Lanthanide-Based Coordination Polymers for the Size-Selective Detection of Nitroaromatics

Lanthanide coordination polymers (LnCPs), [Eu­(HL)₃(CH₃OH)₂]_<i>n</i> (<b>1</b>) and [Tb­(HL)₃(CH₃OH)­(H₂O)]_<i>n</i>·H₂O (<b>2</b>) (H₂L = 3-(picolinamido)­benzoic acid)), have been synthesized and characterized. Single crystal analyses of both LnCPs display that HL ligands not only coordinate to Ln ions but also act as the bridge between them generating one-dimensional (1D) chains. Such 1D chains further pack into three-dimensional (3D) architectures by the mediation of H-bonding interactions. Both LnCPs offer strategically placed exposed Lewis basic sites, which potentially interact with the electron-deficient nitroaromatics, whereas H-bonded 3D architecture having hydrophobic channels allows their facile inclusion within the network. A notable feature is the size-dependent sensing of nitroaromatics potentially governed by the packing of 1D chains into a 3D architecture. Both LnCPs act as the fluorescent sensor for quick, sensitive, and selective detection of nitrobenzene not only in solution but also in the vapor phase suggesting potential applications in the sensing devices for the detection of nitroaromatics

Tunable Mechanical, Electrical, and Thermal Properties of Polymer Nanocomposites through GMA Bridging at Interface

Polymer nanocomposites (PNCs) have become an exciting field of current research and have attracted a huge interest among both academia and industry during the last few decades. However, the multifunctional single-nanocomposite film exhibiting the combination of desired structure and properties still remains a big challenge. Herein, we report a novel strategy to address these problems by using versatile polymer glycidyl methacrylate (GMA) as a bridging medium between the filler and the polymer matrix, resulting in high density of interfaces as well as strong interactions, which lead to generation of tunable thermal, mechanical, and electrical properties in the materials. The nanocomposites prepared by GMA bridging exhibit the remarkable combination of thermal (<i>T</i>_d = 342.2 °C, <i>T</i>_g = 150.1 °C ), mechanical (<i>E</i> = 7.6 Gpa and <i>H</i> = 0.45 Gpa ) and electrical (σ = 3.15 × 10⁻⁵ S/cm) properties. Hence, the conjugation approaches related to GMA bridging facilitate a new paradigm for producing multifunctional polymer nanocomposites having a unique combination of multifunctional properties, which can be potentially used in next-generation polymer-based advanced functional devices

Fabrication of a Flexible UV Band-Pass Filter Using Surface Plasmon Metal–Polymer Nanocomposite Films for Promising Laser Applications

We introduce a strategy for the fabrication of silver/polycarbonate (Ag/PC) nanocomposite flexible films of (20 ± 0.01) μm thickness with different filling factor of surface plasmon metal using customized solution cast–thermal evaporation method. Structural characterizations confirmed the good crystallinity with cubic phase of Ag nanoparticles in PC films. Moreover, the microstructural evolutions of nanocomposite films are investigated by transmission electron microscopy, which indicates that the metal fraction is in the form of fractals. Additionally, the surface plasmonic behavior of nanocomposite films has been explored in detail to examine the distribution of Ag nanoparticles in PC film by spectroscopic technique. Furthermore, the obtained transmittance spectral features of this nanocomposite film are suitable for the applications of band-pass filter at 320 nm UV range, which is highly desirable for a HeCd laser

Fabrication of Artificially Stacked Ultrathin ZnS/MgF₂ Multilayer Dielectric Optical Filters

We report a design and fabrication strategy for creating an artificially stacked multilayered optical filters using a thermal evaporation technique. We have selectively chosen a zinc sulphide (ZnS) lattice for the high refractive index (<i>n</i> = 2.35) layer and a magnesium fluoride (MgF₂) lattice as the low refractive index (<i>n</i> = 1.38) layer. Furthermore, the microstructures of the ZnS/MgF₂ multilayer films are also investigated through TEM and HRTEM imaging. The fabricated filters consist of high and low refractive 7 and 13 alternating layers, which exhibit a reflectance of 89.60% and 99%, respectively. The optical microcavity achieved an average transmittance of 85.13% within the visible range. The obtained results suggest that these filters could be an exceptional choice for next-generation antireflection coatings, high-reflection mirrors, and polarized interference filters

Probing of Ni-Encapsulated Ferromagnetic Boron Nitride Nanotubes by Time-Resolved and Steady-State Photoluminescence Spectroscopy

Here we report the synthesis of multifunctional Ni-encapsulated boron nitride nanotubes (BNNTs), with average diameter and length measuring ∼30 nm and ∼25 μm, by a facile ball-milling–chemical vapor deposition route. The resulting BNNTs exhibit an intense blue emission peaking at ∼480 nm upon ∼365 nm excitation, and the time-resolved emission spectroscopy shows a photoluminescence decay lifetime of picoseconds. The SQUID magnetization measurements show an enhanced coercivity of 140 Oe. Obtained collective optical and magnetic properties of BNNT suggest that it could be an exceptional choice for future optomagnetic-based sensor devices, biomedical therapy, and bioimaging applications

Conversion of Industrial Bio-Waste into Useful Nanomaterials

Chromium-complexed collagen is generated as waste during processing of skin into leather. Here, we report a simple heat treatment process to convert this hazardous industrial waste into core–shell chromium–carbon nanomaterials having a chromium-based nanoparticle core encapsulated by partially graphitized nanocarbon layers that are self-doped with oxygen and nitrogen functionalities. We demonstrate that these core–shell nanomaterials can be potentially utilized in electromagnetic interference (EMI) shielding application or as a catalyst in aza-Michael addition reaction. The results show the ability to convert industrial bio-waste into useful nanomaterials, suggesting new scalable and simple approaches to improve environmental sustainability in industrial processes

Graphene Quantum Dots Derived from Carbon Fibers

Graphene quantum dots (GQDs), which are edge-bound nanometer-size graphene pieces, have fascinating optical and electronic properties. These have been synthesized either by nanolithography or from starting materials such as graphene oxide (GO) by the chemical breakdown of their extended planar structure, both of which are multistep tedious processes. Here, we report that during the acid treatment and chemical exfoliation of traditional pitch-based carbon fibers, that are both cheap and commercially available, the stacked graphitic submicrometer domains of the fibers are easily broken down, leading to the creation of GQDs with different size distribution in scalable amounts. The as-produced GQDs, in the size range of 1–4 nm, show two-dimensional morphology, most of which present zigzag edge structure, and are 1–3 atomic layers thick. The photoluminescence of the GQDs can be tailored through varying the size of the GQDs by changing process parameters. Due to the luminescence stability, nanosecond lifetime, biocompatibility, low toxicity, and high water solubility, these GQDs are demonstrated to be excellent probes for high contrast bioimaging and biosensing applications