Phase tuned quantum confined InS nanocrystals are accessible solvothermally using task-specific ionic liquids (ILs) as structure directing agents. Selective tuning of size, shape, morphology, and, most importantly, crystal phase of InS is achieved by changing the alkyl side chain length, the H-bonding, and aromatic π-stacking ability of the 1-alkyl-3- methylimidazolium bromide ILs, [Cmim]Br (n = 2, 4, 6, 8, and 10). It is observed that crystallite size is significantly less when ILs are used compared to the synthesis without ILs keeping the other reaction parameters the same. At 150 °C, when no IL is used, pure tetragonal form of β-InS appears however in the presence of [Cmim]Br [n = 2,4], at the same reaction condition, a pure cubic phase crystallizes. However, in case of methylimidazolium bromides with longer pendant alkyl chains such as hexyl (C), octyl (C) or decyl (C), nanoparticles of the tetragonal polymorph form. Likewise, judicious choice of reaction temperature and precursors has a profound effect to obtain phase pure and morphology controlled nanocrystals. Furthermore, the adsorption driven catalytic and photocatalytic activity of as-prepared nanosized indium sulfide is confirmed by studying the degradation of crystal violet (CV) dye in the presence of dark and visible light. A maximum of 94.8% catalytic efficiency is obtained for the InS nanocrystals using tetramethylammonium bromide (TMAB) ionic liquid.

In an ionic liquid assisted solvothermal synthesis developed by us for the synthesis of rare-earth (RE) fluorides, it is possible to control the product formation by the choice of the rare earth ion. For rareearth cations with smaller ionic radii (below 1.075Å), cubic NaREF 4 with a spherical morphology is obtained, whilst for rare-earth cations with radii between 1.08Å and 1.13Å, the formation of hexagonal NaREF 4 with a nanorod-like morphology is observed. For rare earth ions with a larger radius than that of La 3+ (1.216Å), instead of ternary fluorides, binary fluorides REF 3 in the trigonal modification is obtained.The growth mechanism behind this morphology change is explained from atomistic origin using electron microscope studies. The lattice strain changes with the rare-earth fluoride phase. For cubic NaREF 4 a tensile strain is observed, whilst for the hexagonal and trigonal binary fluoride a compressive strain is observed. The optical properties of the obtained materials promises use for various optoelectronic applications. Scheme 1 Tuning of crystal phase and nature of product (binary/ ternary) depending on the size of the RE 3+ ions for RE-doped NaREF 4 . 33468 | RSC Adv., 2017, 7, 33467-33476 This journal is NaYbF 4 :Er 3+ nanoparticles prepared solvothermally in the presence of [C 2 mim]Br at 200 C. This journal isFig. 7 (a) Excitation spectrum of NaGdF 4 :Eu 3+ nanocrystals (l em ¼ 615 nm); (b) emission spectra of NaGdF 4 :Eu 3+ ; and (c) NaYF 4 :Eu 3+ nanocrystals measured upon excitation at 393 nm (d) CeF 3 ; as well as CeF 3 :Tb 3+ nanocrystals measured upon excitation at 270 nm. 33474 | RSC Adv., 2017, 7, 33467-33476 This journal is

A task-specific ionic liquid (IL) is employed as a structure directing agent for the synthesis of quantum cutting BaGdF5:Eu3+ nanophosphors.

Pure Eu3+ ion doped BaF2 nanoparticles with tunable properties or property combinations are accessible via an ionic liquid-assisted solvothermal method. Structural parameters such as cell parameters, lattice strain, and especially morphology are judiciously tuned with calcination temperatures. For example, tensile strain is observed in samples calcined up to 400 °C; however, compressive strain appears in samples calcined at 600 °C and beyond. Larger surface area up to the sample calcined at 400 °C and observation of layer structure at higher calcinations temperature (650 °C and beyond) have been rationalized based on secondary nucleation. Three-dimensional island-like morphology with step-like layer structure caused by secondary nucleation and self-assembly are visualized and explained by scanning electron microscope analysis. Moreover, emission intensity, decay time, quantum yield, and Judd-Ofelt parameter of the Eu3+ ions increase systematically with calcination temperature to a maximum at 400 °C, above which they decrease and finally vanish at 800 °C. Our results suggest that smaller-sized nanoparticles with 3-dimensional island-like structures, generated due to secondary nucleation at higher calcinations temperature, may cause the increase of surface defects and subsequent luminescence quenching. To the best of our knowledge, the interplay between calcinations and secondary nucleation followed by drastic changes in the luminescence properties is new and previously unreported for the nanopowders. In addition, to improve the dispersibility, as-prepared nanoparticles are coated with silica and solubility of nanoparticles is measured in different solvents so that it can be useful for bioimaging applications also.

Phase pure BaF2 doped with Ce3+ (0.1%) nanocrystals are synthesized using an ionic liquid (IL) ([C4mim][BF4]) assisted solvothermal method where the IL is not only used as a reaction medium and a capping agent, but also as a reaction partner.

The nanoparticles with biomedical applications should be evaluated for its biocompatibility. Rare-earth doped nanoparticles with unique spectral properties are superior in-vivo optical probes over quantum dots and organic dyes; however,...

Phase pure quantum confined In2S3 nanocrystals with high catalytic/photocatalytic efficiency are accessible solvothermally using task specific ionic liquid (IL) as structure directing agent and thiourea as sulphur source. Selective tuning of the shape, morphology and most importantly purity of the nanomaterials are controlled by changing the reaction time, IL and specially sulphur concentration. For instances, at 150oC, when IL is used cubic phase is obtained; however in absence of IL, tetragonal phase with bigger crystallite size appears. In most of the cases In(OH)3 is coming as an impurity; however pure In2S3 with highest catalytic efficiency and band gap of 2.23 eV is achieved when 18 times sulphur concentration is used keeping other reaction parameters same. Photoluminescence emission spectra show that quantum confined pure In2S3 nanoparticles are blue emitting material. Furthermore, pure In2S3 nanoparticles are used for degradation of both cationic [crystal violet, methylene blue, rhodamine B] and anionic organic dyes [methyl orange]. Rate and overall catalytic efficiency are found highest for crystal violet (91%) followed by methylene blue (77%), rhodamine B (44.7%) and least for methyl orange (15.29%). Analysis reveals that along with electrostatic interaction, molecular structures of dye molecules have also significant impact on adsorption capacity which finally governs the catalytic (even in the dark) and photocatalytic efficiency of nanocrystals.

Graphene oxide-based nanocomposites (NCMs) exhibit diverse photonic and biophotonic applications. Innovative nanoengineering using a task-specific ionic liquid (IL), namely, 1-butyl-3-methyl tetrafluoroborate [C 4 mim][BF 4 ], allows one to access a unique class of luminescent nanocomposites formed between lanthanide-doped binary fluorides and graphene oxide (GO). Here the IL is used as a solvent, templating agent, and as a reaction partner for the nanocomposite synthesis, that is, “all three in one”. Our study shows that GO controls the size of the NCMs; however, it can tune the luminescence properties too. For example, the excitation spectrum of Ce 3+ is higher-energy shifted when GO is attached. In addition, magnetic properties of GdF 3 :Tb 3+ nanoparticles (NPs) and GdF 3 :Tb 3+ -GO NCMs are also studied at room temperature (300 K) and very low temperature (2 K). High magnetization results for the NPs (e.g., 6.676 emu g –1 at 300 K and 184.449 emu g –1 at 2 K in the applied magnetic field from +50 to −50 kOe) and NCMs promises their uses in many photonic and biphotonic applications including magnetic resonance imaging, etc.