Synthesis,characterization, duplex-DNA interactions,and anticancer activities of novel octahedral [Ni(phen)2(dppz-idzo)]2+ and [Co(phen)2(dppz-idzo)]3+ complexes

Two new octahedral [Ni(phen)₂(dppz-idzo)]²⁺ and [Co(phen)₂(dppz-idzo)]³⁺ complexes have been synthesized and characterized by CHN analysis, electrospray ionization-MS, nuclear magnetic resonance, and UV–Vis spectra. The DNA-binding ability of these complexes was spectrophotometrically, hydrodynamically, and electrophoretically evaluated which indicated that they strongly intercalate into the DNA double helix, and that both induced severe DNA damage in the presence of peroxide. The complexes also showed strong antiproliferative effect against HepG2 and MDA-MB-231 cells. By contrast, they were found to be inactive against the MCF-7 cell line. The ligand itself was found to be inactive against the cells tested.     

Structural characterization of disperse black 9 based Cu (II) complex and investigation of its some properties

We obtained the azo‐imine ligand (2,2′‐[4‐(5‐methoxy salicylidene‐4‐iminophenylazo)phenylimino]diethanol) (HL) and its Cu (II) complex (CuL) from the ethanol solution. The complex Cu(L)₂ was obtained as single crystals from the CH₃OH solution and structurally characterized. The electronic and photoluminescence properties of the ligand and its Cu (II) complex were investigated both in DMF solution and solid state. The oxidation and reduction behaviours of the compounds were studied in the solution and found that the redox processes are irreversible. Thermal studies show that the ligand has higher thermal stability than the CuL complex. Single crystals of the complex were obtained from slow evaporation of a DMF solution of the complex. Crystals of the complex showed a diffraction pattern; however, the structure of the complex was able to be solved.     

Transition-Metal Catalysis of Triene 6π Electrocyclization: The π-Complexation Strategy Realized

Triene 6π electrocyclization, wherein a conjugated triene undergoes a concerted stereospecific cycloisomerization to a cyclohexadiene, is a reaction of great historical and practical significance. In order to circumvent limitations imposed by the normally harsh reaction conditions, chemists have long sought to develop catalytic variants based upon the activating power of metal–alkene coordination. Herein, we demonstrate the first successful implementation of such a strategy by utilizing [(C₅H₅)Ru(NCMe)₃]PF₆ as a precatalyst for the disrotatory 6π electrocyclization of highly substituted trienes that are resistant to thermal cyclization. Mechanistic and computational studies implicate hexahapto transition-metal coordination as responsible for lowering the energetic barrier to ring closure. This work establishes a foundation for the development of new catalysts for stereoselective electrocyclizations.     

Fabrication and characterization of Ag- and Cu-doped TiO2 nanotubes (NTs) by in situ anodization method as an efficient photocatalyst

Journal of Solid State Electrochemistry - In this study, copper (Cu) and silver (Ag)–doped TiO2 nanotubes were fabricated by in situ anodization method to improve their photocatalytic...     

How to Predict Excited State Geometry by Using Empirical Parameters Obtained from Franck-Condon Analysis of Optical Spectrum

Excited state geometries of molecules can be calculated with highly reliable wavefunction schemes. Most of such schemes, however, are applicable to small molecules and can hardly be viewed as error-free for excited state geometries. In this study, a theoretical approach is presented in which the excited state geometries of molecules can be predicted by using vibrationally resolved experimental absorption spectrum in combination with the theoretical modelling of vibrational pattern based on Franck-Condon approximation. Huang-Rhys factors have been empirically determined and used as input for revealing the structural changes occurring between the ground and the excited state geometries upon photoexcitation. Naphthalene molecule has been chosen as a test case to show the robustness of the proposed theoretical approach. Predicted 1B_2u excited state geometry of the naphthalene has similar but slightly different bond length alternation pattern when compared with the geometries calculated with CIS, B3LYP, and CC2 methods. Excited state geometries of perylene and pyrene molecules are also determined with the presented theoretical approach. This powerful method can be applied to other molecules and specifically to relatively large molecules rather easily as long as vibrationally resolved experimental spectra are available to use.     

Assessing and predicting changes in vegetation cover associated with military land use activities using field monitoring data at Fort Hood, Texas

We assessed short-term impacts of changes in military training load on vegetative cover at Fort Hood, TX. From 1989 to 1995, permanent field transects were monitored for vegetative cover and land use disturbance using standard army monitoring methods [Land Condition Trend Analysis (LCTA)]. Land use intensity (training load) was quantified and used to develop a model to predict future vegetation cover values. We found that standard Army monitoring methods detected changes in installation resources associated with changes in training load. Increased training loads were associated with increased measures of disturbance, decreased ground cover, and decreased aerial vegetative cover. We found that the spatial pattern of disturbance and vegetation cover remained relatively constant over the study period despite large variations in overall training load. Our model used the consistency in spatial cover patterns over time and the strong relationship between training load and vegetation cover to predict the impact of future training loads on vegetation.     

The kinetics of methane ignition in fuel-rich HCCI engines: DME replacement by ozone

Fuel-rich combustion of methane in a homogeneous-charge compression-ignition (HCCI) engine can be used as a polygeneration process producing work, heat, and useful chemicals like syngas. Due to the inertness of methane, additives such as dimethyl ether (DME) are needed to achieve ignition at moderate inlet temperatures and to control combustion phasing. Because significant concentrations of DME are then needed, a considerable part of the fuel energy comes from DME. An alternative ignition promotor known from fuel-lean HCCI is ozone (O₃). Here, a combined experimental and modelling study on the ignition of fuel-rich partial oxidation of methane/air mixtures at Φ = 1.9 with ozone and DME as additives in an HCCI engine is conducted. Experimental results show that ozone is a suitable additive for fuel-rich HCCI, with only 75 ppm ozone reducing the fuel-fraction of DME needed from 11.0% to 5.3%. Since ozone does not survive until the end of the compression stroke, the reaction paths are analyzed in a single-zone model. The simulation shows that different ignition precursors or buffer molecules are formed, depending on the additives. If only DME is added, hydrogen peroxide (H₂O₂) and formaldehyde (CH₂O) are the most important intermediates, leading to OH formation and ignition around top dead center (TDC). With ozone addition, methyl hydroperoxide (CH₃OOH) becomes very important earlier in the compression stroke under these fuel-rich conditions. It is then later converted to CH₂O and H₂O₂. Thus, ozone is a very effective additive not only for fuel-lean, but also for fuel-rich combustion. However, the mechanism differs between both regimes. Because less of the expensive additives are needed, ozone could help improving the economics of a polygeneration process with fuel-rich operated HCCI engines.     

A practical access to new pyrrolizine carboxylates via KHMDS-catalyzed carbocyclizations

Easy and effective preparation of new 1H-pyrrolizine carboxylates was achieved with high efficiency via KHMDS-induced carbocyclization of N-alkynyl proline carboxylates under substantially mild conditions. Meanwhile, some trans-diiodoallylic N-proline carboxylates were obtained from N-propargyl proline carboxylates using molecular I₂ with or without KHMDS. This method is quite feasible in terms of practical and quick access to the pyrrolizines and their derivatives over the formation of carbanions.