Ferrocenylmethylation of estrone and estradiol: Structure,electrochemistry, and antiproliferative activity of new ferrocene–steroid conjugates

Conjugates of ferrocene with steroidal estrogens as selective antiproliferative agents against hormone-dependent breast cancer cells are believed to be limited by the inherent estrogenicity of the conjugates. Motivated by a significant cytotoxicity of the ester of ferrocenecarboxylic acid and the phenolic group of estradiol toward such a cell line, we decided to explore other a -ring-tethered ferrocene–estra-1,3,5(10)-triene conjugates; in this study, ferrocenylmethylation of estradiol and estrone with (ferrocenylmethyl)trimethylammonium iodide in the presence of potassium carbonate yielded five new compounds ( 1 – 5 ). In dimethylformamide, only O-alkylated products formed ( 1 and 3 ), while a mixture of O- and C-alkylated products was obtained when methanol was used ( 2 , 4 , and 5 in addition to 1 and 3 ). All compounds were characterized using 1D and 2D NMR, IR, UV–Vis, and high-resolution mass spectrometry. Two of the conjugates, a 3-O- and a 4-C-alkylated derivative of estrone ( 3 and 4 , respectively), were also analyzed using single-crystal X-ray diffraction. A cyclic voltammetric investigation of the electrochemical properties of 1 – 5 was performed. While some of the compounds were shown to have a slight-to-moderate antiproliferative activity against at least one of the six tested human tumor cell lines and were nontoxic to (the noncancerous) fetal human fibroblasts, compound 2 (4-(ferrocenylmethyl)estra-1,3,5(10)-triene-3,17β-diol) with an IC₅₀ value of 0.34 μM was found to be more active against the hormone-dependent breast cancer cell line MCF-7 than doxorubicin. These results suggest that a -ring substitution of steroidal estrogens is a plausible strategy for preparing other ferrocene–steroid conjugates acting against tumor cells.     

Compact complex surfaces with geometric structures related to split quaternions

We study the problem of existence of geometric structures on compact complex surfaces that are related to split quaternions. These structures, called para-hypercomplex, para-hyperhermitian and para-hyperkähler, are analogs of the hypercomplex, hyperhermitian and hyperkähler structures in the definite case. We show that a compact 4-manifold carries a para-hyperkähler structure iff it has a metric of split signature together with two parallel, null, orthogonal, pointwise linearly independent vector fields. Every compact complex surface admitting a para-hyperhermitian structure has vanishing first Chern class and we show that, unlike the definite case, many of these surfaces carry infinite-dimensional families of such structures. We provide also compact examples of complex surfaces with para-hyperhermitian structures which are not locally conformally para-hyperkähler. Finally, we discuss the problem of non-existence of para-hyperhermitian structures on Inoue surfaces of type S⁰$S^0$ and provide a list of compact complex surfaces which could carry para-hypercomplex structures.     

Effects of organic additives on alumina coatings on stainless steel obtained by spray pyrolysis

Alumina coatings were obtained by deposition of boehmite sol, with added polyvinyl alcohol or polyethylene glycol, on stainless steel foil by spray pyrolysis method. Characterizations of coatings were performed by SEM, XRD, XPS, AFM and S_BET analysis. Alumina coating prepared with polyethylene glycol has improved resistance to surface area loss than coating obtained with polyvinyl alcohol. At elevated temperatures polyethylene glycol has preserved the morphology of alumina coating and prevents the diffusion of Fe from stainless steel substrate. Porous, foam-like aluminium oxide coating, consisted of accidentally distributed rings of alumina, was created from both additives. Such coating morphology, with a hierarchical porosity, has application in numerous catalytic processes.     

Sharp Turán inequalities via very hyperbolic polynomials

We present new sharp inequalities for the Maclaurin coefficients of an entire function from the Laguerre-Pólya class. They are obtained by a new technique involving the so-called very hyperbolic polynomials. The results may be considered as extensions of the classical Turán inequalities.     

Canonical connection on a class of Reimannian almost product manifolds

The canonical connection on a Reimannian almost product manifold is an analogue to the Hermitian connection on an almost Hermitian manifold. In this paper we consider the canonical connection on a class of Reimannian almost product manifolds with non-integrable almost product structure.     

Laguerre polynomials as Jensen polynomials of Laguerre-Pólya entire functions

We prove that the only Jensen polynomials associated with an entire function in the Laguerre-Pólya class that are orthogonal are the Laguerre polynomials.     

Catalytic abatement of CO and volatile organic compounds in waste gases by gold catalysts supported on ceria-modified mesoporous titania and zirconia

Mesoporous oxides TiO2 and ZrO2, synthesized by surfactant templating via a neutral C13(EO)6–Zr(OC3H7)4 assembly pathway, and ceria‐modified TiO2 and ZrO2, prepared by a deposi‐tion–precipitation (DP) method, featuring high surface areas and uniform pore size distributions were used as supports for gold catalysts. The supported gold catalysts were assessed for the cata‐lytic abatement of air pollutants, i.e., CO, CH3OH, and (CH3)2O. The gold was supported on the mes‐oporous oxides by a DP method. The supports and catalysts were characterized by powder X‐ray diffraction, high‐resolution transmission electron microscopy, N2 adsorption–desorption analysis, and temperature‐programmed reduction technique. A high degree of synergistic interaction be‐tween ceria and mesoporous ZrO2 and TiO2 as well as a positive modification of the structural and catalytic properties by ceria was observed. The ceria additive interacts with the mesoporous oxides and induces a strong effect on the reducibility of the supports. The catalytic behavior of the catalysts was discussed to determine the role of the ceria modifying additive and possible interaction be‐tween the gold nanoparticles and ceria‐mesoporous oxide supports. The gold catalysts supported on ceria‐modified mesoporous ZrO2 displayed superior catalytic activity (~100%conversion of CO at 10 °C and CH3OH at 60 °C). The high catalytic activity can be attributed to the ability of the sup‐port to assist oxygen vacancies formation. The studies indicate that the ceria‐modified mesoporous oxide supports have potential as supports for gold‐based catalysts.     

Surface-enhanced Raman scattering active substrates by liquid flame spray deposited and inkjet printed silver nanoparticles

Surface-enhanced Raman scattering (SERS) active substrates were made via liquid flame spray deposition and inkjet printing of silver nanoparticles. Both processes are suitable for cost-effective fabrication of large-area SERS substrates. Crystal violet (CV) solutions were used as target molecules and in both samples the detection limit was approximately 10 nM. In addition, sintering temperature of the inkjet printed silver nanoparticles was found to have a large effect on the SERS activity with the higher curing temperature of 200 °C resulting in contamination layer on silver and cancelation of the SERS signal. This layer was characterized using an X-ray photoelectron spectroscopy (XPS).     

Zeros of Gegenbauer and Hermite polynomials and connection coefficients

In this paper, sharp upper limit for the zeros of the ultraspherical polynomials are obtained via a result of Obrechkoff and certain explicit connection coefficients for these polynomials. As a consequence, sharp bounds for the zeros of the Hermite polynomials are obtained.