Synthesis and Characterization of Lightweight Beryllium Chloro Silicate Phosphor

In this chapter, low weight barium-based cholorsilicate Ba5Cl6Si2O6:Eu2+ is prepared through a solid-state reaction. To confirm the structure of the synthesized phosphors, powder photographs were obtained using an x-ray diffractometer. Photoluminescence spectra and FTIR spectra were recorded. Photoluminescence spectra are studied. The emission peak is observed at 407 nm at excitation 275 nm. The intense violet-blue emission is obtained. The broad excitation band and strong emission indicate that Ba5Cl6Si2O6:Eu2+could be a good phosphor candidate for blue LED and white LEDs. Decay curve indicates the phosphor has a long afterglow feature.

Modular chiral Eu(III) complexes for efficient circularly polarized OLEDs

Achieving both high dissymmetry factors and strong emission in circularly polarized (CP) luminescent materials and, at the same time, compatibility with manufacturing processes for organic electronic devices, is a crucial...

Pyrene-based monomer-excimer dual response organosilicon polymer for selective detection of 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenol (TNP)

The formation or destruction of pyrene excimer with strong emission change make it a versatile fluorophore to construct excimer emission-based fluorescence probes for various analytes detection. The distinct difference between...

Optical Characteristics and Applications of AIE Racemic C6-Unsubstituted Tetrahydropyrimidines

Racemic C6-unsubstituted tetrahydropyrimidines (THPs) are the products of an efficient five-component reaction that we developed. THPs show strong AIE characteristics, that is, completely no fluorescence in different solvents but strong emission with fluorescence quantum yields (ΦF) up to 100% upon aggregation. However, the ΦF values of their pure enantiomers are lower than 46%. Unlike common AIE compounds with crowded aryl rotors on a π-bond or on an aryl ring, THPs have three completely non-crowded aryl rotors on a non-aromatic chiral central ring (tetrahydropyrimidine). In this mini review, we first discuss the AIE characteristics of THPs and the influences of molecular structures on their molecular packing modes and optical properties, and then present their applications and forecast the development of other racemic AIE compounds.

A new luminescent metal-organic framework with 2,6-di(1H-imidazol-1-yl)naphthalene and biphenyl-3,4′,5-tricarboxylic acid

In this work, a novel metal-organic framework (MOF) based on 2,6-di(1H-imidazol-1-yl)naphthalene (L) and biphenyl-3,4′,5-tricarboxylic acid (H3bptc), namely [Co(L)(Hbptc)(H2O)] (1), has been prepared. 1 has a distinct infinite chain structure, further linked together by winding interactions to give the three-dimensional (3D) network structure. 1 was characterized by X-ray crystallography, infrared spectra (IR) spectroscopy, elemental and thermal analysis. Photoluminescence studies revealed that 1 shows a strong emission at 361 nm upon excitation at 290 nm at room temperature. Moreover, 1 can efficiently detect Fe3+ ions by luminescence quenching.

Valley polarization of trions in monolayer MoSe2 interfaced with bismuth iron garnet

Interfacing atomically thin van der Waals semiconductors with magnetic substrates enables additional control on their intrinsic valley degree of freedom and provides a promising platform for the development of novel valleytronic devices for information processing and storage. Here we study circularly polarized photoluminescence in heterostructures of monolayer MoSe2 and thin films of ferrimagnetic bismuth iron garnet. We observe strong emission from charged excitons with circular polarization opposite to that of the pump and demonstrate contrasting response to left and right circularly polarized excitation, associated with finite out-of-plane magnetization in the substrate. We propose a theoretical model accounting for magnetization-induced imbalance of charge carriers in the two valleys of MoSe2, as well as for valley-switching scattering from B to A excitons and fast formation of trions with extended valley relaxation times, which shows excellent agreement with the experimental data. Our results establish monolayer MoSe2 interfaced with bismuth iron garnet as a promising system for valley control of charged excitons.

Synthesis and photophysical properties of benzo[c]phenanthrene derivatives

Background: Three polycyclic aromatic hydrocarbons derived from benzo[c]phenanthrene have been synthesized through a one-step procedure involving palladium Suzuki coupling and are characterized by 1 H and 13C NMR, MS and HRMS spectroscopies. Methods: UV-vis absorption and fluorescence properties of these π-conjugated compounds have been evaluated in solutions and strong emission in the blue region of the visible spectrum was noted. Results: The optical spectra of these small polycyclic aromatic compounds are unusual because absorption is entirely in the UV region (λmax = 281-285 nm), yet fluorescence occurs at 410-422 nm. Conclusion: This equates to a Stokes shift of 1.32-1.39 eV (10756-11256 cm−1 ) and is among the large Stokes shifts that have been reported for small molecules, making them promising candidates for optoelectronic applications.

Synthesis and Macrocyclization-Induced Emission Enhancement of Benzothiadiazole-based Macrocycle

We presented a novel strategy for the improvement of luminophore’s solid-state emission, i.e., macrocyclization-induced emission enhancement (MIEE), by linking luminophores through C(sp3) bridges to give a macrocycle. Benzothiadiazole-based macrocycle (BT-LC) has been synthesized by a one-step condensation of the monomer 4,7-bis(2,4-dimethoxyphenyl)-2,1,3-benzothiadiazole (BT-M) with paraformaldehyde, catalyzed by Lewis acid. BT-LC shows strong emission in both dilute solution and aggregated state. Moreover, in comparison with the monomer, macrocycle BT-LC produces much more intense fluorescence in the solid state (ΦPL=99%) and exhibits better device performance in the application of OLEDs. The MIEE can be ascribed to the restriction of intramolecular motion and the alleviation of the concentration quenching by the macrocyclic topological structure.

Synthesis, Characterization, Fluorescence and Antimicrobial studies of Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) complexes derived from Schiff’s base (E)-2-(5-chloro-2-hydroxybenzylidene)-N-(4-phenylthiazol-2-yl)hydrazinecarboxamide

A series of Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) complexes of (E)-2-(5-chloro-2-hydroxybenzylidene)-N-(4-phenylthiazol-2-yl)hydrazinecarboxamide (HL) with ONO donor ligand was synthesized. The ligand (HL) was prepared by the condensation of N-(4-phenylthiazol-2-yl)hydrazinecarboxamide with 5-chloro-2-hydroxybenzaldehyde. The HL and its metal complexes have been characterized using elemental analysis and various spectral techniques such as, FTIR, 1H and 13C NMR, Mass, UV–Visible, ESR, thermal analysis (TGA), magnetic moment, conductivity and powder-XRD. The Powder XRD pattern indicates hexagonal or tetragonal system for HL and its metal complexes. The fluorescence studies exhibits strong emission in the range of 400-500 nm for HL. Further in comparison the HL, Zn(II) and Cd(II) complexes showed enhanced emission whereas Cu(II), Co(II) and Ni(II) showed poor emission. The antimicrobial activities of the HL and its metal complexes were studied by minimum inhibitory concentration (MIC) method wherein the metal complexes showed better activity as compare to free ligand.