Structure-function studies of modular aromatics that form molecular organogels
Christopher Baddeley1, Zhiqing Yan, Graham King
1Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA.
The Journal of Organic Chemistry
|August 25, 2007
Summary
Compound 1, a urea-based aromatic, effectively gels organic solvents by forming ordered cylinders through hydrogen bonds and pi-pi interactions. This hierarchical assembly, aided by ultrasonication, is crucial for gelation in alcohols.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Organic Chemistry
Background:
- Urea-based aromatics are explored for their self-assembly properties.
- Hierarchical assembly is key for forming functional materials like gels.
- Understanding structure-property relationships is vital for designing new materials.
Purpose of the Study:
- To synthesize and investigate three distinct urea-based aromatics (1-3).
- To determine their capacity for hierarchical assembly and gelation of organic solvents.
- To elucidate the mechanisms governing their self-assembly and gelation behavior.
Main Methods:
- Synthesis of urea-based aromatic compounds.
- Sol-gel transition studies in various primary alcohols.
- Characterization using IR spectroscopy, X-ray powder diffraction (XRPD), and transmission electron microscopy (TEM).
- Computational analysis including molecular mechanics (Amber) and semiempirical (AM1) calculations.
Main Results:
- Compound 1 successfully promoted sol-gel transitions in primary alcohols (CGC < 15 mg/mL).
- Compound 1 self-assembled into "cylinders" via hydrogen bonding and pi-pi interactions, further organizing into pairs.
- Increased solvent polarity enhanced lateral packing of cylinders, demonstrating solvophobic control over morphology.
- Compounds 2 and 3 failed to gel due to inadequate hierarchical assembly.
- Ultrasonication was identified as a critical factor for effective gelation of compound 1.
Conclusions:
- The specific steric and electronic features of compound 1 enable hierarchical assembly and effective gelation of organic solvents.
- Hierarchical assembly into a 3D fibrillar network is essential for sol-gel transitions.
- Solvophobic effects and ultrasonication play significant roles in controlling material morphology and facilitating gelation.
More Related Videos
09:22Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
15:33Microwave-assisted Functionalization of Poly(ethylene glycol) and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation
Published on: October 29, 2013
Related Concept Videos
01:18Aromatic Hydrocarbon Anions: Structural Overview
Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous overlap of p...
Due to the absence of continuous overlap of p...
01:13Olefin Metathesis Polymerization: Overview
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
02:08Introduction to Functional Groups
Functional groups are group of atoms with specific chemical properties that occur within organic molecules and sometimes denoted as “R”. Functional groups are found along the carbon backbone of macromolecules can form chains or rings of carbon atoms. Functional groups can “functionalize” a compound by enabling it to adopt different physical and chemical properties.
Types of common functional groups
The table below summarizes some of the major functional groups in organic chemistry. (The...
01:18Aromatic Hydrocarbon Cations: Structural Overview
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group with both...
Removing one hydrogen from the intervening CH2 group with both...
01:03Step-Growth Polymerization: Overview
Step-growth or condensation polymerization is a stepwise reaction of bi or multifunctional monomers to form long-chain polymers. As all the monomers are reactive, most of the monomers are consumed at the early stages of the reaction to form small chains of reactive oligomers, which then combine to form long polymer chains in the late stages. Hence, the reaction has to proceed for a long time to achieve high molecular weight polymers.
Many natural and synthetic polymers are produced by...
Many natural and synthetic polymers are produced by...
01:14Polymer Classification: Architecture
Polymers are classified as linear or branched on the basis of their chain architecture. The polymer chains in linear polymers have a long chain-like structure with minimal to no branching at all. Even if a polymer features large substituent groups on the monomer, which appear as branches to the skeleton, it is not considered a branched polymer. A branched polymer contains secondary polymer chains that arise from the main polymer chain. The branching occurs when the polymer growth shifts from...