Related Experiment Video
Updated: Aug 8, 2026
11:21
Photoconversion of Purified Fluorescent Proteins and Dual-probe Optical Highlighting in Live Cells
Published on: June 26, 2010
Proton-triggered octopolar NLO chromophores
Inge Asselberghs1, Gunther Hennrich, Koen Clays
1Department of Chemistry, University of Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium.
The Journal of Physical Chemistry. A
|May 12, 2006
Summary
Protonation significantly enhances the nonlinear optical (NLO) properties of C(3)-symmetric, octopolar 1,3,5-alkynylbenzenes by up to 17-fold. These pyridyl-substituted compounds retain their octopolar nature after protonation, confirmed by depolarization ratio measurements.
Area of Science:
- Organic Chemistry
- Materials Science
- Nonlinear Optics
Background:
- Octopolar molecules are crucial for second-order nonlinear optical (NLO) applications.
- Tuning molecular properties through chemical modification is key to optimizing NLO performance.
Purpose of the Study:
- To synthesize and characterize C(3)-symmetric, octopolar 1,3,5-alkynylbenzenes with terminal pyridyl substituents.
- To investigate the effect of protonation on the second-order NLO activity and octopolar character of these compounds.
Main Methods:
- Synthesis of novel C(3)-symmetric alkynylbenzenes.
- Protonation of pyridyl-substituted compounds.
- Measurement of second-order NLO activity.
- Determination of octopolar character via depolarization ratio measurements.
Main Results:
- Synthesized compounds exhibit C(3)-symmetry and octopolar characteristics.
- Protonation leads to a significant enhancement (up to 17-fold) in second-order NLO activity.
- Octopolar nature is maintained after protonation, as evidenced by depolarization ratios.
Conclusions:
- Protonation is an effective strategy for boosting the NLO response of these octopolar alkynylbenzenes.
- The studied compounds demonstrate potential for advanced NLO materials and devices.
Related Concept Videos
01:06Nuclear Overhauser Enhancement (NOE)
Irradiation of a spin-active nucleus causes an increase or decrease in the signal intensity of neighboring nuclei that are not necessarily chemically bonded or involved in J-coupling. This phenomenon, called the nuclear Overhauser enhancement (NOE), results from through-space interactions between the nuclear spins. The NOE effect decreases with increasing internuclear distance and is generally not observed beyond 4 angstroms. In NOE, dipole-dipole interactions between neighboring spin-active...
01:13¹H NMR: Complex Splitting
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
01:10Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1 triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the others.
01:11Channel Rhodopsins
Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
01:15Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...
01:09¹H NMR: Pople Notation
The Pople nomenclature system classifies spin systems based on the difference between their chemical shifts. Coupled spins are denoted by capital letters with subscripts indicating the number of equivalent nuclei. When the coupled nuclei have well-separated chemical shifts, they are assigned letters that are far apart in the alphabet, such as A and X. When the difference in chemical shifts is small, coupled nuclei are named using adjacent letters of the alphabet (AB, MN, or XY).
A proton...
A proton...