Simona Samaritani

Polar liquid crystalline monomers with two or three lactate groups for the preparation of side chain polysiloxanes

Two new chiral liquid crystalline monomers with bilactate or trilactate chiral units were synthesized and studied. The monomers show the paraelectric SmA and ferroelectric SmC* phases. The antiferroelectric phase was detected only for the monomer possessing the bilactate unit. The temperature dependences of the spontaneous polarization and spontaneous tilt angle were measured. Real and imaginary parts of the complex permittivity were studied as a function of frequency and temperature. The synthesized monomers contain a double bond at the end of the achiral terminal chain, and were used to prepare liquid crystalline polysiloxanes.

2-alkyl-4,6-dialkylamino-1,3,5-triazines via Grignard alkylation of cyanuric chloride: An aged reaction revisited

Abstract Suitable one-pot reaction conditions are suggested to prepare, in good overall yields, some 2-(alk-1′-ynyl)- and 2-alkyl-4,6-dialkylamino-1,3,5-triazines via reaction of cyanuric chloride with Grignard reagents followed by amination.

Palladium on carbon catalyzed cross-coupling between alk-1-ynes and 2-chloro-4,6-dialkoxy-1,3,5-triazines

Abstract 2-(Alk-1′-ynyl)-4,6-dialkoxy-1,3,5-triazines have been synthesized in satisfactory yields by (Pd/C)/PPh 3 /CuI catalyzed cross-coupling between alk-1-ynes and 2-chloro-4,6-dialkoxy-1,3,5-triazines carried out in the presence of diisopropylethylamine or K 2 CO 3 /18-crown-6.

2-(Alk-1’-ynyl)-4,6-dimethoxy-1,3,5-triazines via Pd-mediated alkynylation of 2-chloro-4,6-dimethoxy-1,3,5-triazine

Abstract In the presence of a catalytic amount of (Ph 3 P) 4 Pd, 2-chloro-4,6-dimethoxy-1,3,5-triazine reacts with alk-1-ynes to give the corresponding 2-(alk-1′-ynyl)-derivatives in satisfactory yields. Depending on the nature of the alk-1-ynes, Pd(10%) C can also be used to catalyze the cross-coupling.

Selective Amination of Cyanuric Chloride in the Presence of 18‐Crown‐6

An interpretation of the role of 18-crown-6 in the selective di- and trialkylamination of 2,4,6-trichloro-1,3,5-triazine is reported, and the usefulness of the procedure is shown. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

2,4,6-Tri[(S)-1′-methylbenzylamino]-1,3,5-triazine: a new NMR chiral solvating agent for 3,5-dinitrophenyl derivatives; an attempt at a chiral discrimination rationale

Abstract The use of 2,4,6-tri[( S )-1′-methylbenzylamino]-1,3,5-triazine as a chiral solvating agent for the NMR evaluation of the enantiomeric excess of 3,5-dinitrophenyl derivatives is reported along with an investigation into the origin of the enantiodiscrimination process.

Smart Grafting of Lanthanides onto Silica via N,N-Dialkylcarbamato Complexes.

The grafting and the postgrafting functionalization of lanthanide ions on commercial amorphous silica have been herein carried out by using as a precursor the terbium N,N-dibutylcarbamato derivative [Tb(O2CNBu2)3]. The reaction of the complex with the surface silanols involved only a fraction of the carbamato ligands. The following protolytic substitution of the residual carbamato ligands was carried out by exploiting the Brønsteds acidity of the β-diketone dibenzoylmethane (Hdbm), in view of the antenna effect of the β-diketonato groups, which are commonly used in lanthanide photoluminescence studies. The reaction proceeded at room temperature in a clean and easy way affording the introduction of the chosen functionality in the lanthanide coordination sphere. The same procedure has been followed by using as a precursor the X-ray characterized heterometallic N,N-dibutylcarbamato complex [NH2Bu2]2[Ln4(CO3)(O2CNBu2)12] (Ln = Eu, Tb, Tm). In both cases, X-ray photoelectron spectroscopy evidenced the chemical implantation of the lanthanide ions on the silica surface, and photoluminescence studies pointed out the potentiality of the proposed synthetic approach in the preparation of highly luminescent materials.

Preparation of N,N-Dialkylcarbamato Lanthanide Complexes by Extraction of Lanthanide Ions from Aqueous Solution into Hydrocarbons

Lanthanides are easily extracted as N,N-dibutylcarbamato complexes from aqueous solutions of their chlorides into heptane solutions of dibutylamine saturated with CO2. The products are recovered in high yields and are soluble in hydrocarbons. The derivatives [Ln(O2CNBu2)3]n [Ln = Nd (1), Eu (2), Tb (3)], [NH2Bu2]2[Ln4(CO3)(O2CNBu2)12] [Ln = Tb (4), Sm (5), Eu (6)], and [Sm4(CO3)(O2CNBu2)10], 7, have thus been obtained. The crystal and molecular structure of 4 has been solved; the samarium and europium complexes 5 and 6 were found to be isostructural. Mass spectra of the complexes 1-3, 4, and 7 (in MeCN/toluene) reveal that equilibria are present in solution. Compound 2 has been reacted in toluene with NHBz2 in the presence of CO2 affording [NH2Bz2][Eu(O2CNBz2)4], 8, through a ligand exchange process. By thermal treatment, 8 afforded [Eu(O2CNBz2)3]n, 9. With a similar procedure [Sm(O2CNBz2)3]n, 10, was obtained from 5. According to the photoluminescence study carried out on solid samples of 2, 4, 5, 7, and 8, the metal centered f-f transitions represent the only effective way to induce lanthanide luminescence in these complexes.

Synthesis, antiproliferative and mitochondrial impairment activities of bis-alkyl-amino transplatinum complexes.

A convenient synthetic route and the characterization of complexes trans-[PtCl2(L)(PPh3)] (L=Et2NH (2), (PhCH2)2NH (3), (HOCH2CH2)2NH) (4) are reported. The antiproliferative activity was evaluated on three human tumor cell lines. The investigation on the mechanism of action highlighted for the most active complex 4 the capacity to affect mitochondrial functions. In particular, both the induction of the mitochondrial permeability transition phenomenon and an aspecific membrane damage occurred, depending on concentration.

New trans dichloro (triphenylphosphine)platinum(II) complexes containing N-(butyl),N-(arylmethyl)amino ligands: Synthesis, cytotoxicity and mechanism of action

Some new platinum(II) complexes have been prepared, of general formula trans-[PtCl2(PPh3){NH(Bu)CH2Ar}], where the dimension of the Ar residue in the secondary amines has been varied from small phenyl to large pyrenyl group. The obtained complexes, tested in vitro towards a panel of human tumor cell lines showed an interesting antiproliferative effect on both cisplatin-sensitive and -resistant cells. For the most cytotoxic derivative 2a the investigation on the mechanism of action highlighted the ability to induce apoptosis on resistant cells and interestingly, to inhibit the catalytic activity of topoisomerase II.