Related Experiment Video
Updated: Jul 13, 2026
09:35
Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Alkynyl expanded donor-acceptor calixarenes: geometry and second-order nonlinear optical properties.
Gunther Hennrich1, Ma Teresa Murillo, Pilar Prados
1Departamento de Química Orgánica, C-I, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid, Spain. gunther.hennrich@uam.es
Chemistry (Weinheim an Der Bergstrasse, Germany)
|July 5, 2007
Summary
Functionalized alkynylcalix[4]arenes exhibit tunable nonlinear optical (NLO) properties. Their charge-transfer characteristics and NLO responses are influenced by substituents and calixarene geometry, with nitro derivatives showing high performance.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Organic Chemistry
Background:
- Calixarenes are versatile macrocyclic hosts with tunable properties.
- Functionalized alkynylcalix[4]arenes offer potential for advanced optical materials.
- Understanding structure-property relationships is crucial for designing novel NLO materials.
Purpose of the Study:
- To synthesize functionalized alkynylcalix[4]arenes via Sonogashira coupling.
- To investigate the influence of substituents and geometry on their optical and nonlinear optical (NLO) properties.
- To explore the relationship between molecular structure and NLO performance.
Main Methods:
- Sonogashira coupling for synthesis of alkynylcalix[4]arenes.
- UV/visible and fluorescence spectroscopy for optical characterization.
- Hyper-Rayleigh scattering (HRS) and X-ray crystallography for NLO and structural analysis.
Main Results:
- Synthesized wide- and narrow-rimmed alkynylcalix[4]arenes with varying electron-withdrawing substituents (NO2, CF3, H).
- Demonstrated that NLO properties and charge-transfer character depend on substituent nature and calixarene geometry.
- Nitro derivatives exhibited high quadratic hyperpolarizability (beta); NLO properties correlated with subchromophore arrangement and calixarene cavity angle.
Conclusions:
- Alkynylcalix[4]arenes are promising candidates for NLO applications.
- Molecular design, including substituent choice and calixarene conformation, is key to optimizing NLO properties.
- HRS and X-ray crystallography are effective tools for evaluating NLO materials.
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...
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
01:07Radicals: Electronic Structure and Geometry
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
01:11ortho–para-Directing Activators: –CH3, –OH, –NH2, –OCH3
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...