Related Experiment Video
Updated: Jan 12, 2026
05:48
Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes
Published on: November 21, 2017
8.6K
pH-Regulated Ring-Opening/Closing Transformation in Polyoxometalates Enables High-Performance Nonlinear Optical
Wei Zeng1, Jing Zhang2, Yao Tian3
1Center for Noncentrosymmetric Materials, Department of Chemistry, Sogang University, Seoul, 04107, Republic of Korea.
Angewandte Chemie (International Ed. in English)
|November 6, 2025
Summary
We synthesized novel inorganic polyoxometalate (POM) crystals, revealing pH-controlled transformations that significantly boost nonlinear optical (NLO) properties for advanced laser applications.
Area of Science:
- Inorganic Chemistry
- Materials Science
- Crystallography
Background:
- Inorganic polyoxometalate (POM) crystals show promise for laser science and technology.
- Limited understanding of POM formation and structure-property relationships hinders NLO crystal design.
Purpose of the Study:
- Synthesize novel polar heteropolymolybdates.
- Investigate pH-regulated structural transformations in POMs.
- Establish a mechanistic pathway for POM formation and link it to NLO properties.
Main Methods:
- Synthesis of two novel POM compounds: (NH4)4[Mo5O15(SeO3)2]·2H2O (NMSeO-5) and (NH4)8[Mo6O18(SeO3)4]·5H2O (NMSeO-6).
- Theoretical calculations and experimental verification to elucidate formation mechanisms.
- Analysis of structural transformations and second-harmonic generation (SHG) responses.
Main Results:
- Demonstrated pH-regulated ring-opening and ring-closing transformations in an inorganic POM system.
- Observed structural transformation from symmetrical [Mo5O15(SeO3)2]2- clusters (NMSeO-5) to lower-symmetry [Mo6O18(SeO3)4]8- clusters (NMSeO-6) under acidic conditions.
- Achieved a dramatic enhancement in second-harmonic generation (SHG) response from 0.07 × KDP to 10 × KDP.
Conclusions:
- Provided mechanistic insight into POM structural evolution.
- Established a paradigm for designing high-performance inorganic POM-based NLO materials.
- Highlighted the potential of POMs for next-generation NLO applications.
Related Concept Videos
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
3.1K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
3.1K
02:26Base-Catalyzed Ring-Opening of Epoxides
10.0K
Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile...
10.0K
02:24Acid-Catalyzed Ring-Opening of Epoxides
8.6K
Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...
8.6K
01:13Olefin Metathesis Polymerization: Overview
2.5K
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...
2.5K
01:11ortho–para-Directing Activators: –CH3, –OH, –NH2, –OCH3
7.3K
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...
7.3K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.9K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
2.9K