Unusual reactions of [{micro-(phthalazine-N2:N3)}Fe2(micro-CO)(CO)6] with organolithium reagents. A novel coordination mode of 1,2-diazane diiron carbonyl compounds

[{Micro-(phthalazine-N2:N3)}Fe2(micro-CO)(CO)6](1) reacts with organolithium reagents, RLi (R = CH3, C6H5, p-CH3C6H4, p-CH3OC6H4, p-CF3C6H4, p-C6H5C6H4), followed by treatment with Me3SiCl to give the novel diiron carbonyl complexes with a saturated N-N six-membered diazane ring ligand, [{C6H4CH(R)NNCH2}Fe2(C=O)(CO)6](2, R = CH3; 3, R = C6H5; 4, R =p-CH3C6H4; 5, R =p-CH3OC6H4; 6, R =p-CF3C6H4; 7, R =p-C6H5C6H4). Compounds 4 and 5 were treated with [(NH4)2Ce(NO3)6] to afford the aryl-substituted phthalazine-coordinated diiron carbonyl compounds [(micro-{1-(p-CH3C6H4)-phthalazine-N2:N3})Fe2(micro-CO)(CO)6](8) and [(micro-{1-(p-CH3OC6H4)-phthalazine-N2:N3})Fe2(micro-CO)(CO)6](9), respectively. The structures of complexes 4 and 9 have been established by X-ray diffraction studies.     

Unimolecular dissociation of aniline molecular ion: A theoretical study

The potential energy surface (PES) for dissociation of aniline ion was determined using density functional theory molecular orbital calculations at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d) level. On the basis of the PES obtained, kinetic analysis was performed by Rice–Ramsperger–Kassel–Marcus (RRKM) calculations. The RRKM dissociation rate constants agreed well with previous experimental data. The most favorable channel was formation of the cyclopentadiene ion by loss of HNC, occurring through consecutive ring opening and re-closure to a five-membered ring. Loss of H could compete with the HNC loss at high energy, which occurred by direct cleavage of an N–H bond or through ring expansion.     

The shape of beta-alanine

The combination of Fourier transform microwave spectroscopy in a pulsed supersonic jet with laser ablation has made beta-alanine amenable to a structural study in the gas phase. Two new conformers of beta-alanine have been identified together with the two previously observed by McGlone and Godfrey [J. Am. Chem. Soc. 1995, 117, 1043]. The comparison between the experimental rotational and 14N nuclear quadrupole coupling constants and those calculated ab initio provide a definitive test for molecular structures and confirm unambiguously the identification of all conformers. For the two most abundant conformers, an intramolecular hydrogen bond between the amino group and carbonyl oxygen (N-H...O=C) is established, and the COOH adopts a cis-COOH configuration. The next conformer in order of abundance presents an O-H...N intramolecular hydrogen bond with a trans configuration for the COOH group. The high sensitivity of the experiment has allowed us to detect for the first time a conformer uniquely stabilized by an n-pi* hyperconjugative interaction between the nucleophile N: of the amino group and the pi* orbital at the carbonyl group. Partial conformational relaxation has been observed in the supersonic expansion.     

Neutron spectrometry and determination of neutron ambient dose equivalents in different LINAC radiotherapy rooms

A project has been set up to study the effect on a radiotherapy patient of the neutrons produced around the LINAC accelerator head by photonuclear reactions induced by photons above ～8 MeV. These neutrons may reach directly the patient, or they may interact with the surrounding materials until they become thermalised, scattering all over the treatment room and affecting the patient as well, contributing to peripheral dose. Spectrometry was performed with a calibrated and validated set of Bonner spheres at a point located at 50 cm from the isocenter, as well as at the place where a digital device for measuring neutrons, based on the upset of SRAM memories induced by thermal neutrons, is located inside the treatment room. Exposures have taken place in six LINAC accelerators with different energies (from 15 to 23 MV) with the aim of relating the spectrometer measurements with the readings of the digital device under various exposure and room geometry conditions. The final purpose of the project is to be able to relate, under any given treatment condition and room geometry, the readings of this digital device to patient neutron effective dose and peripheral dose in organs of interest. This would allow inferring the probability of developing second malignancies as a consequence of the treatment. Results indicate that unit neutron fluence spectra at 50 cm from the isocenter do not depend on accelerator characteristics, while spectra at the place of the digital device are strongly influenced by the treatment room geometry.     

A novel series of pyrazole derivatives toward biological applications: experimental and conceptual DFT characterization

Molecular Diversity - A new series of 13 pyrazole-derivative compounds with potential antifungal activity were synthetized with good yields. The series have the...     

Synthesis,characterization, and water sorption properties of new aromatic polyamides containing benzimidazole and ethylene oxide moieties

New polyamides, containing a benzimidazole side group and ethylene oxide moieties in the structural repeat unit, were synthesized by low‐temperature polycondensation. The aim of this design was to obtain polyamides that were more soluble in common organic solvents and hence had better processability than benzimidazole polyamides while maintaining the water sorption properties characteristic of the latter. The results showed that the number of ether linkages of the repeat unit played an important role in the glass‐transition temperature and in the water sorption properties, the polyamides with one or two ethylene oxide units being more hydrophilic than benzimidazole polyamides. However, the length of the ethylene oxide chain played a minor role in the solubility because the second member of the series, with two ether linkages (i.e., one ethylene oxide unit), reached the same level of solubility as those polyamides with more ethylene oxide moieties. No crystallinity was observed by X‐ray and calorimetric measurements for the new polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 112–121, 2005     

Synthesis, crystal structure, magnetic properties, and theoretical studies of [(Cu(mepirizole)Br)2(mu-OH)(mu-pz)] (mepirizole=4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine; pz=pyrazolate), a novel mu-pyrazolato-mu-hydroxo-dibridged copper(II) complex

A novel mu-pyrazolato-mu-hydroxo-dibridged copper(II) complex has been synthesized and structurally characterized: [(Cu(mepirizole)Br)2(mu-OH)(mu-pz)] (mepirizole=4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine; pz=pyrazolate). The title compound crystallizes in the monoclinic system, space group P2(1)/c, with a=15.618(2) A, b=15.369(3) A, c=16.071(3) A, and beta=112.250(1) degrees. The structure is built up of dinuclear [(Cu(mepirizole)Br)2(mu-OH)(mu-pz)] units with five-coordinated copper(II) ions (CuBrN3O chromophores) linked by mu2-OH and mu2-pyrazolato bridges that are well separated from each others. The intramolecular copper-copper distance is 3.378(3) A. Magnetic susceptibility data show that the copper atoms are strongly antiferromagnetically coupled with J=-770 cm(-1). The obtained triplet-singlet energy gap is compared with those reported for a series of related dimers. The strong antiferromagnetic coupling arising from the complementarity of the hydroxo and pyrazolato bridges has been discussed on the basis of DFT calculations.     

Single Fusion Events at Polarized Liquid–Liquid Interfaces

A new electrochemical framework for tracking individual soft particles in solution and monitoring their fusion with polarized liquid–liquid interfaces is reported. The physicochemical principle lies in the interfacial transfer of an ionic probe confined in the particles dispersed in solution and that is released upon their collision and fusion with the fluid interface. As a proof-of-concept, spike-like transients of a stochastic nature are reported in the current–time response of 1,2-dichloroethane(DCE)|water(W) submilli-interfaces after injection of DCE-in-W emulsions. The sign and potential dependence of the spikes reflect the charge and lipophilicity of the ionic load of the droplets. A comparison with dynamic light scattering measurements indicates that each spike is associated with the collision of a single sub-picoliter droplet. This opens a new framework for the study of single fusion events at the micro- and nanoscale and of ion transport across biomimetic soft interfaces.     

Synthesis of bridged molecular gyroscopes with closed topologies: triple one-pot macrocyclization

We describe the synthesis and characterization of six bridged molecular gyroscopes with m-alkoxy-substituted trityl stators and dialkynylphenylene rotators. All of the bridged molecular gyroscopes were synthesized convergently to form the phenolic stator-rotator framework, while the alkyl and benzophenone bridges were installed in one step by relatively efficient one-pot reactions to form macrocyclic diether or diester linkages. The isolated yield per bond-forming reaction varied from ca. 42% to 80%, with one exception where macrocyclization failed to produce the desired product. The molecular structure and crystal packing of each of the bridged molecular gyroscopes were determined via single crystal X-ray diffraction. Like most molecular gyroscopes with open topologies previously studied, the singly bridged structures pack by interdigitating one trityl stator in one molecule next to the rotator of an adjacent molecule in the lattice. In contrast, the triply bridged molecular gyroscopes were found to pack in lamellar sheets that prevent the rotator-stator interdigitation of adjacent molecules. However, solvent molecules and conformationally flexible bridges tend to fill in the packing volume by collapsing next to the rotator or by extending one of their bridges into the cavity of a neighboring molecule.