A Novel Series Colorimetric and Off–On Fluorescent Chemosensors for Fe3+ Based on Rhodamine B Derivative

A novel series colorimetric and off–on fluorescent chemosensors (2a, 2b, 2c) were designed and synthesized, which showed reversible and highly selective and sensitive recognition toward Fe³⁺ over other examined metal ions. Upon addition of Fe³⁺, sensors (2a, 2b) exhibit remarkably and 2c exhibits moderate enhanced absorbance intensity and color change from colorless to pink in CH₃OH–H₂O(1:1, v/v). The three compounds (2a, 2b, 2c) may therefore be applicable as rhodamine-based turn-on type fluorescent chemosensors.     

Phosphorus(V)corrole- Porphyrin Based Hetero Trimers: Synthesis,Spectroscopy and Photochemistry

‘Axial-bonding’-type hetero trimers have been constructed by employing a simple ‘inorganic’ reaction such as axial bond formation of main group element containing phosphorus corrole. The approach is simple and modular in nature. The architecture of these hetero trimers such that, while a phosphorus(V)corrole forms the basal scaffolding unit, either two free-base porphyrins [(H ₂ ) ₂ –PCor] or Zn^II porphyrins [(Zn) ₂ –PCor] occupy the two axial sites via an aryloxy bridge. Both hetero trimeric species have been completely characterized by mass (FAB), UV/Vis, proton nuclear magnetic resonance spectroscopies and also by the differential pulse voltammetric method. Comparison of their spectroscopic and electrochemical data of these trimers with those of the corresponding reference compounds reveal that there is no apparent ring-to-ring interactions in these ‘vertically’ linked hetero trimers. Reduced fluorescence quantum yields were observed for [(H ₂ ) ₂ –PCor] and [(Zn) ₂ –PCor] when compared to corresponding monomeric chromophores. Finally, a comparison is made between the presently reported phosphorus(V)corrole based hetero arrays and the previously reported analogous arrays based on Ge(IV)corrole with regard to their spectroscopic properties and photochemical activities.     

Synthesis and Study the Effect of Donor-Acceptor Substituent on Fluorescence Behavior of Thieno[3, 2-c]pyridine Derivatives

4-Hetero-1-yl-2-bromothieno[3,2-c]pyridines 3(a–d) were synthesized by the reaction of 2-bromo-4-chlorothieno[3,2-c]pyridine (1) and cyclic amine 2(a–d), which on Suzuki coupling with substituted boronic acids 4(a–f) exclusively converted to corresponding 4-hetero -1-yl-2-arylthieno[3,2-c]pyridine 5(a–x) in good yields. The effect of donor-acceptor substituent on absorption emission properties and fluorescent quantum yield of new thienopyridine derivatives 5(a-x) were studied.     

EPR,the X-ray Structure and DFT Calculations of the Nitroxide Biradical with One Acetylene Group in the Bridge

Two short nitroxide biradicals of similar composition, R6′–R6′ (B0) and R6′–(C ≡ C)–R6′ (B1), where R6′ is 1-oxyl-2,2,6,6-tetramethyl-3,4-ene-nitroxide ring, have been investigated by electron paramagnetic resonance spectroscopy and X-ray structural analysis. Quantum chemical calculations at UDFT/B3LYP/cc-pVDZ level were also performed and compared with the X-ray structural data. Zero-field splitting parameters D for B0 and B1 were found to be equal ?0.0048 and ?0.0022 cm^?1, respectively, in good agreement with quantum chemical prediction. Potential energy surface scans corresponding to pathways of the conformational rearrangements were calculated; rotation barriers for B0 and B1 were found to be 19.2 and 4.0 kJ/mol, respectively; and structural rigidity and probable differences in biradicals behavior are discussed. Calculations of spin density distribution in biradicals B0 and B1 were also carried out.     

Coordination preference and magnetic properties of FeII assemblies with a bis-azole bearing 1,2,4-triazole and tetrazole

With a new bis-azole molecular fragment (Htt) bearing 1,2,4-triazole and tetrazole, a mononuclear complex [Fe(tt)₂(H₂O)₄]·2H₂O (1), a trinuclear complex [Fe₃(tt)₆(H₂O)₆]·2H₂O (2) and a 1D coordination polymer [Fe(tt)(Htt)₂]BF₄·2CH₃OH (3) were obtained by varying reaction conditions. Htt acts either as an anionic or neutral ligand depending upon the reaction medium and pH. Thermal variation of spin states of 1–3 were investigated in the range 77–300?K by ⁵⁷Fe M?ssbauer spectroscopy. 1 totally remains in high-spin state over the entire temperature range whereas no spin crossover was evidenced in 2. Nearly 1:1 high-spin and low-spin population ratio is found in 3, which remains constant over the entire temperature range investigated.     

Grating tuned Ti:Sa laser for in-source spectroscopy of Rydberg and autoionizing states

Due to the large absorption cross section for optical transitions into Rydberg and autoionizing states compared to non-resonant ionization, these states are of particular interest for use in efficient laser resonance ionization excitation schemes as used in Resonant Ionization Laser Ion Sources (RILIS). In order to identify these atomic states extensive laser spectroscopy has to be performed. The lasers employed at TRIUMF’s laser ion source are birefringent filter tuned titanium:sapphire (Ti:Sa) lasers which are designed for long term frequency stability rather than continuous tuning. The design and characteristics of a grating tuned, high repetition rate, pulsed Ti:Sa laser for spectroscopy applications are presented. This laser allows fast scans of up to 40 THz with a laser linewidth of approximately 6 GHz. First tests were performed by scanning across the Rydberg series of gallium.     

Fluorescent Styryl Dyes Based on Novel 4-Methoxy-9-Methyi-9H-Carbazole-3-Carbaldehyde—Synthesis,Photophysical Properties and DFT Computations

Novel carbazole based styryl derivatives (6a–6c) having styryl group at third position and a methoxy substitution were synthesized by condensing 4-methoxy-9-methyl-9H-carbazole-3-carbaldehyde 3 and different active methylene derivatives (5a–5c). Evaluated photophysical properties of these synthesized novel chromophores, studied the effect of solvent polarity on absorption, emission and quantum yield of these styryl derivatives. DFT and TD-DFT computations are carried out to study structural, molecular, electronic and photophysical parameters of dyes. The ratio of ground state to excited state dipole moment was calculated using Bakhshiev and Kawski-Chamma-Viallet correlations.     

Indole-based Fluorescent Sensors for Selective Detection of Hg2+

A series of indole-based fluorescent chemosensors 1–4 were prepared and investigated characteristick features with transition metal ions. Sensors 1 and 2 were selective for Hg²⁺ ion among a series of metal ions in H₂O–DMSO with association constants of 4.60×10⁴ and 5.90×10⁴?M^?1 and detection limits of 140 and 101.6 μM, respectively.

Directed photocurrent in Langmuir-Schaefer organic molecular films

In the three-layer Langmuir-Schaefer films consisting of a monolayer of donor-acceptor phtalocyanine-fullerene dyad molecules (Bu ₃ ProM ₂ F) and two layers of poly(3-hexylthiophene) (PHT), placed into an electrochemical cell, the electric current resulted from optical excitation of sampleswas measured with no external voltage source. Samples were excited by the xenon lamp light passed through amonochromator or by a source simulating the solar spectrum. It was shown that the current density in samples reached 40–50 µA/cm² in the latter case. Current-voltage characteristics of samples were measured. Photovoltaic responses of three-layer structures were studied by the time-resolved Maxwell displacement charge method. The preferred orientation of dyad molecules in the film was demonstrated.     

Synthesis and Spectroscopy of Novel Branched Fluorescent Dyes Containing Benzophenone Parts and the Possibility as Fluorescence Probes

This paper describes a new fluorescent family of branched dyes containing benzophenone unit including 4-N, N-diphenylamino-4??-phenacyl-stilbene (C1), 4,4??-di(4-benzoylphenylethylene)yl-triphenylamine (C2) and 4,4??,4??-tri(4-benzoylphenylethylene)yl-triphenylamine (C3). Benzophenone part is coupled with core through C?CC double bond. The chemical structures of the derivatives are characterized with ¹H and ¹³C nuclear magnetic resonance and elemental analysis. Strong ?ШC?? stacking interactions are discovered with the analysis of the X-ray crystallographic data of C1. The absorption maxima and emission maxima of the derivatives exhibit gradual bathochromic shift from C1 to C3. The optical density of C1, C2 and C3 are shown to be related to the number of branches. The changes of dipole moments between the excited and ground states for C1, C2 and C3 were estimated to be 4.356, 8.091 and 8.479 Derby, respectively by Lippert equation, confirming that the internal charge transfer (ICT) dominates the process of excited singlet state. The possibility as fluorescence probes of the derivatives on the estimation of what region of micelles interacting with samples was evaluated.     

Structure, phase (aggregate) state, and optical properties of a new heat-resistant polymer with a nonlinear optical chromophore

A new heat-resistant copolymer (II) with a nonlinear optical chromophore in a side chain was synthesized by the etherification of side hydroxyl groups in chains of silicon-containing poly(o-hydroxyamide) (I) with 4′-{(6-chlorohexyl)methylamino}-4-nitroazobenzene (chromophore) under conditions of phase-transfer catalysis. The structure and phase (aggregate) states of copolymer II were investigated using x-ray diffraction and differential scanning calorimetry. It was shown that the substitution of chromophore molecules for up to 15% of hydrogen atoms in hydroxyl groups of amorphous copolymer I most likely leads to an independent arrangement of the chromophoric groups and the formation of crystal domains. It was established that this ordering substantially affects the stability and efficiency of the nonlinear optical properties of films prepared from copolymer II and is probably responsible for the slow decay of the second-harmonic generation signal in the sample.     

Basic kinetic wealth-exchange models: common features and open problems

We review the basic kinetic wealth-exchange models of Angle [J. Angle, Social Forces 65, 293 (1986); J. Math. Sociol. 26, 217 (2002)], Bennati [E. Bennati, Rivista Internazionale di Scienze Economiche e Commerciali 35, 735 (1988)], Chakraborti and Chakrabarti [A. Chakraborti, B. K. Chakrabarti, Eur. Phys. J. B 17, 167 (2000)], and of Dragulescu and Yakovenko [A. Dragulescu, V.M. Yakovenko, Eur. Phys. J. B 17, 723 (2000)]. Analytical fitting forms for the equilibrium wealth distributions are proposed. The influence of heterogeneity is investigated, the appearance of the fat tail in the wealth distribution and the relaxation to equilibrium are discussed. A unified reformulation of the models considered is suggested.     

The existence of a phase transition in classical antiferromagnetic models

For a wide class of antiferromagnetic models we prove the existence of a phase transition using an extended Peierls argument, taking into account a result of Dobrushin [R. L. Dobrushin,Funct. Anal. Appl. 2:44 (1968); in English,2:302 (1968)] for an antiferromagnetic Ising model and the results of Malyshev [V. Malyshev,Comm. Math. Phys. 40:75–82 (1975)] for ferromagnetic models (such as the anisotropic rotator). In particular we review a result of Fröhlich, Israel, Lieb, and Simon [J. Fröhlichet al., J. Stat. Phys. 22(3):297–347 (198)] obtained when reflection positivity holds.     

Electronic structure and optical properties of lead chloride

Spectra for the sets of optical functions for lead chloride are obtained for polarizations E ‖ a and E ‖ b at 10 K in the range of 4 to 30 eV. The calculations are carried out using synchrotron reflectivity spectra and a software package. The main features of the spectra of optical functions were established; they include the energies for volume and surface plasmons of two types. The bands and the spectra of permittivity and other optical functions for lead chloride crystals are calculated using the FP LAPW method. There was good agreement between the theoretical calculations and the data of the experimental spectra of R and other optical functions calculated using these R spectra.     

Synthesis of zinc oxide nanostructures catalytically active in the optical range without irradiation

A technique for synthesizing catalytically active zinc oxide-based nanostructures is described. The synthesis product represents a blue-gray powder. When it is introduced into a water solution of methyl orange the latter bleaches out both under daylight and in the dark. The activity of the material is measured by the Kubelka-Munk formula in the wavelength range 0.3–1.8 μm. As follows from X-ray phase analysis data, the synthesized material is a composite consisting of hexagonal structures with the parameters ZnO [a: 3.2491, c: 5.2046] and Zn [a: 2.6639, c: 4.9397]. A mechanism underlying the formation of a ZnO-Zn nanocomposite is suggested.     

Analysis of Forgery Attack on One-Time Proxy Signature and the Improvement

In a recent paper, Yang et al. (Quant. Inf. Process. 13(9), 2007–2016, 2014) analyzed the security of one-time proxy signature scheme Wang and Wei (Quant. Inf. Process. 11(2), 455–463, 2012) and pointed out that it cannot satisfy the security requirements of unforgeability and undeniability because an eavesdropper Eve can forge a valid proxy signature on a message chosen by herself. However, we find that the so-called proxy message-signature pair forged by Eve is issued by the proxy signer in fact, and anybody can obtain it as a requester, which means that the forgery attack is not considered as a successful attack. Therefore, the conclusion that this scheme cannot satisfy the security requirements of proxy signature against forging and denying is not appropriate in this sense. Finally, we study the reason for the misunderstanding and clarify the security requirements for proxy signatures.     

Model independent bounds on the modulus of the pion form factor on the unitarity cut below the ωπ threshold

We study the structure of local baryon fields using the method of QCD sum rule. We only consider the single baryon fields and calculate their operator product expansions. We find that the octet baryon fields belonging to the chiral representations $[(\mathbf{3},\bar{\mathbf{3}}) \oplus(\bar{\mathbf{3}}, \mathbf{3})]$ and [(8,1)??(1,8)] and the decuplet baryon fields belonging to the chiral representations [(3,6)??(6,3)] lead to the baryon masses which are consistent with the experimental data of ground baryon masses. We also calculate their decay constants, check our normalizations for baryon fields in Chen et?al. (Phys. Rev.?D 81:054002, 2009) and find that they are well-defined.     

Fast calculation of HELAS amplitudes using graphics processing unit (GPU)

We use the graphics processing unit (GPU) for fast calculations of helicity amplitudes of physics processes. As our first attempt, we compute $u\overline{u}\rightarrow n\gamma$ (n=2 to 8) processes in pp collisions at $\sqrt{s}=14$  TeV by transferring the MadGraph generated HELAS amplitudes (FORTRAN) into newly developed HEGET (HELAS Evaluation with GPU Enhanced Technology) codes written in CUDA, a C-platform developed by NVIDIA for general purpose computing on the GPU. Compared with the usual CPU programs, we obtain a 40–150 times better performance on the GPU.     

Hyperfine structure investigations of some odd levels of Co I by level crossing and optical methods

Using the level crossing technique the ratios and absolute values of the hyperfine structure (hfs) constants of the levelsz ⁴F_9/2 andz ⁴F_7/2 of the configuration 3d ⁷4s4p of Co I were measured:z ⁴ F _9/2: ¦A¦=(811±12)MHz; ¦B¦=(48±93) MHz;B/A=?0.06±0.11 A>0; B<0z ⁴ F _7/2: ¦A¦ = (659 ±11)MHz; ¦B¦=(33±84)MHz;B/A=?0.05±0.13 A>0; B<0. In addition the hfs constants of three other excited levels of Co I could be determined by optical methods:z ⁴ F _9/2:A=525±26 MHz;B=200 MHzy ⁴ F _9/2:A=300±30 MHz;B=?500 MHzy ⁴ G _11/2:A=315±20 MHz;B=400 MHz. The experimental results are compared with known experimental and also with theoretical values which where calculated using the parametric potential method.     

Anisotropic resonant magnetoplasticity of NaCl crystals in the Earth’s magnetic field

Resonant relaxation of the dislocation structure under the action of crossed magnetic fields, i.e., constant magnetic field of the Earth (B _Earth) and alternating radio-frequency field ( $\tilde B$ ), has been experimentally studied in a series of dielectric (NaCl) crystals with various compositions of impurities under variations in the frequency, direction of the pumping field $\tilde B$ , and orientation of the samples in the Earth’s magnetic field. The frequency dependence of the dislocation path length l(ν) exhibits peaks with various heights (l _max) and resonant frequencies (ν_res). The maximum resonant effect has been observed for dislocations with the direction L orthogonal to the plane of crossed magnetic fields in a configuration of mutually perpendicular vectors {L, $\tilde B$ , B _Earth} belonging, together with sample edges {a, b, c}, to the 〈100〉 system. Variation of the concentration C of calcium impurity in crystals of the NaCl_Ca series only influenced the resonant peak height as $l_{\max } \propto 1/\sqrt C $ . Rotation of the magnetic field $\tilde B$ in the (b, c) plane from direction $\tilde B$ ⊥ B _Earth to $\tilde B$ ∥ B _Earth also did not influence the frequency of the resonance but changed its amplitude. Depending on the crystal type, this influence changed from rather insignificant (in crystals of the NaCl_LOMO series) to complete suppression of the effect for $\tilde B$ ∥ B _Earth (in the NaCl_Nik series). The resonant frequency ν_res is sensitive to orientation of the sample with respect to B _Earth. Upon rotation of the crystal by the angle θ = ∠(c, B _Earth) about the a ⊥ B _Earth edge, the initial peak for dislocations L ‖ a at the crystal orientation θ = 0 and the frequency ν _res ⁰ is replaced by a pair of peaks at frequencies ν_{1, 2} ≈ ν _res ⁰ cosθ_{1, 2}, where θ₁ = 90° ? θ and θ₂ = θ. Previously, these peaks were observed separately in NaCl_Nik crystals for $\tilde B$ ∥ c and $\tilde B$ ∥ b. In the present study, these peaks have been observed simultaneously for both orientations of $\tilde B$ in NaCl_LOMO and NaCl_Ca crystals, where the resonance is not completely suppressed for $\tilde B$ ∥ B _Earth.