Structural studies and cytotoxic activity of a new dinuclear coordination compound of palladium(II)–2,2′:6′,2″‐terpyridine with rigid dianionic 1,2,4‐triazole‐3‐sulfonate linker

A new dinuclear coordination compound of palladium(II), [Pd₂(terpy)₂(μ‐tas‐N¹,N⁴)]SO₄?11H₂O ( 1 ), was synthesized by tethering a doubly deprotonated 1,2,4‐triazole‐3‐sulfonate (tas) linker generated in situ via oxidation of 1,2,4‐triazole‐3‐thione (tat) under the synthetic conditions. X‐ray diffraction analysis reveals that tat molecules adopt the thione form in the solid state, and are combined in infinite chains by symmetrically related classical intermolecular hydrogen bonds N1─H1???S1, N3─H3???N2 to give rise to R₂²(7) pattern in one‐dimensional chains along the b‐axis propagating along the a‐axis. Further short contacts through lone pairs of N2???S1 on the rings between the adjacent chains along the a‐axis lead to a two‐dimensional network structure. Compound 1 was characterized using infrared, ¹H NMR and UV–visible spectroscopies, electrospray ionization mass spectrometry and X‐ray crystallography. The crystal structure determination of 1 reveals that the Pd(II) ions are coordinated with four nitrogen atoms: three from terpy and one from tas acting as an end‐to‐end (μ‐1,4) bridging ligand. The Pd(II) ions in 1 adopt a distorted square planar geometry. The anti‐growth effect of 1 was tested on colorectal cancer (HCT‐15), non‐small‐cell lung cancer (A549), prostate cancer (PC‐3) and cervical cancer (HeLa) cell lines using sulforhodamine B viability assay. The cytotoxic effect was further confirmed using adenosine triphosphate viability assay. Compound 1 shows a promising cytotoxic activity in the diverse cancer cell models in vitro (p <0.0001).     

Effects of Heavy Iodine Atoms and π-Expanded Conjugation on Charge Transfer Dynamics in Carboxylic Acid BODIPY Derivatives as Triplet Photosensitizers

Borondipyrromethene (BODIPY) chromophores are composed of a functional-COOH group at meso position with or without a biphenyl ring, and their compounds with heavy iodine atoms at −2, −6 positions of the BODIPY indacene core were synthesized. The photophysical properties of the compounds were studied with steady-state absorption and fluorescence measurements. It was observed that the absorption band is significantly red-shifted, and fluorescence signals are quenched in the presence of iodine atoms. In addition to that, it was indicated that the biphenyl ring does not affect the spectral shifting in the absorption as well as fluorescence spectra. In an attempt to investigate the effect of π-expanded biphenyl moieties and heavy iodine atoms on charge transfer dynamics, femtosecond transient absorption spectroscopy measurements were carried out in the environment of the tetrahydrofuran (THF) solution. Based on the performed ultrafast pump-probe spectroscopy, BODIPY compounds with iodine atoms lead to intersystem crossing (ISC) and ISC rates were determined as 150 ps and 180 ps for iodine BODIPY compounds with and without π-expanded biphenyl moieties, respectively. According to the theoretical results, the charge transfer in the investigated compounds mostly appears to be intrinsic local excitations, corresponding to high photoluminescence efficiency. These experimental findings are useful for the design and study of the fundamental photochemistry of organic triplet photosensitizers.     

Green synthesis of fluorescent carbon dots from Kumquat (Fortunella margarita) for detection of Fe3+ ions in aqueous solution

In this study, kumquat was first time used for synthesizing carbon dot structures (CDs) with the hydrothermal method. These newly synthesized CDs was characterized structurally and optically. The ion sensor application of the new CDs was carried out using 20 different metal ions. It was observed that CDs have high selectivity only for Fe³⁺ ions among the metal ions studied. Detection limit for Fe³⁺ ions was calculated as 0.70 µM. The results showed that these new CDs are highly selective against Fe³⁺ ions and have a very short response time such as 0.5 min. The Fe³⁺ ions selectivity of CDs was tested on real (tap water) samples. The results exhibited that this new CDs, obtained with green synthesis from Kumquat fruit without using chemical agents in one-pot simple and economical process, can be used as fluorometric sensor for detection of Fe³⁺ ions with high selectivity and sensitivity, low detection limit and rapid response time.

     

On the automorphisms of generalized algebraic geometry codes

Designs, Codes and Cryptography - We consider the class of generalized algebraic geometry codes (GAG codes) formed by two collections of places, with places of the same degree in each collection....     

An approximation for kanban controlled assembly systems

An approximation is proposed to evaluate the steady-state performance of kanban controlled two-stage assembly systems. The development of the approximation is as follows. The considered continuous-time Markov chain is aggregated keeping the model exact, and this aggregate model is approximated replacing some state-dependent transition rates with constant rates. The approximate aggregate model is, then, decomposed into submodels and a product-form steady-state distribution is obtained for each submodel. Finally, the submodels are combined in such a way that the size of the problem becomes independent of the number of kanbans. This leads to the computational advantage in solving the combined model using numerical matrix-geometric solution algorithms. Numerical comparisons of the combined model with simulation, exact model, approximate aggregate model and an approximation in the literature show that the proposed approximation performs well in terms of accuracy and computational burden.     

On the complex factorization of the Lucas sequence

In this paper, firstly we present a connection between determinants of tridiagonal matrices and the Lucas sequence. Secondly, we obtain the complex factorization of Lucas sequence by considering how the Lucas sequence can be connected to Chebyshev polynomials by determinants of a sequence of matrices.     

The effect of B2O3 addition to the microstructure and magnetic properties of Ni0.4Zn0.6Fe2O4 ferrite

The effects of 0.01 and 0.1 mol B₂O₃ addition to the microstructure and magnetic properties of a Ni–Zn ferrite composition expressed by a molecular formula of Ni_0.4Zn_0.6Fe₂O₄ were investigated. The toroid-shaped samples prepared by pressing the milled raw materials used in the preparation of the composition were sintered in the range of 1000–1300 °C. The addition of 0.01 mol B₂O₃ increased the grain growth and densification giving rise to reduced intergranular and intragranular porosity due to liquid-phase sintering. The sintered toroid sample at 1300 °C gave the optimum magnetic properties of B_r=170 mT, H_c=0.025 kA/m and a high initial permeability value of μ_i=4000. The increment of the B₂O₃ content to 0.1 mol resulted in a pronounced grain growth and also gave rise to large porosity due to the evaporation of B₂O₃ at higher sintering temperatures. Hence, it resulted in an air-gap effect in the hysteresis curves of these samples.     

Intercalation of graphite and hexagonal boron nitride by lithium

Although graphite and hexagonal form of BN (h-BN) are isoelectronic and have very similar lattice structures, it has been very difficult to intercalate h-BN while there are hundreds of intercalation compounds of graphite. We have done a comparative first principles investigation of lithium intercalation of graphite and hexagonal boron nitride to provide clues for the difficulty of h-BN intercalation. In particular lattice structure, cohesive energy, formation enthalpy, charge transfer and electronic structure of both intercalation compounds are calculated in the density functional theory framework with local density approximation to the exchange-correlation energy. The calculated formation enthalpy of the considered forms of Li intercalated h-BN is found to be positive which rules out h-BN intercalation without externally supplied energy. Also, the Li(BN)₃ form of Li-intercalated h-BN is found to have a large electronic density of states at the Fermi level and an interlayer state that crosses Fermi level at the zone center; these properties make it an interesting material to investigate the role of interlayer states in the superconductivity of alkali intercalated layered structures. The most pronounced change in the charge distribution of the intercalated compounds is found to be charge transfer from the planar σ states to the π states.