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21.
Jonathan Martinelli Lorenzo Tei Simonetta Geninatti Crich Diego Alberti Kristina Djanashvili 《Molecules (Basel, Switzerland)》2021,26(6)
It is known that phenylboronic acid (PBA) can target tumor tissues by binding to sialic acid, a substrate overexpressed by cancer cells. This capability has previously been explored in the design of targeting diagnostic probes such as Gd- and 68Ga-DOTA-EN-PBA, two contrast agents for magnetic resonance imaging (MRI) and positron emission tomography (PET), respectively, whose potential has already been demonstrated through in vivo experiments. In addition to its high resolution, the intrinsic low sensitivity of MRI stimulates the search for more effective contrast agents, which, in the case of small-molecular probes, basically narrows down to either increased tumbling time of the entire molecule or elevated local concentration of the paramagnetic ions, both strategies resulting in enhanced relaxivity, and consequently, a higher MRI contrast. The latter strategy can be achieved by the design of multimeric GdIII complexes. Based on the monomeric PBA-containing probes described recently, herein, we report the synthesis and characterization of the dimeric analogues (GdIII-DOTA-EN)2-PBA and (GdIII-DOTA-EN)2F2PBA. The presence of two Gd ions in one molecule clearly contributes to the improved biological performance, as demonstrated by the relaxometric study and cell-binding investigations. 相似文献
22.
Mesoporous Zirconium Phenylenesiliconate‐phosphonate Hybrids with Ordered Lamellar Nanostructures 下载免费PDF全文
Prof. Dr. Kazuyuki Maeda Hiroki Kobayashi Kaku Oguro Masato Otsu Dr. Atsushi Kondo Dr. Tei Maki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):17091-17099
Novel ordered lamellar mesostructure pZrPS‐2 was hydrothermally prepared by using zirconium propoxide and 4‐(EtO)2OPC6H4Si(OEt)3 (pPPS‐E), which was hydrolyzed to organic building units substituted with both siliconate and phosphonate groups, in the presence of CnTAB and TMAOH. The pZrPS‐2 materials were obtained at a Zr/PPS ratio of 2 or higher and the basal spacing was increased by using a longer‐chain surfactant (n=12–18). Removal of the occluded surfactants at 300 °C resulted in retention of the lamellar structure with negligible shrinkage of the interlayer distance. Nitrogen adsorption studies revealed the ordered mesoporous nature of pZrPS‐2 with a pore diameter of approximately 2 to 3 nm. The lamellar structure is assumed to be composed of layers that include zirconia‐based crystalline nanodomains and interlayer pillars mainly based on PPS units. Although lamellar structures with the same crystalline phase also formed when no surfactant was added or when the meta isomer of PPS was used, no mesoporous materials were obtained except pZrPS‐2. A possible schematic model to elucidate these results is also proposed. 相似文献
23.
N,N'-Dibenzyl-6-hydroxymethyl-6-nitroperhydro-1,4-diazepine was converted into a nitronate via retro-Henry reaction, followed by either Michael reaction with several acrylic derivatives or Mannich reaction with different amines, thus leading to 6-substituted 6-nitroperhydro-1,4-diazepines. The tandem retro-Henry/Mannich reaction was also carried out using benzylamine as base, solvent, and reagent at the same time. Selective hydrogenation of the nitro group and complete hydrogenolysis were also successfully achieved. 相似文献
24.
Lorenzo Tei Marina Benzi Filip Kielar Mauro Botta Camilla Cavallotti Giovanni Battista Giovenzana Silvio Aime 《Helvetica chimica acta》2009,92(11):2414-2426
Two new derivatives based on an s‐triazine structural motif were synthesized by attaching two 2,2′‐hydrazinylidenebis[acetic acid] moieties to the triazine ring to reach an overall heptadenticity for the complexation of lanthanide(III) cations. The remaining reactive site was exploited for the substitution with a functionizable amino group (see H4 L1 ) and a lipophilic moiety (see H4 L2 ). Luminescence‐lifetime determinations revealed the presence of a single H2O molecule coordinated for [Eu( L1 )]. A complete 1H‐NMR relaxometric study was carried out for the octacoordinated [Gd( L1 )] and [Gd( L2 )] complexes. A remarkably long H2O residence lifetime (298τM =5.2 μs) was found by 17O‐NMR in the case of [Gd( L1 )]. Micelle formation of the lipophilic complex [Gd( L2 )] was evidenced, the critical micellization concentration (cmc) determined, and relaxometric properties of the system investigated. 相似文献
25.
Masafumi Baba Takehiko Fujishiro Shigeru Yamaguchi Kazuyoku Tei Makoto Yoshida Tsutomu Sakurai Ken-ichi Tanaka 《Optical Review》2010,17(2):50-53
We report progress in the design and fabrication of a monolithic, linearly polarized, pulsed, Yb-doped fiber laser. This laser
has a peak power of more than 100 kW, a tunable repetition rate from 100 kHz to 1 MHz, a tunable pulse duration from 2 ns
to 2.5 μs, and a diffraction-limited, linearly polarized output beam with a mean power of 21 W and a wavelength of 1064 nm.
A seed source that consists of a microchip Nd:YVO4 laser and an electro optic deflector is developed. Using this source, the repetition rate and pulse duration are varied independently
of each other. In addition, an excellent pulse-to-pulse repeatability is achieved. 相似文献
26.
Aragoni MC Arca M Demartin F Devillanova FA Isaia F Garau A Lippolis V Jalali F Papke U Shamsipur M Tei L Yari A Verani G 《Inorganic chemistry》2002,41(25):6623-6632
The macrocycles L(1)-L(3) incorporating N(2)S(3)-, N(2)S(2)O-, and N(2)S(2)-donor sets, respectively, and containing the 1,10-phenanthroline unit interact in acetonitrile solution with heavy metal ions such as Pb(II), Cd(II), and Hg(II) to give 1:1 ML, 1:2 ML(2), and 2:1 M(2)L complex species, which specifically modulate the photochemical properties of the ligands. The stoichiometry of the complex species formed during spectrofluorometric titrations and their formation constants in MeCN at 25 degrees C were determined from fluorescence vs M(II)/L molar ratio data. The complexes [Pb(L(1))][ClO(4)](2).(1)/(2)H(2)O (1), [Pb(L(2))][ClO(4)](2).MeNO(2) (1a), [Pb(L(3))(2)][ClO(4)](2).2MeCN (1b), and [Cd(L(3))][NO(3)](2) (2b) were also characterized by X-ray diffraction studies. The conformation adopted by L(1)-L(3) in these species reveals the aliphatic portion of the rings folded over the plane containing the heteroaromatic moiety with the ligands trying to encapsulate the metal center within their cavity. In 1, 1a, and 2b the metal ion completes the coordination sphere by interacting with counteranion units and solvent molecules. On the contrary, the 1:2 complex 1b shows Pb(II) sandwiched between two symmetry-related molecules of L(3) reaching an overall [4N + 4S] eight-coordination. 相似文献
27.
Dr. Loredana Leone Luca Guarnieri Dr. Jonathan Martinelli Prof. Massimo Sisti Prof. Andrea Penoni Prof. Mauro Botta Prof. Lorenzo Tei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(46):11811-11817
The first binuclear Gd-complex of the 12-membered pyridine-based polyaminocarboxylate macrocyclic ligand PCTA was synthesized by C−C connection of the pyridine units through two different synthetic procedures. A dimeric AAZTA-ligand was also synthesized with the aim to compare the relaxometric results or the two ditopic Gd-complexes. Thus, the 1H relaxometric study on [Gd2PCTA2(H2O)4] and on [Gd2AAZTA2(H2O)4]2− highlighted the remarkable rigidity and compactness of the two binuclear complexes, which results in molar relaxivities (per Gd), at 1.5 T and 298 K of ca. 12–12.6 mM−1 s−1 with an increase of ca. 80 % at 1.5 T and 298 K (+70 % at 310 K) with respect to the corresponding mononuclear complexes. 相似文献
28.
The core structure of cis-3,5-diaminopiperidine was N-alkylated with excess t-butylbromoacetate in order to exploit the successive N-quaternarization and Stevens rearrangement to access the pentaalkylated product and the bifunctional chelating agent containing a N-butanedioic acid pendant arm at the same time. The relaxometric properties of the Gd(III) complexes with these ligands were studied also in terms of pH and serum stabilities. 相似文献
29.
Dr. Fabio Carniato Dr. Lorenzo Tei Dr. Aldo Arrais Prof. Leonardo Marchese Prof. Mauro Botta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(4):1421-1428
The optimization of the physico‐chemical properties of both GdIII chelates and nanocarriers is of great importance for the development of effective nanosystems for magnetic resonance imaging (MRI) applications. With this aim, macrocyclic GdIII chelates were selectively attached to the pendant amino groups exposed to the external surface of spheroidal mesoporous silica nanoparticles (MSNs). This was achieved by treating the metal complexes with MSNs that contained the templating surfactant molecules confined within the silica channels (hexadecyltrimethylammonium (CTA)/MSN), followed by extraction of the surfactant. The nanoparticles showed greatly improved 1H relaxometric efficiency relative to corresponding systems that also feature GdIII chelates conjugated inside the pores. A further significant relaxivity enhancement was observed after chemical transformation of the free amino groups into amides. The ionic relaxivity of the final nanoparticles (r1p=79.1 mM ?1 s?1; 0.5 T, 310 K) is one of the highest reported so far. 相似文献