Dicyanoaurate(I) anion, [Au(CN) 2 ] À , plays a central role in the current industrial production of gold, as its extraction from crude ore samples represents the most money-consuming step. Herein, we present the strongest host-guest recognition of dicyanoaurate anion using the bambusuril receptor in water, a highly competitive solvent. The micromolar stability of such a complex facilitated the up to date most efficient supramolecular stripping of dicyanoaurate from activated carbon at ambient temperature. Thermodynamic characteristics of bambusuril binding with [Au(CN) 2 ] À differing from binding of other inorganic chaotropic anions are rationalized, as well as the bambusuril selectivity for [Au(CN) 2 ] À over [Ag(CN) 2 ] À .
Aβ (1-40) can transfer from the aqueous phase to the bilayer and thus form stable ion-channel-like pores where the protein has alpha-helical conformation. The stability of the pores is due to the presence of the GXXXG motif. It has been reported that these ion-channel-like pores are stabilized by a Cα―H···O hydrogen bond that is established between a glycine of the GXXXG sequence of an alpha-helix and another amino acid of a vicinal alpha-helix. However, conflicting data are reported in the literature. Some authors have suggested that hydrogen bonding does not have a stabilizing function. Here we synthesized pentapeptides having a GXXXG motif to explore its role in pore stability. We used molecular dynamics simulations, quantum mechanics, and experimental biophysical techniques to determine whether hydrogen bonding was formed and had a stabilizing function in ion-channel-like structures. Starting from our previous molecular dynamics data, molecular quantum mechanics simulations, and ATR data showed that a stable ion-channel-like pore formed and a band centered at 2910 cm−1 was attributed to the interaction between Gly 7 of an alpha-helix and Asp 23 of a vicinal alpha-helix.
Aggregation of phthalocyanines (Pcs) represents a problematic
feature
that decreases the potential of these macrocycles in a number of applications.
In this work, we present a supramolecular approach based on the interaction
of aminoadamantyl-substituted Pcs with bulky and hydrophilic cucurbit[7]uril
(CB[7]) to increase the levels of Pc monomers in water. A series of
zinc(II) Pcs substituted at positions α or β by an aminoadamantyl
substituent (with a different level of alkylation of nitrogen) were
prepared from the corresponding phthalonitriles. A 1H nuclear
magnetic resonance study of the interaction of phthalonitriles with
CB[7] in water confirmed the formation of an inclusion complex with
an aminoadamantyl moiety with K
a values
of ∼1012 M–1. The interaction
of CB[7] with Pcs in water substantially weakened H-type aggregation
and improved both fluorescence and singlet oxygen production, confirming
that this approach is efficient for the monomerization of Pcs. In vitro evaluation of the photodynamic activity of prepared
Pcs led to EC50 values in the submicromolar range on HeLa
and SK-MEL-28 cells. However, the activity decreased for at least
an order of magnitude after host–guest interaction with CB[7]
despite better photophysical properties. This was attributed to a
much lower uptake by cells due to the very bulky and hydrophilic character
of the Pc-CB[7] assembly.
Dicyanoaurate(I) anion, [Au(CN)2]−, plays a central role in the current industrial production of gold, as its extraction from crude ore samples represents the most money‐consuming step. Herein, we present the strongest host–guest recognition of dicyanoaurate anion using the bambusuril receptor in water, a highly competitive solvent. The micromolar stability of such a complex facilitated the up to date most efficient supramolecular stripping of dicyanoaurate from activated carbon at ambient temperature. Thermodynamic characteristics of bambusuril binding with [Au(CN)2]− differing from binding of other inorganic chaotropic anions are rationalized, as well as the bambusuril selectivity for [Au(CN)2]− over [Ag(CN)2]−.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.