Symmetrical Derivatives Research Articles

A study of the interaction between inverted cucurbit[7]uril and symmetric viologens

The interaction between iQ[7] and a series of symmetric viologen derivatives, namely dicationic dialkyl-4,4′-bipyridinium guests where the alkyl is CH3(CH2)n with n = 0 to 6, has been studied in aqueous solution and solid state.

Improved synthesis of symmetrically & asymmetrically N-substituted pyridinophane derivatives.

The N,N'-di(toluenesulfonyl)-2,11-diaza[3,3](2,6)pyridinophane (TsN4) precursor was sought after as a starting point for the preparation of various symmetric and asymmetric pyridinophane-derived ligands. Various procedures to synthesize TsN4 had been published, but the crucial problem had been the purification of TsN4 from the larger 18- and 24-membered azamacrocycles. Most commonly, column chromatography or other laborious methods have been utilized for this separation, yet we have found an alternate selective dissolution method upon protonation which allows for multi-gram scale output of TsN4·HCl. This optimized synthesis of TsN4 also led to the development of symmetric RN4 derivatives as well as the asymmetric derivative N-(tosyl)-2,11-diaza[3,3](2,6)pyridinophane (TsHN4). Using this TsHN4 precursor, different N-substituents can be added to create a library of asymmetric RR'N4 macrocyclic ligands. These asymmetric RR'N4 derivatives expand the utility of the RN4 framework in coordination chemistry and the ability to study the electronic, steric, and denticity effects of these pyridinophane ligands on the metal center.

New condensed nitrogen–phosphorus heterocycles

To extend our previous study aimed at the reactions of chlorodithiophosphoric acid pyridiniumbetaine (py·PS2Cl) with thiosemicarbazide derivatives, we performed the reactions of chlorodithiophosphoric acid pyridiniumbetaine with a new group of polyfunctional nucleophiles – symmetrical and nonsymmetrical derivatives of hydrazine-1,2-bis(thiocarboamide) of general formula R(H)N–C(S)N(H)N(H)C(S)–N(H)R (R=methyl, i-propyl, ethyl, t-butyl, phenyl). In analogy to heterocyclic anions obtained with the thiosemicarbazide derivatives, the hydrazine derivatives were expected to form heterobicyclic dianions from the reactions with py·PS2Cl. All the reactions were carried out in acetonitrile in the presence of pyridine to keep the same reaction conditions as with the previous experiments. Four new compounds were prepared and characterized by 31P NMR, FTIR, Raman spectroscopy, and single crystal X-ray diffraction. Molecular structures of the products are based on heterobicyclic dianion consisting of two condensed five membered P–N–N–C–N rings, each of them bearing an organic group. Both of the organic groups in heterobicyclic dianion are either identical (Me, iPr) or different (Et/tBu, Et/Ph). The molecular structure of the heterobicyclic dianion with unusual structural features was further examined by quantum chemistry calculations.

Structural and ultrastructural characterization of the spermatozoa in Pachycondyla striata and P. marginata

This study characterizes the male gametic cells in two ant species (Pachycondyla striata and Pachnoda marginata) by light and transmission electron microscopies. The sperm of both species is composed of head, flagellum, and transition regions. The head consists of the acrosome, tapered and bilayer, and a cylindrical nucleus. In P. marginata, the intranuclear material is homogeneously compacted, and in P. striata, there are translucent inclusions and density variations. In the transition region of both species, centriolar adjunct, nuclear base, and the modified basal body (structure of the spermatozoa equivalent to the spermatids’ centriole) coexist and are progressively replaced by two oval and symmetrical mitochondrial derivatives and an axoneme 9 + 9 + 2, respectively, in addition to two symmetrical triangular accessory bodies. Moreover, cytochemical analysis with Ethanolic Phosphotungstic Acid Method (E-PTA) revealed species-specific features not previously reported in the Formicidae, such as the presence of E-PTA negative acrosomal vesicle, E-PTA positive perforatorium, and E-PTA positive nucleus, all in P. marginata. Mitochondrial derivatives exhibited distinct behavior in its internal composition, with E-PTA negative mitochondrial cristae and E-PTA positive paracrystalline in both species. Sperm morphology in Pachycondyla has marked morphological similarities with other ant groups, and its specific features can be useful tools to understand phylogenetic relationships within the Formicidae and Hymenoptera.

ChemInform Abstract: Synthesis of meta‐Terphenyl‐2,2′′‐diols by Anodic C—C Cross‐Coupling Reactions.

The anodic C−C cross-coupling reaction is a versatile synthetic approach to symmetric and non-symmetric biphenols and arylated phenols. We herein present a metal-free electrosynthetic method that provides access to symmetric and non-symmetric meta-terphenyl-2,2′′-diols in good yields and high selectivity. Symmetric derivatives can be obtained by direct electrolysis in an undivided cell. The synthesis of non-symmetric meta-terphenyl-2,2′′-diols required two electrochemical steps. The reactions are easy to conduct and scalable. The method also features a broad substrate scope, and a large variety of functional groups are tolerated. The target molecules may serve as [OCO]3− pincer ligands.

On existence of optimal solutions for stochastic differential equations and inclusions with current velocities

For a stochastic differential inclusion given in terms of current velocities (symmetric mean derivatives) on flat n-dimensional torus, we prove the existence of optimal solution minimizing a certain cost criterion. Then this result is applied to the problem of optimal control for equations with current velocities.

Synthesis, photophysical and electrochemical properties of symmetric silicon-linked coumarin-oxadiazole derivatives

A novel, silicon-linked, symmetric, V-shaped, coumarin derivative (1) with an electron-deficient 1,3,4-oxadiazoles unit and a phenyl moiety was synthesized and characterized. An efficient multifunctional organic light-emitting diode material was obtained through the use of optical, electrochemical, thermal, and theoretical investigations. We show that the Si atom induces a V-shaped structure that weakens π–π stacking and thus limits aggregation-induced quenching. As expected, a gradual transition from a locally excited state to an intramolecular charge-transfer state is observed with increasing solvent polarity. This new type of compound exhibits tunable light emission in solution making it a versatile emitter.

Selective Synthesis, Characterization of Isomerically Pure Arylated Benzo[1,2-b:6,5-b′]dithiophenes by Regioselective Suzuki–Miyaura Reaction and Evaluation of the Catalytic Properties of Nickel versus Palladium Complexes

Selective synthesis of isomerically pure, angular-shaped benzo[1,2- b :6,5- b ′]dithiophenes and various aryl-substituted analogues via the regioselective Suzuki–Miyaura cross-coupling reaction is described. The structural assignments of symmetrical and unsymmetrical derivatives of benzodithiophenes and coumarin-type polyheterocycles are based on X-ray crystallography and spectroscopic studies. A comparative study of nickel versus palladium complexes demonstrated that the nickel complex NiCl 2 (dppe) is more effective in terms of reactivity and yields than palladium catalysis in the Suzuki–Miyaura cross-coupling of hindered 3,6-dichlorobenzo[1,2- b :6,5- b ′]dithiophenes with arylboronic acids.

Novel tetrazole-based symmetrical diselenides as corrosion inhibitors for N80 carbon steel in 1 M HCl solutions: Experimental and theoretical studies

Two new tetrazole-based symmetrical diselenide derivatives (TDS1 and TDS2) were synthesized via one-pot azido-Ugi reaction and in good yields. The inhibiting action of these compounds was further studied on the corrosion of N80 carbon steel in 1M HCl using different techniques such as weight loss method, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM). Interestingly, TDS2 (50ppm) manifested inhibition efficiency up to 93% and this was confirmed using different experimental techniques such as EIS and EFM. Potentiodynamic polarization measurements showed that the investigated compounds belong to mixed type inhibitors and they are working according to the Langmuir adsorption isotherm. Calculated quantum chemical parameters provided a theoretical rational for the adsorption and inhibition activities of TDS1 and TDS2 on N80 carbon steel corrosion inhibition. Moreover, TDS1 and TDS2 have been simulated as adsorbate on Fe (1 1 0) substrate and their relative adsorption energies were identified on iron surface and the quantum chemical calculation and molecular dynamics simulation were in agreement with the experimental observations. These results indicate that TDS1 and TDS2 are good corrosion inhibitors.

Air-Stable Pd Catalytic Systems for Sequential One-Pot Synthesis of Challenging Unsymmetrical Aminoaromatics.

The selective functionalization of dibromoaromatic scaffolds using air-stable palladium catalytic systems was carried out. This methodology involved rapid mono and diselective Buchwald-Hartwig aminations via microwave irradiation. The conditions were optimized to couple sequentially different moieties in one pot. Couplings with a wide scope of amines allowed accessing a new library of symmetrical and unsymmetrical derivatives (35 examples). Using this versatile method, a near-IR push-pull sensor was prepared installing the electron-donating and -withdrawing groups through a multicomponent reaction. These conditions revealed to be gram-scalable and adaptable to various groups; hence, promoting facile use in synthetic chemistry.

Synthesis of meta-Terphenyl-2,2''-diols by Anodic C-C Cross-Coupling Reactions.

The anodic C-C cross-coupling reaction is a versatile synthetic approach to symmetric and non-symmetric biphenols and arylated phenols. We herein present a metal-free electrosynthetic method that provides access to symmetric and non-symmetric meta-terphenyl-2,2''-diols in good yields and high selectivity. Symmetric derivatives can be obtained by direct electrolysis in an undivided cell. The synthesis of non-symmetric meta-terphenyl-2,2''-diols required two electrochemical steps. The reactions are easy to conduct and scalable. The method also features a broad substrate scope, and a large variety of functional groups are tolerated. The target molecules may serve as [OCO](3-) pincer ligands.

Anion response of symmetric hydrazide derivatives: Dependence on the number of hydrazide units

Two symmetric hydrazide derivatives with different numbers of hydrazide groups were synthesized, and their anion responsive behaviors were studied. The UV–vis spectra showed that the compounds with only one hydrazide group can allow highly selective fluoride detection, whereas the compound with two hydrazide groups can respond to F− and AcO−. This is due to the difference in the acidity of the compounds, which is caused by the quantity of hydrazide. This demonstrates that altering the number of hydrazide groups can realize the effective adjustment and control of the anionic recognition ability of compounds.

Highly Luminescence Anthracene Derivatives as Promising Materials for OLED Applications

Novel symmetrical anthracene derivatives with bulky carbazolyl‐fluorene, diphenylamino‐fluorene, or carbazolyl‐carbazole units connected to the anthracene frame through an ethynyl bridge were synthesized in excellent yield by using Sonogashira cross‐coupling. The ethynyl bridge in the anthracene dyes increases π‐electron conjugation and the bulky substituents considerably attenuate intermolecular interactions. The dyes possess high thermal stability, tremendous solubility in common organic solvents, and especially high photoluminescence quantum yield (Φf) in solution in the range of 77–98 %. OLED devices were fabricated. The AFM images of thin films and blends prepared from all compounds show a uniform and flat surface, indicating excellent film‐forming properties. Devices incorporating the anthracene derivative with diphenylamino‐fluorene end‐capping groups exhibited the highest value of current density (J). All of the fabricated OLED devices emitted yellowish‐orange light under applied voltage.

Nonlinear optical properties of symmetrical and asymmetrical porphyrin derivatives with click chemistry modification

The novel kind of charge-transfer porphyrin complexes with symmetrical and asymmetrical side groups were synthesized by the high-yielding [2 + 2] click chemistry reaction involved a two-step procedure. Both electrochemical and UV–vis studies were characterized and proved that the side groups of the porphyrin complexes played an important role on optical properties and energy gaps. The novel series did show the narrower band gap and broader absorption in the visible and near infrared region. As the side groups, the click moieties also affected the third-order nonlinear optical responses, and all the compounds exhibited the expected nonlinear optical properties which were affected by the chemical structures. The optical-limiting performance had also been studied, which was in agreement with the result of Z-scan experiments.

Synthesis, structure, electrochemistry, and photophysics of 2,5-dibenzylidenecyclopentanones containing in benzene rings substituents different in polarity

A series of cross-conjugated dienones was synthesized to study the dependence of physicochemical characteristics on the nature of substituents in the aromatic groups of symmetric cyclopentanone dibenzylidene derivatives. The structure of compounds was established by electronic, IR, and NMR spectroscopy and X-ray diffraction study. All the compounds obtained possess the E,E-geometry. In the crystalline state, the arrangement of the dienone molecules is unfavorable for the intermolecular [2+2] photocycloaddition to take place. The low-temperature phases transition for unsubstituted diphenyl derivative of cyclopentanone was detected using variable-temperature X-ray diffraction and differential scanning calorimetry. Oxidation and reduction potentials of the dienones were measured by cyclic voltammetry. Their dependence on the nature and placement of substituents in the benzene rings was demonstrated. A linear correlation (R = 0.9343) between the difference of electrochemical oxidation and reduction potentials and the energy of the long-wavelength absorption maximum was found, that allows us to recommend the use of the data obtained in the correlation analysis of other compounds of this class.

On the geometry of mixed states and the Fisher information tensor

In this paper, we will review the co-adjoint orbit formulation of finite dimensional quantum mechanics, and in this framework, we will interpret the notion of quantum Fisher information index (and metric). Following previous work of part of the authors, who introduced the definition of Fisher information tensor, we will show how its antisymmetric part is the pullback of the natural Kostant–Kirillov–Souriau symplectic form along some natural diffeomorphism. In order to do this, we will need to understand the symmetric logarithmic derivative as a proper 1-form, settling the issues about its very definition and explicit computation. Moreover, the fibration of co-adjoint orbits, seen as spaces of mixed states, is also discussed.

ChemInform Abstract: Synthesis of Symmetrical Terphenyl Derivatives by PdCl2‐Catalyzed Suzuki—Miyaura Reaction of Dibromobenzene Using 3‐(Diphenylphosphino)propanoic Acid as a Ligand.

AbstractA simple and efficient catalytic system consisting of 3‐(diphenylphosphino) propanoic acid PdCl2 catalyzes the title reaction to obtain the desired terphenyl products, in good to excellent yields.

Some New Results of Symmetric Derivative on Time Scales

Some New Results of Symmetric Derivative on Time Scales

On The K-Pseudo Symmetric and Ordinary Differentiation

AbstractIn 1972, S. Valenti introduced the definition of k-pseudo symmetric derivative and has shown that the set of all points of a continuous function, at which there exists a finite k-pseudo symmetric derivative but the finite ordinary derivative does not exist, is of Lebesgue measure zero. In 1993, L. Zajícek has shown that for a continuous function f, the set of all points, at which f is symmetrically differentiable but no differentiable, is σ-(1 - ε) symmetrically porous for every ε > 0. The question arises: can we transferred the Zajícek’s result to the case of the k-pseudo symmetric derivative?In this paper, we shall show that for each 0 < ε < 1 the set of all points of a continuous function, at which there exists a finite k-pseudo symmetric derivative but the finite ordinary derivative does not exist, is σ-(1 - ε)-porous.

Quantum Fisher information and symmetric logarithmic derivative via anti-commutators

The symmetric logarithmic derivative (SLD) is a key quantity to obtain quantum Fisher information (QFI) and to construct the corresponding optimal measurements. Here we develop a method to calculate the SLD and QFI via anti-commutators. This method has originated from the Lyapunov representation and would be very useful for cases where the anti-commutators among the state and its partial derivative exhibit periodic properties. As an application, we discuss a class of states whose squares linearly depend on the states themselves, and give the corresponding analytical expressions of SLD and QFI. A noisy scenario of this class of states is also considered and discussed. Finally, we readily apply the method to the block-diagonal states and the multi-parameter estimation scenarios.