Related Experiment Video
Updated: Mar 14, 2026
08:28
Single-molecule Manipulation of G-quadruplexes by Magnetic Tweezers
Published on: September 19, 2017
8.7K
Tuning supramolecular G-quadruplexes with mono- and divalent cations
Mariana Martín-Hidalgo1, Marilyn García-Arriaga1, Fernando González1
1Department of Chemistry, University of Puerto Rico, Río Piedras Campus, Río Piedras 00931, Puerto Rico.
Supramolecular Chemistry
|October 7, 2016
Summary
Cation choice influences supramolecular G-quadruplexes (SGQs) assembly. Different cations dictate SGQ size and stability, offering tunable molecular architectures for advanced applications.
Area of Science:
- Supramolecular Chemistry
- G-quadruplexes
- Nucleic Acid Nanotechnology
Background:
- Supramolecular G-quadruplexes (SGQs) self-assemble from guanine derivatives.
- Cations play a crucial role in templating SGQ formation and stability.
Purpose of the Study:
- To investigate how different cations influence the formation, molecularity, and stability of SGQs derived from the 8-(m-acetylphenyl)-2'-deoxyguanosine (mAGi) derivative.
- To explore the impact of monovalent and divalent cations on SGQ structural fidelity and thermal/kinetic stability.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy.
- High-Resolution Electrospray Ionization Mass Spectrometry (HR ESI-MS).
- Molecular Dynamics (MD) simulations.
Main Results:
- Monovalent cations (K+, Na+, Rb+, Cs+) templated the formation of hexadecameric SGQs (mAGi16) with high fidelity.
- Divalent cations (Pb2+, Sr2+, Ba2+) templated the formation of octameric SGQs (mAGi8).
- Sr2+ and Ba2+ ions induced higher thermal stabilities in the octameric SGQs compared to other divalent cations.
Conclusions:
- Cation selection is a critical factor in controlling the assembly and properties of SGQs.
- The study demonstrates tunable SGQ formation, with potential for designing novel supramolecular structures.
- MD simulations provide mechanistic insights into cation-templated SGQ assembly.
Related Concept Videos
00:43Complexometric Titration: Ligands
2.5K
Different monodentate and polydentate ligands are used as complexing agents in complexometric titration reactions. The formation of complexes by mono- and bidentate ligands involves two or more intermediate steps, limiting their use as complexing agents. In comparison, polydentate ligands can form complexes with metal ions in a single-step process, facilitating sharper end points. This means polydentate ligands, such as amino carboxylic acid derivatives, are most commonly employed in...
2.5K
01:22EDTA: Chemistry and Properties
3.7K
Polydentate ligands are most widely used in complexometric titrations because they form more stable complexes with the metal ions than mono- or bidentate ligands due to the chelate effect. Examples of polydentate ligands are ethylenediaminetetraacetic acid (EDTA), crown ethers, and cryptands. The most important feature of optimal polydentate ligands is the ability to form 1:1 complexes in a single-step process. Amino carboxylic acid derivatives are frequently used as complexing agents. EDTA is...
3.7K
01:19Complexation Equilibria: The Chelate Effect
1.5K
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
1.5K
02:42Valence Bond Theory
11.5K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
11.5K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
49.4K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
49.4K
01:26EDTA: Auxiliary Complexing Reagents
1.5K
EDTA titrations are usually carried out in highly basic conditions, where the fully deprotonated form of EDTA, Y4−, actively complexes with the free metal ions in the solution. Several metal ions precipitate as hydrous oxide (hydroxides, oxides, or oxyhydroxides) under these conditions, lowering the concentration of free metal ions in the solution. For this reason, auxiliary complexing agents or ligands such as ammonia, tartrate, citrate, or triethanolamine are used in EDTA titrations to...
1.5K