Sara Dolci

A crystallographic and spectroscopic study on the reactions of WCl6 with carbonyl compounds

WCl6, 1, reacted with two equivalents of HC(O)NR2 (R = Me, Et) in CH2Cl2 to afford the W(VI) oxo-derivatives WOCl4(OCHNR2) (R = Me, 2a; R = Et, 2b) as main products. The hexachlorotungstate(V) salts [{O=C–N(Me)CH2CH2CH2}2(μ-H)][WCl6], 3, and [PhNHC(Me)N(Ph)C(O)Me][WCl6], 4, were isolated in moderate yields from the 1:2 molar reactions of 1 with N-methyl-2-pyrrolidone (in CH2Cl2) and acetanilide (in CDCl3), respectively. The additions of two equivalents of ketones/aldehydes to 1/CH2Cl2 yielded the complexes WOCl4[OC(R)(R′)] (R = Me, R′ = Ph, 5a; R = R′ = Ph, 5b; R = R′ = Me, 5c; R = R′ = Et, 5d; R = H, R′ = 2-Me-C6H4, 5e) and equimolar amounts of C(R)(R′)Cl2. Analogously, WOCl3[κ(2)-{1,2-C6H4(O)(CHO)}], 5f, and 1,2-C6H4(OH)(CHCl2) were obtained from 1 and salicylaldehyde. The 1:1 reaction of 1 with acetone in CH2Cl2 resulted in the clean formation of WOCl4 and 2,2-dichloropropane. Compounds 5a,b,f were isolated as crystalline solids, whereas 5c,d,e could be detected by solution NMR only. The interaction of 1/CH2Cl2 with isatin, in a 1:1 molar ratio, revealed to be a new, convenient route for the synthesis of 3,3-dichloro-2,3-dihydro-1H-indol-2-one, 6. The 1:1 reactions of 1 with R′OCH(R)CO2Me (R = H, R′ = Me; R = Me, R′ = H) in a chlorinated solvent afforded the tungsten(V) adducts WCl4[κ(2)-OCH(R)CO2Me] (R = H, 7a; R = Me, 7b). 1/CH2Cl2 reacted sluggishly with equimolar quantities of trans-(CO2Et)CH=CH(CO2Et) and CH2(CO2Me)2 to give, respectively, the W(IV) derivatives WCl4[κ(2)-CH2(CO2Me)2], 8a, and [WCl4-κ(2)-{trans-(CO2Et)CH=CH (CO2Et)}]n, 8b, in about 70% yields. The molecular structures of 2a, 3, 4, 5a, 5f, 7a and 7b were ascertained by X-ray diffraction studies.

C-N bond-forming self-condensation of amide promoted by MoCl5 at room temperature.

The acylamidinium complex MoOCl(4)[MeC(O)N(Ph)C(Me)═NHPh] (2) was obtained by selective self-condensation of MeC(O)NHPh promoted by MoCl(5). Otherwise, the stable chloroiminium salt [MoOCl(4){HC(O)NMe(2)}][CH(Cl)═NMe(2)] (3) was isolated from HC(O)NMe(2)/MoCl(5).

Immune compatible cystine-functionalized superparamagnetic iron oxide nanoparticles as vascular contrast agents in ultrasonography

Superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively investigated for many biomedical applications. A good quality functionalization that combines imaging goals with a high-level of biocompatibility remains one of the challenges for particle translation into medical practice. Here, we focus on a new functionalization of SPIONs with cystine (Cy-SPIONs). Cystine is able to make SPIONs stable and dispersible in water and in culture cell media. New insights are provided into the biological and immune effects of Cy-SPIONs with a wide variety of standard and molecular assays to evaluate cytotoxicity, cell activation, cytokine release and the expression of 84 genes related to immune responses. A good immune biocompatibility of Cy-SPIONs on primary immune cells was found. The great potential of Cy-SPIONs for further in vivo studies and as contrast agents for magnetic resonance imaging (MRI) is highlighted. In addition, we also exploited ultrasonography, since it is a safer, less expensive and common imaging technology. The good echogenic properties of Cy-SPIONs in water and in whole blood are shown, both in vitro and in a phantom vein for bloodstream simulations. Our results open up a new scenario for future applications of cystine-functionalized SPIONs as immune-compatible ultrasound and MRI contrast agents.

Precursors of Magnetic Resonance Imaging Contrast Agents Based on Cystine-coated Iron-oxide Nanoparticles

Super Paramagnetic Iron-Oxide Nanoparticles (SPION) are currently used as magnetic resonance imaging (MRI) contrast agents. The functionalization of their surface with organic and biocompatible molecules has the purpose to produce carriers selective for different tissues and organs. In this paper, we present the preparation of new cystine-coated ultra small super paramagnetic iron-oxide nanoparticles (USPION) of different core size, from 4 nm to 11 nm. The physical-chemical characterization of these nanoparticles was performed by using several experimental techniques, such as atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM) and magnetic measurements. 1 H NMR relaxation times at different magnetic field strengths have been measured for several water- dispersions of cystine-coated iron-oxide nanoparticles of the smallest dimensions (4 nm). These preliminary results confirm their potentialities as molecular imaging probes and MRI contrast agents.

Ultrasmall superparamagnetic iron oxide nanoparticles with titanium-N,N-dialkylcarbamato coating

This work deals with the preparation and physical-chemical characterization of new ultrasmall iron oxide superparamagnetic nanoparticles (USPIONs) functionalized with titanium-N,N-dialkylcarbamato. The preparation was performed starting with monodispersed USPIONs covered with oleic acid, synthesized by thermal-decomposition, and subsequently functionalized with metal-carbamato by a ligand-exchange reaction. The surface and coating structure was characterized by infrared (FT-IR) spectroscopy on the solid powders and thermogravimetry (TG) coupled with an FT-IR detector in order to better investigate the self-assembling properties of the coating. A detailed dimensional and morphological study was carried out by transmission electron microscopy (TEM) and atomic force microscopy (AFM) analysis. Zero-field-cooled (ZFC) and field-cooled (FC) magnetic susceptibility curves as well as the magnetization behavior as a function of temperature were investigated on both the starting oleic-USPIONs and those covered by titanium-N,N-dialkylcarbamato. These results confirmed the superparamagnetic properties of the new nanoparticles (NPs), highlighting the quite high saturation value of the magnetization. Based on the results obtained by combining different experimental techniques, a model of the coating structure and ligand organization around the magnetic core is proposed for both NPs, i.e. the starting USPIONs covered by oleic acid and the new USPIONs functionalized by titanium-N,N-dialkylcarbamato.

Carbon nanomaterials as contrast agents for breast cancer diagnosis and therapy

Nanotechnology is the promise to fight breast cancer (BC) more specifically and effectively [1]. In this context carbon nanomaterials (CNs) have attracted the scientific community and the public interest [2]. Common modalities for BC diagnosis are ultrasonography (US) and magnetic resonance imaging (MRI). US is the most useful modality in the evaluation of palpable BC masses that are mammographically occult in women younger than 30’s. Here we show CNs as highly and long lasting echogenic materials. Experiments on swine models confirmed that CNs are clearly visible under US and didn’t exert toxicity. In the current market dual-imaging agents are missed; here we also demonstrate the immune-compatibility and high echogenic properties in water and in whole blood of cysteine functionalized super paramagnetic nanoparticles (CY-SPION), well-known MRI agents [3]. Thanks to these findings, and the ability to load CNs to many moieties [4-6], we propose dual-contrast agents, CNs-CY-SPION conjugates, to improve BC diagnosis. Future perspectives is to conjugate CN-SPION to targeted drugs against BC. In summary, we lay the foundations for novel contrast agents, for therapy and multimodal diagnosis of BC, combining high imaging performances with unique potential therapeutic applications, such as specific targeting capabilities, drug delivery, immunotherapy and hyperthermia.