Related Experiment Video
Updated: Jun 21, 2026
06:40
Synthesis of a Water-soluble Metal–Organic Complex Array
Published on: October 8, 2016
Water helicate (H(2)O)(7), hosted by a diamondoid metal-organic framework
Mohammad Hedayetullah Mir1, Li Wang, Ming Wah Wong
1Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, Singapore 117543.
Chemical Communications (Cambridge, England)
|July 21, 2009
Summary
Researchers discovered a novel (H2O)7 water helicate trapped within a diamondoid metal-organic framework (MOF). Modifying the MOF ligand structure altered the water aggregate from cyclic to acyclic.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Crystallography
Background:
- Metal-organic frameworks (MOFs) are porous crystalline materials with diverse applications.
- Water aggregates within MOF channels are of interest for understanding host-guest interactions.
- Diamondoid MOFs offer unique structural scaffolds for encapsulating guest molecules.
Purpose of the Study:
- To characterize a novel (H2O)7 water helicate.
- To investigate the influence of MOF ligand modification on water aggregate structure.
- To explore the formation of cyclic versus acyclic water helicates within MOF channels.
Main Methods:
- Single-crystal X-ray diffraction to determine the structure of the MOF and encapsulated water.
- Synthesis of MOFs with varying ligand backbones (1,10-phenanthroline and 2,2'-bipyridine).
- Analysis of hydrogen bonding networks within the water aggregates.
Main Results:
- A cyclic (H2O)7 water helicate was successfully trapped within the channels of a diamondoid MOF, stabilized by perchlorate anions.
- A minor structural modification of the MOF ligand, from 1,10-phenanthroline to 2,2'-bipyridine, induced a transformation from a cyclic to an acyclic water helicate.
- The study reveals the sensitivity of water aggregate structure to the host framework's geometry.
Conclusions:
- The formation of specific water aggregate structures, like helicates, can be controlled by the MOF's pore environment and ligand design.
- This work demonstrates a new method for templating and stabilizing discrete water clusters within porous materials.
- The findings contribute to the fundamental understanding of water behavior in confined spaces and the design of functional MOFs.
Related Concept Videos
01:20Aldehydes and Ketones with Water: Hydrate Formation
An oxygen-based nucleophile, like water, can undergo addition reactions with aldehydes and ketones. The reaction leads to the formation of hydrates, also referred to as 1,1-diols or geminal diols.
The formation of hydrates is a reversible reaction. Hydrate formation is influenced by steric and electronic factors accompanying the alkyl substituents on the carbonyl group: The rate of hydrate formation increases with a decrease in the number of alkyl groups attached to the carbonyl carbon. Hence,...
The formation of hydrates is a reversible reaction. Hydrate formation is influenced by steric and electronic factors accompanying the alkyl substituents on the carbonyl group: The rate of hydrate formation increases with a decrease in the number of alkyl groups attached to the carbonyl carbon. Hence,...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
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,...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:37Metallic Solids
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
02:57Coordination Number and Geometry
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.
03:24Hybridization of Atomic Orbitals I
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...