Related Experiment Video
Updated: Mar 20, 2026
09:35
Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
12.2K
Per-Substituted [8]Circulene and Its Non-Planar Fragments: Synthesis, Structural Analysis, and Properties.
Chieh-Ning Feng1, Wen-Ching Hsu1, Jen-Yi Li1
1Department of Chemistry, National Cheng Kung University, No.1 Ta-Hsueh Road, 70101, Tainan, Taiwan.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|June 1, 2016
Summary
Benzannulation of tetraphenylenes creates strained [8]circulenes and fragments. Their structures, dynamics, and properties, including photophysical and electrochemical behavior, are influenced by the degree of annulation and π-conjugation.
Area of Science:
- Organic Chemistry
- Supramolecular Chemistry
- Materials Science
Background:
- Tetraphenylenes are polycyclic aromatic hydrocarbons with potential applications in materials science.
- Benzannulation offers a route to modify the structure and properties of tetraphenylenes.
- Understanding the impact of annulation on molecular geometry and dynamics is crucial for designing new materials.
Purpose of the Study:
- To synthesize and characterize a series of benzannulated tetraphenylenes.
- To investigate the structural, dynamic, photophysical, and electrochemical properties of these compounds.
- To establish structure-property relationships influenced by successive benzannulations.
Main Methods:
- Palladium-catalyzed annulation reactions.
- X-ray crystallography for structural determination.
- Experimental and theoretical studies of dynamic behaviors (e.g., ring flipping).
- Spectroscopic (absorption, emission) and electrochemical measurements.
Main Results:
- Successful synthesis of per-substituted [8]circulene and its non-planar fragments.
- [8]circulene exhibits significant deplanarization and high strain energy (120.6 kcal/mol).
- Ring flipping in [8]circulene occurs via pseudorotation (barrier ~21 kcal/mol), with fragments requiring higher energy for inversion.
- Photophysical and electrochemical properties are tunable with the extent of π-conjugation, showing red-shifted absorption/emission and reduced oxidation potential upon benzannulation.
Conclusions:
- Benzannulation significantly alters molecular geometry, dynamics, and electronic properties of tetraphenylenes.
- [8]circulene represents a highly strained system with unique dynamic characteristics.
- The degree of π-conjugation, controlled by benzannulation, dictates the photophysical and electrochemical behavior of these molecules.
More Related Videos
09:45Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
Published on: March 20, 2017
10.9K
06:561,3,5-Triphenylbenzene and Corannulene as Electron Receptors for Lithium Solvated Electron Solutions
Published on: October 10, 2016
8.3K
Related Concept Videos
02:30Stability of Substituted Cyclohexanes
17.0K
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
17.0K
02:37Disubstituted Cyclohexanes: cis-trans Isomerism
15.0K
Depending upon the different spatial orientation of the substituents, the disubstituted cycloalkanes exhibit two types of stereoisomers. The cis isomers have the substituents on the same side of the ring, whereas the trans isomers have the substituents on the opposite sides. These stereoisomers exhibit different physical properties and cannot be interconverted without breaking the carbon-carbon bonds.
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
15.0K
02:02Chair Conformation of Cyclohexane
20.8K
The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
20.8K
02:29Conformations of Cycloalkanes
16.2K
Adolf von Baeyer attempted to explain the instabilities of small and large cycloalkane rings using the concept of angle strain — the strain caused by the deviation of bond angles from the ideal 109.5° tetrahedral value for sp3 hybridized carbons. However, while cyclopropane and cyclobutane are strained, as expected from their highly compressed bond angles, cyclopentane is more strained than predicted, and cyclohexane is virtually strain-free. Hence, Baeyer’s theory that...
16.2K
01:16Structure of Conjugated Dienes
8.2K
Introduction
Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...
Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...
8.2K
02:05Prochirality
5.3K
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
5.3K