Organometallic estrogens: synthesis, interaction with lamb uterine estrogen receptor, and detection by infrared spectroscopy

Naphthalene Exchange in [Re(η6 -napht)2 ]+ with Pharmaceuticals Leads to Highly Functionalized Sandwich Complexes [M(η6 -pharm)2 ]+ (M=Re/99m Tc)

Bis‐arene sandwich complexes are generally prepared by the Fischer‐Hafner reaction, which conditions are incompatible with most O‐ and N‐ functional groups. We report a new way for the synthesis of sandwich type complexes [Re(η⁶‐arene)₂]⁺ and [Re(η⁶‐arene)(η⁶‐benzene)]⁺ from [Re(η⁶‐napht)₂]⁺ and [Re(η⁶‐napht)(η⁶‐benzene)]⁺, with functionalized arenes and pharmaceuticals. N‐methylpyrrolidine (NMP) facilitates the substitution of naphthalene with the incoming arene. A series of fully characterized rhenium sandwich complexes with simple arenes, such as aniline, as well as with active compounds like lidocaine and melatonin are presented. With these rhenium compounds in hand, the radioactive sandwich complexes [^99mTc(η⁶‐pharm)₂]⁺ (pharm=pharmaceutical) can be unambiguously confirmed. The direct labelling of pharmaceuticals with ^99mTc through η⁶‐coordination to phenyl rings and the confirmation of the structures with the rhenium homologues opens a path into molecular theranostics.

Marquage du 2-aminothiazole avec une unité cyclohexadiène fer tricabonyle. Étude structurale et activité antibactérienne du complexe marqué (1-4-η-5-N-2-aminothiazoliocyclohexa-1,3-diène) fer tricarbonyle

La réaction du 2-aminothiazole (C3H4N2S) avec le complexe tétrafluoroborate de (1-4-η-5-N-pyridiniocyclohexa-1,3-diène) fer tricarbonyle [C11H12NFe(CO)3]+[BF4]− (1), précurseur du cation marqueur [(1-5-η-C6H7)Fe(CO)3]+ donne un nouveau complexe de formule C9H10N2SFe(CO)3, le (1-4-η-5-N-2-aminothiazolocyclohexa-1,3-diène) fer tricarbonyle (2). La structure de ce complexe a été caractérisée par les méthodes spectroscopiques IR et RMN 1H suivies d’une étude structurale par diffraction des rayons X, qui a montré que le complexe marqué 2 adopte stéréosélectivement une configuration exo. Dans l’édifice cristallin, les composants de la structure sont liés par des liaisons hydrogènes intermoléculaires de type N–H⋯N formant des chaînes dimériques le long de l’axe b. L’évaluation de l’activité antimicrobienne du ligand libre 2-aminothiazole a montré une activité antibactérienne importante. Après sa complexation par le marqueur organo fer tricarbonyle, cette activité a augmenté.

Large-Scale Nanofabrication of Designed Nanostructures Using Angled Nanospherical-Lens Lithography for Surface Enhanced Infrared Absorption Spectroscopy

Nanophotonics has been a focused research discipline for the past decade and has resulted in many novel concepts that promise to change human life. However, the actual penetration of this research into real products is severely limited mostly due to the slow development of economic nanofabrication. In this study, we have demonstrated a versatile and low-cost nanofabrication method referred to as "angled nanospherical-lens lithography (A-NLL)", which is able to produce large-scale and periodic nanopatterns. The nanopatterns designed within a two-dimensional polar chart can be carefully fabricated on the substrate. The fabricated patterns easily cover an area larger than 1 cm², which is beneficial as platforms for surface enhanced infrared absorption (SEIRA) where an expensive and bulky IR microscope is not required. We believe that the proposed A-NLL method is ideal for industrialization of future nanophotonic applications.

A rapid and label-free SERS detection method for biomarkers in clinical biofluids

A metal carbonyl-functionalized nanostructured substrate can be used in a rapid and simple assay for the detection of A1AT, a potential biomarker for bladder cancer, in clinical urine samples. The assay involves monitoring changes in the carbonyl stretching vibrations of the metal carbonyl via surface-enhanced Raman spectroscopy (SERS). These vibrations lie in the absorption spectral window of 1800-2200 cm(-1), which is free of any spectral interference from biomolecules.

Metal-carbonyl units for vibrational and luminescence imaging: towards multimodality

Metal-carbonyl complexes are attractive structures for bio-imaging. In addition to unique vibrational properties due to the CO moieties enabling IR and Raman cell imaging, the appropriate choice of ancillary ligands opens up the opportunity for luminescence detection. Through a classification by techniques, past and recent developments in the application of metal-carbonyl complexes for vibrational and luminescence bio-imaging are reviewed. Finally, their potential as bimodal IR and luminescent probes is addressed.

Sensitive SERS-pH sensing in biological media using metal carbonyl functionalized planar substrates

Conventional nanoparticle based Surface enhanced Raman scattering (SERS) technique for pH sensing often fails due to the aggregation of particles when detecting in acidic medium or biosamples having high ionic strength. Here, We develop SERS based pH sensing using a novel Raman reporter, arene chromium tricarbonyl linked aminothiophenol (Cr(CO)3-ATP), functionalized onto a nano-roughened planar substrates coated with gold. Unlike the SERS spectrum of the ATP molecule that dominates in the 400-1700 cm(-1) region, which is highly interfered by bio-molecules signals, metal carbonyl-ATP (Cr(CO)3)-ATP) offers the advantage of monitoring the pH dependent strong CO stretching vibrations in the mid-IR (1800-2200 cm(-1)) range. Raman signal of the CO stretching vibrations at ~1820 cm(-1) has strong dependency on the pH value of the environment, where its peak undergo noticeable shift as the pH of the medium is varied from 3.0 to 9.0. The sensor showed better sensitivity in the acidic range of the pH. We also demonstrate the pH sensing in a urine sample, which has high ionic strength and our data closely correlate to the value obtained from conventional sensor. In future, this study may lead to a sensitive chip based pH sensing platform in bio-fluids for the early diagnosis of diseases.

Metallocenes as Target Specific Drugs for Cancer Treatment

The application use of organometallic compounds into the cancer research was established in the late 1970s by Köpf-Maeir and Köpf. This new research area has been developed for the past thirty years. In the early 1980s, Jaouen and coworkers recognized the potential application of organometallic compounds vectorized with pendant groups that can deliver the drug to certain specific receptors. This is what is called nowdays Target Specific Drugs. This review will focus on metallocenes vectorized with steroids derivatives of hormones, nonsteroidal and selective endrocrine modulator.

Synchrotron radiation FTIR detection of a metal-carbonyl tamoxifen analog. Correlation with luminescence microscopy to study its subcellular distribution

1,1-Di(4-hydroxyphenyl)-2-cyrhetrenylbut-1-ene 1 is an organometallic conjugate where a [(Cp)Re(CO)(3)] unit is linked to a hydroxytamoxifen-like structure. Its subcellular nuclear distribution was previously observed in a single cell using the near-field technique AFMIR. We show here that synchrotron radiation FTIR spectromicroscopy (SR-FTIR-SM) enabled the mapping of 1 based on its IR-signature (characteristic bands in the 1850-2200 cm(-1) range) and pointed out the colocalization of 1 with an area of high amide density. Fluorescence microscopy using DAPI staining performed on the same cells confirmed that this area corresponds to the cell nucleus.

Role of aromatic substituents on the antiproliferative effects of diphenyl ferrocenyl butene compounds

We have been exploring the cytotoxic effects of conjugated phenylferrocene systems on breast cancer cells. Complexes with p-OH, p-NH(2), and p-NHC(O)CH(3) substitution show particularly high activity, with IC(50) values in the low or sub micromolar range for both the hormone-dependent MCF-7 and hormone-independent MDA-MB-231 breast cancer cell lines. We now present the synthesis, X-ray crystal structures and biochemical studies of analogous halogen or pseudo-halogen para-substituted compounds with R = Cl, (Z)-7a; Br, (Z)-7b; CF(3), (E)-7c; and CN, (E)-7d and (Z)-7d. Lacking hydrogen bonding groups, the compounds have low, but non-zero, relative binding affinity values for the oestrogen receptor alpha (RBA <or= 0.55%) as well as mildly exothermic ligand binding in in silico ER docking experiments. All compounds show estrogenic (proliferative) activity on the MCF-7 cell line. On MDA-MB-231 cells, the cyano complex (Z)-7d shows a reasonable cytotoxic effect (IC(50) = 11 microM), its isomer (E)-7d is only slightly cytotoxic (IC(50) = 60 microM), while the Cl, Br, and CF(3) derivatives have no effect. Cytotoxic properties, while they correlate somewhat with the resonance donating abilities of the substituent, are more strongly dependent on the presence of a proton in the functional group, supporting our prior proposition that electrophilic quinoid forms of the compounds could be active species in the cell. A correlation of the redox potential of the ferrocenyl moiety with the Hammett-Taft constants of the substituents was observed.

Unexpectedly different reactions of [(arene)Mn(CO)3]+ cations (arene = trindane, indane, tetralin, or dibenzosuberane) with potassium t-butoxide — C-H insertions, haptotropic shifts, dimerization, or elimination

[(η6-Trindane)Mn(CO)3][BF4] (1) reacts with tert-BuOK in THF in the presence of alkyl halides (CH2=CHCH2Br, CH3I) to yield the corresponding (η6-C15H18)Mn(CO)2X, where X = Br (3) or I (4). In contrast, 1 and tert-BuOK react, in the presence of a donor ligand, to generate (η5-C15H15)Mn(CO)2L, where L = CO (7), P(OMe)3 (8), or PPh3 (9), in which the metal has migrated from the central ring onto a peripheral ring that has lost three hydrogens; [(η6-indane)Mn(CO)3][BF4] behaves similarly. A mechanism is proposed in which the initially formed (η6-trindane)Mn(CO)2CO2-tert-Bu suffers the loss of CO2 and isobutene to yield the hydride, (η6-trindane)Mn(CO)2H, that in turn undergoes three successive C-H insertions with concomitant loss of two molecules of dihydrogen. In contrast, [(η6-tetralin)Mn(CO)3][PF6] (17) and [(η6-dibenzosuberane)Mn(CO)3][BF4] (23) each suffer deprotonation at a benzylic site. In the first case, the zwitterion formed attacks its progenitor to yield a tetralenyl-substituted (η5-cyclohexadienyl)Mn(CO)3 complex (21); however, for the dibenzosuberane complex (23) the elimination product (28) is stable. X-ray crystal structures are reported for 3, 4, 7, 8, 23, 28, and for the phosphite complexes [(η6-trindane)Mn(CO){P(OMe)3}2][BF4] (15) and [(η6-tetralin)Mn(CO)2{P(OMe)3}][PF6] (20).Key words: arene-manganese, organometallic cations, deprotonations, X-ray crystallography.

Synthesis, photophysical and electrochemical properties, and protein-binding studies of luminescent cyclometalated iridium(III) bipyridine estradiol conjugates

A new series of luminescent cyclometalated iridium(III) bipyridine estradiol conjugates [Ir(N-C)2(N-N)](PF6) (N-N = 5-(4-(17alpha-ethynylestradiolyl)phenyl)-2,2'-bipyridine, bpy-est, HN-C = 2-phenylpyridine, Hppy (1 a), 1-phenylpyrazole, Hppz (2 a), 7,8-benzoquinoline, Hbzq (3 a), 2-phenylquinoline, Hpq (4 a), 2-((1,1'-biphenyl)-4-yl)benzothiazole, Hbsb (5 a); N-N = 4-(N-(6-(4-(17alpha-ethynylestradiolyl)benzoylamino)hexyl)aminocarbonyl)-4'-methyl-2,2'-bipyridine, bpy-C6-est, HN-C = Hppy (1 b), Hppz (2 b), Hbzq (3 b), Hpq (4 b), Hbsb (5 b)) was synthesized, characterized, and their photophysical and electrochemical properties studied. Upon photoexcitation, all the complexes displayed intense and long-lived emission in fluid solutions at 298 K and in low-temperature glass. The emission of complexes 1 a-3 a and 1 b-3 b was assigned to a triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ir)-->pi*(bpy-est and N-C-)) state mixed with some triplet intraligand ((3)IL) (pi-->pi*) (N-C- and N-N) character. However, the emissive states of the pq- and bsb- complexes 4 a, 4 b, 5 a, and 5 b showed substantial (3)IL (pi-->pi*) (pq-/bsb-) character. The lipophilicity of all the complexes was determined by reversed-phase HPLC. Upon binding to estrogen receptor alpha, all of these iridium(III) estradiol conjugates exhibited emission enhancement and lifetime extension, rendering them a novel series of luminescent probes for this receptor.

A series of unconjugated ferrocenyl phenols: prospects as anticancer agents

We recently reported that a ferrocenyl diphenol butene derivative showed a very strong cytotoxic effect on both hormone-dependent and -independent breast cancer cell lines. In order to obtain more information about the structure-activity relationship in the cytotoxicity of small ferrocene compounds, we have prepared a series of simple unconjugated ferrocenyl diphenol complexes (ortho,para; meta,para; para,para). These compounds retain a reasonable to good affinity for both estrogen receptor types, with higher values for the beta form, and superior binding for the para,para diphenol complex (RBA=28%). In vitro these complexes exhibit significant cytotoxic effects on hormone-independent prostate (PC3) and breast cancer cell lines (MDA-MB231), with IC50 values between 2.5 and 4.1 microM. This effect is more marked with PC3, the ortho,para diphenol complex proving the most effective. On the hormone-dependent MCF7 breast cancer cell line, the observed effect seems to be the result of two components, one cytotoxic (antiproliferative), the other estrogenic (proliferative). Electrochemical studies show that the cytotoxic effect of the complexes correlates with the ease of oxidation of the ferrocene group. All these complexes are much less cytotoxic than the ferrocenyl diphenol butene derivative.

Selective estrogen-receptor modulators (SERMs) in the cyclopentadienylrhenium tricarbonyl series: synthesis and biological behaviour

A series of organometallic antiestrogens based on the OH-tamoxifen (OH-Tam) skeleton and bearing the (eta(5)-C(5)H(4))Re(I)(CO)(3) unit has been prepared by using McMurry coupling for the purpose of studying their biological behaviour. The cyclopentadienylrhenium tricarbonyl moiety is indeed stable in biological media, compact, lipophilic and easy to handle. Furthermore, this study allowed us to select the best candidates for subsequent use as radiopharmaceuticals either for imaging or therapy by using appropriate radionucleides, namely (99m)Tc and (188)Re. In these molecules the beta-phenyl group of OH-Tam has been replaced by the (eta(5)-C(5)H(4))Re(CO)(3) moiety, and the length of the dimethylamino side chain --O(CH(2))(n)N(CH(3))(2) was varied (n=2, 3, 4, 5 and 8). The compounds 7 a-7 e were obtained as mixtures of their Z and E isomers, which could be separated by semipreparative HPLC. Unlike their ferrocene homologues, the compounds do not isomerise in solution. Structural identification was carried out with NMR spectroscopy by using the HMBC and NOE techniques and was confirmed by the X-ray structural determination of (E)-7 a (n=2). These molecules were more lipophilic than OH-Tam (log P(o/w)=4.5-6.3) and they were all reasonably well recognized by the two forms of the estrogen receptor (ERalpha and ERbeta). For example, (Z)-7 b (n=3) has high relative binding affinity (RBA) values of 31 % for ERalpha and 16.8 % for ERbeta. The antiproliferative effects of two pairs of isomers, (Z)- and (E)-7 b (n=3) and (Z)- and (E)-7 d (n=5), were studied at a molarity of 1 microM on two breast-cancer cell lines, MCF7 (ERalpha positive) and MDA-MB231 (ERalpha negative). These molecules had an antiproliferative effect on MCF7 cells slightly higher than that of OH-Tam and no effect on MDA-MB231 cells. Thus, the antiproliferative effect observed on the MCF7 cells seemed essentially to be linked to an antiestrogenic effect. Molecular modelling studies have allowed us to rationalise these effects and select the best compounds for future development of a radioactive series.

Selective Estrogen Receptor Modulators in the Ruthenocene Series. Synthesis and Biological Behavior

A series of ruthenocene derivatives, 1-[4-(O(CH(2))(n)()N(CH(3))(2))phenyl]-1-(4-hydroxyphenyl)-2-ruthenocenylbut-1-ene, with n = 2-5, based on the structure of the breast cancer drug tamoxifen has been prepared. These compounds were obtained, via a McMurry cross-coupling reaction, as a mixture of Z and E isomers that could not be separated by HPLC. The relative binding affinity values for estrogen receptor alpha (ERalpha) for n = 2 and 3 were very high (85 and 53%) and surpassed even that of hydroxytamoxifen (38.5%), the active metabolite of tamoxifen. Ruthenocene derivatives act as anti-estrogens as effective (n = 2) or slightly more effective (n = 3-5) than hydroxytamoxifen on ERalpha-positive breast cancer cell lines but, unlike ferrocifens, do not show antiproliferative effects on ERalpha-negative breast cancer cell lines. Electrochemical studies showed that the ruthenocifen radical cations are unstable, which may account for this behavior. Some of these compounds could be useful as radiopharmaceuticals for ERalpha-positive breast cancer tumors.

Synthesis and characterisation of estrogenic carriers for cytotoxic Pt(ii) fragments: biological activity of the resulting complexes

This paper describes the synthesis and the spectroscopic characterisation of cis-dichloro[N-(4-(17alpha-ethynylestradiolyl)-benzyl)-ethylenediamine]platinum(II) and cis-diamino[2-(4-(17alpha-ethynylestradiolyl)-benzoylamino)-malonato]platinum(II). These complexes were synthesised in good yield according to multi-step procedures based on the classical and non-classical Sonogashira coupling reaction, respectively. These compounds retain an acceptable degree of relative binding affinity (RBA) for the alpha form of estrogen receptor. Combined treatment of breast cancer cell lines, namely hormone-sensitive MCF-7 and hormone-insensitive MDA-MB-231 cell lines, indicates that these compounds maintain agonistic activity so that the potential advantage in vehiculation of the cytotoxic moiety by means of the receptor system is counteracted by the proliferative effect of the estrogenic component of the entire molecule, especially at low concentrations.

Synthesis, receptor binding, molecular modeling, and proliferative assays of a series of 17alpha-arylestradiols

A series of new derivatives of estradiol substituted at position 17alpha by various aryls has been synthesized. This was made possible by efficient activation methods for the addition of aryllithiums to the carbonyl group at position 17 of estrone by using tetramethylethylenediamine (TMEDA) or BF3 x OEt2. Their relative binding affinity (RBA) for the alpha and the beta forms of the estrogen receptor (ER) have been measured. All except one of the compounds synthesized had an RBA value of around 10 % which indicates a level of tolerance towards the bulky substituent at position 17. The lipophilicity values measured for these compounds are higher than that found for estradiol (E2). A study of their proliferative/antiproliferative effects was carried out on hormone-dependent (MCF7) and hormone-independent (MDA-MB231) breast cancer cell lines. It is interesting to note that all the compounds are estrogenic. The possibility of easily attaching an iodine at the end of a phenyl spacer opens up a route to new radiopharmaceuticals for use in radioimaging.