Related Experiment Video
Updated: Jul 26, 2025
11:27
Synthesis and Characterization of Functionalized Metal-organic Frameworks
Published on: September 5, 2014
48.2K
Factors Controlling Complex Morphologies of Isomorphous Metal-Organic Frameworks
Vivek Singh1, Yishay Feldman2, Gregory Leitus2
1Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 7610001, Israel.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|June 19, 2023
Summary
Metal cations influence crystal morphology, forming unique double-decker flowers and hexagonal prisms. Coordination strength and reactant ratios dictate crystal shape and structure in these novel materials.
Area of Science:
- Inorganic Chemistry
- Crystallography
- Materials Science
Background:
- Metal nitrate salts and achiral organic ligands can self-assemble into complex crystalline structures.
- The choice of metal cation significantly impacts the resulting crystal morphology and growth patterns.
- Understanding structure-morphology relationships is crucial for designing novel crystalline materials.
Purpose of the Study:
- To investigate the self-assembly of bivalent metal nitrate salts (Cu, Ni, Co, Mn) with an organic ligand.
- To explore how different metal cations and reactant ratios influence crystal morphology and structure.
- To elucidate the mechanism behind the formation of unique double-decker flower and hexagonal crystal structures.
Main Methods:
- Synthesis of crystalline materials using metal nitrate salts and an achiral organic ligand.
- Crystallographic analysis to determine structural and morphological characteristics.
- Varying metal-to-ligand ratios to observe effects on crystal formation.
- Microscopic analysis to study crystal textures and growth patterns.
Main Results:
- Isomorphous hexagonal crystal structures were formed with diverse morphologies, including double-decker flowers, hexagonal bipyramids, and prisms.
- Stronger coordinating cations (Cu, Ni) yielded unusual, uniform crystal shapes, while weaker coordinating cations (Mn, Co) produced regular hexagonal forms.
- Copper nitrate reactions showed distinct morphologies based on reactant ratios: excess metal salt led to uniform hexagonal crystals, while excess ligand resulted in double-decker structures.
- Chiral frameworks with helical channels were observed, and the double-decker flower crystals were found to be homochiral.
Conclusions:
- The study demonstrates precise control over crystal morphology through the selection of metal cations and reactant ratios.
- Unusual double-decker flower and hexagonal crystal structures were successfully synthesized and characterized.
- The findings provide insights into the self-assembly mechanisms and coordination chemistry governing crystal formation.
Related Concept Videos
02:58Crystal Field Theory - Octahedral Complexes
26.9K
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...
26.9K
02:34Structural Isomerism
19.5K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
19.5K
02:42Ionic Crystal Structures
14.5K
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
14.5K
02:57Coordination Number and Geometry
16.2K
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.
16.2K
01:09Complexation Equilibria: Factors Influencing Stability of Complexes
417
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
417
02:42Valence Bond Theory
8.8K
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...
8.8K