Search results for "combinatorial"

Synthesis of bi- and tricyclic β-lactam libraries in aqueous medium

2007

Water as a solvent is not only inexpensive and environmentally benign, but may allow good reactivity. The present work focuses on the application of a modified Ugi reaction, i.e. the Ugi four-centre three-component reaction (U-4C-3CR), in aqueous medium to construct β-lactam libraries. All the attempted reactions could be successfully performed in water. The reaction conditions under which the precipitation process was effective were investigated; no further work-up or purification was necessary. In several cases when less water-soluble β-amino acids were used, the precipitated products were isolated easily by simple filtration. In other cases, evaporation of the solvent was appropriate for…

2020

The pH-responsive nature of two self-assembled NDI-peptide amphiphile conjugates is reported. The diethoxy substituted NDI showed a pH-dependent assembly behaviour, as expected. In contrast, the isopropylamino- and ethoxy-substituted NDI based supramolecular polymer was stable at acidic and basic aqueous conditions. This finding highlights how subtle changes in the molecular design of π-stacked chromophore-peptide conjugates have a drastic impact on their equilibrium structure and ultimately functional properties.

Molecular Recognition-Induced Function and Competitive Replacement by Hydrogen-Bonding Interactions:  Amphiphilic Barbituric Acid Derivatives, 2,4,6-…

1998

The phenomenon of molecular recognition inducing further function is common in nature. However, there are few synthetic systems which achieve this cascade type mechanism, and those are generally ca...

ChemInform Abstract: Cryptand-Like Anion Receptors

2010

The design of supramolecular hosts for anions began with simple diaza bicycles, named katapinands, and has evolved over the last 40 years to a number of elegantly designed receptors capable of binding many different anions. About the same time the term cryptand appeared in reference to another bicyclic compound that was selective for alkaline-earth ions. Since the first report these simple bicycles, a vast arena of hosts has appeared, including acyclic, monocyclic, and other multicyclic supramolecular receptors. Studies of these systems have revealed considerable information about anion coordination chemistry, including the fact that many of these complexes mimic their transition-metal coro…

From Biocompatible to Biodegradable: Poly(Ethylene Glycol)s with Predetermined Breaking Points

2013

Poly(ethylene glycol) (PEG) is the gold standard polymer for biomedical applications. PEG is known for its biocompatibility and antifouling properties and is widely used for bioconjugation. However, like other synthetic polymers in the field, PEG is not biodegradable, limiting its use for parenteral formulations and protein conjugation to a molecular weight range with a specific upper limit (commonly 40–60 kDa) to avoid polyether accumulation in human tissue. For these biomedical applications, but also for other purposes such as cleavable hydrogels and templates for porous membranes, several routes for the insertion of in-chain biocleavable moieties, such as acetals or disulfides, into PEG …

Straightforward synthesis of bioconjugatable azo dyes. Part 2: Black Hole Quencher-2 (BHQ-2) and BlackBerry Quencher 650 (BBQ-650) scaffolds

2014

Abstract A further extension of the efficient synthetic methodology described in Part 1, to the aromatic bis-diazo scaffold of Black Hole Quencher-2 dye is presented. Bioconjugatable derivatives bearing either azido, terminal alkyne, or maleimide reactive group were easily obtained as well as the free-phenol form of BlackBerry® Quencher 650 (BBQ-650®) initially developed by Berry & Associates, Inc. Company. The efficient conjugation ability of azido- and maleimide-quenchers was demonstrated through the facile preparation of the first water-soluble and formylated BHQ-2 dyes and a FRET-based probe suitable for the in vitro/in cellulo detection of a cancer-associated protease namely urokinase-…

Synthesis of substituted carbamo(dithioperoxo)thioates as potential BCA2-inhibitory anticancer agents

2015

A new, simple, one-step synthetic route to carbamo(dithioperoxo)thioates from commercially available starting materials is described. The key step of this new synthetic approach involves the tetrabromomethane-promoted reaction between secondary amines, carbon disulfide and alkyl thiols under basic conditions at room temperature. New compounds from this series selected for anticancer screening showed selective sub-micromolar activity within BCA2-expressing human breast cancer cell lines.

Synthesis and Photoluminescent Properties of 1,1‘-Binaphthyl-Based Chiral Phenylenevinylene Dendrimers

2003

New chiral, soluble binaphthyl derivatives that incorporate stilbenoid dendrons at the 6,6′-positions have been prepared. The synthesis of the new enantiopure dendrimers was performed in a convergent manner by Horner-Wadsworth-Emmons (HWE) reaction of the appropriately functionalized 1,1′-binaphthyl derivative (R)-1 and the appropriate dendrons (R)2nGn-CHO. Different electroactive units were incorporated in the peripheral positions of the dendrons in order to tune both the optical and electrochemical behavior of these systems. Fluorescence measurements on the chiral dendrimers reveal a strong emission with maxima between 409 and 508 nm depending upon the substitution pattern. Finally, t…

ChemInform Abstract: The Synthesis and Effect of Fluorinated Chalcone Derivatives on Nitric Oxide Production.

2010

Abstract Dimethoxy- and trimethoxychalcone derivatives, with various patterns of fluorination, were synthesized and evaluated for their influence on nitric oxide production. Some of them, chalcones 1 , 5 , 7 , 10 , 11 and 17 , inhibited NO production with an IC 50 in the submicromolar range; 17 is especially noteworthy because of its potency (IC 50 30 nM). These effects were not the consequence of a direct inhibitory action on enzyme activity but the inhibition of enzyme expression.

Antidiabetic Behavior of Biguanides

1983

The existence of active electron pairs on some nitrogen atoms in phenformin hydrochloride is inferred from the presence of a hydrogen catalytic polarographic wave. This finding emphasizes the ability of biguanides to form hydrogen bridges with other molecular species such as amino acids and proteins, as well as to form coordination complexes with zinc and other metallic cations by means of these electron pairs. The antidiabetic action of phenformin and other related biguanides can be explained in terms of competition between these molecules and insulin to coordinate cationic oligoelements together with their ability to form hydrogen bonds between the biguanide moiety and insulin itself.