Intense Fluorescence Band Research Articles

HaloTag® Platform: From Proteomics to Cellular Analysis and Animal Imaging

HaloTag® Platform: From Proteomics to Cellular Analysis and Animal Imaging

Upconversion luminescence in Tm3+/Yb3+ co-doped double-clad silica fibers under 980 nm cladding pumping

An investigation is reported of the visible and near-infrared upconversions in Tm3+/Yb3+ co-doped double-clad silica fibers (TYDFs) under excitation at 980 nm. The TYDFs used were fabricated using the modified chemical vapor deposition (MCVD) and solution doping techniques. Three distinct upconversion luminescences were observed at wavelengths of 482, 649 and 816 nm and their intensities found to increase with Yb3+ concentration. The intensity of blue and red fluorescence bands at 482 and 649 nm were found to be the highest with LTY-8 fiber, which had Tm3+ and Yb3+ concentrations of 5.6 × 1019 and 15.5 × 1019 ions/cc, respectively. The upconversion luminescence intensity was also observed to decrease with an increase in temperature. The main emission switched from 482 nm to 816 nm as the temperature increased above 200°C.

Inclusion complexes naphthalene-γ-cyclodextrin-adamantane and naphthalene-γ-cyclodextrin-o-carborane: the structure and luminescence properties

The luminescence properties of inclusion complexes of naphthalene-d8 with γ-cyclodextrin (γ-CD) in the presence of adamantane or o-carborane added as third parties were studied in aqueous solutions. It was found that the structure of the cage compound added to the aqueous solution of the naphthalene-d8@γ-CD complex completely determines the luminescence type of the ternary complex. For instance, the intensity of excimer fluorescence (EF) band increases considerably at the expense of reduction of the intensity of monomer fluorescence (MF) band on adding adamantane. On the contrary, adding o-carborane causes a decrease in the intensity of the EF band of naphthalene-d8 and simultaneous appearance of MF in addition to long-lived room-temperature phosphorescence (RTP) whose lifetime increases from 1.5 s to 9.1 s after deoxygenation of the solution. Structural differences between the complexes affecting their behavior under the action of the third parties were explained using the results of semiempirical quantum chemical calculations.

Distinctive Optical Properties of Polysilane/TiO2 Nanocomposite Films

Optimal technological conditions for the fabrication of nanocomposite films based on the poly(di-n-hexylsilane) (PDHS) incorporated into a TiO2 nanoporous film have been developed, and such composites are fabricated. Their optical spectra have been investigated in a wide temperature range (15–330) K. It is shown that the distinctive feature of nanocomposite films is related to the predominant fluorescence band of aggregates with respect to the fluorescence bands corresponding to the gauche- and trans-conformations of polymer chains and to the observation of the intense fluorescence band of aggregates even at room temperature.

The fabrication of Er3+/Ce3+ co-doped tellurite- bismuth glasses and the improvement of spectroscopic properties

A series of 80TeO2-10Bi2O3-10TiO2-0.5Er2O3-xCe2O3 (x=0, 0.25, 0.5, 0.75, 1.0 mol%) and (80-y) TeO2-10Bi2O3-10TiO2-yWO3-0.5Er2O3-0.75Ce2O3 (y=3, 6, 9, 12 mol%) tellurite-bismuth glasses are prepared by the conventional high-temperature melting and annealing method. The absorption spectra of 400-1700 nm, upconversion spectra and 1.53 m band fluorescence spectra under the excitation of 975 nm, the 4I11/2 and 4I13/2 level fluorescence lifetimes of Er3+ under the excitation of 808 nm, and the Raman spectra of doping-free glass samples are measured. Meanwhile, the spectroscopic parameters of Er3+ are calculated and analyzed with the help of Judd-Ofelt theory and McCumber theory. The results indicate that the upconversion fluorescence can be suppressed efficiently and the 1.53 m band fluorescence can be enhanced evidently, owing to the energy transfer from Er3 +: 4I11/2Ce3+:2F5/2 levels when the Ce3+ ions are introduced into the Er3+-doped tellurite-bismuth glasses. Moreover, the 1.53 m band fluorescence intensity can be improved and the fluorescence spectral width can be broadened further when an appropriate amount of WO3 component is introduced. The above research results are of theoretical significance for obtaining the tellurite-bismuth glasses with excellent spectroscopic properties, which are used for the 1.53 m broadband Erbium-doped optical fiber amplifier.

Temperature dependent spectral properties of type-I and quasi type-II CdSe/CdS dot-in-rod nanocrystals

We investigated systematically the temperature dependence of the spectral properties such as the band gap, bandwidth and fluorescence intensity of CdSe/CdS dot-in-rod nanocrystals. These asymmetry nanoparticles were synthesized by seeded growth techniques with band alignment of the type-I and quasi type-II with initial core sizes of 3.3 and 2.3 nm, respectively. With increasing temperature the band gap decreases and bandwidth increases, largely due to exciton-phonon scattering. Anomalous variations of the band gap and bandwidth were observed at 200-240 K, and the variations are attributed to the anisotropic strain in the CdSe/CdS interface due to temperature dependent lattice mismatch. The integrated intensity of fluorescence shows two variation regimes. In the low temperature regime, the intensity remained roughly constant due to the temperature dependent carrier mobility and trapping by the defect states in the CdS shell. However, in the higher temperature regime, the intensity decreased quickly due to thermal/phonon assisted escape from the CdSe dot. The barrier depths are estimated to be about 557 and 285 meV for type-I and quasi type-II samples, respectively.

Photophysical properties and photostability of novel unsymmetric polycyclicphenazine-type D-π-A fluorescent dyes and the dye-doped films

Structural isomers of unsymmetric polycyclicphenazine-type D-π-A fluorescent dyes have been newly synthesized and characterized in both solution and polymer films. The dyes exhibited two strong absorption bands at around 328–401 nm and 516–532 nm, and an intense fluorescence band at around 595–629 nm (Φ = 0.32–0.84) in 1,4-dioxane. The dye-doped polymer films showed good ability of wavelength conversion; the films can efficiently convert ultraviolet and green-yellow lights into red light (Φ = 0.43–0.86). Moreover, the photostability of the dyes-doped PS, PMMA, and PLA films has been investigated.

Photophysical properties and photostability of novel symmetric polycyclicphenazine-type fluorescent dyes and the dye-doped films

Novel symmetric polycyclicphenazine-type fluorescent dyes have been synthesized and characterized in solution and in polymer films. The dyes exhibited two strong absorption bands at around 365–428 nm and 519–567 nm and an intense fluorescence band at around 560–600 nm (Ф = 0.70–0.87) in 1,4-dioxane. The dye-doped polymer films showed excellent wavelength conversion function that efficiently convert ultraviolet and yellow lights into red light (Ф = 0.61–0.92). Moreover, the photostability of the dye-doped PS, PMMA, and PLA films has been investigated.

Spectroscopic studies of inclusion complexes of methyl- p-dimethylaminobenzoate and its ortho derivative with α- and β-cyclodextrins

The effects of α- and β-cyclodextrins (CDs) on the both emission modes (LE – locally excited and TICT – twisted intramolecular charge transfer) of the fluorescence spectrum of methyl- p-dimethylaminobenzoate (I) and its o-methoxy (II) derivative in aqueous solution have been investigated using steady-state and time-resolved fluorescence techniques. It is found that the intensity of both fluorescence bands increases with increasing concentration of α- and β-CD. The stoichiometries and equilibrium constants of the fluorophore–cyclodextrin inclusion complexes have been determined by steady-state fluorescence measurements. Performed spectroscopic studies demonstrate that in the case of I in α-CD and β-CD, both 1:1 and 1:2 inclusion complexes are formed, whereas only 1:1 inclusion complex is formed between II and β-CD.

Formation of optical color and fluorescence centers in polytetrafluoroethylene under γ-irradiation

Fluorescent properties and colors of polytetrafluoroethylene (PTFE) samples were studied as functions of absorbed dose of γ-radiation at a temperature above the melting temperature of the crystallites (327°C) in the dose range 0.2–0.8 MGy. The samples were irradiated at low pressure (10–6 Torr) in glass ampuls and at atmospheric pressure in a chamber purged with argon. Samples in ampuls acquired an off-white tint and fluoresced weakly. The fluorescence intensity increased slowly as the radiation dose increased from 0.2 to 0.6 MGy and decreased at 0.8 MGy. Samples irradiated in the chamber fluoresced more strongly and acquired colors that changed from gray (0.2 MGy) to dark-brown (0.8 MGy). Color centers were formed only in the sample surface layer. Their appearance was associated with the adsorption of particles of an unknown nature from the environment. The argon-purged samples turned white upon removing their surface layer (50 μm). The intensity and shape of fluorescence bands emitted by these samples remained essentially unaltered, i.e., depended weakly on the absorbed dose in the range 0.2–0.8 MGy.

Effect of Ce 3+ codoping on Er 3+-doped bismuth-germanate glass and fiber under 980 nm excitation

Er 3+/Ce 3+ codoped bismuth-germanate glasses with the composition of Bi 2O 3-GeO 2-Ga 2O 3-Na 2O were prepared by the conventional melt-quenching method. The absorption spectra, fluorescence spectra, upconversion emission and lifetimes of Er 3+ ions were measured, and the effects of Ce 3+-doping on the spectroscopic properties of 1.53 μm band fluorescence of Er 3+ ion were investigated based on the analysis of energy transfer between Er 3+ and Ce 3+ ions. The results indicate that the 1.53 μm band fluorescence intensity can be improved evidently with the Ce 3+-doped concentration under the excitation of 980 nm. Meanwhile, the theoretical simulation based on the population rate equation and light power propagation equation indicates that the C + L band signal gain can also be improved dramatically by introducing Ce 3+ ions into the Er 3+-doped bismuth-germanate glass fiber. Therefore, it is necessary to introduce Ce 3+ ions when Er 3+-doped bismuth-germanate glass with low phonon energy is applied to the 1.53 μm band broad Er 3+-doped fiber amplifier (EDFA).

Structural and luminescence studies of nickel(ii) and copper(ii) complexes with (1R,2R)-cyclohexanediamine derived unsymmetric Schiff base

Unsymmetrical Schiff base obtained by the condensation reaction of (1R,2R)(-)cyclohexanediamine with 2-hydroxybenzaldehyde and 2-hydroxynaphthaldehyde was used as a ligand for copper(II) and nickel(II). The ligand and complexes were characterized by circular dichroism (CD), UV-VIS, fluorescence, IR and (1)H (NOE diff), NOESY and (13)C NMR (ligand) spectra. The X-ray crystal structures solved for (1R,2R)(-)chxn(salH)(naftalH) and Cu(II)(1R,2R)(-)chxn(sal)(naftal) revealed tetrahedral distortion of coordination sphere in the solid phase. The [Cu(1R,2R)(-)chxn(sal)(naftal)]·0.5EtOH·1.25H(2)O complex crystallized in the monoclinic chiral C2 space group with two molecules in the asymmetric unit as well as disordered ethanol and water molecules. For both molecules Cu(II) ions were found in square-planar environments and adopts conformation described as "semi-open armed", because of distinctly oriented arms according to cyclohexane ring defined by three torsion angles. The thin layers of the ligands, copper(II) and nickel(II) complexes were deposited on Si(111) by a spin coating method and characterized with scanning electron microscopy SEM/EDS and fluorescence spectra. The ligand layers exhibit the most intensive fluorescence band at 498 nm, which can be assigned to emission transition π* → n of Schiff base ligand. For copper(II) layers the most intensive band from intraligand transition at 550 nm was observed. The highest intensity band was registered for the layer obtained when rotation speed was 1000 rpm and time 20 s. The nickel(II) complex layers fluorescence spectra exhibit an intensive band at 564 nm. The emission maxima of the copper(II) and nickel(II) complexes are shifted towards longer wavelength in comparison to the free ligand layers. CD spectra of the complexes in solution are characteristic for tetrahedral planar distortion of the chelate ring. The (1)H NMR NOE diff were measured and the position of the nearest hydrogen atoms in the cyclohexane and aromatic rings were discussed, suggesting the tetrahedral distortion of the central ion of the coordination sphere in solution.

Synthesis, crystal structure, electrochemical and fluorescence studies of a novel Zn(II)-fluorophore, 1,10-phenanthroline-5,6-dione (phen-dione)

The crystal structure of 1,10-phenanthroline-5,6-dione ligand with Zn(II), tris(1,10-phenanthroline-5,6-dione)zinc(II) hexafluorophosphate, [Zn(phen-dione)3](PF6)2, is reported. The complex was characterized by elemental analysis, IR, 1H NMR, electronic absorption spectroscopies, cyclic voltammetry and X-ray crystallography. Yellow crystals of [Zn(phen-dione)3](PF6)2 were formed by ether diffusion into an acetonitrile solution of the complex. The title complex crystallized in monoclinic crystal system (Z = 2) with space groups of P21, a = 12.0299(15) A, b = 14.5306(19) A, c = 13.1879(17) A, β = 94.058(2)o and V = 2299.5(5) A3. The structure was refined by using 10048 independent reflections, with I > 2σ(I) to an R factor of 0.0490. Single-crystal structure showed that the coordination geometry around the Zn(II) was a distorted octahedron. The complex showed an intense fluorescence band at visible region (690 nm) in CH3CN with an excitation wavelength of 310 nm at 25.0 ± 0.1 oC.

ChemInform Abstract: Triazinylaniline Derivatives as Fluorescence Probes. Part 1. Absorption and Fluorescence in Organic Solvents and in Aqueous Media in Relation to Twisted Intramolecular Charge-Transfer State Formation, Hydrogen Bonding, and Protic Equi

The UV absorption and fluorescence characteristics of new optical probes based on a 1,3,5-triazinylaniline chromophore and of general structure p-Et2NC6H4C3N3(Cl)NR1R2 are reported. Increase in alkanol solvent polarity strongly quenches the fluorescence by a process attributed to TlCT (twisted intramolecular charge-transfer) state formation with co-operative solvent relaxation (log kNR/s–1 8.5–10.5). In aqueous media no changes in fluorescence band position or intensity are observed in the pH range 3.5 to 11 but below pH 3.5 protonation of the anilino nitrogen (pKaca. 2.4) eliminates both the λ= 360 nm absorption band and the weak λ= 460 nm fluorescence band. Free and hydrogen-bonded species, with respect to the anilino nitrogen centre, are present in aqueous dioxane solutions.The triazinylaniline derivatives are prototypes of promising sensitive probes for organized media and as models of proteins labelled with the triazinylaniline fluorophore.

An unusual binodal (6,8)-connected 3D supramolecular network with twofold self-penetration

A dicarboxylate ligand, 5-carboxyl-1-carboxymethyl-2-oxidopyridinium (H2L), was utilized to form four complexes with the general formula [M(HL)2(H2O)]·2H2O, M = CuII (1), ZnII (2), MnII (3), CdII (4). The crystals were isomorphous, belonging to the monoclinic C2/c space group. They were constructed from 1D chains and further linked by hydrogen bonds into a novel binodal (6,8)-connected 3D supramolecular network with twofold self-penetration. Photoluminescence studies revealed that complexes 2–4 displayed intense structure-related fluorescent emission bands.

Two 3D supramolecules with helices constructed by hydrogen bonds based on p-thioacetatebenzoic acid ligand

p-Thioacetatebenzoic acid (H2L) and a combination of N-donor ligands such as 4,4′-bipyridine (4,4′-bipy) and 1,3-bi(4-pyridyl)propane (bpp) with metal ions Mn(II) and Ni(II) give rise to two coordination polymers, namely, [Mn(HL)2(bpp)2(H2O)2] n (1), [NiL (4,4′-bipy)(H2O)3] n ·nH2O (2). 1 features an unusual “8” shaped double layer by hydrogen bonds and two different types of helical chains are arrayed alternatively in the 2D double layer framework, which further extends into a 3D supramolecular structure through C–H···O hydrogen bonds. 2 consists of 1D chains which further connect with each other via hydrogen bonds to form the final 3D framework including two different types of helical structure. Photoluminescence study reveals that 1 displays intense structure-related fluorescent emission bands (λex = 369 nm) at 414 nm in the solid state at room temperature. Electrochemical property of 2 reveals that the process of the redox is irreversible. p-Thioacetatebenzoic acid (H2L) and a combination of N-donor ligands such as 4,4′-bipyridine (4,4′-bipy) and 1,3-bi(4-pyridyl)propane (bpp) with metal ions Mn(II) and Ni(II) give rise to two coordination polymers with two different helices, namely, [Mn(HL)2(bpp)2(H2O)2] n (1), [NiL (4,4′-bipy)(H2O)3] n ·nH2O (2).

Fluorescence of N,N-di(2-carboxyethyl)-p-anisidine in solution and crystalline states

The fluorescence properties of N,N-di(2-carboxyethyl)-p-anisidine (I) in solvents of various nature and in the crystalline state have been studied at room temperature (273 K) and at the boiling point of liquid nitrogen (77 K). Fluorescence in aqueous solutions of I with protonated (λ ex /λ fl max = 225/290 nm) and unprotonated (λ ex /λ fl max = 270/380 nm) amino nitrogen has been detected. On going from aqueous solutions to nonaqueous, the fluorescence band of unprotonated I experiences a blue shift and its intensity rises. The fluorescence intensity of the band in aprotic polar solvents is higher than that in protic solvents. A linear dependence of the fluorescence intensity of deprotonated I on Cu(II) concentration (ranging from 1.0 to 5.0 mg/dm3) in aqueous solution has been found. The fluorescence intensity of I in aqueous solutions at 77 K and pH 1–6 has been shown to increase in the presence of Zn(II) (1–170 mg/dm3) and Cd(II) (2–330 mg/dm3) although a similar dependence is not observed at 293 K.

The synthesis, X-ray crystal structure and optical properties of novel 1-ferrocenyl-2-(3-phenyl-1 H-1,2,4-triazol-5-ylthio)ethanone derivatives

A series of novel 1-ferrocenyl-2-(3-phenyl-1 H-1,2,4-triazol-5-ylthio)ethanone derivatives was synthesized by the reaction of 3-substituted-1 H-1,2,4-triazole-5-thiol and chloroacetyl ferrocene in the presence of sodium hydride and potassium iodide at reflux. The structures of the new compounds were determined by IR and 1H NMR spectroscopy and HRMS. The structure of compound 5c was established by X-ray crystallography. UV–vis absorption and fluorescence spectra were recorded in ethanol and dichloromethane. The results showed that compounds 5a–g display similar absorptions ranging from 300 to 500 nm and maximal emission bands are about 566 nm. The intensity of fluorescence and maximal emission bands are dependent on the groups bonded to triazole rings.

A novel 4 4.6 6 5-connected metal-organic framework with strong fluorescent emission constructed by m-thioacetatebenzoic acid

A novel uninodal 5-connected metal-organic framework (MOF), [Cd 2L 2(4,4′-bipy) 3/2(H 2O) 2] n (H 2L= m-thioacetatebenzoic acid and 4,4′-bipy=4,4′-bipyridine), was prepared under hydrothermal condition. It features an unusual brick-wall shape layer by 4,4′-bipy, which consists of right- and left-handed helical chains arrayed alternatively and finally expands by L 2– to a rare 5-connected nov (4 4.6 6) topology network. Photoluminescence study reveals that it displays intense structure-related fluorescent emission bands ( λ ex=355 nm) at 450 nm in the solid state at room temperature.

Optical properties of Dy3+ ion in GGG laser crystal

High optical quality Dy3+-doped Gd3Ga5O12 (abbreviated as Dy : GGG below) crystal was grown by the Czochralski technique along the (1 1 1) orientation. The absorption spectrum, fluorescence spectrum and fluorescence decay curve of Dy : GGG have been recorded at room temperature. Based on the Judd–Ofelt (J–O) theory, the intensity parameters from the measured line strengths were determined. The J–O parameters were used to predict radiative transition probabilities, radiative lifetime and branching ratios for various excited levels of the Dy : GGG crystal. In the visible region, one intense fluorescence band was observed at 581 nm, corresponding to the 4F9/2 → 6H13/2 transition. The room-temperature fluorescence lifetime of this transition of Dy3+ ion in the GGG crystal was measured to be 0.79 ms, and the luminescent quantum efficiency of the 4F9/2 level was evaluated to be 71.4 %. The emission cross-sections of the 4F9/2 → 6H13/2 transition were estimated by the use of the Füchtbauer–Ladengurg method. The research on the emission at 581 nm indicates the possibility of using a commercially available laser diode of 353 nm as a pumping source for a solid-state yellow laser.