Light-Activated Carbon Monoxide Prodrugs Based on Bipyridyl Dicarbonyl Ruthenium(II) Complexes

Two photoactivatable dicarbonyl ruthenium(II) complexes based on an amide-functionalised bipyridine scaffold (4-position) equipped with an alkyne functionality or a green-fluorescent BODIPY (boron-dipyrromethene) dye have been prepared and used to investigate their light-induced decarbonylation. UV/Vis, FTIR and ¹³C NMR spectroscopies as well as gas chromatography and multivariate curve resolution alternating least-squares analysis (MCR-ALS) were used to elucidate the mechanism of the decarbonylation process. Release of the first CO molecule occurs very quickly, while release of the second CO molecule proceeds more slowly. In vitro studies using two cell lines A431 (human squamous carcinoma) and HEK293 (human embryonic kidney cells) have been carried out in order to characterise the anti-proliferative and anti-apoptotic activities. The BODIPY-labelled compound allows for monitoring the cellular uptake, showing fast internalisation kinetics and accumulation at the endoplasmic reticulum and mitochondria.     

Polymer architectures via mass spectrometry and hyphenated techniques: A review

This review covers the application of mass spectrometry (MS) and its hyphenated techniques to synthetic polymers of varying architectural complexities. The synthetic polymers are discussed as according to their architectural complexity from linear homopolymers and copolymers to stars, dendrimers, cyclic copolymers and other polymers. MS and tandem MS (MS/MS) has been extensively used for the analysis of synthetic polymers. However, the increase in structural or architectural complexity can result in analytical challenges that MS or MS/MS cannot overcome alone. Hyphenation to MS with different chromatographic techniques (2D × LC, SEC, HPLC etc.), utilization of other ionization methods (APCI, DESI etc.) and various mass analyzers (FT-ICR, quadrupole, time-of-flight, ion trap etc.) are applied to overcome these challenges and achieve more detailed structural characterizations of complex polymeric systems. In addition, computational methods (software: MassChrom2D, COCONUT, 2D maps etc.) have also reached polymer science to facilitate and accelerate data interpretation. Developments in technology and the comprehension of different polymer classes with diverse architectures have significantly improved, which allow for smart polymer designs to be examined and advanced. We present specific examples covering diverse analytical aspects as well as forthcoming prospects in polymer science.     

The spectral characterization of thiophene radical cation generated by pulse radiolysis

Pulse radiolysis matched with kinetic spectrometry has been employed to produce and characterize the radical cations of the series of unsubstituted oligothiophenes from one to six rings in dichloromethane dilute solutions. The concentration of radicals has been tuned to low values so as to slow down dimerization processes. The spectra obtained for the radical cations with 2 to 6 rings agree with previous literature reports. The novel isolation of the radical cation of thiophene itself and its spectral characterization, both experimental and theoretical, stresses its close relationship to the electronic structure of oligothiophenes. This fact strongly recommends that the charge carrier properties of oligothiophenes be interpreted on the basis of the molecular orbital theory rather than of the polaron model. The state responsible for the main UV absorption band is found to be described by a mixture of configurations where the HOMO→LUMO transition is present with different spin couplings.     

Examining the impact of ancillary ligand basicity on copper(I)–ethylene binding interactions: a DFT study

A theoretical investigation at the density functional theory level (B3LYP) has been conducted to elucidate the impact of ligand basicity on the binding interactions between ethylene and copper(I) ions in [Cu(η ²-C₂H₄)]⁺ and a series of [Cu(L)(η ²-C₂H₄)]⁺ complexes, where L = substituted 1,10-phenanthroline ligands. Molecular orbital analysis shows that binding in [Cu(η ²-C₂H₄)]⁺ primarily involves interaction between the filled ethylene π-bonding orbital and the empty Cu(4s) and Cu(4p) orbitals, with less interaction observed between the low energy Cu(3d) orbitals and the empty ethylene π*-orbital. The presence of electron-donating ligands in the [Cu(L)(η ²-C₂H₄)]⁺ complexes destabilizes the predominantly Cu(3d)-character filled frontier orbital of the [Cu(L)]⁺ fragment, promoting better overlap with the vacant ethylene π*-orbital and increasing Cu → ethylene π-backbonding. Moreover, the energy of the filled [Cu(L)]⁺ frontier orbital and mixing with the ethylene π*-orbital increase with increasing pK _a of the 1,10-phenanthroline ligand. Natural bond orbital analysis reveals an increase in Cu → ethylene electron donation with addition of ligands to [Cu(η ²-C₂H₄)]⁺ and an increase in backbonding with increasing ligand pK _a in the [Cu(L)(η ²-C₂H₄)]⁺ complexes. Energy decomposition analysis (ALMO-EDA) calculations show that, while Cu → ethylene charge transfer (CT) increases with more basic ligands, ethylene → Cu CT and non-CT frozen density and polarization effects become less favorable, yielding little change in copper(I)–ethylene binding energy with ligand pK _a. ALMO-EDA calculations on related [Cu(L)(NCCH₃)]⁺ complexes and calculated free energy changes for the displacement of acetonitrile by ethylene reveal a direct correlation between increasing ligand pK _a and the favorability of ethylene binding, consistent with experimental observations.     

The effects of nano-TiO<Subscript>2</Subscript> on seed germination,development and mitosis of root tip cells of <Emphasis Type="Italic">Vicia narbonensis</Emphasis> L. and <Emphasis Type="Italic">Zea mays</Emphasis> L

This study aimed to provide new information about phyto-toxicology of nano-TiO₂ on plant systems. To contribute to the evaluation of the potential harmful effects of the nanoparticles on monocots and dicots we considered their effects on seed germination and root elongation applying a concentration range from 0.2 to 4.0‰ in the plants Zea mays L. and Vicia narbonensis L. Moreover, we achieved a genotoxicity study at cytological level in root meristems by means of traditional cytogenetic approach, to evidence possible alterations in mitotic activity, chromosomal aberrations, and micronuclei release. From these analyses it comes out that nano-TiO₂ particles, after short-term exposure and under our experimental conditions, delayed germination progression for the first 24 h in both materials. Root elongation was affected only after treatment with the higher nano-TiO₂ concentration. Further significant effects were detected showing mitotic index reduction and concentration-dependent increase in the aberration emergence that evidenced a nano-TiO₂-induced genotoxic effect for both species.     

Critical evaluation of the use of total reflection X-ray fluorescence spectrometry for the analysis of whole blood samples: application to patients with thyroid gland diseases

Analytical and Bioanalytical Chemistry - Multielemental analysis of whole blood can provide significant information for the evaluation of nutritional status and diagnosis of certain diseases as...     

A fullerene-based dyad for organic photovoltaic cells

We describe the synthesis and the photophysical properties of a fullerene–azothiophene dyad, as well as the photovoltaic performance of cells incorporating the dyad and the surface morphology of the device active layer. The results have been compared with those obtained on the blend, in equimolar ratio, between the azothiophene dye and a fulleropyrrolidine. This revealed a pivotal role played by the morphology on both the photophysical behaviour and the device performance. While scanning force microscopy studies for the dyad exhibited fairly smooth surfaces, in the case of the blend they displayed a micrometre-scale phase segregation between the two components. We suggest that, in the latter case, the lack of photo-induced electron transfer evidenced by the photophysical study, and the relevant reduction of the cell performance (up to more than one order of magnitude with respect to the dyad), could be ascribed to the different morphology. Because of the strong optical absorption in the visible region, the dyad-based solar cells gave notable results if compared with those reported in the literature for other donor–acceptor linked systems. A power-conversion efficiency of 0.37% under 80-mWcm^-2 white-light illumination has been achieved by tuning the thickness of the dyad film, though the fullerene–azothiophene is not yet optimised in terms of photo-induced electron transfer. PACS 81.05.Tp; 73.50.Pz; 71.35.Gg; 72.20.Jv     

Simulations of migration, fragmentation and coalescence of non-wetting fluids in porous media

A model based on invasion percolation was used to simulate the migration on a non-wetting fluid through a porous medium filled with an immiscible wetting fluid under the influence of a gradient such as that provided by gravity. The migrating fluid clusters undergo both fragmentation and coalescence. The fragment size distribution obtained from two-dimensional simulations in which the gradient g is slowly increased from 0 can be represented by the scaling form N_s(g)s^-2ƒ(s|g|^-z where z=1+(D−1)ν(ν+1). Here D is the fractal dimensionality of invasion percolation, with trapping, and ν is the ordinary percolation correlation length exponent.