Novel estradiol derivatives labeled with Ru,W, and Co complexes. Influence on hormone-receptor affinity of several organometallic groups at the 17 alpha position

In order to elucidate the extent to which recognition of the estrogen receptor is influenced by addition of an organometallic substituent at the 17 alpha position, modification of 17 beta-estradiol at this position was carried out by using the organometallic groups -C identical to C(eta 5-C5H4)RuCp, CH2-(eta 5-C5H4)RuCp, -C identical to C-(eta 5-C5H4)-W(CO)3(Me), -(C identical to CCHO)Co2(CO)6, and -(C identical to CCH2OH)Co2(CO)6. The relative binding affinity (RBA) values for estradiol receptor alpha showed that recognition was good (RBA between 20 and 13.5%) when the organometallic moiety was attached at the end of a rigid alkyne spacer. However, the affinity of the modified hormone for the receptor was severely reduced (RBA = 1%) for a substituent such as -CH2-(eta 5-C5H4)RuCP, in which the spacer is reduced to a single flexible sp3 carbon atom, allowing the organometallic moiety greater freedom of movement around the attachment point. The RBA values found were in agreement with results obtained from a molecular-modeling study in which 5, an organometallic hormone with a rigid spacer, or 7, a molecule with a flexible spacer, was inserted into the cavity of the recently characterized Ligand-Binding Domain of estrogen receptor alpha.     

Derivatisation for liquid chromatography/electrospray mass spectrometry: synthesis of pyridinium compounds and their amine and carboxylic acid derivatives

A simple method has been developed for the pre-column derivatisation of low molecular weight primary and secondary amines and carboxylic acids using quaternary nitrogen compounds to enhance their detection by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS). The synthesis of seven novel quaternary nitrogen reagents is described. The derivatives are designed to be relatively small molecules to avoid some of the steric hindrance problems that may be associated with larger derivatisation reagents. The compounds have amine and carboxylic acid functional groups with which to derivatise carboxylic acids and amines, respectively. Two of the compounds contain a bromine atom in order to assess the advantages of a bromine isotope pattern in the mass spectra. This acts as a simple marker for derivatisation and enables data processing by cluster analysis.Activation of the carboxylic acid group was achieved by the use of either 1-chloro-4-methylpyridinium iodide (CMPI) or the more reactive 1-fluoro-4-methylpyridinium p-toluenesulphonate (FMP).1 Using both of these active reagents, the degree of nucleophilic substitution was investigated for the derivatisation of a variety of small molecules. Whilst giving some increase in the ESI-MS response for the derivatised compounds, the FMP itself acted as a derivatising reagent in a competing reaction. In the light of this finding, FMP was reacted with the test compounds separately and gave positive results as a derivatising reagent. Detection of the 'pre-charged' derivatives of amines and carboxylic acids by LC/ESI-MS was investigated with respect to their ESI response and chromatography.     

Complexes of TiCl4, VCl4 and SnX4 (X = Cl or Br) with Schiff bases derived from 2-aminobenzimidazole

Summary The reactions of anhydrous titanium(IV), tin(IV) and vanadium(IV) halides with Schiff bases derived from 2-aminobenzimidazole and 4-methylbenzaldehyde (abimbz) and salicylaldehyde (abisal), yield hexacoordinated complexes M(abimbz)Cl₄ and M(abisal)₂X₄ (M = Ti, Sn or V; X = Cl or Br).The compounds have been characterized by elemental analyses, magnetic measurements, e.p.r., electronic and i.r. spectral studies. I.r. spectra suggest that the Schiff base (abimbz) is coordinated as a bidentate ligand with the metal ion and the (abisal) base acts as a monodentate ligand.     

Catalyzed oxidation of alcohols and aldehydes with iodosylbenzene

RuCl₂(PPh₃)₃ catalyzes oxidation of alcohols to carbonyi compounds by iodosylbenzene and that of aldehydes to carboxylic acids. Catalyzed oxidation of primary alcohols with phenyliodosodiacetate affords aldehydes.     

Ab Initio (GIAO) Calculations of Absolute Nuclear Shieldings for Representative Compounds Containing 1(2)H, 6(7)Li, 11B, 13C, 14(15)N, 17O, 19F, 29Si, 31P, 33S,and 35Cl Nuclei

Two kinds of ab initio calculations (B3LYP and HF) using the GIAO approach have been carried out for fifteen H, three Li, three B, eleven C, seven N, nine O, four F, three Si, four P, six S and five Cl containing derivatives. The calculated absolute nuclear shieldings have been compared with experimental absolute values (either measured or estimated from relative chemical shifts) when available or with relative chemical shifts (¹¹B, ³⁵Cl). The correlations range from good to excellent and only three compounds (PN, P₂H₂, SO₂) deviate significantly.     

Raman spectroscopic analysis of the Maya wall paintings in Ek'Balam, Mexico

Raman spectroscopy has been applied to the examination of wall painting fragments from the archaeological site of Ek'Balam (Yucatán, Mexico). Thirty-three samples have been studied, all originating from room 23 of the Acropolis, and being representative of the painting technique at Ek'Balam during the late Classic Maya period. Several pigments such as haematite, calcite, carbon, cinnabar and indigo were identified in these samples. The latter pigment was presumed to be present as 'Maya blue', which is an intercalation product of indigo and palygorskite clay. The observed Raman spectra are reported and some band assignments have been made. This survey is the first Raman spectroscopic examination of a whole set of pigments in archaeological Maya wall painting fragments.     

Structural studies on a novel reaction product of malononitrile with aβb,δ-unsaturated allene aldehyde

Condensation of 2,5,5-trimethylhexa-2,3-dien-6-a1 with malononitrile affords an unexpected product, C₁₅H₁₆N_4X, ($\text{3}$), the structure of which was partially characterized by spectral (infrared, ultraviolet, ¹H, and ¹³C nmr) methods and fully elucidated by single crystal X-ray analysis. $\text{3}$ is l-cyano-2-amino-3-(2-propenyl)-5,5-dimethy-6- dicyanomethycycohexa-l,3-diene in a half-chair conformation. Conjugation of the $\text{cis}$-aminocyanoethenyl moiety leads to intermolecular

hydrogen bonding in the crystal. A reaction sequence and its mechanistic implications are proposed.     

Multivalent ion/polyelectrolyte exchange processes in exponentially growing multilayers

We show, in this paper that multivalent ferrocyanide anions can penetrate into exponentially growing (PGA/PAH)n multilayer films whatever the nature of the last deposited layer. These ions are not able to diffuse out of the film when it is brought in contact with a pure buffer solution. However, the contact of this film with a poly(allylamine) (PAH) or a poly(L-glutamic acid) (PGA) solution leads to the release of ferrocyanide ions from the multilayer. It is shown that the release of ferrocyanide anions, when the film is in contact with a PGA solution, is due to the diffusion of the PGA chains into the film so that an exchange between ferrocyanide ions and PGA chains takes place inside the film. On the other hand, PAH chains do not diffuse into PGA/PAH multilayers. When the film is then brought in contact with a PAH solution, the PAH chains from the solution are expected to strongly interact with the ferrocyanide ions and thus induce a diffusion mechanism of the multivalent anions out of the film, the film/solution interface playing the role of a sink for these ions. This work thus shows that interactions between multivalent ions and exponentially growing films are much more complex than expected at first sight and that polyelectrolyte multilayers must be seen as dynamic entities in which diffusion and exchange processes can take place.     

The stereochemistry of organosulfur compounds. XIX. The crystal and molecular structure of 10-(1,3-dithiolan-2-ylidene)-10H-indeno[1,2-f]-1,2,3,4,5-pentathiepin

The molecular structure of 10-(1,3-Dithiolan-2-ylidene)-10H-indeno[1,2-f] -1,2,3,4,5-pentathiepin S₇C₁₂H₈₉ has been determined by single crystal X-ray diffraction. The crystals are triclinic, space group PI, with two molecules in a unit cell of dimensions α = 8.931(2), b = 9.387(2), c = 10.175(2) Å, α = 75.73(2), β = 73.35(1), γ = 64.37(2)°. The structure was solved by direct methods, and refined to a final R value of 3.3% for 1925 independent reflections. The molecule consists of an indene core with a nearly co-planar dithiolane and a fused pentasulfide chain. The S₅C₂ ring is in the chair configuration, with an average S? S distance of 2.052 Å. There is no variation of bond lengths as is frequently seen in multi-sulfur chains. The indenone ring shows no evidence of any delocalization, while the dithiolane ring is disordered at the two methylene positions. No attempt was made to resolve the disorder, since it is frequently seen and has been thoroughly investigated previously.     

Complexes of divalent nickel and copper with the Schiff base derived from 2-(2-aminophenyl)benzimidazole and benzaldehyde

Summary The reactions of divalent nickel and copper salts with the Schiff base derived from 2-(2-aminophenyl)benzimidazole and benzaldehyde, L, yield complexes of general formulae [CuL₂X₂] (X=Cl, Br, or ClO₄), [CuL(SO₄)], [CuL(SO₄)] · 4H₂O, and NiLX₂ (X=Cl, Br, or NCS).All the complexes have been characterized by elemental analyses, magnetic measurements, e.s.r. electronic and i.r. spectral studies. The results show that the Schiff base acts as bidentate ligand through the pyridine-like imine nitrogen of imidazole ring and the azomethine nitrogen. Tentative structures of the complexes are suggested.