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Chromism from phosphomolybdate – malachite green dye moiety through hydrogen bonding interaction with water molecules is reported. Interestingly, the substance with bound di-nitrogen or di-oxygen together with water molecules also exhibits color change. N2 or O2 binding vis-a-vis chromism is a new insight.

Yellow ammonium phosphomolybdate (YAPM), a waste product of all under graduate (UG) chemistry laboratory classes, has been proved to be an efficient adsorbent for environmental application as a cationic ion exchanger. The water insoluble YAPM selectively removes cationic dye molecules from dye contaminated wastewater. Consequently, dye infested YAPM solid is produced with fascinating color but bears altered band gap energy. Dye contaminated yellow APM is regenerated in air oven from the dye infested YAPM solid powder by heat treatment at ~ 300 °C and reused with full potential. So it becomes a solid phase extractant. Robust yellow APM turns to green APM (GAPM) upon UV light exposure because of the hoarded electrons in the basket like Keggin structure of phosphomolybdate (PMo12O40−3) moiety, and thereby the dye exchange capability is improved, admirably. Thus, the remediation of dye contaminated wastewater by YAPM has been found to be fruitful by YAPM and more potential dye remediation by GAPM.

Herein, for the first time, we applied the metal–metal-bond-energy factor to the evolution of a porous Se–Te alloy. The porous Se–Te material has been prepared from the constituents’ elemental states, through only a heating–cooling process in silicone oil without the use of any reagent, surfactant, or capping agent. Surprisingly, the reaction occurred at a much lower temperature (240 °C) than the mp (450 °C) of Te0. The reaction’s nucleation and growth by means of varied bond energy have been clarified for the first time. A difference in the bond energies of a hetero metal–metal bond (Se–Te) and a homo metal–metal bond (Se–Se) directs nucleation and growth toward the fabrication of a porous structure, even from the constituents’ elemental states, in which low-angle-grain-boundary (LAGB) and high-angle-grain-boundary (HAGB) movements play governing roles. Proper band-gap alignment of Se and Te makes the alloy composite applicable to water-splitting reactions under Xe-arc-lamp illumination. PEC efficiency o...

Chromism, generally a reversible color change of substances, finds vital applications in the fields of switching, catalysis, molecule binding, drug delivery and energy storage applications. Chromism is caused by the change of electronic, conformational, crystal or physical structure of materials due to heat, light, solvent/vapour, applied electric potential, etc. There have been observed different types of chromism such as thermochromism, photochromism, solvetochromism, electrochromism and many others from different compounds. Here in we have discussed different types of chromisms but in brief as inherited by various types of materials. Reversible multicolor chromism by metal halide formamidinium perovskite attests solvetochromism and thermochromism due to the hydrogen bonding. Tetrathiazolylthiophene compound shows mechanochromism because of the structural deformation. Chain length of ligand influences the chromism in copper complex. Gold cluster complex, boron complex, Bi2WO6 also display specific chromic performance. Phosphomolybdate – malachite green dye moiety (PMMG) displays hydrochromism because of bridged water molecules. N2 (or O2) binding to PMMG has recently been shown as an extension of hydrochromism phenomonon. Thus, this account on chromism from various materials is expected to attract the attention of researchers.

Hybrid Cu2O–Ag is attractive because of its many applications in the fields of photocatalysis, surface-enhanced Raman scattering (SERS), and optical features. In this article, we have presented a newer application of Cu2O–Ag. Cu2O–Ag has been found to exhibit excellent anionic dye adsorption properties together with organic transformation for effective water remediation. Cu2O–Ag was prepared through a facile but controlled galvanic reaction between cuprous oxide (Cu2O) and silver nitrate (AgNO3), rendering stability and porosity. The experimental results of adsorption showed that Cu2O–Ag bears an exceptionally high adsorption capacity toward methyl orange (501.23 mg g–1), which is higher than most reported results. The adsorption of MO on Cu2O–Ag happens because of the definite chemical interaction between Cu(I) and the SO3– functionality of MO. A kinetic study revealed that the MO adsorption on Cu2O–Ag primarily followed the pseudo-second-order kinetic model. The kinetic model followed the Langmuir adsor...

Morphology of a material with different facet, edge, kink, etc., generally influences the rate of a catalytic reaction.1,2 Herein, we account for the importance of altered morphology of a nanomaterial for a supercapacitor device and employed CoSn(OH)6 as an electrode material. Suitable fabrication of a stable aqueous asymmetric supercapacitor (AAS) using metal hydroxide as positive electrode can be beneficial if the high energy density is derived without sacrificing the power density. Here we have synthesized an uncommon hierarchical mesoporous nanostructured (HNS) CoSn(OH)6 to fabricate a pseudocapacitor. In this endeavor, NH3 is found to be a well-suited hydrolyzing agent for the synthesis.3 Serendipitously, HNS was transformed into favored cubic nanostructure (CNS) in NaOH solution. In solution, NaOH acts as a structure directing as well as an etching agent. Both the samples (HNSCNS) were used as pseudocapacitor electrodes in KOH electrolyte independently, which is reported for the first time. The HNS exhibits very high specific capacitance value (2545 F/g at 2.5 A/g specific current) with better cyclic durability over CNS sample (851 F/g at 2.5 A/g specific current). To examine the real cell application, we used HNS sample as the positive electrode material with the activated carbon (AC) as the negative electrode material for the development of an aqueous asymmetric supercapacitor (AAS). The as-fabricated AAS exhibited very high specific capacitance value of 713 F/g at a specific current of 1.5 A/g and retained 92% specific capacitance value even after 10 000 charge-discharge cycles. A maximum energy density of 63.5 Wh kg(-1) and a maximum power density of 5277 W kg(-1) were ascertained from the as-fabricated AAS, HNS CoSn(OH)6//AC.

In this work, the syntheses of Cu2O as well as Cu(0) nanoparticle catalysts are presented. Copper acetate monohydrate produced two distinctly different catalyst particles with varying concentrations of hydrazine hydrate at room temperature without using any surfactant or support. Then both of them were employed separately for 4-nitrophenol reduction in aqueous solution in the presence of sodium borohydride at room temperature. To our surprise, it was noticed that the catalytic activity of Cu2O was much higher than that of the metal Cu(0) nanoparticles. We have confirmed the reason for the exceptionally high catalytic activity of cuprous oxide nanoparticles over other noble metal nanoparticles for 4-nitrophenol reduction. A plausible mechanism has been reported. The unusual activity of Cu2O nanoparticles in the reduction reaction has been observed because of the in situ generated ternary nanocomposite, Cu2O-Cu-CuO, which rapidly relays electrons and acts as a better catalyst. In this ternary composite, highly active in situ generated Cu(0) is proved to be responsible for the hydride transfer reaction. The mechanism of 4-nitrophenol reduction has been established from supporting TEM studies. To further support our proposition, we have prepared a compositionally similar Cu2O-Cu-CuO nanocomposite using Cu2O and sodium borohydride which however displayed lower rate of reduction than that of the in situ produced ternary nanocomposite. The evolution of isolated Cu(0) nanoparticles for 4-nitrophenol reduction from Cu2O under surfactant-free condition has also been taken into consideration. The synthetic procedures of cuprous oxide as well as its catalytic activity in the reduction of 4-nitrophenol are very convenient, fast, cost-effective, and easily operable in aqueous medium and were followed spectrophotometrically. Additionally, the Cu2O-catalyzed 4-nitrophenol reduction methodology was extended further to the reduction of electronically diverse nitroarenes. This concise catalytic process in aqueous medium at room temperature revealed an unprecedented catalytic performance which would draw attention across the whole research community.

Herein, a wet-chemical synthetic approach has been adopted, taking advantage of electrostatic interactions between positively charged [CTA]+ capped Au NRs and negative functionalities of graphene oxide (GO), to fabricate dog-bone shaped Au NRcore–Pt/Pdshell decorated reduced graphene oxide (rGO) nanosheets (GMTs) for efficient ethanol electrooxidation reaction (EOR). This new strategy is based on an exceptionally efficient immobilization of trimetallic nanoparticles onto rGO sheets. It is important to note that the sequential addition of Pt and Pd precursor salts into the reaction mixture evolves Pd as the surface layer in the trimetallic assembly (described as GMT-1), whereas reversal of the sequence of addition results in spongy Pt NPs at the outer surface (designated as GMT-2), and thus two different types of Aucore–Pt/Pdsandwich–Pd/Ptshell nanoparticle-decorated rGO nanocomposites have been fabricated. The well recognized electrocatalytic performance of Pt is improved towards EOR by controlled assembling of Au and Pd in the rGO support in both the GMTs, exceeding the performance of the corresponding bimetallic composites. The presence of Pd and rGO decreases the CO poisoning of Pt and rGO supports restrict the aggregation of the nanoparticles during CV cycles. Thus the durability of the GMT catalysts has been improved in contrast to other related materials. Interestingly, the exposed spongy Pt NPs, present at the exterior of the trimetallic particles in GMT-2, help to exhibit better EOR activity (∼1.22 times) but lower durability (∼10%) in comparison to its analogue, GMT-1. The observed electrocatalytic efficiencies of GMTs are superior to commercial Pt/C (more than 6 times better mass utilization and ∼40% higher durability) and most of the recently reported related materials, which suggest cost-effective and efficient practical fuel cell application of GMTs.

The problem of poor electron conductivity is always associated with pseudocapacitive electrode material that deters full utilization of the active material. To have a viable solution to this problem, we report fabrication of a composite material bringing highly conductive carbon nanotube (CNT) wrapped pseudocapacitive with Co(OH) 2 nanoflakes. An in situ growth route evolves the supercapacitor via our laboratory developed modified hydrothermal reaction condition (MHT). An electrochemical investigation substantiates that the composite material electrode is highly active, which delivers a maximum specific capacitance of 603 F g −1 (at 1 mV s −1 scan rate), outstanding long-term cyclic stability with 96% retention at a constant current density of 1.5 A g −1 after 1000 cycles of operation. Thus it offers almost an effortless approach to fabricate high-power and high-energy density supercapacitors. By virtue of having high-capacity of pseudocapacitive hydroxides and desirable conductivity of carbon-based materials, the as-synthesized material could be a promising candidate for the development of supercapacitor electrode material.

In this paper, we report the design, synthesis, and characterization of three different composite nanomaterials (Cu-ZnO, Cu-Cu2O-ZnO, and Cu2O-ZnO) with surface plasmon resonance (SPR) effect and n–p heterojunction for visible light photocatalysis. We have accounted for the first time the SPR effect of Cu in photocatalysis for promotion of efficient electron–hole separation that further enhances visible light induced photocatalytic activity. To make the composite efficient we have judiciously introduced cheap and common Cu and Cu2O in ZnO matrix individually and cojointly to make the composites visible light sensitizer. Furthermore, wide band gap barrier of ZnO crosses its UV limit in the composites and spreads over to visible region. By simply varying the complexing agents, here we achieve success to obtain three kinds of highly stable composite nanomaterials with three distinct structures from identical experimental condition. This synthetic strategy offers a radically different approach where oxidation...

Modified hydrothermal route (MHT)-evolved Mn3O4 nanoparticles of ∼60 nm diameter were anchored onto a conductive multiwalled carbon nanotubes (MWCNTs) backbone (again under MHT) to produce an energy storage composite. To obtain the benefits of a low cost and stable MWCNT/Mn3O4 composite as a supercapacitor, cyclic voltammetry (CV) and galvanostatic charge–discharge measurements (GCD), as well as cycling stability and electrochemical impedance studies (EIS) have been performed. The electrochemical measurements reveal the suitability of the as-synthesized MWCNT/Mn3O4 composite as an electrode material with a highest specific capacitance of 441 F g−1 at 2 mV s−1 scan rate, which is 1.4 times higher than the specific capacitance (312 F g−1 at a scan rate of 2 mV s−1) of the bare Mn3O4 nanoparticle. MWCNT/Mn3O4 shows an excellent rate capability, outstanding long-term cyclic stability (98% capacity retention after 1000 consecutive cycles) and better power density and energy density. Due to the synergistic effect operating between the pseudocapacitor Mn3O4 nanoparticle and the conductive MWCNT, the capacitive performance of the composite electrode was considerably improved, and we perceive that the composite effect could have benefit in terms of supercapacitor application. These interesting improved material properties of the as-synthesized material indicate that the material is a suitable candidate for use in future energy storage applications.

In this report, CuS/ZnS heterojunctions were obtained through ion-exchange between as-prepared ZnS nanoflowers (synthesized using a modified hydrothermal route) and copper(II) sulfate in an aqueous solution. Then, the as-prepared CuS/ZnS heterojunctions prompted exceptional visible-light driven (λ ≥ 400 nm) photocatalytic activity, which surpasses almost all the reported ones. The photocatalyst performs best when a particular ratio of CuS and ZnS is maintained during the synthesis. This is observed at the ratio where CuS anchors onto the pre-formed ZnS, and gives rise to an effective heterojunction, which is found to be capable of degrading cationic dyes (such as methylene blue, crystal violet, and malachite green) within 120 s under visible-light exposure. Furthermore, the efficiency of the photocatalyst is preserved up to the 4th cycle of operation without any photo-corrosion. The dramatic enhancement in the visible-light photocatalytic performance of the CuS/ZnS heterojunctions over pure ZnS and CuS can be attributed to the effective electron–hole separation at the interfaces of the two semiconductors due to the formation of a superior heterojunction between the n-type semiconductor, ZnS, and p-type semiconductor, CuS, which facilitates the interfacial transfer of photoinduced carriers. The CuS loading onto ZnS is crucial to make the composite exceptionally photoactive for fast kinetics, which leads to prompt waste water treatment. The present study provides a new avenue to gain in-depth insight to the design of a highly efficient photocatalyst with heterojunctions.

High purity Sn(0) has been obtained as a result of reduction of SnO by sodium stannite (Na2SnO2) in aqueous solution. The process stands unique for the production of tin metal. The as-synthesized tin finds applications in synthetic organic chemistry as a reagent for the allylation of aldehydes and ketones in distilled water at room temperature to give rise to the corresponding homoallylic alcohols with high yield. The reaction occurs without the assistance of heat, ultrasonic vibration, co-solvents/co-reagents, etc. Enhancement of the reaction rate of allylation was observed in water rather than THF. The manipulation of allylation reaction becomes easy with active tin material.

A modified hydrothermal protocol (MHT) has been adopted for the synthesis of a single-crystal of CoV2O6·2H2O. The crystals grew as a result of prolonged hydrothermal reaction between precursor salts of CoCl2 and ammonium vanadate. At first, the adopted reaction conditions resulted in nanowires of CoV2O6·4H2O. Then with increased reaction time, nanowires changed to single crystals of molecular formula CoV2O6·2H2O. The nanowires have lengths of several tens of micrometers and average diameter of 100 nm. The well defined structure crystallizes in the orthorhombic crystal system having space group Pnma and it displays a = 5.5647(2) A, b = 10.6870(5) A, c = 11.8501(5) A, α = β = γ = 90.00°. Here, each vanadium atom is tetrahedrally connected to four oxygens where two oxygens are connected to vanadium atoms and another two connected to cobalt atoms. Magnetic moment measurement of the nanowires indicates that antiferromagnetic ordering is observed at around 14.9 K and 6.8 K and field induced antiferromagnetic to ferromagnetic (spin-flop-type) transitions have been observed at a low temperature (5–8.8 K) range while these are absent in the as-synthesized single crystals.

Ultralong Ag1.92Mo3O10·H2O nanowires have been serendipitously obtained due to selective etching of ammonium phosphomolybdate (APM) only by Ag+ ions in water under stirring conditions. The spherical yellow APM particle upon etching by Ag+ ions generates a hollow sphere, and PO43– ions are expelled as a consequence of etching. The etching and hollowing disrupt the APM structure. Concentration of the etching agent and reaction time are crucial for the formation of Ag1.92Mo3O10·H2O nanowire. The growth of nanowires occurs probably due to etching followed by Ostwald ripening, oriented attachment, and splitting process. Finally, the as-synthesized nanowire exhibits a high capacity to adsorb cationic dyes on its surface. It shows superb adsorption properties, with maximum adsorption capacity of 110 mg g–1, 175 mg g–1, 160 mg g–1 for Methylene Blue, Methyl Green, Crystal Violet, respectively. Moreover, the adsorption process of Methylene Blue on the nanomaterial was investigated taking it as a representative ads...

A wide variety of [1,2,3]triazolo[5,1-c][1,4]benzoxazines were synthesized through palladium-copper catalyzed reactions of 1-azido-2-(prop-2-ynyloxy)benzene with aryl/vinyl iodides. A plausible reaction mechanism has also been proposed.

Homoallylic alcohols (III), (V) are obtained by allylation of the various substituted aldehydes or ketones using high purity Sn(0) as catalyst.

Superhydrophobic surfaces prevent percolation of water droplets and thus render roll-off, self-cleaning, corrosion protection, etc., which find day-to-day and industrial applications. In this work, we developed a facile, cost-effective, and free-standing method for direct fabrication of copper nanoparticles to engender superhydrophobicity for various flat and irregular surfaces such as glass, transparency sheet (plastic), cotton wool, textile, and silicon substrates. The fabrication of as-prepared superhydrophobic surfaces was accomplished using a simple chemical reduction of copper acetate by hydrazine hydrate at room temperature. The surface morphological studies demonstrate that the as-prepared surfaces are rough and display superhydrophobic character on wetting due to generation of air pockets (The Cassie-Baxter state). Because of the low adhesion of water droplets on the as-prepared surfaces, the surfaces exhibited not only high water contact angle (164 ± 2°, 5 μL droplets) but also superb roll-off and self-cleaning properties. Superhydrophobic copper nanoparticle coated glass surface uniquely withstands water (10 min), mild alkali (5 min in saturated aqueous NaHCO3 of pH ≈ 9), acids (10 s in dilute HNO3, H2SO4 of pH ≈ 5) and thiol (10 s in neat 1-octanethiol) at room temperature (25-35 °C). Again as-prepared surface (cotton wool) was also found to be very effective for water-kerosene separation due to its superhydrophobic and oleophilic character. Additionally, the superhydrophobic copper nanoparticle (deposited on glass surface) was found to exhibit antibacterial activity against both Gram-negative and Gram-positive bacteria.

Selenium generally exhibits preferential habitual 1D growth as a result of redox reactions of selenium compounds. Commercial Se powder melts in silicone oil under refluxing conditions and upon subsequent cooling evolve amorphous Se nanoballs (SNBs). Further ultrapure crystalline 1D Se grows from SNBs due to solvent mediated oriented attachment.

Thermochromic properties of a series of non-ionic copper compounds have been reported. Herein, we demonstrate that Cu(II) ion with straight-chain primary amine (A) and alpha-linolenic (fatty acid, AL) co-jointly exhibit thermochromic properties. In the current case, we determined that thermochromism becomes ligand chain length-dependent and at least one of the ligands (A or AL) must be long chain. Thermochromism is attributed to a balanced competition between the fatty acids and amines for the copper(II) centre. The structure–property relationship of the non-ionic copper compounds Cu(AL)2(A)2 has been substantiated by various physical measurements along with detailed theoretical studies based on time-dependent density functional theory. It is presumed from our results that the compound would be a useful material for temperature-sensor applications.

In this work, we propose a systematic and delicate size- and shape-controlled synthesis of CuO-MnO2 composite nanostructures from time-dependent redox transformation reactions between Cu2O and KMnO4. The parental size and shape of Cu2O nanostructures are retained, even after the redox transformation, but the morphology becomes porous in nature. After prolonged reaction times (24 h), the product shapes are ruptured, and as a result, tiny spherical porous nanocomposites of ∼100 nm in size are obtained. This method is highly advantageous due to its low cost, its easy operation, and a surfactant or stabilizing agent-free approach with high reproducibility, and it provides a facile but new way to fabricate porous CuO-MnO2 nanocomposites of varied shape and size. The composite nanomaterials act as efficient recyclable catalysts for nitroarene reduction in water at room temperature. The time-dependent reduction kinetics can be easily monitored by using UV-vis spectrophotometer. The catalytic system is found to be very useful toward the reduction of nitro compounds, regardless of the type and position of the substituent(s). Furthermore, it is revealed that CuO-MnO2 composite nanomaterials exhibit facet-dependent catalytic activity toward nitroarene reduction, where the (111) facet of the composite stands to be more active than that of the (100) facet. The results are also corroborated from the BET surface area measurements. It is worthwhile to mention that porous tiny spheres (product of 48 h reaction) exhibit the highest catalytic activity due to pronounced surface area and smaller size.

A new, one-pot palladium catalyzed reaction has been developed for the general synthesis of (E)-3-arylidene-3,4-dihydro-2H-1,4-benzoxazines at room temperature. The reaction procedure tolerates various functional groups. The method is characterized by regio- and stereoselectivity, operational simplicity, mild reaction conditions, and short reaction time.

The method includes a Sonogashira coupling of aryl iodides with substrate (I) or its homologue (VI), in situ diazotization, azidation and cycloaddition.

We describe herein a convenient approach for the general synthesis of novel tricyclic scaffolds incorporating a fusion of the 1,2,3-triazole ring with difficultly obtainable medium sized rings such as [1,4]benzodiazepin-5-ones and [1,5]benzodiazocin-6-ones through Sonogashira coupling of an aryl iodide with 2-amino-N-methyl-N-(prop-2-ynyl)benzamide or homologue followed by in situ diazotisation, azidation and cycloaddition reactions. The strategy also allows easy accessibility of the corresponding amide-reduced analogues. The operational simplicity and easy substrate availability make the process cost effective and practical.

A general one-pot Pd-catalyzed synthesis of the target compounds (E)-3-arylidene-1,4-benzoxazines starts from inexpensive and readily available starting materials.

A wide variety of [1,2,3]triazolo[5,1-c][1,4]benzoxazines were synthesized through palladium-copper catalyzed reactions of 1-azido-2-(prop-2-ynyloxy)benzene with aryl/vinyl iodides. A plausible reaction mechanism has also been proposed.

An efficient strategy for the general synthesis of 3-aryl substituted pyrazolo[5,1-c][1,4]benzoxazines and pyrazolo[1,5-a][1,4]benzodiazepin-6(4H)-ones has been developed using intramolecular 1,3-dipolar cycloaddition. The hydrazonoyl chloride, the precursor of the cycloadduct, is accessed easily through a two-step reaction carried out in one-pot. It is then used without purification for the base induced formation of the nitrilimine, which undergoes subsequent in situ intramolecular cycloaddition with an alkyne to afford the desired product. The reaction protocol has also been applied in bis-heteroannulation and in the synthesis of uracil derivatives of biological interest. The operational simplicity of the process, the use of cheap starting materials, and the relatively short reaction times required make the process convenient and practical.