Related Experiment Video
Updated: Sep 12, 2025
08:22
Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
7.0K
Stable Iminium Singlet and Triplet Diradical(oid)s with Intense NIR-II Absorptions
1Center of Single-Molecule Sciences, Institute of Modern Optics, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin, 300350, China.
Angewandte Chemie (International Ed. in English)
|August 8, 2025
Summary
Researchers synthesized stable iminium diradical(oids) with tunable electronic states. These novel organic materials exhibit intense absorption in the second near-infrared (NIR-II) region, offering new possibilities for advanced applications.
Area of Science:
- Organic Chemistry
- Materials Science
- Spectroscopy
Background:
- Stable organic diradicaloids are rare but desirable for advanced materials.
- Iminium compounds offer a versatile platform for electronic tuning.
Purpose of the Study:
- To synthesize and characterize novel stable iminium diradical(oids).
- To investigate their electronic ground states and optical properties.
- To explore their potential for applications in the NIR-II region.
Main Methods:
- Synthesis of iminium diradical(oids) from methoxy precursors using triflic acid.
- Characterization using Electron Spin Resonance (ESR) and Superconducting Quantum Interference Device (SQUID) measurements.
- Spectroscopic analysis to determine absorption properties.
Main Results:
- Successful synthesis of three stable iminium diradical(oids): CNR1+, CNR2+, and CNR3+OTf-.
- Demonstrated tunable ground states: closed-shell (CNR1+), open-shell singlet (CNR2+), and triplet (CNR3+).
- Observed red-shifted, long-wavelength absorption bands extending to ~2400 nm for open-shell species, characteristic of NIR-II absorption.
Conclusions:
- A novel synthetic route for stable iminium diradical(oids) with tunable ground states was established.
- These compounds exhibit unique optical properties with intense absorption in the NIR-II region.
- The findings open new avenues for designing organic materials with tailored electronic and optical characteristics for advanced applications.
More Related Videos
Related Concept Videos
01:08IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
1.2K
Identical bonds within a polyatomic group can stretch symmetrically (in-phase) or asymmetrically (out-of-phase). Similar to hydrogen bonding, these vibrations also influence the shape of the IR peak. Generally, asymmetric stretching frequencies are higher than symmetric stretching frequencies. For example, primary amines exhibit two distinct IR peaks between 3300–3500 cm−1 corresponding to the symmetric and asymmetric N-H stretching, while secondary amines exhibit a single...
1.2K
00:55IR Spectrum Peak Intensity: Amount of IR-Active Bonds
707
When infrared radiation is passed through a molecule, absorption occurs if the molecule's vibration leads to a substantial change in its bond dipole moment. Transitions between vibrational energy levels, typically corresponding to infrared frequencies (4000–400 cm−1), allow absorption if the vibration significantly alters the dipole moment, making the molecule infrared active. The molecular bonds have different stretching and bending vibrations, resulting in various peaks with...
707
01:20IR Spectrum Peak Intensity: Dipole Moment
817
The dipole moment of a bond is the product of the partial charge on either atom and the distance between them. Dipole moments influence the efficiency of IR absorption and the peak intensity. When a bond with a dipole moment is placed in an electric field, the direction of the field determines if the bond is compressed or stretched. Electromagnetic radiation consists of an electric field component that rapidly reverses direction. It follows that polar bonds are alternately stretched and...
817
01:10Radical Reactivity: Steric Effects
2.0K
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic...
Along with electronic...
2.0K
01:17Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals
2.7K
Ideally, an unpaired electron shows a single peak in the EPR spectrum due to the transition between the two spin energy states. However, coupling interactions can occur between the spins of the unpaired electron and any neighboring spin-active nuclei. This hyperfine coupling results in hyperfine splitting, where the EPR signal is split into multiplets. The signals split into 2nI + 1 peaks, where n is the number of equivalent nuclei and I is the nuclear spin. These splitting patterns provide...
2.7K
01:24IR Frequency Region: X–H Stretching
1.1K
In IR spectroscopy, signals produced by the X−H bonds (such as C−H, O−H, or N−H) can be observed in the frequency range of 2700–4000 cm–1. The C−H stretching vibration forms sharp bands in the region 2850–3000 cm–1. The presence of the O−H stretching vibration leads to the forming of an absorption band in the frequency range 3650–3200 cm−1. At the same time, N−H stretching can be confirmed by absorption bands in...
1.1K