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From Specific γ-CD/[Nb6 Cl12 (H2 O)6 ]2+ Recognition to Biological Activity Tuning
Anton A Ivanov1, Tatiana N Pozmogova2,3, Anastasiya O Solovieva3,4
1Nikolaev Institute of Inorganic Chemistry SB RAS, 3 acad. Lavrentiev ave., 630090, Novosibirsk, Russia.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|March 18, 2020
Summary
The niobium cluster [Nb6Cl12(H2O)6]2+ forms a 1:1 complex with gamma-cyclodextrin (γ-CD), reducing cytotoxicity while enhancing cellular uptake. Crystallization yields a 1:2 complex with two γ-CD molecules.
Area of Science:
- Supramolecular chemistry
- Inorganic chemistry
- Materials science
Background:
- Cationic hexanuclear niobium clusters, specifically [Nb6Cl12(H2O)6]2+, exhibit interesting biological activities.
- Cyclodextrins, such as gamma-cyclodextrin (γ-CD), are known for their host-guest complexation abilities.
Purpose of the Study:
- To investigate the molecular recognition and supramolecular assembly between [Nb6Cl12(H2O)6]2+ and γ-CD in aqueous solutions.
- To characterize the resulting host-guest complexes and evaluate their impact on the biological activity of the niobium cluster.
Main Methods:
- Nuclear magnetic resonance (NMR) spectroscopy
- Isothermal titration calorimetry (ITC)
- Electrospray ionization mass spectrometry (ESI-MS)
- X-ray diffraction (XRD)
- Elemental analysis
- Infrared (IR) spectroscopy
- Thermogravimetric analysis (TGA)
- Quantum chemical calculations
Main Results:
- A 1:1 supramolecular assembly, {[Nb6Cl12(H2O)6]@γ-CD}2+, was formed in solution.
- This 1:1 complex demonstrated decreased cytotoxicity and enhanced cellular uptake of the niobium cluster.
- Crystallization resulted in a 1:2 host-guest complex, [Nb6Cl12(H2O)6@(γ-CD)2]Cl2·20H2O, with the cluster encapsulated between two γ-CD molecules.
- Host-guest interactions were modeled using quantum chemical calculations.
Conclusions:
- Specific molecular recognition occurs between the cationic niobium cluster and γ-CD, leading to well-defined supramolecular assemblies.
- The formation of these supramolecular complexes significantly modulates the biological properties of the niobium cluster, offering potential for therapeutic applications.
- The stoichiometry of the complex can be controlled by solution conditions versus crystallization, yielding distinct structural motifs.
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