Anatomy of the trace formula for the baker's map

The structure of the trace formula for quantum maps on a compact phase space is analyzed. An explicit expression for the functional determinant in terms of a finite number of traces is derived which is algebraic and independent of any approximation. For the specific case of the baker's map, its simple structure allows the implementation of a symbolic decomposition of the propagator which is exact and which has the structure of usual semiclassical formulas. The method allows the testing of the accuracy of the individual contribution of each periodic orbit to the functional determinant.     

Vanadyl ion complexes with nucleotides

Summary Complexes of adenosine-5-triphosphate, adenosine-5-monophosphate, guanosine-5-monophosphate, inosine-5-monophosphate, cytidine-5-monophosphate and uridine-5-monophosphate with vanadyl ion, have been studied in the solid state by i.r. spectroscopy and magnetochemically. All complexes have normal magnetic moments, very close to the spin-only values. From the i.r. spectra it is suggested that the vanadyl ion is interacting with adenosine-5-triphosphate, through the N-1 of the purine ring, with adenosine-5-monophosphate, guanosine-5-monophosphate, inosine-5-monophosphate, through the N-7 of the purine ring, with cytidine-5-monophosphate through the N-3 of the pyrimidine ring, and most probably through the phosphate group with uridine-5-monophosphate. The complexes of vanadyl ion with the nucleotides are probably polymeric.     

Comment on "Excitations in photoactive molecules from quantum Monte Carlo" [J. Chem. Phys. 121, 5836 (2004)

It is shown that the qualitative differences between high-level ab initio calculations and restricted open-shell Kohn-Sham (ROKS) results for the lowest singlet excited electronic state of formaldimine along a particular isomerization path found by Schautz, Buda, and Filippi [J. Chem. Phys.121, 5836 (2004)] play a minor role in molecular dynamics simulations of photoisomerization at room temperature. In fact, ROKS yields, within its well-known limitations, a good representation of the physically relevant isomerization pathway.     

Ligand-controlled and nanoconfinement-boosted luminescence employing Pt(ii) and Pd(ii) complexes: from color-tunable aggregation-enhanced dual emitters towards self-referenced oxygen reporters

In this work, we describe the synthesis, structural and photophysical characterization of four novel Pd(ii) and Pt(ii) complexes bearing tetradentate luminophoric ligands with high photoluminescence quantum yields (Φ_L) and long excited state lifetimes (τ) at room temperature, where the results were interpreted by means of DFT calculations. Incorporation of fluorine atoms into the tetradentate ligand favors aggregation and thereby, a shortened average distance between the metal centers, which provides accessibility to metal–metal-to-ligand charge-transfer (³MMLCT) excimers acting as red-shifted energy traps if compared with the monomeric entities. This supramolecular approach provides an elegant way to enable room-temperature phosphorescence from Pd(ii) complexes, which are otherwise quenched by a thermal population of dissociative states due to a lower ligand field splitting. Encapsulation of these complexes in 100 nm-sized aminated polystyrene nanoparticles enables concentration-controlled aggregation-enhanced dual emission. This phenomenon facilitates the tunability of the absorption and emission colors while providing a rigidified environment supporting an enhanced Φ_L up to about 80% and extended τ exceeding 100 μs. Additionally, these nanoarrays constitute rare examples for self-referenced oxygen reporters, since the phosphorescence of the aggregates is insensitive to external influences, whereas the monomeric species drop in luminescence lifetime and intensity with increasing triplet molecular dioxygen concentrations (diffusion-controlled quenching).

Pt(ii) and Pd(ii) complexes with unprecedented photophysical properties were developed. Encapsulation in nanoparticles boosted their performance while rendering them as self-referenced oxygen sensors.     

A comparison of different types of gold–carbon composite electrode for detection of arsenic(III)

A study has been conducted using abrasively modified basal and edge-plane graphite, carbon-paste, and carbon–epoxy electrodes to create gold–carbon composite electrodes. Using either nano or micro-sized gold particles their suitability for use in detecting arsenic(III) is assessed. It was found that gold arrays prepared from micron-sized particles gave the best performance for arsenic detection. In particular micron arrays produced in carbon-paste electrodes with an easily renewable surface work well for detection of arsenic, producing a detection limit of 5(±2)×10^–9 mol L^–1, with a high sensitivity of 10(±0.1) A mol^–1 L.     

Ruthenium(III) ion complexes with nucleotides

Summary Complexes of adenosine-5-monophosphate (5-AMP), guanosine-5-monophosphate (5-GMP), inosine-5-monophosphate (5-IMP) and cytidine-5-monophosphate (5-CMP) with ruthenium trichloride have been prepared and studied by i.r. spectroscopy, diffuse reflectance spectra and magnetochemical measurements.All complexes are probably polymeric as indicated by their insolubility in polar solvents.The i.r. spectra suggest that the ruthenium(III) ion interacts with the ligands through N(7) of the purine mononucleotides and through N(3) of the pyrimidine mononucleotide from one side and with the phosphate group of another mononucleotide molecule from another side. The formation of hydrogen bonds reinforces the interaction.The complexes have normal magnetic moments close to the spin-only value. The electronic spectra confirm their octahedral structure.     

Tetracrystalline Tetrablock Quarterpolymers: Four Different Crystallites under the Same Roof

Multicrystalline block polymers having three or more crystalline segments are essential materials for the advancement of physics in the field of crystallinity. The challenging synthesis of multicrystalline polymers has resulted in only a limited number of tricrystalline terpolymers having been reported to date. We report, for the first time, the synthesis of polyethylene‐b‐poly(ethylene oxide)‐b‐poly(?‐caprolactone)‐b‐poly(l ‐lactide) (PE‐b‐PEO‐b‐PCL‐b‐PLLA), a tetracrystalline tetrablock quarterpolymer, by combining polyhomologation, ring‐opening polymerization, and an organic/metal “catalyst switch” strategy. ¹H NMR spectroscopy and gel‐permeation chromatography confirmed the formation of the tetrablock quarterpolymer, while differential scanning calorimetry, X‐ray diffraction, and wide‐line separation solid‐state NMR spectroscopy revealed the existence of four different crystalline domains.     

Chemical Functionalization of 2D Materials

This Special Issue of Chemistry–A European Journal is dedicated to the Chemical Functionalization of 2D Materials, and features some great contributions from experts in the field of 2D materials. This issue was originally assembled to support the Symposium G “Chemical Functionalization of 2D Materials” at the European Materials Research Society (E-MRS) 2020 Spring Meeting, which was originally scheduled to be held in Strasbourg, France, from May 25th to 29th, 2020. Although the E-MRS 2020 Spring Meeting has been cancelled due to the COVID-19 outbreak, the publication of this Special Issue has proceeded and has become even more important as the contributors discuss diverse and timely research themes related to 2D materials. In this Editorial, a brief overview of the different types of 2D materials is given, together with the chemical functionalization schemes that can be applied to them to achieve new properties as well as enable improved performance in applications. Some of the articles featured in this Special Issue are also highlighted, with the hope that they will inspire readers and further advance the field.     

A modified protocol for isolation and purity evaluation of a staphylococcal acidic polysaccharide by chromatography and capillary electrophoresis

The extracellular slime of Staphylococcus epidermidis contains, amongst various macromolecules, an acidic polysaccharide (PS) of a molecular mass of 20 kDa with significant antigenic and biological properties. The isolation procedure used so far includes multiple fractionations in anion‐exchange chromatographic columns before its final purification by gel filtration chromatography. This protocol is laborious, time‐consuming and includes the risk of unnecessary loss of PS quantities. Because of the significance of this PS, a modified protocol resulting in an easier and quicker isolation procedure was developed. Furthermore, identification, purity, charge density and molecular integity of the isolated polysaccharide were evaluated by a reverse‐polarity capillary electrophoresis method. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation,Photophysical and Electrochemical Evaluation of an Azaborondipyrromethene/Zinc Porphyrin/Graphene Supramolecular Nanoensemble

The preparation of an entirely supramolecular, multichromophoric azaborondipyrromethene ( ABDP )/zinc tetraphenylporphyrin ( ZnTPP )/exfoliated graphene ( GR ) nanoensemble was accomplished. The ABDP derivative bears glycol chains for enhancing solubility and a pyridine functionality for allowing coordination with ZnTPP . The ABDP / ZnTPP/GR nanoensemble was characterized in terms of morphology and composition by using complementary microscopy imaging, thermogravimetric analysis, Raman as well as steady-state and time-resolved absorption and emission spectroscopy. The photophysical and electrochemical assessment of ABDP / ZnTPP/GR as well as the binding properties of the ABDP / ZnTPP complex, employed as a reference, are presented. Energy and electron transfer events were observed in ABDP / ZnTPP upon photoexcitation. However, in the case of ABDP / ZnTPP/GR , the graphene-induced aggregation of the chromophores alters their electronic interactions, enhancing the energy/electron transfer process between them.