Reactions of Co2(CO)8 and of Co2(CO)6L (L = 3-pentyn-1-ol, 1,4-butyn-diol or 2-methyl-3-butyn-2-ol) with 2(diphenylphosphino)ethyl-trietoxysilane and tris(hydroxymethyl)phosphine for applications to new sol-gel materials

The complex Co₂(CO)₆[μ-η²-(H₃CCCCH₂CH₂OH)] (1) with the ligand 3-pentyn-1-ol (pol) has been synthesized following established procedures. Its structure has been determined by X-ray analysis. The complex Co₂(CO)₆(mbo) (mbo = 2-methyl-3-butyn-2-ol, HCCC(CH₃)₂OH), (3), along with the already known Co₂(CO)₆(bud) (bud = 1,4-butyn-diol, HOCH₂CCCH₂OH) (2), and Co₂(CO)₈ were reacted with 2(diphenylphosphino)ethyl-triethoxysilane [Ph₂PCH₂CH₂Si(OCH₂CH₃)₃] (dpts) and tris(hydroxymethyl)phosphine [P(CH₂OH)₃] (thp). With dpts, mono- and di-substituted complexes were obtained: these were characterized by analytical and spectroscopic techniques. The structures of Co₂(CO)₆(dpts)₂ (5) and of Co₂(CO)₄(pol)(dpts)₂ (8) have been determined by X-ray analysis.Complex (1) was reacted with 3-(triethoxysilyl)propyl isocyanate [(H₃CCH₂O)₃Si(CH₂)₃NCO] (tsi): the new complex Co₂(CO)₆[H₃CCCCH₂CH₂OC(O)NH(CH₂)₃Si(OCH₂CH₃)₃] (9) was obtained and spectroscopically characterized. The complex has also been reacted with tetraethyl orthosilicate (teos); a new inorganic-organometallic material was obtained. Complex (5) has been grafted on the mesoporous material SBA-15. The hybrid inorganic-organometallic materials obtained have been characterized by inductively coupled plasma-mass spectrometry (ICP-MS), infrared spectroscopy (FT-IR) under vacuum conditions, X-ray diffraction (XRD) and scanning electron microscopy coupled to EDS probe (SEM-EDS).     

The discrete representation correspondence between quantum and classical spatial distributions of angular momentum vectors

This work demonstrates that the quantum mechanical moments of a state described by the density matrix correspond to discrete spherical harmonic moments of the classical multipole expansion of the spatial distribution of the angular momentum vectors. For the diagonal density matrix elements, this work exploits the fact that the quantum mechanical vector coupling (Clebsch-Gordan) coefficients become increasingly accurate discrete representations of spherical harmonics as j increases. A Schwinger-type basis accounts for nonaxially symmetric angular distributions, which result in nonzero off-diagonal elements of the density matrix. The resulting discrete minimum uncertainty picture of the classical moments has a stringent equivalence with the quantum mechanical one for all j and provides an unambiguous connection for the classical and quantum moments in the large j limit. The equivalence is numerically tested for simple models, and there is a satisfying equivalence even for small j. Applications, implications, and extensions are indicated, and the relevance of this work for the interpretation of classical mechanical simulations of inelastic and reactive molecular collisions will be documented elsewhere.     

Preparation and characterization of aryl or heteroaryl(3-indolyl)methylium o-benzenedisulfonimides

An initial study has been accomplished into the synthetic feasibility of the preparation of diarylcarbenium salt via the direct coupling of aryl (or heteroaryl) aldehydes and arenes (or heteroaryl analogues) in the presence of a strong organic Br?nsted acid. A number of stabilized aryl or heteroaryl(3-indolyl)carbenium ions, never previously prepared in the solid state, have been isolated in excellent yields as highly stable o-benzenedisulfonimide salts and have been fully characterized. Their purity has been proven by spectroscopic methods and chemical reduction with NaBH(4). An X-ray crystal structure analysis has been performed on one of the products: an azafulvenium species was shown to be the exclusive structure in the solid state.     

Identification and structural characterization by LC‐ESI‐IONTRAP and LC‐ESI‐TOF of some metabolic conjugation products of homovanillic acid in urine of neuroblastoma patients

The levels of urinary catecholamine metabolites, such as homovanillic acid (HVA) and vanillylmandelic acid, are routinely used as a clinical tool in the diagnosis and follow‐up of neuroblastoma (NB) patients. Recently, in the Clinical Pathology Laboratory Unit of G. Gaslini Children Hospital, a commercial method that employs liquid chromatography coupled to electrochemical detection (LC‐EC) has been introduced for the measurement of these metabolites in the routine laboratory practice. Using this LC‐EC method, an unknown peak could be observed only in samples derived from NB patients. To investigate the nature of this peak, we used a combination of liquid chromatography‐time‐of‐flight mass spectrometry (LC‐TOF‐MS) and liquid chromatography‐ion trap tandem mass spectrometry (LC‐IT‐MS). The first approach was used to obtain the elemental composition of the ions present in this new signal. To get additional structural information useful for the elucidation of unknown compounds, the ion trap analyzer was exploited. We were able to identify not just one, but three unknown signals in urine samples from NB patients which corresponded to three conjugated products of HVA: HVA sulfate and two glucuronoconjugate isomers. The enzymatic hydrolysis with β‐glucuronidase confirmed the proposed structures, while the selective alkaline hydrolysis allowed us to distinguish the difference between phenol‐ and acyl‐glucuronide of HVA. The latter was the unknown peak observed in LC‐EC separations of urine samples from NB patients. Copyright © 2012 John Wiley & Sons, Ltd.     

The Astrochemical Observatory: Molecules in the Laboratory and in the Cosmos

Astrochemistry is a discipline consolidated recently, although its roots extend back to the dawn of early civilization with the observation and mapping of the sky. The way to the understanding of the common natural laws on earth and in space paved by Galilei's observations by the telescope, has been extended in the last decades, by new technologies such as radioastronomy and space missions. Plenty of new chemistry was surprisingly discovered. Extreme rich information on the chemical “composition” of the universe is being obtained, either from the other planets and satellites in the Solar System, from meteorites and comets, or from the interstellar space. In this article we will present selected topics regarding the chemical structures and reactions being discovered. Particular attention will be devoted to aspects considered as relevant for the prebiotic processes on earth, such as those involving chirality and its role played in the origin and evolution of life.     

Fluorinated PLGA Nanoparticles for Enhanced Drug Encapsulation and 19F NMR Detection

In the continuous search for multimodal systems with combined diagnostic and therapeutic functions, several efforts have been made to develop multifunctional drug delivery systems. In this work, through a covalent approach, a new class of fluorinated poly(lactic-co-glycolic acid) co-polymers (F-PLGA) were designed that contain an increasing number of magnetically equivalent fluorine atoms. In particular, two novel compounds, F₃-PLGA and F₉-PLGA, were synthesized and their chemical structure and thermal stability were analyzed by solution NMR, DSC, and TGA. The obtained F-PLGA compounds were proven to form in aqueous solution colloidal stable nanoparticles (NPs) displaying a strong ¹⁹F NMR signal. The fluorinated NPs also showed an enhanced ability to load hydrophobic drugs containing fluorine atoms compared to analogous pristine PLGA NPs. Preliminary in vitro studies showed high cell viability and the NP ability to intracellularly deliver and release a functioning drug.     

Specific heats of clusters near a phase transition: Energy partitions among internal modes

This Letter proposes a way to answer the question of how energy is shared by internal degrees of freedom, when nanoaggregates are heated and undergo phase transitions. Microcanonical molecular dynamics simulations of clusters of 13 and 55 atoms are assisted by our analysis of energy partitions in terms of contributions connected with groups of degrees of freedom of the nanoaggregates. The merit of the partition is shown to be the effective decoupling of modes, demonstrating its role as an indicator of the phase transitions and its perspective use for statistical mechanical approaches by the identification of active degrees of freedom.     

Isotope effects in hydrogen and muonium exchange processes

Muonium and hydrogen exchange in collinear I + MuI, I + HI, H + MuH and H + H₂ reactions are studied by semiclassical techniques within the hyperspherical formalism. Bound states in IMuI, as an example of bond formation on repulsive surfaces, are also considered.