Search results for "combinatorial"
showing 10 items of 1208 documents
Synthetic strategy for preparation of a folate corrole DOTA heterobimetallic Cu–Gd complex as a potential bimodal contrast agent in medical imaging
2015
Abstract An efficient sequential route to synthesize heterobimetallic complexes is reported herein. A folate, Cu corrole, Gd DOTA complex that addresses the requirements of a potential contrast agent (CA) for bimodal imaging (e.g., MRI/PET) is reported. The over-expression of the folate receptor in a variety of malignant tumors, along with its limited expression in healthy tissues, makes this an attractive tumor-specific molecular target. Synthesis of a bimetallic ligand potentially targeting the folate receptor, was easily achieved in only a few steps. Interestingly, preliminary studies showed that the relaxivity of the folic heterobimetallic derivative was higher in comparison to a clinic…
Design of Porphyrin-dota-Like Scaffolds as All-in-One Multimodal Heterometallic Complexes for Medical Imaging
2013
A series of four multimodal ligands incorporating one porphyrin moiety and one or more dota-like macrocycles all-in-one in the same molecular architecture have been synthesized and full characterized. The corresponding gadolinium(III) complexes were also synthesized and heterometallic complexes incorporating both gadolinium(III) and copper(II) ions were prepared as potential MRI/PET multimodal contrast agents. One ligand (L4) includes an amine moiety that can be activated for easy conversion into an isothiocyanate group for further anchoring to a biological vector. Preliminary relaxivity, cytotoxicity, and MRI studies showed that the complexes developed in this work are very promising medic…
Template synthesis of multi-macrocycles by metathesis reaction.
2004
Selective heterodimerisation of tetraurea calix[4]arenes containing four or eight ω-alkenyl groups with a tetratosyl urea calix[4]arene has been effectively used to synthesize multi-macrocycles via metathesis reaction.
Modular functionalized polyphosphines for supported materials: previously unobserved (31)P-NMR «through-space» ABCD spin systems and heterogeneous pa…
2014
The modular design of polyphosphines, diversely functionalized for facile immobilization on virtually any kind of support, is reported. Previously unobserved ABCD (31)P NMR spin-spin systems evidence the control exercised on the polyphosphines conformation. We illustrate the catalytic performance at low Pd loading of the recyclable immobilized polyphosphines in C-C bond formation reactions.
Fluoroquinolone–metal complexes: A route to counteract bacterial resistance?
2014
Abstract Microbial resistance to antibiotics is one of the biggest public health threats of the modern world. Antibiotic resistance is an area of much clinical relevance and therefore research that has the potential to identify agents that may circumvent it or treat resistant infections is paramount. Solution behavior of various fluoroquinolone (FQ) complexes with copper(II) in the presence and absence of 1,10-phenanthroline (phen) was studied in aqueous solution, by potentiometry and/or spectrophotometry, and are herein described. The results obtained showed that under physiological conditions (micromolar concentration range and pH 7.4) only copper(II):FQ:phen ternary complexes are stable.…
Versatile synthesis of cationic N-heterocyclic carbene–gold(i) complexes containing a second ancillary ligand. Design of heterobimetallic ruthenium–g…
2016
We describe a versatile and quick route to cationic gold(i) complexes containing N-heterocyclic carbenes and a second ancillary ligand (such as phosphanes, phosphites, arsines and amines) of interest for the synthesis of compounds with potential catalytic and medicinal applications. The general synthetic strategy has been applied in the preparation of novel cationic heterobimetallic ruthenium(ii)-gold(i) complexes that are highly cytotoxic to renal cancer Caki-1 and colon cancer HCT 116 cell lines while showing a synergistic effect and being more selective than their monometallic counterparts.
Peptide Metal–Organic Frameworks for Enantioselective Separation of Chiral Drugs
2017
We report the ability of a chiral Cu(II) 3D MOF based on the tripeptide Gly-L-His-Gly (GHG) for the enantioselective separation of metamphetamine and ephedrine. Monte Carlo simulations suggest that chiral recognition is linked to preferential binding of one of the enantiomers as result of either stronger or additional H-bonds with the framework that lead to energetically more stable diastereomeric adducts. Solid phase extraction (SPE) of a racemic mixture by using Cu(GHG) as extractive phase permits isolating more than 50% of the (+)-ephedrine enantiomer as target compound in only four minutes. To the best of our knowledge, this represents the first example of a MOF capable of separating ch…
Towards Waltheriones C and D: Synthesis of the Oxabicyclic Core
2017
A route to the oxabicyclic cores of the HIV cytoprotective quinolone alkaloids, waltheriones C and D, is described. The approach relies on a stereospecific transannular bromoetherification followed by reductive debromination. The route can also be rendered enantioselective via enzymatic reduction of a key intermediate (>99:1 er).
Overcoming Steric Hindrance in Aryl‐Aryl Homocoupling via On‐Surface Copolymerization
2019
On-surface synthesis is a unique tool for growing low-dimensional carbon nanomaterials with precise structural control down to the atomic level. This novel approach relies on carefully designed precursor molecules, which are deposited on suitable substrates and activated to ultimately form the desired nanostructures. One of the most applied reactions to covalently interlink molecular precursors is dehalogenative aryl-aryl coupling. Despite the versatility of this approach, many unsuccessful attempts are also known, most of them associated to the poor capability of the activated precursors to couple to each other. Such failure is often related to the steric hindrance between reactants, which…
Direct High-Performance Liquid Chromatographic Separation of Peptide Enantiomers: Study on Chiral Recognition by Systematic Evaluation of the Influe…
2002
All-R/all-S enantiomers of oligoalanines (Ala(n), n = 1-10) with N-terminal protection group have been separated by HPLC on chiral stationary phases based on various cinchona alkaloid selectors. Structure-enantioselectivity relationships derived by extensive selector structure optimization provided insights into binding mechanisms and chiral recognition. Their interpretation was supported by X-ray crystal structures of amino acid and dipeptide, respectively, in complex with chiral selector. Optimized selectors have bulky elements representing steric barriers and deep binding pockets that afforded very high enantioselectivities; e.g., for the all-R and all-S enantiomers of N-(3,5-dinitrobenz…