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Incorporation of suitable lanthanide (Ln3+) ions into semiconducting WO3 can be useful to produce host-sensitized luminescence for solid-state lighting applications. Codoping of another Ln3+ ion ca...

NaLnF4 nanoparticles (NPs) with lighter lanthanides (where Ln = La, Ce, Nd, or Pr) are more difficult to prepare than those with heavier lanthanides [Naduviledathu et al. Chem Mater., 2014, 26, 568...

We report the synthesis and studies of self-assembly in solution of two related polyferrocenyldimethylsilane (PFS) ABC triblock terpolymers (TTPs), in which the BC blocks are amphiphilic comb diblo...

We describe a polyferrocenyldimethylsilane (PFS) block copolymer (BCP), PFS27-b-P(TDMA65-ran-OEGMA69) (the subscripts refer to the mean degrees of polymerization), in which the corona-forming block is a random brush copolymer of hydrophobic tetradecyl methacrylate (TDMA) and hydrophilic oligo(ethylene glycol) methyl ether methacrylate (OEGMA). Thus, the corona is amphiphilic. This BCP generates a remarkable series of different structures when subjected to crystallization-driven self-assembly (CDSA) in solvents of different polarity. Long ribbon-like micelles formed in isopropanol, and their lengths could be controlled using both self-seeding and seeded growth protocols. In hexanol, the BCP formed more complex structures. These objects consisted of oval platelets connected to long fiber-like micelles that were uniform in width but polydisperse in length. In octane, relatively uniform rectangular platelets formed. Finally, a distinct morphology formed in a mixture of octane/hexanol, namely uniform oval structures, whose height corresponded to the fully extended PFS block. Both long and short axes of these ovals increased with the initial annealing temperature and with the BCP concentration. The self-seeding protocol also afforded uniform two-dimensional structures. Seeded growth experiments, in which a solution of the BCP in THF was added to a colloidal solution of the oval micelles led to a linear increase in area while maintaining the aspect ratio of the ovals. These experiments demonstrate the powerful effect of the amphiphilic corona chains on the CDSA of a core crystalline BCP in solvents of different hydrophilicity., A crystalline-coil block copolymer with an amphiphilic corona-forming block affords a variety of different 2D structures in different self-assembly media.

This work presents a simple approach to access uniform fiber-like micelles by single-step crystalization-driven co-self-assembly of a polyferrocenyldimethylsilane (PFS) block copolymer with a trace of a PFS homopolymer. The length of micelles in the μm range could be controlled by changing the amount of homopolymer in the mixture.

The engineering of high-performance functional nanomaterials for efficient monitoring of Vitamin-C/Ascorbic Acid (AA) is highly desirable in the food, chemical, cosmetics, and pharmaceutical industries. In this regard, this report presents the engineering of novel cerous sulfate Ce2(SO4)3 nanoflowers, decorated reduced graphene oxide (rGO) through an economic, energy-efficient and rapid one-pot hydrothermal strategy for electrochemical detection of AA. The obtained nanocomposite demonstrates the successful formation of nano Ce2(SO4)3 with flower morphology having large surface area and potential to promote the electrolyte accessibility as well as electronic transmission during sensing phenomenon. The Ce2(SO4)3/rGO (CSG) nanoflower composite was drop casted on screen printed carbon electrode (SPCE) and tested for its electrochemical detection of AA. At +0.337 V, a well-defined oxidation peak of AA occurred in phosphate buffer solution of pH 7. A linear response of the CSG electrode was further obtained under optimum conditions, for the AA concentration range of 10 − 1000 μM with a sensitivity of 0.2973 μA μM−1cm−2 and lowest detection limit of 900 μM. The excellent Vitamin-C sensing ability of CSG is attributed to the synergistic effect from the dimensional anisotropy of flower-like morphological features of Ce2(SO4)3 as well as the interfacial structure. The CSG was also tested for vitamin C tablets, VeeCee-Z, to validate its commercial applicability. Furthermore, fabricated electrochemical sensor exhibited significant reproducibility (98.63%) and optimum stability. Thus, the significant findings of this work are believed to hold the prospect for sensitive and prompt determination of Vitamin-C in the industrial domains.

Lanthanide-doped nanomaterials exhibit fascinating luminescence properties such as sharp emission, long luminescence lifetime, and emission over a wide wavelength span ranging from ultraviolet to far infrared. Exploiting these optical properties, they have been widely utilized in bioimaging, drug delivery, display devices, lasers, solid-state lighting, and solar cells. Interestingly, their luminescence characteristics are strongly correlated with the doping concentration, dopant–host combination, morphology, crystal structure, and the ligand present over the surface of the nanoparticles. Various physical methods (e.g., ball milling, physical vapor deposition, sputtering, and laser ablation) and chemical routes (e.g., chemical vapor deposition, hydrothermal, thermolysis, coprecipitation, sol–gel, and so on) are well established for the formation of lanthanide ion–doped nanomaterials. Among all, the solution-based synthesis methods or wet chemical methods are proven to be very promising in synthesizing the nanoparticles of desired structural features (e.g., particle size, shape, uniformity, phase, chemical composition, and functionality). Numerous wet chemical methods are well established for the synthesis of a variety of nanomaterials with each of them having some merits and demerits. A prior understanding about each of them is essential before adapting them for material preparation. In this direction, the current book chapter covers brief discussion about a few of important wet chemical methods that are 56very promising for the preparation of Ln-NPs of desired structural features. The chapter also deals with the basics of lanthanide ions luminescence discussing various factors that influence the luminescence characteristics of lanthanide ion–doped nanoparticles. Finally, a brief discussion about the application of luminescent Ln3+-doped nanomaterials in various fields such as biomedical, lighting, and energy harvesting is also presented based on the recent literature review.

Although there have been many reports on the synthesis of NaLnF4 nanoparticles (NPs), in particular ones that show upconversion luminescence, there is still an insufficient understanding of the mec...

Morphology of lanthanide (Ln3+)-doped nanostructures plays a crucial role in determining the crystal-field-dependent luminescent properties as that modulates the surface-to-bulk ratio of Ln3+ ions....

Undoped and europium (Eu3+) doped CaWO4 samples were prepared at room temperature using co-precipitation method and investigated for their thermal stability by annealing at different temperatures, namely 300, 500, 700 and 900 °C in air. It is observed that incorporation of Eu3+ ions destabilizes CaWO4 lattice and favors its decomposition at elevated temperatures. Powder X-ray diffraction (XRD) studies confirmed that as-synthesized CaWO4: 1% Eu3+ remains stable up to an annealing temperature of 500 °C, and above that it partially decomposes into WO3 phase. Unlike this, undoped CaWO4 remains stable under similar annealing conditions. Photoluminescence, UV–Visible, and infra-red absorption studies provide important evidence for partial decomposition of CaWO4: 1% Eu3+ into its constituent oxides upon annealing at temperatures above 500 °C.

NaLnF

The up-converting nanophosphors are the nano-crystalline materials that produce luminescence by converting low-energy radiation (e.g., infrared or near-infrared) into high energy radiation (ultraviolet and visible) via an anti-Stokes shift process. These can be prepared by incorporating up-converting luminescent centers such as lanthanide ions (Ln3+ ions, where Ln = Nd, Ho, Er, and Tm) and/or transition metal ions (e.g., Mn2+, Ti2+, Ni2+, Mo3+, Re4+, and Os4+) into a suitable nano-crystalline host material. The choice of dopant–host combination is decisive in determining the luminescence characteristics of a nanophosphor. Inorganic fluoride hosts such as ALnF4 and LnF3 (where A and Ln refer to alkali metal ions and lanthanide ions, respectively) and BF2 (B stands for Ca and Sr) are found suitable for up-converting Ln3+ ions as they exhibit; (i) low phonon energy, (ii) promising doping conditions, (iii) favorable electronic structure, and (iv) excellent chemical, thermal, and photo-stability. Ln3+ ions doped fluoride nanophosphors (where Ln = Ho3+, Er3+, and Tm3+) exhibit unique up-conversion luminescence characteristics such as strong emission in visible window, substantial anti-Stokes shifts (>600 nm), prolonged luminescence lifetimes (up to several milliseconds), and sensitization under infrared (IR) or near-infrared (NIR) irradiation. Due to these fascinating luminescence properties, they find potential applications in bio-imaging, drug delivery, tumor targeting, solid-state lighting, energy harvesting. Interestingly, their luminescence characteristics can be altered by varying the doping concentration, dopant–host combination, morphology, crystal structure, and the functional group present over the surface of the nanoparticles. This has given prime focus toward developing novel synthesis techniques that are promising in preparing the fluoride-based nanophosphors of desired morphological, compositional, structural, and optical characteristics. The solution-based synthesis methods or wet chemical methods are very promising in producing nanophosphors of controlled size–shape, phase, and chemical composition. Several solution-based methods were developed in past for the preparation of fluoride-based nanocrystals, with each of them having some merits and demerits. Therefore, a prior understanding of each method is essential before adapting it for material preparation. In this regard, this chapter provides a brief description about a few of solution-based synthesis methods such as hydrothermal, co-precipitation, and thermolysis, which are most versatile in the controlled preparation of a variety of Ln3+-doped fluoride nanophosphors (e.g., ALnF4, BF2, and LnF3, where A, B, and Ln stand for alkali metal, alkaline earth metal, and lanthanide ions, respectively).The critical role of reaction parameters such as pH of the reaction medium, precursor amount, ligands, reaction temperature and time on the controlled preparation of Ln3+-doped fluoride nanophosphors will be discussed in light of available literature. Further, the impact of morphological, structural, and compositional characteristics of the nanophosphors on their luminescence behavior will be discussed in regard to their biomedical, energy harvesting, and lighting applications.

Elongated colloidal nanoparticles (NPs) have significant potential for drug delivery and imaging applications in cancer therapy, but progress depends on developing a deeper understanding of how their physicochemical properties affect their interactions with cells and with tumors. Cellulose nanocrystals (CNCs) are biocompatible, rodlike colloids that are broadly surface-functionalizable, making them interesting as modular drug carriers. In this report, we describe the attachment of a statistical copolymer containing oligoethylene glycol methacrylate (OEGMA

Zircon-type tetragonal LaVO4 phase is a suitable host for luminescent lanthanide ions but exhibits poor stability and transforms to monazite-type monoclinic phase at elevated temperatures and pressures. Here, we have studied the effect of partial substitution of La3+ with Eu3+ ions on the phase stability of tetragonal LaVO4 using the temperature and pressure induced phase transformation characteristics. Experimentally measured activation energy required for the initiation of phase transformation is found to increase with increasing europium content and suggests dopant induced stabilization of the tetragonal phase. The critical pressure (Pc) and critical temperature (Tc) required for tetragonal to monoclinic phase transition increase with increasing Eu3+ ions concentration, values being Tc = 300, 500, and 600 °C and Pc = 2, 4, and 6.5 GPa for compositions x = 0, 0.025, and 0.05, respectively. The simulations based on density functional theory (DFT) support the Pc data, and the decrease in the formation ene...

Dye-sensitized photoelectrochemical (DSPEC) device for solar hydrogen generation is gaining significant attention. However, there are some fundamental challenges such as dye desorption, aggregation and photo-stability impediment its long term performance. To circumvent the subset of these challenges herein, we demonstrate click chemistry based fabrication methodology to develop optically complemented multiple dyes anchored P25-TiO 2 scaffold over ITO plate. A photocurrent density of ∼2.1 mA/cm 2 and ABPE of ∼1.0% have been obtained with optically complemented multiple dyes (N719 and FITC) clicked P25-TiO 2 @ITO photoanode compared to single N719 (ABPE ∼ 0.72%), N749 (ABPE ∼ 0.60%), and N3 (ABPE ∼ 0.51%) at 0.7 V applied bias. We trust that proposed approach can pave a pathway to anchor combination of different optically complemented dyes over number of semiconductor photocatalyst.

Doping of size mismatched aliovalent ions is challenging due to the associated elastic and electronic stress making the thermodynamics unfavorable. Despite such features, its utilization may be viable if such systems can be made metastable by suppressing the kinetics of phase segregation. In light of such a possibility, we utilize sol-gel synthesis for preparing a size mismatched trivalent europium doped MgO (Mg(1-x)Eu(x)O:(x/2)V"(Mg)) system, which can be potentially used in optical applications. It is found that such a doped system can be metastabilized and the extent of metastability can be correlated with critical temperature (Tc) required for phase segregation which decreases with the dopant concentration. For x = 0.005, 0.01, and 0.02, Tc is above 1200 °C, 500-800 °C and less than 500 °C, respectively. As the synthesis temperature is 500 °C, these trends in critical temperatures make it impossible to metastabilize europium in MgO with x0.01. Doping is evident from X-ray diffraction data, excitation spectra, high resolution emission spectra, and luminescence lifetimes. A characteristic strong red emission of Eu(3+) has been observed via energy transfer from the MgO matrix to Eu(3+). Density functional theory based simulations suggest stabilization of Eu(3+) in MgO at lower doping concentration through the formation of cation vacancies which is also evident from optical studies. Furthermore, thin films deposited using the e-beam evaporation technique from the Mg(1-x)Eu(x)O:(x/2)V"(Mg) (x = 0.005) system show UV sensitized emission with CIE coordinates (0.26, 0.21).

Four dinuclear lanthanide complexes [Gd2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (1), [Tb2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (2), [Dy2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (3) and [Eu2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (4) were synthesized by the reaction of appropriate Ln(III) chloride salts and a multidentate ligand, 2,2'-(2-hydroxy-3-methoxy-5-methylbenzylazanediyl)diethanol (H3L) in the presence of pivalic acid. 1-4 are neutral and are held by two monoanionic, [H2L](-) ligands. The two lanthanide ions are doubly bridged to each other via two phenolate oxygen atoms. Both the lanthanide ions are nine coordinated and possess a distorted capped square antiprism geometry. Photophysical studies reveal that Tb(3+) (2) and Dy(3+) (3) complexes display strong ligand-sensitized lanthanide-characteristic emission. The Tb(3+) complex (2) shows a very high overall quantum yield of 76.2% with a lifetime of 1.752 ms. Magnetic studies reveal single-molecule magnet behavior for 3 which shows in its ac susceptibility studies a two-step slow relaxation yielding two effective relaxation energy barriers of ΔE = 8.96 K and 35.51 K.

White light has been generated from dispersible lanthanide ion-doped LaVO4 core–shell nanoparticles by using a single UV excitation source. The core–shell nanoparticles are excited with single wavelength 280 nm UV light, in which the energy transfer from [VO4]3− groups to Ln3+ ions occurs to produce bright white light. The absolute quantum yields of LaVO4:Tm3+/Tb3+/Eu3+ (Type 1) and LaVO4:Tm3+/Dy3+ (Type 2) core–shell nanoparticles have been estimated as 5% and 7% respectively. The control core nanoparticles doped with all the lanthanide ions did not produce white light which proves the need of a core–shell structure. The core–shell structure of LaVO4 nanoparticles has been investigated by TEM, EDX, XRF, and PL spectroscopy techniques.