Stereoselective protecting group free synthesis of d,l-gulose ethyl glycoside via multicomponent enyne cross metathesis—hetero Diels–Alder reaction

An efficient and stereoselective synthesis of d,l-gulose was described. The key step of the synthetic route is represented by a multicomponent enyne cross metathesis—hetero Diels–Alder reaction which allows the formation of the pyran ring from cheap and commercially available substrates in a single synthetic step. The synthesis of d,l-gulose was accomplished without the use of protecting groups making this approach highly desirable also in terms of atom economy

High spin Fe(III)-doped nanostructures as T1 MR imaging probes

Magnetic Resonance Imaging (MRI) T1 contrast agents based on Fe(III) as an alternative to Gd-based compounds have been under intense scrutiny in the last 6-8 years and a number of nanostructures have been designed and proposed for in vivo diagnostic and theranostic applications. Excluding the large family of superparamagnetic iron oxides widely used as T2 -MR imaging agents that will not be covered by this review, a considerable number and type of nanoparticles (NPs) have been employed, ranging from amphiphilic polymer-based NPs, NPs containing polyphenolic binding units such as melanin-like or polycatechols, mixed metals such as Fe/Gd or Fe/Au NPs and perfluorocarbon nanoemulsions. Iron(III) exhibits several favorable magnetic properties, high biocompatibility and improved toxicity profile that place it as the paramagnetic ion of choice for the next generation of nanosized MRI and theranostic contrast agents. An analysis of the examples reported in the last decade will show the opportunities for relaxivity and MR-contrast enhancement optimization that could bring Fe(III)-doped NPs to really compete with Gd(III)-based nanosystems. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease

One-pot multicomponent synthesis of 2,3-dihydropyrans: new access to furanose–pyranose 1,3-C–C-linked-disaccharides

An efficient synthesis of 2,3-dihydropyrans starting from different terminal alkynes was developed. The 2,3-dihydropyrans were obtained in a few minutes through a microwave-assisted multicomponent enyne cross-metathesis/hetero-Diels–Alder reaction. Starting from C-ethynyl-ribofuranose, a new multicomponent approach to furanose–pyranose 1,3-C–C-linked disaccharides was also developed

Modular chiral Eu(iii) complexes for efficient circularly polarized OLEDs

Achieving both high dissymmetry factors and strong emission in circularly polarized (CP) luminescent materials and, at the same time, compatibility with manufacturing processes for organic electronic devices, is a crucial issue for reliable applications of CP emitters in many fields, such as chiral electronics and optoelectronics. In this communication, we show that the independent choice of the sensitizing and the chirality inducing ligands allows europium(III) complexes to meet the multiple requirements for solution processed efficient CP electroluminescent devices

Optimizing the relaxivity of MRI probes at high magnetic field strengths with binuclear GdIIIComplexes

The key criteria to optimize the relaxivity of a Gd(III) contrast agent at high fields (defined as the region 65 1.5 T) can be summarized as follows: (i) the occurrence of a rotational correlation time \u3c4R in the range of ca. 0.2\u20130.5 ns; (ii) the rate of water exchange is not critical, but a \u3c4M < 100 ns is preferred; (iii) a relevant contribution from water molecules in the second sphere of hydration. In addition, the use of macrocycle-based systems ensures the formation of thermodynamically and kinetically stable Gd(III) complexes. Binuclear Gd(III) complexes could potentially meet these requirements. Their efficiency depends primarily on the degree of flexibility of the linker connecting the two monomeric units, the absence of local motions and the presence of contribution from the second sphere water molecules. With the aim to maximize relaxivity (per Gd) over a wide range of magnetic field strengths, two binuclear Gd(III) chelates derived from the well-known macrocyclic systems DOTA-monopropionamide and HPDO3A (Gd2L1 and Gd2L2, respectively) were synthesized through a multistep synthesis. Chemical Exchange Saturation Transfer (CEST) experiments carried out on Eu2L2 at different pH showed the occurrence of a CEST effect at acidic pH that disappears at neutral pH, associated with the deprotonation of the hydroxyl groups. Then, a complete 1H and 17O NMR relaxometric study was carried out in order to evaluate the parameters that govern the relaxivity associated with these complexes. The relaxivities of Gd2L1 and Gd2L2 (20 MHz, 298 K) are 8.7 and 9.5 mM 121 s 121, respectively, +77% and +106% higher than the relaxivity values of the corresponding mononuclear GdDOTAMAP-En and GdHPDO3A complexes. A significant contribution of second sphere water molecules was accounted for the strong relaxivity enhancement of Gd2L2. MR phantom images of the dinuclear complexes compared to GdHPDO3A, recorded at 7 T, confirmed the superiority of Gd2L2. Finally, ab initio (DFT) calculations were performed to obtain information about the solution structure of the dinuclear complexes

GdDOTAGA(C18)2: an efficient amphiphilic Gd(iii) chelate for the preparation of self-assembled high relaxivity MRI nanoprobes

A new amphiphilic GdDOTA-like complex functionalized with two octadecyl chains was synthesised and incorporated into the bilayer of liposomes and dendrimersomes. (1)H NMR relaxometric studies and in vivo MRI experiments on mice bearing a syngeneic melanoma tumour have shown a great improvement in performance

USER-FIRENDLY INTERFACE FOR TRAJECTORY LEARNING OF AN ASSISTIVE MOBILE MANIPULATOR

This paper presents a novel method to enable non-expert operators to drive a mobile manipulator and to teach new trajectories through interaction with the robotic arm. The paper describes how the generator of velocity reference is implemented. It takes as input the force applied by the user to the robotic arm and, through some post-processing, produces a velocity reference related to the input. The paper also investigates which input can be used as a reference signal and the post-processing done to obtain a velocity reference. A comparison between torque and force input is presented, explaining the reason that leads to the use of torque. The proposed method is useful to increase the number of people that can drive the mobile manipulator and reconfigure the trajectory. Although this method has been developed to increase the usability of the Paquitop platform among the medical staff in the hospital environment, the strength is that it can be implemented and used for all mobile manipulators that perform tasks of personal assistance

Decoupled motion planning of a mobile manipulator for precision agriculture

Thanks to recent developments in service robotics technologies, precision agriculture (PA) is becoming an increasingly prominent research field, and several studies were made to present and outline how the use of mobile robotic systems can help and improve farm production. In this paper, the integration of a custom-designed mobile base with a commercial robotic arm is presented, showing the functionality and features of the overall system for crop monitoring and sampling. To this aim, the motion planning problem is addressed, developing a tailored algorithm based on the so-called manipulability index, that treats the base and robotic arm mobility as two independent degrees of motion; also developing an open source closed-form inverse kinematics algorithm for the kinematically redundant manipulator. The presented methods and sub-system, even though strictly related to a specific mobile manipulator system, can be adapted not only to PA applications where a mobile manipulator is involved but also to the wider field of assistive robotics

Surprising Complexity of the [Gd(AAZTA)(H2O)2]− Chelate Revealed by NMR in the Frequency and Time Domains

[Abstract] Typically, Ln(III) complexes are isostructural along the series, which enables studying one particular metal chelate to derive the structural features of the others. This is not the case for [Ln(AAZTA)(H2O)x]− (x = 1, 2) systems, where structural variations along the series cause changes in the hydration number of the different metal complexes, and in particular the loss of one of the two metal-coordinated water molecules between Ho and Er. Herein, we present a 1H field-cycling relaxometry and 17O NMR study that enables accessing the different exchange dynamics processes involving the two water molecules bound to the metal center in the [Gd(AAZTA)(H2O)2]− complex. The resulting picture shows one Gd-bound water molecule with an exchange rate ∼6 times faster than that of the other, due to a longer metal–water distance, in accordance with density functional theory (DFT) calculations. The substitution of the more labile water molecule with a fluoride anion in a diamagnetic-isostructural analogue of the Gd-complex, [Y(AAZTA)(H2O)2]−, allows us to follow the chemical exchange process by high-resolution NMR and to describe its thermodynamic behavior. Taken together, the variety of tools offered by NMR (including high-resolution 1H, 19F NMR as a function of temperature, 1H longitudinal relaxation rates vs B0, and 17O transverse relaxation rates vs T) provides a complete description of the structure and exchange dynamics of these Ln-complexes along the series.This research was supported by the Università del Piemonte Orientale (Ricerca locale FAR2019). F.C., L.T., and M.B. acknowledge the financial support from the Ministero dell’Università e della Ricerca (PRIN 2017A2KEPL project “Rationally designed nanogels embedding paramagnetic ions as MRI probes”). This work was carried out within the framework of the COST CA15209 Action “European Network on NMR Relaxometry”Italia. Ministero dell'Università e della Ricerca; PRIN-2017A2KEP

Surprising Impact of Donor Charge on the Water Exchange Rates of Gd(III) AAZTA Derivatives

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract]: We report the synthesis of three new heptadentate ligands derived from H4AAZTA (6-amino-6-methylperhydro-1,4-diazepinetetraacetic acid) that contain a dimethyl-amide group (AAZ-TA-MA)3−, two dimethyl-amide groups (AAZTA-BMA)2− or two acetylglycine groups (AAZ-TA(Gly)2)4−. The corresponding Gd(III) complexes were investigated using 1H NMR relaxome-try and 17O NMR chemical shifts and transverse relaxation rates. A computational DFT study was also performed to aid the analysis of the NMR data. The Gd(III) complexes contain two water molecules coordinated to the metal ion. In contrast to the prevailing trend, the amide derivatives discussed in this context exhibit comparatively rapid water exchange rates that do not align with the changes in the overall electric charge of the complexes: kex298=14.4×106 s−1, 14.5×106 s−1 and 9.56×106 s−1 for [Gd(AAZTA-MA)(H2O)2], [Gd(AAZTA-BMA)(H2O)2]+ and [Gd(AAZTA(Gly)2(H2O)2]−, respectively. The analysis of the data and the computational work suggest that the relatively fast water exchange rates could be linked to the occurrence of associatively activated mechanisms, which is somewhat unexpected for nine-coordinated complexes.C.P.-I. thanks Ministerio de Ciencia e Innovación (Grants PID2019-104626GB−I00 and PID2022-138335NB−I00) and Xunta de Galicia (ED431 C 2023/33) for generous financial support. C. P.-I. also thanks Centro de Supercomputación de Galicia (CESGA) for providing the computer facilities. D.L. acknowledges the financial support from the Universi-tá del Piemonte Orientale (Bando Ricerca UPO 2022, Grant Number: 1083660). Funding for open access provided by Universidade da Coruña/CISUG.Xunta de Galicia; ED431C 2023/33Universitá del Piemonte Orientale; 108366