Spin crossover active iron(II) complexes of selected pyrazole-pyridine/pyrazine ligands

This review begins with a brief introduction to pyrazole and to spin crossover. The focus then moves to a detailed consideration of the synthesis and magnetic properties of structurally characterized iron(II) spin crossover (SCO) active complexes of pyrazole- and pyrazolate-based ligands that also contain at least one pyridine or pyrazine unit within the ligand motif. The syntheses and crystallization methods reported in the original publications are emphasized in this review. The reason for this is that these factors often affect the exact nature of the final product, including the amount and nature of the crystallization solvent molecules present and/or what polymorph is obtained, and hence they can impact strongly on the SCO properties of the resulting materials, as can be seen in this review.     

Metal-free and dicopper(II) complexes of Schiff base [2 + 2] macrocycles derived from 2,2'-iminobisbenzaldehyde: syntheses, structures, and electrochemistry

Three new bis-terdentate Schiff base [2 + 2] macrocycles (H(2)L(Et), H(2)L(Pr), and H(2)L(Bu)) have been prepared in high yields by 1:1 condensation of 2,2'-iminobisbenzaldehyde with 1,2-diaminoethane, 1,3-diaminopropane, and 1,4-diaminobutane, respectively. Metalation of these macrocycles yields the corresponding dicopper(II) acetate (1, 2, and 3) and tetrafluoroborate (4, 5, and 6) complexes. The structures of H(2)L(Et), H(2)L(Pr), H(2)L(Bu), [Cu(II)(2)L(i)(OAc)(2)]·solvents (where i is Et, Pr or Bu) and [Cu(II)(2)L(Pr)(DMF)(4)] (BF(4))(2)·0.5H(2)O are reported. Intramolecular hydrogen bonding is a feature of the metal-free macrocycles. The copper(II) centers in [Cu(II)(2)L(i)(OAc)(2)]·solvents are four coordinate, and the macrocycles have U-shaped (Et, Bu) or stepped (Pr) conformations. Complex 5 crystallizes with two dimethylformamide (DMF) molecules bound per five coordinate copper(II) center. Electrochemical studies revealed ligand based oxidations for all of the macrocycles and complexes. Complexes 1 and 2 undergo two quasi-reversible oxidations in DCM which are associated with the deposition of a visible film on the electrode after multiple scans in this oxidative region, suggestive of electropolymerization. Complexes 4-6, studied in MeCN, have Cu(II) → Cu(I) redox potentials at more positive potentials than for 1-3.     

Topical Application of Photofrin® for Oral Neoplasms in Animal

Early diagnosis improves oral cancer prognosis. Exact demarcation of tumor margins improves surgical outcomes. This study evaluates Photofrin^® fluorescence: a new diagnostic procedure for detection of oral neoplasms in animal models. Fourteen male Golden Syrian hamsters were used. 0.5% D.M.B.A (9,10 dimethyl1-1,2-benzanethracene) was brushed onto cheek pouches bilaterally daily for 2,weeks. Hamsters with oral neoplasms received 2.5,mg/ml Photofrin^® solution topically. After 3h the neoplasms underwent fluorescence illumination (λex=380–420,nm). A quantitative analysis of the fluorescence contrast between the neoplastic and surrounding tissue was performed using the RGB Mode and the Gray Scale. (GS) Statistical analysis was performed using the ANOVA test. Analysis of the 14 hamsters’ 28 biopsies revealed 4 (14.3%) displayed squamous hyperplasia (1 mild, 3 severe) and 24 (85.7%) displayed squamous cell carcinoma. The sensitivity of neoplasms evaluated using the RGB and GS modes combined resulted in 92.15% (in vivo macroscopic image) and 93.45% (histological). The specificity of neoplasms evaluated via RGB and GS modes combined resulted in 94.78% (in vivo macroscopic image) and 97.30% (histological). The difference between healthy tissue and the lesions as a group is statistically significant. Photofrin^® fluorescence provides a sensitive, non-invasive technique for early identification of malignant neoplasms in the oral cavities of animal models.     

Search for new SS states in the K− induced K+K− system

Results from the first PWA of the K⁺K^? system produced by incident K^?, are presented in the mass range from the threshold to 1.70 GeV. In the P and D waves only the φ and f′ mesons are observed and their production mechanism studied. A broad S wave peaking at 1.4 GeV is observed but the lack of information about its phase makes the search for new 0⁺⁺ mesons inconclusive.     

Accuracy of the IOS approximation for highly inelastic R-T collisional energy transfer

Rate constants for rotational excitation of CO by collisions with He atoms computed within the infinite order sudden (IOS) approximation are compared with accurate quantum (coupled-states) and classical trajectory values. Taking the IOS energy as the initial kinetic energy for upward. 0 → J, transitions is found to overestimate the rates, especially for higher J (larger inelasticity). Taking the IOS energy as the initial energy for downward, J → 0, transitions underestimates the rates by a comparable amount. The geometric average of IOS rates computed in these two ways is found to provide accurate values.     

Production of f'(1520) in 8.25 GeV/c K−p interactions

We present results for the hypercharge exchange reaction K^?p→f' λ from a high statistics experiment at 8.25 GeV/c using the CERN 2m HBC. The total and differential cross sections have been measured; the polarisation of the Λ hyperon and the f' density matrix elements have been calculated as functions of momentum transfer. We also present detailed information on the relative strength of the natural and unnatural parity exchange contributions to the production mechanism.     

Study of the centrally produced ωρ0 and ωω systems inpp interactions at 300 GeV/c

We have performed a search for vector-vector final states centrally produced in proton proton interactions at 300 GeV/c using the CERN Ω spectrometer. Evidence is found for ωρ⁰ production in the reactionpp→p _f (2π⁺2π^?2π⁰)p _s and for ωω production in the reactionpp→p _f (2π⁺2π^?2π⁰)p _s . However no evidence is found for ωø production in the reactionpp→p _f (K ⁺ K ^?π⁺π^?π⁰)p _s .