storage could be ascribed to the synergistic effects of the SnS2 nanoplatelet/graphene nanosheets as an integrated hybrid nanoarchitecture, in which the graphene nanosheets provide electronic conductivity and cushion for the active SnS2 nanoplatelets during Na-ion insertion and extraction processes.
169 citations
TL;DR: This short overview summarizes the recent advances in chiral phosphines based on the concept of bi-/multifunctionality and highlights the most-significant achievements.
Abstract: Chiral phosphines are versatile Lewis basic catalysts that are capable of promoting a wide range of asymmetric reactions. In particular, recently designed chiral phosphines based on the concept of bi-/multifunctionality have been demonstrated to be effective catalysts for many types of asymmetric reactions, such as (aza)-MBH reactions, cycloaddition reactions, and nucleophilic addition reactions. This short overview summarizes the recent advances in this field and highlights the most-significant achievements.
147 citations
TL;DR: Owing to the pH-responsive and biocompatible features of chitosan, the in vitro kill potency against MCF-7 breast-cancer cells was enhanced over time, as well as with increasing concentration of the drug-loaded CS-MSNs.
Abstract: Herein, we present a straightforward synthesis of pH-responsive chitosan-capped mesoporous silica nanoparticles (MSNs). These MCM-41-type MSNs could be used as nanocapsules to accommodate guest molecules. Subsequently, (3-glycidyloxypropyl)trimethoxysilane was grafted onto the surface of the MSNs, which served as a bridge to link between MSNs and chitosan, which is ubiquitous in nature and commercially available. Owing to the pH-responsive and biocompatible features of chitosan, the loading and release of an anti-cancer drug, doxorubicin hydrochloride, were carried out in vitro, in which the composite chitosan-capped MSNs (CS-MSNs) showed excellent environmental response. As the pH value of the media decreased, the degree of drug release correspondingly increased. Moreover, thanks to the perfect biocompatibility of chitosan, the CS-MSNs exhibited lower cytotoxicity than that of the naked MSNs in an MTT assay. In addition, the in vitro kill potency against MCF-7 breast-cancer cells was enhanced over time, as well as with increasing concentration of the drug-loaded CS-MSNs. These results indicate that CS-MSNs are promising candidates for pH-responsive drug delivery in cancer therapy.
123 citations
TL;DR: This Focus Review discusses recent structural modifications and syntheses of phosphorus-based materials, illustrates property tuning at the same time, and highlights specific examples for device applications.
Abstract: Phosphorus-based materials have received widespread attention in recent years, in particular as possible candidates for practical application in organic electronics. The geometry and electronic nature of phosphorus make it a favorable heteroatom for property tuning in order to obtain better performing organic electronics. This Focus Review discusses recent structural modifications and syntheses of phosphorus-based materials, illustrates property tuning at the same time, and highlights specific examples for device applications.
119 citations
TL;DR: A novel N-substituted heteroacene 2-(4'-(diphenylamino)phenyl)-4,11-bis((triisopropylsilyl)ethynyl)-1H-imidazo[4,5-b]phenazine (DBIP) has been designed, synthesized, and characterized and the devices show non-volatile and stable memory character with good endurance performance.
Abstract: N-substituted heteroacenes have been widely used as electroactive layers in organic electronic devices, and only a few of them have been investigated in organic resistive memory devices. Here, a novel N-substituted heteroacene 2-(4'-(diphenylamino)phenyl)-4,11-bis((triisopropylsilyl)ethynyl)-1H-imidazo[4,5-b]phenazine (DBIP) has been designed, synthesized, and characterized. Sandwich-structure memory devices based on DBIP have been fabricated and the devices show non-volatile and stable memory character with good endurance performance.
118 citations
TL;DR: The development of gold(I)-catalyzed intermolecular carbo- and hetero-cycloadditions of alkynes and allenes with alkenes has been more challenging than their intramolecular counterparts.
Abstract: The development of gold(I)-catalyzed intermolecular carbo- and hetero-cycloadditions of alkynes and allenes has been more challenging than their intramolecular counterparts. Here we review, with a mechanistic perspective, the most fundamental intermolecular cycloadditions of alkynes and allenes with alkenes.
TL;DR: The ZIS MSs co-loaded with CQDs and Pt exhibited a high photocatalytic H2 production rate of 1032.2 % (420 nm) in triethanolamine aqueous solution under visible-light irradiation, which was much higher than the respective photoc atalytic rates of pure ZIS, Pt loaded Z IS, and C QDs-decorated ZIS.
Abstract: ZnIn2S4 microspheres (ZIS MSs) were for the first time decorated with carbon quantum dots (CQDs) and plat- inum nanoparticles (NPs) as dual co-catalysts of for photo- catalytic H2 production. The ZIS MSs co-loaded with CQDs and Pt exhibited a high photocatalytic H2 production rate of 1032.2 mmol h � 1 g � 1 with an apparent quantum efficiency of 2.2 % (420 nm) in triethanolamine aqueous solution under visible-light irradiation, which was much higher than the re- spective photocatalytic rates of pure ZIS, Pt loaded ZIS, and CQDs-decorated ZIS. Such a great enhancement was attrib- uted to the integrative effect of good crystallization, en- hanced light absorption, high electrical conductivity of CQDs, and the vectorial electron transfer from ZIS to CQDs and Pt NPs (ZIS!CQDs!Pt).
TL;DR: Several leading methods for the preparation of nanometer-sized Janus particles are discussed and the important properties and applications of these Janus nanoparticles in electrochemistry, sensing, and catalysis are highlighted.
Abstract: In chemical functionalization of colloidal particles, the functional moieties are generally distributed rather homogeneously on the particle surface. Recently, a variety of synthetic protocols have been developed in which particle functionalization may be carried out in a spatially controlled fashion, leading to the production of structurally asymmetrical particles. Janus particles represent the first example in which the two hemispheres exhibit distinctly different chemical and physical properties, which is analogous to the dual-faced Roman god, Janus. Whereas a variety of methods have been reported for the preparation of (sub)micron-sized polymeric Janus particles, it has remained challenging for the synthesis and (unambiguous) structural characterization of much smaller nanometer-sized Janus particles. Herein, several leading methods for the preparation of nanometer-sized Janus particles are discussed and the important properties and applications of these Janus nanoparticles in electrochemistry, sensing, and catalysis are highlighted. Some perspectives on research into functional patchy nanoparticles are also given.
TL;DR: This Focus Review describes recent advances in the use of basic biological building blocks for creating molecules that act as hydrogelators and the potential applications of the corresponding hydrogels and offers a perspective and outlook on this fast-growing field at the interface of organic chemistry, materials, biology, and medicine.
Abstract: As a consequence of the self-assembly of small organic molecules in water, supramolecular hydrogels are evolving from serendipitous events during organic synthesis to become a new type of materials that hold promise for applications in biomedicine. In this Focus Review, we describe recent advances in the use of basic biological building blocks for creating molecules that act as hydrogelators and the potential applications of the corresponding hydrogels. After introducing the concept of supramolecular hydrogels and defining the scope of this review, we briefly describe the methods for making and characterizing supramolecular hydrogels. We then discuss representative hydrogelators according to the categories of their building blocks, such as amino acids, nucleobases, and saccharides, and highlight the applications of the hydrogels when necessary. Finally, we offer our perspective and outlook on this fast-growing field at the interface of organic chemistry, materials, biology, and medicine. By providing a snapshot for chemists, engineers, and medical scientists, we hope that this Focus Review will contribute to the development of multidisciplinary research on supramolecular hydrogels for a wide range of applications in different fields.
TL;DR: The various stimuli used and the utility of stimulus-responsive smart MOFs for various applications such as gas storage and separation, sensing, clean energy, catalysis, molecular motors, and biomedical applications are highlighted by using representative examples.
Abstract: Materials that can recognize the changes in their local environment and respond by altering their inherent physical and/or chemical properties are strong candidates for future "smart" technology materials. Metal-organic frameworks (MOFs) have attracted a great deal of attention in recent years owing to their designable architecture, host-guest chemistry, and softness as porous materials. Despite this fact, studies on the tuning of the properties of MOFs by external stimuli are still rare. This review highlights the recent developments in the field of stimulus-responsive MOFs or so-called smart MOFs. In particular, the various stimuli used and the utility of stimulus-responsive smart MOFs for various applications such as gas storage and separation, sensing, clean energy, catalysis, molecular motors, and biomedical applications are highlighted by using representative examples. Future directions in the developments of stimulus-responsive smart MOFs and their applications are proposed from a personal perspective.
TL;DR: The data clearly reveal that the electrochemical performance of Fe2 O3 can be improved by fluorine doping, thereby dramatically improving the energy density of the system.
Abstract: Nanostructured α-Fe2 O3 with and without fluorine substitution were successfully obtained by a green route, that is, microwave irradiation. The hematite phase materials were evaluated as a high-performance electrode material in a hybrid supercapacitor configuration along with activated carbon (AC). The presence of fluorine was confirmed through X-ray photoelectron spectroscopy and transmission electron microscopy. Fluorine-doped Fe2 O3 (F-Fe2 O3 ) exhibits an enhanced pseudocapacitive performance compared to that of the bare hematite phase. The F-Fe2 O3 /AC cell delivered a specific capacitance of 71 F g(-1) at a current density of 2.25 A g(-1) and retained approximately 90 % of its initial capacitance after 15 000 cycles. Furthermore, the F-Fe2 O3 /AC cell showed a very high energy density of about 28 W h kg(-1) compared to bare hematite phase (∼9 W h kg(-1) ). These data clearly reveal that the electrochemical performance of Fe2 O3 can be improved by fluorine doping, thereby dramatically improving the energy density of the system.
TL;DR: This Focus Review presents recent developments in the cleavage of C-C bonds in organic molecules and explains the development of a variety of new synthetic strategies that have recently been developed.
Abstract: This Focus Review presents recent developments in the cleavage of C-C bonds in organic molecules. Significant progress in C-C activation, including the development of a variety of new synthetic strategies, has contributed to the development of this field over the past few decades. Transition-metal-mediated C-C bond cleavage has been shown to be a quite efficient process and several elegant metal-free methods have also recently been developed. Strained rings have been widely used in C-C cleavage transformations; however, unstrained C-C activation has increasingly caught the attention of organic researchers, which inspired us to clarify the developments in this field.
TL;DR: The high local concentration of carbohydrates around the C60 core in fullerene sugar balls is perfectly suited to the binding of lectins through the "glycoside cluster effect", and these compounds are potential anti-adhesive agents against bacterial infection.
Abstract: Among the large variety of bioactive C60 derivatives, fullerene derivatives substituted with sugar residues, that is, glycofullerenes, are of particular interest. The sugar residues are not only solubilizing groups; their intrinsic biological properties also provide additional appealing features to the conjugates. The most recent advances in the synthesis and the biological applications of glycofullerenes are summarized in the present review article with special emphasis on globular glycofullerenes, that is, fullerene sugar balls, constructed on a hexa-substituted fullerene scaffold. The high local concentration of carbohydrates around the C60 core in fullerene sugar balls is perfectly suited to the binding of lectins through the "glycoside cluster effect", and these compounds are potential anti-adhesive agents against bacterial infection. Moreover, mannosylated fullerene sugar balls have shown antiviral activity in an Ebola pseudotyped infection model. Finally, when substituted with peripheral iminosugars, dramatic multivalent effects have been observed for glycosidase inhibition. These unexpected observations have been rationalized by the interplay of interactions involving the catalytic site of the enzyme and non-glycone binding sites with lectin-like abilities.
TL;DR: The efficient synthesis of a corticotropin-releasing factor1 (CRF1) receptor antagonist based on a late-stage C-H borylation strategy demonstrates the utility of the C8 borylated reaction.
Abstract: Site-selective C-H borylation of quinoline derivatives at the C8 position has been achieved by using a heterogeneous Ir catalyst system based on a silica-supported cage-type monophosphane ligand SMAP. The efficient synthesis of a corticotropin-releasing factor1 (CRF1) receptor antagonist based on a late-stage C-H borylation strategy demonstrates the utility of the C8 borylation reaction.
TL;DR: In this paper, the role played by localized surface plasmon resonance (LSPR) in catalyzing organic transformations and the role that light irradiation plays in catalystizing the reactions are discussed.
Abstract: Recent advances in direct-use plasmonic-metal nanoparticles (NPs) as photocatalysts to drive organic synthesis reactions under visible-light irradiation have attracted great interest. Plasmonic-metal NPs are characterized by their strong interaction with visible light through excitation of the localized surface plasmon resonance (LSPR). Herein, we review recent developments in direct photocatalysis using plasmonic-metal NPs and their applications. We focus on the role played by the LSPR of the metal NPs in catalyzing organic transformations and, more broadly, the role that light irradiation plays in catalyzing the reactions. Through this, the reaction mechanisms that these light-excited energetic electrons promote will be highlighted. This review will be of particular interest to researchers who are designing and fabricating new plasmonic-metal NP photocatalysts by identifying important reaction mechanisms that occur through light irradiation.
TL;DR: The reactions of aromatic compounds and elemental chalcogens catalyzed by a copper salt with molecular oxygen as an oxidant were carried out and could be applied to the copolymerization of bifunctional bisimidazopyridines and elemental sulfur to give oligomeric copolymers in quantitative yield.
Abstract: The reactions of aromatic compounds and elemental chalcogens catalyzed by a copper salt with molecular oxygen as an oxidant were carried out. The reaction of 3-substituted imidazo[1,5-a]pyridines and elemental sulfur in the presence of CuTC (copper(I) thiophenecarboxylate) gave the corresponding bisimidazopyridyl sulfides in good to quantitative yields. The reaction proceeded even under aerobic oxidation conditions. The use of a polar solvent was crucial for the reaction, and DMSO (dimethyl sulfoxide) in particular stimulated the reaction. The reaction could be applied to common aromatic compounds, such as N-methyl indole and dialkyl anilines. The reaction of indole proceeded at the nucleophilic C3 position rather than at the acidic C2 position. In addition, the reaction of dialkyl anilines proceeded with an ortho, para orientation. The reactions of imidazopyridines and elemental selenium under similar conditions gave the corresponding bisimidazopyridyl diselenides along with bisimidazopyridyl monoselenides. The resulting diselenides were readily converted to the corresponding monoselenides with unreacted imidazopyridines under the same conditions. The reaction could be applied to the copolymerization of bifunctional bisimidazopyridines and elemental sulfur to give oligomeric copolymers in quantitative yield.
TL;DR: The dyes with two anchors have more efficient interfacial charge generation and transport compared with their congeners with only single anchor and incorporation of hexyl chains into the π-conjugated spacer of these double-anchoring dyes can efficiently suppress dye aggregation and reduce charge recombination.
Abstract: A series of new push–pull phenothiazine-based dyes (HL1, HL2, HL3, HL4) featuring various π spacers (thiophene, 3-hexylthiophene, 4-hexyl-2,2′-bithiophene) and double acceptors/anchors have been synthesized, characterized, and used as sensitizers for dye-sensitized solar cells (DSSCs). Among them, the best conversion efficiency (7.31 %) reaches approximately 99 % of the N719-based (7.38 %) DSSCs fabricated and measured under similar conditions. The dyes with two anchors have more efficient interfacial charge generation and transport compared with their congeners with only single anchor. Incorporation of hexyl chains into the π-conjugated spacer of these double-anchoring dyes can efficiently suppress dye aggregation and reduce charge recombination.
TL;DR: Although the metalation of N-confused porphyrins has been explored in great detail, the formation of metallo-derivatives of other carbaporphyrinoids remains far less well explored.
Abstract: The cavities of carbaporphyrinoid systems provide unique environments for the formation of organometallic species. These systems commonly act as either dianionic or trianionic ligands, and may stabilize unusual oxidation states such as silver(III). Although the metalation of N-confused porphyrins has been explored in great detail, the formation of metallo-derivatives of other carbaporphyrinoids remains far less well explored. Nevertheless, exciting advances have been made on the metalation of carbaporphyrins, azuliporphyrins, benziporphyrins and related macrocycles.
TL;DR: The results indicate that surfactant-thermal synthesis could be a promising method for growing novel crystalline oxochalcogenides with interesting structures and properties.
Abstract: A new two-dimensional (2D) oxosulfide, (N2H4)2Mn3Sb4S8(μ3-OH)2 (1), has been successfully synthesized under surfactant-thermal conditions with hexadecyltributylphosphonium bromide as the surfactant. Compound 1 has a layered structure and contains a novel [Mn3(μ3-OH)2]n chain along the b-axis. The photocatalytic activity for compound 1 has been demonstrated under visible-light irradiation and continuous H2 evolution was observed. Our results indicate that surfactant-thermal synthesis could be a promising method for growing novel crystalline oxochalcogenides with interesting structures and properties.
TL;DR: It can be concluded that the synthesized CuNPs are catalytically highly efficient in spite of the presence of a protective PAA coating, which provides them with a long shelf life and thereby enhances the application potential of these CuNBP.
Abstract: We report an aqueous-phase synthetic route to copper nanoparticles (CuNPs) using a copper–surfactant complex and tests of their catalytic efficiency for a simple nitrophenol reduction reaction under atmospheric conditions. Highly stable, water-dispersed CuNPs were obtained with the aid of polyacrylic acid (PAA), but not with other dispersants like surfactants or polymethacrylic acid (PMAA). The diameter of the CuNPs could be controlled in the range of approximately 30–85 nm by modifying the ratio of the metal precursor to PAA. The catalytic reduction of p-nitrophenol to p-aminophenol takes place at the surface of CuNPs at room temperature and was accurately monitored by UV/Vis spectroscopy. The catalytic efficiency was found to be remarkably high for these PAA-capped CuNPs, given the fact that at the same time PAA is efficiently preventing their oxidation as well. The activity was found to increase as the size of the CuNPs decreased. It can therefore be concluded that the synthesized CuNPs are catalytically highly efficient in spite of the presence of a protective PAA coating, which provides them with a long shelf life and thereby enhances the application potential of these CuNPs.
TL;DR: IFMC-3 is stable in air and acidic/basic aqueous solutions at room temperature, and constitutes a selective luminescent sensing material for Ln(3+) ions and a recyclable probe for the sensitive detection of nitrobenzene.
Abstract: A hexagonal channel-based porous anionic metal-organic framework was successfully constructed. IFMC-3 is stable in air and acidic/basic aqueous solutions at room temperature, and constitutes a selective luminescent sensing material for Ln(3+) ions and a recyclable probe for the sensitive detection of nitrobenzene.
TL;DR: This study reports the first preparation of phase-pure Co9S8 yolk–shell microspheres in a facile two-step process and their improved electrochemical properties.
Abstract: In this study, we report the first preparation of phase-pure Co9S8 yolk–shell microspheres in a facile two-step process and their improved electrochemical properties. Yolk–shell Co3O4 precursor microspheres are initially obtained by spray pyrolysis and are subsequently transformed into Co9S8 yolk–shell microspheres by simple sulfidation in the presence of thiourea as a sulfur source at 350 °C under a reducing atmosphere. For comparison, filled Co9S8 microspheres were also prepared using the same procedure but in the absence of sucrose during the spray pyrolysis. The prepared yolk–shell Co9S8 microspheres exhibited a Brunauer–Emmett–Teller (BET) specific surface area of 18 m(2) g(−1) with a mean pore size of 16 nm. The yolk–shell Co9S8 microspheres have initial discharge and charge capacities of 1008 and 767 mA h g(−1) at a current density of 1000 mA g(−1), respectively, while the filled Co9S8 microspheres have initial discharge and charge capacities of 838 and 638 mA h g(−1), respectively. After 100 cycles, the discharge capacities of the yolk–shell and filled microspheres are 634 and 434 mA h g(−1), respectively, and the corresponding capacity retentions after the first cycle are 82% and 66%.
TL;DR: The idea of combining regular chemotherapy with radiation therapy to minimize side effects as well as increase drug-delivery efficiency is proposed as an overview of recent advances that can combine chemotherapy and radiotherapy.
Abstract: Research on anticancer therapies has advanced significantly in recent years. New therapeutic platforms that can further improve the health of patients are still highly demanded. We propose the idea of combining regular chemotherapy with radiation therapy to minimize side effects as well as increase drug-delivery efficiency. In this Focus Review, we seek to provide an overview of recent advances that can combine chemotherapy and radiotherapy. We begin by reviewing the current state of systems that can combine chemotherapy and gamma radiation. Among them, diselenide-containing polymers are highlighted as sensitive drug-delivery vehicles that can disassemble under gamma radiation. Then X-ray responsive materials as promising alternative systems are summarized, including X-ray responsive drug-delivery vehicles, prodrugs that can be activated by X-rays, and radiation-site-targeting systems. Finally, we describe strategies that involve phototherapies.
TL;DR: The neutral pyrazole precursor and its salts are remarkably thermally stable and compare favorably with those of TNT and RDX, which make them competitive as insensitive and thermallystable high-energy density materials.
Abstract: 3,6-Dinitropyrazolo[4,3-c]pyrazole was prepared using an efficient modified process. With selected cations, ten nitrogen-rich energetic salts and three metal salts were synthesized in high yield based on the 3,6-dinitropyrazolo[4,3-c]pyrazolate anion. These compounds were fully characterized by IR and multinuclear NMR spectroscopies, as well as elemental analyses. The structures of the neutral compounds 4 and its salt 16 were confirmed by single-crystal X-ray diffraction showing extensive hydrogen-bonding interactions. The neutral pyrazole precursor and its salts are remarkably thermally stable. Based on the calculated heats of formation and measured densities, detonation pressures (22.5-35.4 GPa) and velocities (7948-9005 m s(-1)) were determined, and they compare favorably with those of TNT and RDX. Their impact and friction sensitivities range from 12 to >40 J and 80 to 360 N, respectively. These properties make them competitive as insensitive and thermally stable high-energy density materials.
TL;DR: Upon introducing Ca(2+) dopants into the grain lattices by substituting Gd(3+) ions, irregular Yb/Er:NaGdF4 nanocrystals prepared through a simple solvothermal route convert into highly uniform nanorods.
Abstract: Upon introducing Ca(2+) dopants into the grain lattices by substituting Gd(3+) ions, irregular Yb/Er:NaGdF4 nanocrystals prepared through a simple solvothermal route convert into highly uniform nanorods. Meanwhile, their upconversion luminescence intensifies by about 200 times, probably due to a modification of the crystal structure of NaGdF4 and an improvement in the crystallinity of the nanophase.