Maximum Emission Peak Research Articles

Theory and experiment studies of the 1,4-bis(4-methoxylstyryl)benzene as a wavelength shifter of liquid scintillator

A novel wavelength shifter of the 1,4-bis(4-methoxylstyryl)benzene (bis-4-MOSB) was synthesized by employing the classical Horner-Wadsworth-Emmons reaction. Feasible analysis of the bis-4-MOSB as the wavelength shifter in a ternary liquid scintillator, in which p-xylene (PX) was as the solvent and 2,5-diphenyloxazole (PPO) was as the primary fluor, was carried out. The optimum prescription with 3.5g/L PPO and 25mg/L bis-4-MOSB was obtained with regard to the light yield. A series of characterization tests based on the optimal formulation were performed. Compared with the 1,4-bis(2-methylstyryl)benzene (bis-MSB), the maximum absorption peak at 356nm and maximum emission peak at 421nm in n-hexane with the red shift of 10nm and 3nm, respectively, were measured accordingly. The light yield characterized by using a relative measurement method achieved as high as 75.85% of the anthracene crystal. A brief density functional calculation was conducted to have an insight into the electronic structure characteristic of the bis-4-MOSB in the scintillation process.

Determination of norfloxacin in food by an enhanced spectrofluorimetric method

Using a norfloxacin (NFLX)-Nd3+ -cetyltrimethylammonium bromide (CTAB) system for the detection of NFLX, a simple and sensitive method based on fluorescence enhancement was developed. In pH 7.0 buffer solution, NFLX reacted with Nd3+ to form a complex, which resulted in fluorescence enhancement of NFLX, and the maximum emission peak shifted from 415 nm for NFLX to 450 nm for NFLX-Nd3+ . Moreover, the fluorescence intensity increased further when the surfactant CTAB was added to NFLX-Nd3+ . Under the optimum conditions, the fluorescence intensity of the NFLX-Nd3+ -CTAB system was linearly correlated with the NFLX concentration in the range 0.038-10 µmol L-1 , with a correlation coefficient (R2 ) of 0.9997. The detection limit (3σ/k) was 0.021 µmol L-1 , indicating that this method can be applied to detect trace NFLX levels. The mechanism of fluorescence enhancement is discussed. The method was used to detect NFLX in fish and chicken samples with satisfactory results. The present results indicate that this method has the potential for fast and real-time determination of NFLX in food samples © 2016 Society of Chemical Industry.

Synthesis and characterization of a new borate Ba6Al4B14O33 with building blocks of AlO4, Al4O14, BO3, B6O14, and B6O13

A new barium aluminoborate, Ba6Al4B14O33, has been synthesized by the high-temperature solution reaction at 700°C. The single-crystal XRD analysis showed that it crystallizes in a new structure type with space group P1¯, a=7.0070(14)Å, b=13.880(3)Å, c =14.702(3)Å, α=86.48(3)°, β=88.99(3)°, γ=83.46(3)°, V=1417.8(5)Å3, and Z=2. The fundamental building blocks in this structure are AlO4 tetrahedra, BO3 triangles, [Al4O14]16− groups composed of two AlO4 tetrahedra and two AlO5 trigonal bipyramids, [B6O14]10− groups formed by one BO3 triangle bonded to one [B5O12]9− double ring, and [B6O13]8− groups consisting of one BO3 triangle linked to one [B5O11]7− double ring. They are held together via common O atoms to form a 3D network, with intersecting open channels accommodating Ba2+ cations. The existence of both BO3 and BO4 groups is confirmed by FT-IR spectrum and an optical band gap of 3.44eV is obtained from UV–VIS diffuse reflectance spectrum. Solid-state fluorescence spectrum has also been studied exhibiting the maximum emission peak at around 527nm. Band structure calculations by the density functional theory method indicate that it is a direct band-gap insulator.

Synthesis of Protein-Directed Orange/Red-Emitting Copper Nanoclusters via Hydroxylamine Hydrochloride Reduction Approach and Their Applications on Hg2+ Sensing

Herein, we report a facile one-pot method for the synthesis of orange/red-emitting fluorescent copper nanoclusters (Cu NCs), in which bovine serum albumin (BSA) served as the capping scaffold (Cu NCs@BSA) and hydroxylamine hydrochloride (NH2OH[Formula: see text][Formula: see text][Formula: see text]HCl) as the reducing agent. To the best of our knowledge, this is the first time to adopt this mild reductant to synthesize fluorescent Cu NCs. The as-prepared Cu NCs@BSA exhibits strong orange or red fluorescence at room temperature depending on the synthesis process, and the maximum excitation and emission peaks were at 355[Formula: see text]nm and 615[Formula: see text]nm, 395[Formula: see text]nm and 645[Formula: see text]nm, respectively. Synthesis conditions including the amounts of NH2OH[Formula: see text][Formula: see text][Formula: see text]HCl, the selection of reducing agent, the molar ratio of BSA/Cu(NO3)2, the pH value, the reaction temperature, the reaction time, and various kinds of Cu sources have been systematically studied. Importantly, these Cu NCs exhibit excellent stability for at least 2 months when stored at 4[Formula: see text]C in the dark, and they also show strong oxidation resistance toward H2O2. Moreover, the prepared Cu NCs have been successfully applied to sensitively and selectively sensing Hg[Formula: see text] without suffering any interference from other metal ions and anions.

Synthesis, structure, and properties of a new Co(II) diphosphonate based on auxiliary ligand 2,2'-bipyridine

ABSTRACT The example of Co(II)-N-heterocyclic complex based on 1-hydroxyethylidenediphosphonic acid (H5L = CH3C(OH)(PO3H2)2), namely [Co2(H3L)2(2,2′-bipy)2] 1, has been solvothermally isolated using the second ligand 2,2'-bipyridine (2,2'-bipy) and characterized by powder X-ray diffraction (PXRD), elemental analysis, IR, and thermal gravimetric analyses. The single-crystal X-ray diffractions show that complex 1 possesses a 0-D structure built from binuclear unit [Co2(O–P–O)2] by μ2-(O–P–O) bridge. Then, H-bonding and π–π stacking interactions further expand this 0-D structure into a 3-D supramolecular framework. Fluorescent measurements reveal that the maximum emission peak is centered at 421.5 nm, mainly deriving from intraligand π*–π transition state of the second ligand 2,2'-bipy (λem = 419.5 nm, λex = 235 nm). Magnetism data indicate that 1 exhibits ferromagnetic behavior within binuclear Co(II) unit via μ2-(O–P–O) bridge in syn-anti mode.

Eu(2+)-Activated Alkaline-Earth Halophosphates, M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) for NUV-LEDs: Site-Selective Crystal Field Effect.

Eu(2+)-activated M5(PO4)3X (M = Ca, Sr, Ba; X = F, Cl, Br) compounds providing different alkaline-earth metal and halide ions were successfully synthesized and characterized. The emission peak maxima of the M5(PO4)3Cl:Eu(2+) (M = Ca, Sr, Ba) compounds were blue-shifted from Ca to Ba (454 nm for Ca, 444 nm for Sr, and 434 nm for Ba), and those of the Sr5(PO4)3X:Eu(2+) (X = F, Cl, Br) compounds were red-shifted along the series of halides, F → Cl → Br (437 nm for F, 444 nm for Cl, and 448 nm for Br). The site selectivity and occupancy of the activator ions (Eu(2+)) in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) crystal lattices were estimated based on theoretical calculation of the 5d → 4f transition energies of Eu(2+) using LCAO. In combination with the photoluminescence measurements and theoretical calculation, it was elucidated that the Eu(2+) ions preferably enter the fully oxygen-coordinated sites in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) compounds. This trend can be well explained by "Pauling's rules". These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field.

Enhanced chemiluminescence from reactions between CdTe/CdS/ZnS quantum dots and periodate

A novel chemiluminescence (CL) performance of CdTe/CdS/ZnS quantum dots (QDs) with periodate (KIO4) was studied. Effects of concentration and pH on the CL system were investigated. Electron spin resonance (ESR) and the effects of radical scavenger analysis were employed for identification of intermediate species. The CL spectra for this system showed only one maximum emission peak centered around 620nm, which was similar with photoluminescence (PL) spectra of CdTe/CdS/ZnS QDs. The CL of CdTe/CdS/ZnS QDs was induced by direct chemical oxidation and the possible mechanism could be explained by radiative recombination of injected holes and electrons. This investigation not only provided new sight into the optical characteristics of CdTe/CdS/ZnS QDs, but also broadened their potential optical utilizations.

Solution-processed blue and blue-green phosphorescent organic light-emitting devices using iridium(III) complexes based on 9-(6-(4-phenyl-1H-1,2,3-triazol-1-yl)hexyl)-9H–carbazole ligand

We have designed and successfully synthesized a series of solution-processed iridium(III) complexes of (Czphtz)2Ir(NˆN) bearing main ligand of 9-(6-(4-phenyl-1H-1,2,3 -triazol-1-yl)hexyl)-9H-carbazole, namely (Czphtz)2Ir(tfmptz) (Ir1) (Czphtz)2Ir(pptz) (Ir2) and (Czphtz)2Ir(fpptz) (Ir3). The hole-transporting carbazole and electron-transporting 1, 2, 4-trizole moieties were introduced through hexyl to balance carrier transport. The solution-processed host-free and doped phosphorescent organic light-emitting devices (PhOLEDs) were fabricated. Here, in this paper, we will present the photophysical, electrochemical properties and performances in devices of three complexes. All of them exhibit excellent solubilities in common organic solvents. The pure-blue-light-emitting Ir1 with the maximum emission peak at 463 nm was attained by varying the structure of ancillary ligand and have the CIE coordinate of (0.19, 0.18) in host-free PhOLED. Our work shows that the rational structure modification of ancillary ligand is an effective approach to develop deep blue-light-emitting materials.

The effect of annealing on the structural, optical and electrical properties of Titanium Nitride (TiN) thin films prepared by DC magnetron sputtering with supported discharge

Nano-crystalline Titanium Nitride (TiN) thin films were deposited on glass substrates by reactive DC magnetron sputtering in the presence of a supported discharge (dc triode magnetron sputtering). A hot thermionic filament which was negatively biased is kept between the target and substrate, and was used to sustain the discharge at much lower pressures. The TiN films deposited at room temperature (RT) were annealed at different temperatures of 373, 473 and 573 K in a high vacuum for 1 h. The films were characterized for their morphological, structural, micro-structural, optical and electrical properties. RT deposited titanium to nitrogen ratio was found to be 1:1 which has been confirmed by EDAX. XRD studies showed that the as-deposited TiN thin film were amorphous in nature and transformed to a nano-crystalline structure with increasing annealing temperatures. The crystallite growth of TiN thin films started around 373 K onwards, and it became a face-centered cubic structure with a preferred orientation along the (111) plane. The band gap of TiN thin films was found to increase from 2.7 to 3.2 eV with an increase in the annealing temperature. The photoluminescence spectrum of TiN thin films indicates a broadening of emission wavelength in the visible region with a maximum emission peak around 360 nm. The electrical resistivity of TiN thin films was found to drop significantly from 1800 to 400 µΩ cm with an increase in the annealing temperature. The AFM micrographs of annealed TiN thin films show uniform surface pattern associated with a large accumulation of fine grains. Through this work, it has been demonstrated that it is possible to achieve the required physical properties of TiN films at lower annealing temperatures by the supported discharge dc magnetron technique compared to other sputtering techniques.

Synthesis, spectroscopic characterization, thermal and luminescent properties of new organosulfur-functionalized platinum(II) bis(alkenylarylalkynyl) complexes

A series of organosulfur-functionalized trans-platinum(II) bis(alkenylarylalkynyl) complexes, having one tolylthio moiety in each alkenyl backbone with general formula trans-[(PEt3)2Pt{CC-Ar-CHCH(SC6H4CH3)}2], (2a–2d), (where, Ar = phenylene, biphenylene, 2,5-dimethylphenylene, and 2,5-dimethoxyphenylene) were synthesized in good to excellent yields with good regioselectivity. As compared to the absorption band of trans-platinum(II) bis(alkynylarylalkynyl) complexes, we found that the position of the lowest energy absorption bands in the trans-platinum(II) bis(alkenylarylalkynyl) complexes were red-shifted, after the functionalization of the trans-platinum(II) bis(alkynylarylalkynyl) complexes with arylthiol. For all trans-platinum(II) complexes, the lowest energy absorption bands in the UV/Vis spectra, in chloroform solution, at room temperature, were observed in the range 362–394 nm, and under excitation at the wavelength of the absorption maximum exhibited the emission peak maximum at room temperature in the range 401–426 nm. The newly synthesized complexes are not exhibited phosphorescence at room temperature but are exhibited at low temperature, 77 K. All the new platinum(II) complexes have been fully characterized by spectroscopic analysis as well as elemental analysis, and the trans square-planar arrangement at the platinum centre has been confirmed by single-crystal X-ray diffraction study of complex 2a.

A highly emissive distyrylthieno[3,2-b]thiophene based red luminescent organic single crystal: Aggregation induced emission, optical waveguide edge emission, and balanced ambipolar carrier transport

A highly emissive red luminescent single crystal which shows aggregation induced emission (AIE) property and optical waveguide edge emission based on small organic functional molecule, cyano-substituted 2,5-di((E)-styryl)thieno[3,2-b]thiophene (CNP2V2TT) has been prepared by the physical vapor transport (PVT) method. The fluorescence quantum efficiency of crystal is up to 37% and an emission peak maximum (λmax) locates at 645 nm. Cystallographic data indicate that uniaxially oriented molecular packing with slipped face-to-face π-π stacking forms by the hydrogen bonding network among CNP2V2TT molecules. The single crystal FET devices were fabricated using Au and Ca as hole and electron injection electrodes, respectively. The molecular design, introducing cyano groups into molecular skeleton, effectively lower the LUMO level and achieve well-balanced ambipolar electron (0.13 cm2 V−1 s−1) and hole (0.085 cm2 V−1 s−1) mobilities.

Preparation of quantum size of tin oxide: Structural and physical characterization

SnO2 NPs were successfully prepared via a hydrothermal method. X-ray diffraction analysis confirmed the rutile tetragonal structure of SnO2 NPs. The crystallite size increased from 1.18 to 5.06nm with increasing the preparation temperature from 100 to 180°C. The SEM photography of the products exhibited the agglomeration of the SnO2 nanocrystals to large view particles, while TEM images confirmed the polycrystalline phase and crystallite size those analyzed from XRD. The UV–vis absorption of ethanol suspended SnO2 NPs was measured. The optical band-gap energies (Eg) were significantly blue-shifted due to quantum confinement. Fluorescence spectra came to confirm this shift, where a clear shift in the maximum emission peak was observed. Stokes shift of SnO2 nanocrystals was found to be crystallite size dependent.

Bovine serum albumin template synthesis of fluorescent gold nanoclusters for nitric oxide detection in vitro

Bovine serum albumin (BSA) stabilised gold nanoclusters (Au NCs) were prepared and used for nitric oxide (NO) detection in vitro. The prepared BSA-Au NCs with an average diameter of 1.5 nm emitted strong red photoluminescence (PL), accompanied with the maximum emission peak at 640 nm. Furthermore, the BSA-Au NCs were developed as a PL probe for NO detection in vitro. Owing to the damage of BSA-Au NCs structure caused by the interaction between NO and BSA, the PL intensity of BSA-Au NCs regularly reduced with the increase in NO concentration [NO]. There is a proportional relationship between the PL intensity of BSA-Au NCs and the [NO] (0.05–0.35 mM), together with a detection limit of 0.017 mM. Experimental results confirmed high selectivity and sensitivity of the NO probe over other reactive oxygen and nitrogen species, and presented excellent detection capacity in aqueous model samples.

Synthesis and C70 complexation studies of a fluorescent 5,5’-bi-p-tert-butylcalix[4]arene scaffold

In this paper, we report the synthesis and C70 complexation studies of a new fluorescent 5,5′-bi-p-tert-butylcalix[4]arene capsule with an extended hydrophobic cavity. The synthetic route required development of a series of selective protection and de-protection reactions, such as esterification and ester cleavage, as well as a cross-coupling reaction at the lower rim. The resulting 5,5′-bi-p-tert-butylcalixarene was fully characterised, including by X-ray crystallography. In the solid state, the compound exists in an ‘open-capsule’ orientation, with a perfectly planar bridging biphenylene unit resulting in high fluorescence with a maximum emission peak at 390 nm. Preliminary fluorescence-based complexation experiments with C70 fullerene did not provide conclusive evidence for formation of inclusion complexes.

New Bismuth Germanate Oxide Nanoparticle Material for Biolabel Applications in Medicine

Bismuth germanate (Bi4Ge3O12, BGO) has been the focus of several studies due to its scintillation properties. It has been employed as detector in scientific research and medicine, and herein we studied its possible biomedical applications. The photoluminescence properties of the uncoated and protein-coated nanoparticles were analyzed in different body fluids, at different pH. The nanoparticles yielded blueish-white luminescence with a maximum emission peak at 485 nm corresponding to the3P1→1S0electron transition of Bi3+. They showed luminescence properties at different pH values and in human fluids, such as urine and blood serum. Finally, the BGO nanoparticles were functionalized with the anti-HLA I W6/32 monoclonal antibody and the capacity of the antibody-loaded nanoparticles to recognize the cognate antigen (HLA I) of the W6/32 mAb was assessed on the human promyelocytic leukemia cell line THP-1. The possibility of functionalizing BGO nanoparticles with W6/32 antibodies and their specificity to identify THP-1 cells make them promising candidates for biomedical applications as biolabels.

Synthesis and Characterization of Fluorene-Based Polymers Having Azine Unit for Blue Light Emission

Two types of donor-acceptor copolymers were designed and synthesized by combination of an electron donor unit of fluorene sequences and an electron acceptor azine unit such as 1,2,4,5-tetrazine and 1,3,5-triazine. They were well soluble in common organic solvents with the number average molecular weight (Mn) of 7.0 and 14.5 kg mol-1, respectively, and have good thermal stability showing about at 360 °C with 5 wt% loss in TGA. Two copolymers exhibited intense blue photoluminescence with emission peak maxima at 437 and 421 nm in CHCl3, and 451 and 422 nm in the film state, respectively. These polymers exhibited good fluorescence quantum efficiencies in CHCl3 (φfl = 0.63, 0.97). Energy levels of the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels estimated by cyclic voltammetry were to be –5.83, –6.0 eV and –2.85, –2.88 eV, respectively.

Synthesis and Characterization of Fluorene-Based Polymers Having Azine Unit for Blue Light Emission

Two types of donor-acceptor copolymers were designed and synthesized by combination of an electron donor unit of fluorene sequences and an electron acceptor azine unit such as 1,2,4,5-tetrazine and 1,3,5-triazine. They were well soluble in common organic solvents with the number average molecular weight (Mn) of 7.0 and 14.5 kg mol-1, respectively, and have good thermal stability showing about at 360 °C with 5 wt% loss in TGA. Two copolymers exhibited intense blue photoluminescence with emission peak maxima at 437 and 421 nm in CHCl3, and 451 and 422 nm in the film state, respectively. These polymers exhibited good fluorescence quantum efficiencies in CHCl3 (φfl = 0.63, 0.97). Energy levels of the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels estimated by cyclic voltammetry were to be –5.83, –6.0 eV and –2.85, –2.88 eV, respectively.

Highly efficient electrogenerated chemiluminescence of natural chlorophyll a

Highly efficient electrogenerated chemiluminescence (ECL) of natural chlorophyll a (Chl a) was observed in acetonitrile with 1-butyl-3-methylimidazolium hexafluorophosphate as electrolyte and tri-n-propylamine (TPrA) as a coreactant. The collected ECL spectrum displayed a maximum emission peak at ca. 670nm, suggesting that the same excited states with the photo-excitation processes were generated. The possible ECL reaction mechanism of this Chl a–TPrA system was discussed and established. ECL intensity of Chl a was proportional to its concentration over the range of 0.1–11μM, and a high ECL efficiency (Φecl) of 0.86 was calculated using Ru(bpy)32+ as the standard (Φecl=1). Herein, an important property of natural Chl a was expanded and a new kind of ECL luminophores was developed. Moreover, it is expected that this high ECL efficiency of natural porphyrin complex has great potential to expand its ECL sensing application.

Synthesis and characterization of poly (N-Hexyl-2, 7-di(2-(4-hexylthiophene)carbazole)

One conjugated polymer consisting of carbazole and 3-hexylthiophene moiety, poly (N-Hexyl-2,7-di(2-(4-hexylthiophene)carbazole) (PNDC), has been synthesized by ferric chloride oxidative polymerization. The monomer N-Hexyl-2,7-di(2-(4-hexylthiophene)carbazole was synthesized and characterized by IR, 1H-NMR, 13C-NMR and MS. UV-vis absorption spectrum, fluorescence spectrum, photoluminescence spectrum and electrochemical properties of the polymer were investigated. Polymer PNDC shows maximum peak appearing at 394 nm in UV-vis absorption spectrum, strongest fluorescence-emission at 482 nm in fluorescence spectrum and maximum emission peak at 492 nm in photoluminescence spectrum. The band-gap (E g), HOMO energy (E HOMO), and LUMO energy (E LUMO) of the polymer were obtained as 2.58, -5.32, and -2.74 eV, respectively.

Three Metal(II) Diphosphonates with d 10 Electron Configuration: Structural, Fluorescent and Electrochemical Studies

By introducing the second ligand 1,10-phenanthroline (phen), three low-dimensional examples of CdII/ZnII diphosphonates based on 1-hydroxyethylidenediphosphonic acid (H5L = CH3C(OH)(PO3H2)2), [Cd2(H3L)2(phen)2(H2O)2] 1, {[Zn3(H2L)2(phen)2]·2H2O}n 2 and [Zn2(H3L)2(phen)2]·(HOCH2CH2OH) 3, have been hydro- or solvo-thermally obtained and characterized by powder X-ray diffraction (PXRD), elemental analysis, IR, TG-SDTA. The single-crystal X-ray diffractions show that both compounds 1 and 3 display zero-dimensional structures built from binuclear units [M2(OPO)2] n (M = CdII/ZnII) via a double O–P–O bridge, and compound 2 possesses one-dimensional fish-bone inorganic chain structure with three types of coordination modes of Zn(II) ions. Then H-bond or/and π–π stacking interactions further expand the low-dimensional structures into the three-dimensional supramolecular frameworks. Fluorescent measurements reveal that the maximum emission peaks (371.5, 391.5 nm for 2 and 376.5, 392.5 nm for 3) of 2–3 have a significant increase in intensity compared to those of the phen ligand (λ em = 362.5, 379 nm, λ ex = 335 nm), which are mainly caused by intraligand π*–π emission state of the phen ligand. The results of electrochemical measurements indicate the donor ability of 1–3 has gone up, compared with the ligands (H5L and phen). Three examples of CdII/ZnII diphosphonates have been hydro- or solvo-thermally obtained. Two Zn(II) diphosphonates with 1,10-phenanthroline indicate a significant increase in intensity of fluorescence. The results of electrochemical measurements indicate the donor ability of CdII/ZnII diphosphonates increase, compared with the ligands H5L and phen.