1
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Chen N, Li D, Nie S. Theoretical and Experimental Study on the Preparation of High-Viscosity Magnetic Nanofluid by Combined Surfactants. ACS OMEGA 2024; 9:33522-33527. [PMID: 39130547 PMCID: PMC11307273 DOI: 10.1021/acsomega.4c01060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/01/2024] [Accepted: 04/02/2024] [Indexed: 08/13/2024]
Abstract
In this study, the mechanism by which combined surfactants affect the dispersion stability of magnetic nanofluids (MNFs) was improved. Two stable lubricating oil-based magnetic nanofluids with high viscosity and one with low viscosity were prepared by chemical coprecipitation. Erucic acid and octanoic acid were used as the combined surfactants to modify the Fe3O4 nanoparticles (MNPs). The size and morphology of the particles were observed using TEM. The rheological properties were tested with a rotational rheometer. The magnetization of the lubricating oil-based magnetic nanofluids was characterized by VSM. The results indicated that the prepared magnetic nanofluids had high viscosity, high magnetism, and good stability. This study provided ideas for the preparation of a high-viscosity magnetic nanofluid. By using combined surfactants, sufficient steric repulsion energy can be provided to counteract the attraction energy of sterically protected nanoparticles, thus achieving a balance of the dispersion stability of MNF.
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Affiliation(s)
- Nuo Chen
- Tsinghua University State
Key Laboratory of Tribology, Beijing 100084, China
| | - Decai Li
- Tsinghua University State
Key Laboratory of Tribology, Beijing 100084, China
| | - Shilin Nie
- Tsinghua University State
Key Laboratory of Tribology, Beijing 100084, China
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2
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Goodwin MJ, Dickenson JC, Ripak A, Deetz AM, McCarthy JS, Meyer GJ, Troian-Gautier L. Factors that Impact Photochemical Cage Escape Yields. Chem Rev 2024; 124:7379-7464. [PMID: 38743869 DOI: 10.1021/acs.chemrev.3c00930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The utilization of visible light to mediate chemical reactions in fluid solutions has applications that range from solar fuel production to medicine and organic synthesis. These reactions are typically initiated by electron transfer between a photoexcited dye molecule (a photosensitizer) and a redox-active quencher to yield radical pairs that are intimately associated within a solvent cage. Many of these radicals undergo rapid thermodynamically favored "geminate" recombination and do not diffuse out of the solvent cage that surrounds them. Those that do escape the cage are useful reagents that may undergo subsequent reactions important to the above-mentioned applications. The cage escape process and the factors that determine the yields remain poorly understood despite decades of research motivated by their practical and fundamental importance. Herein, state-of-the-art research on light-induced electron transfer and cage escape that has appeared since the seminal 1972 review by J. P. Lorand entitled "The Cage Effect" is reviewed. This review also provides some background for those new to the field and discusses the cage escape process of both homolytic bond photodissociation and bimolecular light induced electron transfer reactions. The review concludes with some key goals and directions for future research that promise to elevate this very vibrant field to even greater heights.
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Affiliation(s)
- Matthew J Goodwin
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - John C Dickenson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Alexia Ripak
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Alexander M Deetz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jackson S McCarthy
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Ludovic Troian-Gautier
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
- Wel Research Institute, Avenue Pasteur 6, 1300 Wavre, Belgium
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3
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Shimazumi R, Tobisu M. Unimolecular Fragment Coupling: A New Bond-Forming Methodology via the Deletion of Atom(s). JACS AU 2024; 4:1676-1695. [PMID: 38818052 PMCID: PMC11134393 DOI: 10.1021/jacsau.3c00827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 02/25/2024] [Accepted: 02/26/2024] [Indexed: 06/01/2024]
Abstract
Unimolecular fragment coupling (UFC) is defined as a reaction format, wherein atom(s) located in the middle of a molecule are extruded, and the remaining fragments are coupled. UFC is a potentially powerful strategy that is an alternative to transition-metal-catalyzed cross-coupling because the target chemical bond is formed in an intramolecular fashion, which is inherently beneficial for chemoselectivity and stereoselectivity issues. In this Perspective, we will present an overview of the recent advances in UFC reactions, which encompass those proceeding through the elimination of CO2, CO, SO2, isocyanates, N2, or single atoms primarily via transition metal catalysis.
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Affiliation(s)
- Ryoma Shimazumi
- Department
of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Mamoru Tobisu
- Department
of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
- Innovative
Catalysis Science Division, Institute for Open and Transdisciplinary
Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
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4
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Wee-Léonard MV, Elias B, Troian-Gautier L. Photoinduced One-Electron Chloride Oxidation in Water Using a Pentacationic Ir(III) Photosensitizer. J Am Chem Soc 2024. [PMID: 38621164 DOI: 10.1021/jacs.4c00478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
A novel iridium(III) photosensitizer containing pyridinium-decorated terpyridines has been used for the photo-oxidation of chloride in water. Despite its abundance, the very positive one-electron reduction potential (E° Cl•/- = 2.1-2.4 V vs NHE) restricted its use in energy conversion schemes and artificial photosynthesis. The kinetics of the photoinduced electron transfer process were investigated through Stern-Volmer quenching experiments and nanosecond transient absorption spectroscopy, which provided unambiguous evidence that photoinduced chloride oxidation occurred with a quenching rate constant kq = 5.0 × 1010 M-1 s-1. Complementary spectroelectrochemistry and photolysis experiments confirmed the formation of the reduced photosensitizer and showcased the redox and photostability of the Ir(III) photosensitizer that holds great promise for the HX splitting approach.
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Affiliation(s)
- Milan Vander Wee-Léonard
- UCLouvain, Institute of Condensed Matter and Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1/L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Benjamin Elias
- UCLouvain, Institute of Condensed Matter and Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1/L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Ludovic Troian-Gautier
- UCLouvain, Institute of Condensed Matter and Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1/L4.01.02, 1348 Louvain-la-Neuve, Belgium
- Wel Research Institute, Avenue Pasteur 6, 1300 Wavre, Belgium
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5
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Boulesteix D, Buch A, Samson J, Millan M, Jomaa J, Coscia D, Moulay V, McIntosh O, Freissinet C, Stern JC, Szopa C. Influence of pH and salts on DMF-DMA derivatization for future Space Applications. Anal Chim Acta 2023; 1266:341270. [PMID: 37244655 DOI: 10.1016/j.aca.2023.341270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/24/2023] [Accepted: 04/23/2023] [Indexed: 05/29/2023]
Abstract
For gas chromatography - mass spectrometry (GC-MS) analyses performed in situ, pH and salts (e.g., chlorides, sulfates) may enhance or inhibit the detection of targeted molecules of interest for astrobiology (e.g. amino acids, fatty acids, nucleobases). Obviously, salts influence the ionic strength of the solutions, the pH value, and the salting effect. But the presence of salts may also produce complexes or mask ions in the sample (masking effect on hydroxide ion, ammonia, etc.). For future space missions, wet chemistry will be conducted before GC-MS analyses to detect the full organic content of a sample. The defined organic targets for space GC-MS instrument requirements are generally strongly polar or refractory organic compounds, such as amino acids playing a role in the protein production and metabolism regulations for life on Earth, nucleobases essential for DNA and RNA formation and mutation, and fatty acids that composed most of the eukaryote and prokaryote membranes on Earth and resist to environmental stress long enough to still be observed on Mars or ocean worlds in geological well-preserved records. The wet-chemistry chemical treatment consists of reacting an organic reagent with the sample to extract and volatilize polar or refractory organic molecules (i.e. dimethylformamide dimethyl acetal (DMF-DMA) in this study). DMF-DMA derivatizes functional groups with labile H in organics, without modifying their chiral conformation. The influence of pH and salt concentration of extraterrestrial materials on the DMF-DMA derivatization remains understudied. In this research, we studied the influence of different salts and pHs on the derivatization of organic molecules of astrobiological interest with DMF-DMA, such as amino acids, carboxylic acids, and nucleobases. Results show that salts and pH influence the derivatization yield, and that their effect depend on the nature of the organics and the salts studied. Second, monovalent salts lead to a higher or similar organic recovery compared to divalent salts regardless of pH below 8. However, a pH above 8 inhibits the DMF-DMA derivatization influencing the carboxylic acid function to become an anionic group without labile H. Overall, considering the negative effect of the salts on the detection of organic molecules, future space missions may have to consider a desalting step prior to derivatization and GC-MS analyses.
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Affiliation(s)
- D Boulesteix
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 Rue Joliot-Curie, 91190, Gif-sur-Yvette, France.
| | - A Buch
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 Rue Joliot-Curie, 91190, Gif-sur-Yvette, France.
| | - J Samson
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 Rue Joliot-Curie, 91190, Gif-sur-Yvette, France
| | - M Millan
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - J Jomaa
- Planetary Environments Laboratory (Code 699), NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA; School of Medicine, Wayne State University, 42 W. Warren Ave, Detroit, MI, 48202, USA
| | - D Coscia
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - V Moulay
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - O McIntosh
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - C Freissinet
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - J C Stern
- Space Science Exploration Division (Code 690), NASA, Goddard Space Flight Center, Greenbelt, MD, 20771, USA
| | - C Szopa
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
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6
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Lee Y, Nam YS, Kim SY, Ki JE, Lee HG. Mechanistic duality of indolyl 1,3-heteroatom transposition. Chem Sci 2023; 14:7688-7698. [PMID: 37476715 PMCID: PMC10355096 DOI: 10.1039/d3sc00716b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 06/15/2023] [Indexed: 07/22/2023] Open
Abstract
A novel mechanistic duality has been revealed from the indolyl 1,3-heteroatom transposition (IHT) of N-hydroxyindole derivatives. A series of in-depth mechanistic investigations suggests that two separate mechanisms are operating simultaneously. Moreover, the relative contribution of each mechanistic pathway, the energy barrier for each pathway, and the identity of the primary pathway were shown to be the functions of the electronic properties of the substrate system. Based on the mechanistic understanding obtained, a mechanism-driven strategy for the general and efficient introduction of a heteroatom at the 3-position of indole has been developed. The reaction developed exhibits a broad substrate scope to provide the products in various forms of the functionalised indole. Moreover, the method is applicable to the introduction of both oxygen- and nitrogen-based functional groups.
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Affiliation(s)
- Yujin Lee
- Department of Chemistry, Seoul National University 1, Gwanak-ro, Gwanak-gu Seoul 08826 South Korea
| | - Yun Seung Nam
- Department of Chemistry, Seoul National University 1, Gwanak-ro, Gwanak-gu Seoul 08826 South Korea
| | - Soo Young Kim
- Department of Chemistry, Seoul National University 1, Gwanak-ro, Gwanak-gu Seoul 08826 South Korea
| | - Jeong Eun Ki
- Department of Chemistry, Seoul National University 1, Gwanak-ro, Gwanak-gu Seoul 08826 South Korea
| | - Hong Geun Lee
- Department of Chemistry, Seoul National University 1, Gwanak-ro, Gwanak-gu Seoul 08826 South Korea
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7
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Strauch C, Schroeder S, Grelier G, Niggemann M. Homolytic N-S Bond Cleavage in Vinyl Triflimides Enabled by Triplet-Triplet Energy Transfer. Chemistry 2022; 28:e202201830. [PMID: 35793203 DOI: 10.1002/chem.202201830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Indexed: 01/07/2023]
Abstract
Vinyl triflimides are a new compound class with unknown reactivity. A computational analysis identified homolytic cleavage of the N-Tf bond induced by triplet-triplet energy transfer (EnT) as a highly interesting reaction type that might be accessible. A combination of experimental and mechanistic work verified this hypothesis and proved the generated radicals to be amenable to radical-radical coupling. Thereby, vinyl triflimides were transformed into a range of α-quaternary, β-trifluoromethylated amines in a 1,2-difunctionalization reaction with no need for external CF3 reagents.
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Affiliation(s)
- Christina Strauch
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52074, Aachen, Germany
| | - Sebastian Schroeder
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52074, Aachen, Germany
| | - Gwendal Grelier
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52074, Aachen, Germany
| | - Meike Niggemann
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52074, Aachen, Germany
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8
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Machín Rivera R, Burton NR, Call LD, Tomat MA, Lindsay VNG. Synthesis of Highly Congested Tertiary Alcohols via the [3,3] Radical Deconstruction of Breslow Intermediates. Org Lett 2022; 24:4275-4280. [PMID: 35657720 DOI: 10.1021/acs.orglett.2c01627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pericyclic processes such as [3,3]-sigmatropic rearrangements leading to the rapid generation of molecular complexity constitute highly valuable tools in organic synthesis. Herein, we report the formation of particularly hindered tertiary alcohols via rearrangement of Breslow intermediates formed in situ from readily available N-allyl thiazolium salts and benzaldehyde derivatives. Experimental mechanistic studies performed suggest that the reaction proceeds via a close radical pair which recombine in a regio- and diastereoselective manner, formally leading to [3,3]-rearranged products.
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Affiliation(s)
- Roger Machín Rivera
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695, United States
| | - Nikolas R Burton
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695, United States
| | - Luke D Call
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695, United States
| | - Marshall A Tomat
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695, United States
| | - Vincent N G Lindsay
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695, United States
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9
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Miller DC, Lal RG, Marchetti LA, Arnold FH. Biocatalytic One-Carbon Ring Expansion of Aziridines to Azetidines via a Highly Enantioselective [1,2]-Stevens Rearrangement. J Am Chem Soc 2022; 144:4739-4745. [PMID: 35258294 PMCID: PMC9022672 DOI: 10.1021/jacs.2c00251] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We report enantioselective one-carbon ring expansion of aziridines to make azetidines as a new-to-nature activity of engineered "carbene transferase" enzymes. A laboratory-evolved variant of cytochrome P450BM3, P411-AzetS, not only exerts unparalleled stereocontrol (99:1 er) over a [1,2]-Stevens rearrangement but also overrides the inherent reactivity of aziridinium ylides, cheletropic extrusion of olefins, to perform a [1,2]-Stevens rearrangement. By controlling the fate of the highly reactive aziridinium ylide intermediates, these evolvable biocatalysts promote a transformation which cannot currently be performed using other catalyst classes.
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Affiliation(s)
- David C. Miller
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Ravi G. Lal
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Luca A. Marchetti
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
- Present Address: Department of Biosystems Science and Engineering, ETH Zürich, 4058 Basel, Switzerland
| | - Frances H. Arnold
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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10
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Berger KJ, Driscoll JL, Yuan M, Dherange BD, Gutierrez O, Levin MD. Direct Deamination of Primary Amines via Isodiazene Intermediates. J Am Chem Soc 2021; 143:17366-17373. [PMID: 34637305 PMCID: PMC8892627 DOI: 10.1021/jacs.1c09779] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We report here a reaction that selectively deaminates primary amines and anilines under mild conditions and with remarkable functional group tolerance including a range of pharmaceutical compounds, amino acids, amino sugars, and natural products. An anomeric amide reagent is uniquely capable of facilitating the reaction through the intermediacy of an unprecedented monosubstituted isodiazene intermediate. In addition to dramatically simplifying deamination compared to existing protocols, our approach enables strategic applications of iminium and amine-directed chemistries as traceless methods. Mechanistic and computational studies support the intermedicacy of a primary isodiazene which exhibits an unexpected divergence from previously studied secondary isodiazenes, leading to cage-escaping, free radical species that engage in a chain, hydrogen-atom transfer process involving aliphatic and diazenyl radical intermediates.
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Affiliation(s)
- Kathleen J. Berger
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Julia L. Driscoll
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Mingbin Yuan
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Balu D. Dherange
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Osvaldo Gutierrez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Mark D. Levin
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
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11
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Yoon H, Park S, Lim M. Photodissociation Dynamics of Nitric Oxide from N-Acetylcysteine- or N-Acetylpenicillamine-bound Roussin's Red Ester. ACS OMEGA 2021; 6:27158-27169. [PMID: 34693136 PMCID: PMC8529681 DOI: 10.1021/acsomega.1c03820] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/29/2021] [Indexed: 05/05/2023]
Abstract
The photochemical release of nitric oxide (NO) from a NO precursor is advantageous in terms of spatial, temporal, and dosage control of NO delivery to target sites. To realize full control of the quantitative NO administration from photoactivated NO precursors, it is necessary to have detailed dynamical information on the photodissociation of NO from NO precursors. We synthesized two new water-soluble Roussin's red esters (RREs), [Fe2(μ-N-acetylcysteine)2(NO)4] and [Fe2(μ-N-acetylpenicillamine)2(NO)4], which have five times longer lifetime than the well-known [Fe2(μ-cysteine)2(NO)4]. The photodissociation dynamics of NO from these RREs in water were investigated over a broad time range from 0.3 ps to 10 μs after excitation at 310 and 400 nm using femtosecond time-resolved infrared (IR) spectroscopy. When these RREs are excited, they either release one NO, producing a radical species deficient in one NO (R), [Fe2(μ-RS)2(NO)3], or relax into the ground state without photodeligation via an electronically excited intermediate state (M). R appears immediately after photoexcitation, suggesting that one NO is photodissociated faster than 0.3 ps. A certain fraction of R undergoes geminate recombination (GR) with NO with a time constant of 7-9 ps, while the remaining R competitively binds to the solvent. Solvent-bound R eventually bimolecularly recombines with NO with a rate constant of (1.3-1.6) × 108 M-1 s-1. For a given RRE molecule, the fractional yield of M (0.62-0.76) depends on the excitation wavelength (λex); however, the relaxation time of M (6 ± 1 ns) is independent of λex. Although the primary quantum yield of NO photodissociation (Φ1) was found to be 0.24-0.38, the final yield of NO suitable for other reactions (Φ2) was reduced to 0.14-0.29 due to the picosecond GR of the dissociated NO with R. Detailed photoexcitation dynamics of RRE can be utilized in the quantitative control of NO administration at a specific site and time, promoting pin-point usage of NO in chemistry and biology. We demonstrate that femtosecond IR spectroscopy combined with quantum chemical calculations is a powerful method for obtaining detailed dynamic information on photoactivated NO precursors such as Φ1 and Φ2, the GR yield, and secondary reactions of the nascent photoproducts, which are essential information for the design of efficient photoactivated NO precursors and their quantitative utilization.
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12
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Zhao K, Seidler G, Knowles RR. 1,3-Alkyl Transposition in Allylic Alcohols Enabled by Proton-Coupled Electron Transfer. Angew Chem Int Ed Engl 2021; 60:20190-20195. [PMID: 34159700 DOI: 10.1002/anie.202105285] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 06/02/2021] [Indexed: 12/11/2022]
Abstract
A method is described for the isomerization of acyclic allylic alcohols into β-functionalized ketones via 1,3-alkyl transposition. This reaction proceeds via light-driven proton-coupled electron transfer (PCET) activation of the O-H bond in the allylic alcohol substrate, followed by C-C β-scission of the resulting alkoxy radical. The transient alkyl radical and enone acceptor generated in the scission event subsequently recombine via radical conjugate addition to deliver β-functionalized ketone products. A variety of allylic alcohol substrates bearing alkyl and acyl migratory groups were successfully accommodated. Insights from mechanistic studies led to a modified reaction protocol that improves reaction performance for challenging substrates.
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Affiliation(s)
- Kuo Zhao
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Gesa Seidler
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Robert R Knowles
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
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13
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Zhao K, Seidler G, Knowles RR. 1,3‐Alkyl Transposition in Allylic Alcohols Enabled by Proton‐Coupled Electron Transfer. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202105285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kuo Zhao
- Department of Chemistry Princeton University Princeton NJ 08544 USA
| | - Gesa Seidler
- Department of Chemistry Princeton University Princeton NJ 08544 USA
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14
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Yoon H, Park S, Lim M. Dynamics of photodissociation of nitric oxide from S-nitrosylated cysteine and N-acetylated cysteine derivatives in water. Phys Chem Chem Phys 2021; 23:13512-13525. [PMID: 34124727 DOI: 10.1039/d1cp01743h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cysteine and N-acetylated cysteine derivatives are ubiquitous in biological systems; they have thiol groups that bind NO to form S-nitrosothiols (RSNOs) such as S-nitrosocysteine (CySNO), S-nitroso-N-acetylcysteine (NacSNO), and S-nitroso-N-acetylpenicillamine (NapSNO). Although they have been utilised as thermally or catalytically decomposing NO donors, their photochemical applications are yet to be fully explored owing to the lack of photodissociation dynamics. To this end, the photoexcitation dynamics of these RSNOs in water at 330 nm were investigated using femtosecond time-resolved infrared (TRIR) spectroscopy over a broad time range encompassing the entire reaction, which includes the primary reaction, secondary reactions of the reaction intermediates, and product formation. We discovered that the acetate and amide groups in these RSNOs have strong vibrational bands sensitive to the bondage of NO and the electronic state of the compound, which facilitates the identification of reaction intermediates involved in photoexcitation. The simplest thiol available with the acetate group-thioglycolic acid-was nitrosylated; it produced S-nitrosothioglycolic acid (TgSNO) and was comparatively investigated. Transient absorption bands in the TRIR spectra of the RSNOs were assigned using quantum chemical calculations. Photoexcited cysteine-related RSNOs either decompose into RS and NO within 0.3 ps after excitation at 330 nm with a primary quantum yield (Φ1) of 0.46-1 or relax into an electronically excited intermediate state lying at 42 ± 3 kcal mol-1 above the ground state, which relaxes into the ground state with a time constant of 460-520 ps. A majority (62-80%) of the RS radical geminately rebinds with NO at a time constant of 3-7 ps. The remaining RS reacts with the neighbouring RSNO, which produces additional NO and RSSR with a (nearly) diffusion-limited rate constant that doubles the amount of NO produced; further, it remarkably extends the time window for the dissociated NO to react with the target compound. The final fraction of NO produced from these RSNOs at 330 nm was 0.32-0.58, and it depends on the geminate rebinding yield and Φ1. The detailed dynamics of the photoexcited RSNO can be utilised in the quantitative application of these RSNOs in practical use and in the synthesis of more efficient photoactivated NO precursors.
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Affiliation(s)
- Hojeong Yoon
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Seongchul Park
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Manho Lim
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
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15
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Huang J, Pan Y, Wang T, Cui S, Feng L, Han D, Zhang W, Zeng Z, Li X, Du P, Wu X, Zhu J. Topology Selectivity in On-Surface Dehydrogenative Coupling Reaction: Dendritic Structure versus Porous Graphene Nanoribbon. ACS NANO 2021; 15:4617-4626. [PMID: 33591725 DOI: 10.1021/acsnano.0c08920] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Selective control on the topology of low-dimensional covalent organic nanostructures in on-surface synthesis has been challenging. Herein, with combined scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), we report a successful topology-selective coupling reaction on the Cu(111) surface by tuning the thermal annealing procedure. The precursor employed is 1,3,5-tris(2-bromophenyl)benzene (TBPB), for which Ullmann coupling is impeded due to the intermolecular steric hindrance. Instead, its chemisorption on the Cu(111) substrate has triggered the ortho C-H bond activation and the following dehydrogenative coupling at room temperature (RT). In the slow annealing experimental procedure, the monomers have been preorganized by their self-assembly at RT, which enhances the formation of dendritic structures upon further annealing. However, the chaotic chirality of dimeric products (obtained at RT) and hindrance from dense molecular island make the fabrication of high-quality porous two-dimensional nanostructures difficult. In sharp contrast, direct deposition of TBPB molecules on a hot surface led to the formation of ordered porous graphene nanoribbons and nanoflakes, which is confirmed to be the energetically favorable reaction pathway through density functional theory-based thermodynamic calculations and control experiments. This work demonstrates that different thermal treatments could have a significant influence on the topology of covalent products in on-surface synthesis and presents an example of the negative effect of molecular self-assembly to the ordered covalent nanostructures.
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Affiliation(s)
- Jianmin Huang
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230029, P.R. China
| | - Yu Pan
- Hefei National Laboratory of Physical Science at the Microscale, CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Synergetic Innovation of Quantum Information and Quantum Technology, and CAS Center for Excellence in Nanoscience, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230026, P.R. China
| | - Tao Wang
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230029, P.R. China
| | - Shengsheng Cui
- Hefei National Laboratory of Physical Science at the Microscale, CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Synergetic Innovation of Quantum Information and Quantum Technology, and CAS Center for Excellence in Nanoscience, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230026, P.R. China
| | - Lin Feng
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230029, P.R. China
| | - Dong Han
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230029, P.R. China
| | - Wenzhao Zhang
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230029, P.R. China
| | - Zhiwen Zeng
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230029, P.R. China
| | - Xingyu Li
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230029, P.R. China
| | - Pingwu Du
- Hefei National Laboratory of Physical Science at the Microscale, CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Synergetic Innovation of Quantum Information and Quantum Technology, and CAS Center for Excellence in Nanoscience, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230026, P.R. China
| | - Xiaojun Wu
- Hefei National Laboratory of Physical Science at the Microscale, CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Synergetic Innovation of Quantum Information and Quantum Technology, and CAS Center for Excellence in Nanoscience, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230026, P.R. China
| | - Junfa Zhu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230029, P.R. China
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16
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Kim H, Kim JG, Kim TW, Lee SJ, Nozawa S, Adachi SI, Yoon K, Kim J, Ihee H. Ultrafast structural dynamics of in-cage isomerization of diiodomethane in solution. Chem Sci 2020; 12:2114-2120. [PMID: 34163975 PMCID: PMC8179290 DOI: 10.1039/d0sc05108j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Despite extensive studies on the isomer species formed by photodissociation of haloalkanes in solution, the molecular structure of the precursor of the isomer, which is often assumed to be a vibrationally hot isomer formed from the radical pair, and its in-cage isomerization mechanism remain elusive. Here, the structural dynamics of CH2I2 upon 267 nm photoexcitation in methanol were probed with femtosecond X-ray solution scattering at an X-ray free-electron laser. The determined molecular structure of the transiently formed species that converts to the CH2I–I isomer has the I–I distance of 4.17 Å, which is longer than that of the isomer (3.15 Å) by more than 1.0 Å and the mean-squared displacement of 0.45 Å2, which is about 100 times larger than those of typical regular chemical bonds. These unusual structural characteristics are consistent with either a vibrationally hot form of the CH2I–I isomer or the loosely-bound radical pair (CH2I˙⋯I˙). The structural dynamics of in-cage isomerization of CH2I2 and the unusual structure of the loosely-bound isomer precursor were unveiled with femtosecond X-ray liquidography (solution scattering).![]()
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Affiliation(s)
- Hanui Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea .,KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea.,Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Jong Goo Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Tae Wu Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Sang Jin Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea .,KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea.,Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Shunsuke Nozawa
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) Tsukuba Ibaraki 305-0801 Japan.,Department of Materials Structure Science, School of High Energy Accelerator Science, The Graduate University for Advanced Studies Tsukuba Ibaraki 305-0801 Japan
| | - Shin-Ichi Adachi
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) Tsukuba Ibaraki 305-0801 Japan.,Department of Materials Structure Science, School of High Energy Accelerator Science, The Graduate University for Advanced Studies Tsukuba Ibaraki 305-0801 Japan
| | - Kihwan Yoon
- Department of Chemistry, The Catholic University of Korea Bucheon 14662 Republic of Korea
| | - Joonghan Kim
- Department of Chemistry, The Catholic University of Korea Bucheon 14662 Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea .,KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea.,Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
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17
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Park S, Choi J, Ki H, Kim KH, Oang KY, Roh H, Kim J, Nozawa S, Sato T, Adachi SI, Kim J, Ihee H. Fate of transient isomer of CH 2I 2: Mechanism and origin of ionic photoproducts formation unveiled by time-resolved x-ray liquidography. J Chem Phys 2019; 150:224201. [PMID: 31202228 DOI: 10.1063/1.5099002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Diiodomethane, CH2I2, in a polar solvent undergoes a unique photoinduced reaction whereby I2 - and I3 - are produced from its photodissociation, unlike for other iodine-containing haloalkanes. While previous studies proposed that homolysis, heterolysis, or solvolysis of iso-CH2I-I, which is a major intermediate of the photodissociation, can account for the formation of I2 - and I3 -, there has been no consensus on its mechanism and no clue for the reason why those negative ionic species are not observed in the photodissociation of other iodine-containing chemicals in the same polar solvent, for example, CHI3, C2H4I2, C2F4I2, I3 -, and I2. Here, using time-resolved X-ray liquidography, we revisit the photodissociation mechanism of CH2I2 in methanol and determine the structures of all transient species and photoproducts involved in its photodissociation and reveal that I2 - and I3 - are formed via heterolysis of iso-CH2I-I in the photodissociation of CH2I2 in methanol. In addition, we demonstrate that the high polarity of iso-CH2I-I is responsible for the unique photochemistry of CH2I2.
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Affiliation(s)
- Sungjun Park
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea
| | - Jungkweon Choi
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, South Korea
| | - Hosung Ki
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, South Korea
| | - Kyung Hwan Kim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
| | - Key Young Oang
- Radiation Center for Ultrafast Science, Quantum Optics Division, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057, South Korea
| | - Heegwang Roh
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea
| | - Joonghan Kim
- Department of Chemistry, The Catholic University of Korea, Bucheon 14662, South Korea
| | - Shunsuke Nozawa
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
| | - Tokushi Sato
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
| | - Shin-Ichi Adachi
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
| | - Jeongho Kim
- Department of Chemistry, Inha University, 100 Inha-ro, Michuhol-gu, Incheon 22212, South Korea
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea
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18
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Yang Y, Zhou Q, Cai J, Xue T, Liu Y, Jiang Y, Su Y, Chung L, Vicic DA. Exploiting the trifluoroethyl group as a precatalyst ligand in nickel-catalyzed Suzuki-type alkylations. Chem Sci 2019; 10:5275-5282. [PMID: 31191883 PMCID: PMC6540912 DOI: 10.1039/c9sc00554d] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/16/2019] [Indexed: 01/01/2023] Open
Abstract
We report herein the exploitment of the partially fluorinated trifluoroethyl as precatalyst ligands in nickel-catalyzed Suzuki-type alkylation and fluoroalkylation coupling reactions. Compared with the [L n NiII(aryl)(X)] precatalysts, the unique characters of bis-trifluoroethyl ligands imparted precatalyst [(bipy)Ni(CH2CF3)2] with bench-top stability, good solubilities in organic media and interesting catalytic activities. Preliminary mechanistic studies reveal that an eliminative extrusion of a vinylidene difluoride (VDF, CH2[double bond, length as m-dash]CF2) mask from [(bipy)Ni(CH2CF3)2] is a critical step for the initiation of a catalytic reaction.
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Affiliation(s)
- Yi Yang
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan , School of Chemistry and Environmental Engineering , Sichuan University of Science & Engineering , 180 Xueyuan Street, Huixing Lu , Zigong , Sichuan 643000 , China .
| | - Qinghai Zhou
- Shenzhen Grubbs Institute and Department of Chemistry , Southern University of Science and Technology , Shenzhen 518055 , China .
| | - Junjie Cai
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan , School of Chemistry and Environmental Engineering , Sichuan University of Science & Engineering , 180 Xueyuan Street, Huixing Lu , Zigong , Sichuan 643000 , China .
| | - Teng Xue
- Department of Chemistry , Lehigh University , 6 E. Packer Ave. , Bethlehem , PA 18015 , USA .
| | - Yingle Liu
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan , School of Chemistry and Environmental Engineering , Sichuan University of Science & Engineering , 180 Xueyuan Street, Huixing Lu , Zigong , Sichuan 643000 , China .
| | - Yan Jiang
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan , School of Chemistry and Environmental Engineering , Sichuan University of Science & Engineering , 180 Xueyuan Street, Huixing Lu , Zigong , Sichuan 643000 , China .
| | - Yumei Su
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan , School of Chemistry and Environmental Engineering , Sichuan University of Science & Engineering , 180 Xueyuan Street, Huixing Lu , Zigong , Sichuan 643000 , China .
| | - Lungwa Chung
- Shenzhen Grubbs Institute and Department of Chemistry , Southern University of Science and Technology , Shenzhen 518055 , China .
| | - David A Vicic
- Department of Chemistry , Lehigh University , 6 E. Packer Ave. , Bethlehem , PA 18015 , USA .
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19
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Xing L, Peng Z, Li W, Wu K. On Controllability and Applicability of Surface Molecular Self-Assemblies. Acc Chem Res 2019; 52:1048-1058. [PMID: 30896918 DOI: 10.1021/acs.accounts.9b00002] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Molecular self-assembly (MSA) refers to spontaneous arrangement of molecular building blocks into ordered structures governed by weak interactions. Due to its high versatility and reversibility, MSA has been widely employed as a robust bottom-up approach to fabricating low-dimensional functional nanostructures, which are used in various applications in nanoscience and technology. To date, tremendous effort has been devoted to constructing various MSAs at surfaces, ranging from self-assembled monolayers and two-dimensional (2D) nanoporous networks to complex 2D quasicrystals and Sierpiński triangle fractals. However, precise control of the assembled structures and efficient achievement of their full applicability remain two major challenges in the MSA field. As another widely employed bottom-up approach to fabricating nanostructures, on-surface reaction (OSR) refers to a reaction that occurs on the surface and is two-dimensionally confined. OSR offers the possibility to synthesize compounds that may not be feasibly achieved in solution chemistry. Compared with MSA based on weak intermolecular interactions, OSR-based structures possess high thermal and chemical stabilities due to internal strong covalent bonds. In this Account, we briefly overview recent achievements of MSAs on single crystal metal surfaces with a focus on their controllability and applicability in tweaking the properties of the molecular building blocks involved. Emphasis will be particularly placed upon mediation of OSRs with the MSA strategy. To explore surface MSAs, on the one hand, scanning tunneling microscopy and spectroscopy have been routinely employed as the experimental tools to probe the intermolecular interactions as well as geometric and electronic structures of the assemblies at the atomic and molecular levels. On the other hand, density functional theory and molecular dynamics have been theoretically applied to model and calculate the assembling systems, furthering our understanding of the experimental results. In principle, MSA is primarily balanced by molecule-molecule and molecule-substrate interactions under vacuum conditions. In terms of the assembling methodologies, people have been attempting to achieve rational design, accurate prediction, and controllable construction of assembled molecular nanostructures, namely, tentative design of specific backbones and functional groups of the molecular building blocks, and careful control of the assembling parameters including substrate lattice, temperature, coverage, and external environment as well. An obvious goal for the development of these methodologies lies in the ultimate applications of these MSAs. MSA can retrospectively affect the properties of the assembling molecules. For instance, self-assembled structures not only can serve as secondary templates to host guest molecules but also can stabilize surface metal adatoms. In fact, the electronics, magnetism, and optics of MSAs have been successfully explored. In surface chemistry, the MSA strategy can be further applied to mediate OSRs in at least three aspects: tweaking reaction selectivity, changing reaction pathway, and restricting reaction site. The governing principle lies in that the self-assembled molecules are confined in the assemblies so that the pre-exponential factors and the energy barriers in the Arrhenius equation of the involved reactions could be substantially varied because the subtle reaction mechanisms may change upon assembling. In this sense, the MSA strategy can be efficiently exploited to tune the properties of the assembling molecules and mediate OSRs in surface chemistry.
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Affiliation(s)
- Lingbo Xing
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Zhantao Peng
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wentao Li
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Kai Wu
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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20
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Yang Y, Cai J, Luo G, Jiang Y, Su Y, Su Y, Li C, Zheng Y, Zeng J, Liu Y. Nickel-catalyzed fluoroethylation of arylboronic acids via Suzuki-type coupling. Org Chem Front 2019. [DOI: 10.1039/c9qo00066f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A new and step-economic method for the synthesis of homobenzylic fluorides through nickel-catalyzed Suzuki-type fluoroethylation coupling is developed.
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Affiliation(s)
- Yi Yang
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Junjie Cai
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Gen Luo
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Yan Jiang
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Yumei Su
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Yang Su
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Chaolin Li
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Yubin Zheng
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Jijiao Zeng
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Yingle Liu
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
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21
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Xu L, Li Y, Yan X, Yuan C. Substitution position modulating the photophysical properties of anthracene derivatives based on Tröger's base. Tetrahedron 2018. [DOI: 10.1016/j.tet.2018.07.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Zhou X, Dai J, Wu K. Steering on-surface reactions with self-assembly strategy. Phys Chem Chem Phys 2018; 19:31531-31539. [PMID: 29171852 DOI: 10.1039/c7cp06177c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The control of assembly structures that subsequently help achieve viable functionalities has been one of the key motivations for the exploration of surface molecular assembly. In terms of its functionality and applicability, the assembly is explored as a strategy to steer on-surface reactions primarily by two methods: assembly-assisted and assembly-involved reactions. The functions of the self-assembly strategy are threefold: tweaking reaction selectivities, steering reaction pathways, and directing reaction sites. The governing principle herein is that the assembly strategy can apply a surface confinement effect that affects the energy barrier and pre-exponential factor of the Arrhenius equation for the dynamics of the target reaction. Development of such a strategy may reveal new routes to steer on-surface reactions and even single molecule properties in surface chemistry.
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Affiliation(s)
- Xiong Zhou
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
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23
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Zhou X, Wang C, Zhang Y, Cheng F, He Y, Shen Q, Shang J, Shao X, Ji W, Chen W, Xu G, Wu K. Steering Surface Reaction Dynamics with a Self-Assembly Strategy: Ullmann Coupling on Metal Surfaces. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201705018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Xiong Zhou
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Chenguang Wang
- Department of Physics; Renmin University of China; Beijing 100872 China
| | - Yajie Zhang
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Fang Cheng
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Yang He
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Qian Shen
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Jian Shang
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Xiang Shao
- Department of Chemical Physics; School of Chemistry and Materials Science; University of Science and Technology of China; Hefei 230026 China
| | - Wei Ji
- Department of Physics; Renmin University of China; Beijing 100872 China
| | - Wei Chen
- Department of Chemistry; National University of Singapore; Singapore 117543 Singapore
| | - Guoqin Xu
- Department of Chemistry; National University of Singapore; Singapore 117543 Singapore
| | - Kai Wu
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
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24
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Zhou X, Wang C, Zhang Y, Cheng F, He Y, Shen Q, Shang J, Shao X, Ji W, Chen W, Xu G, Wu K. Steering Surface Reaction Dynamics with a Self-Assembly Strategy: Ullmann Coupling on Metal Surfaces. Angew Chem Int Ed Engl 2017; 56:12852-12856. [DOI: 10.1002/anie.201705018] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 07/05/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Xiong Zhou
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Chenguang Wang
- Department of Physics; Renmin University of China; Beijing 100872 China
| | - Yajie Zhang
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Fang Cheng
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Yang He
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Qian Shen
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Jian Shang
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
| | - Xiang Shao
- Department of Chemical Physics; School of Chemistry and Materials Science; University of Science and Technology of China; Hefei 230026 China
| | - Wei Ji
- Department of Physics; Renmin University of China; Beijing 100872 China
| | - Wei Chen
- Department of Chemistry; National University of Singapore; Singapore 117543 Singapore
| | - Guoqin Xu
- Department of Chemistry; National University of Singapore; Singapore 117543 Singapore
| | - Kai Wu
- BNLMS; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
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Naskar S, Das I. Elusive Thiyl Radical Migration in a Visible Light Induced Chemoselective Rearrangement of γ-Keto Acrylate Thioesters: Synthesis of Substituted Butenolides. Adv Synth Catal 2016. [DOI: 10.1002/adsc.201601016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Sandip Naskar
- Organic and Medicianl Chemistry Division; CSIR-Indian Institute of Chemical Biology; 4, Raja S. C. Mullick Road Jadavpur, Kolkata 700032 India, Fax: (+91)- 33-2473-5197
| | - Indrajit Das
- Organic and Medicianl Chemistry Division; CSIR-Indian Institute of Chemical Biology; 4, Raja S. C. Mullick Road Jadavpur, Kolkata 700032 India, Fax: (+91)- 33-2473-5197
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26
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Mfuh AM, Nguyen VT, Chhetri B, Burch JE, Doyle JD, Nesterov VN, Arman HD, Larionov OV. Additive- and Metal-Free, Predictably 1,2- and 1,3-Regioselective, Photoinduced Dual C-H/C-X Borylation of Haloarenes. J Am Chem Soc 2016; 138:8408-11. [PMID: 27347688 PMCID: PMC4958914 DOI: 10.1021/jacs.6b05436] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report herein a simple, additive- and metal-free, photoinduced, dual C-H/C-X borylation of chloro-, bromo-, and iodoarenes. The reaction produces 1,2- and 1,3-diborylarenes on gram scales under batch and continuous flow conditions. The regioselectivity of the dual C-H/C-X borylation is determined by the solvent and the substituents in the parent haloarenes.
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Affiliation(s)
- Adelphe M. Mfuh
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Vu T. Nguyen
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Bhuwan Chhetri
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Jessica E. Burch
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - John D. Doyle
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Vladimir N. Nesterov
- Department of Chemistry, University of North Texas, Denton, Texas 76201, United States
| | - Hadi D. Arman
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Oleg V. Larionov
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
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27
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Shokri A, Que L. Conversion of Aldehyde to Alkane by a Peroxoiron(III) Complex: A Functional Model for the Cyanobacterial Aldehyde-Deformylating Oxygenase. J Am Chem Soc 2015; 137:7686-91. [PMID: 26030345 DOI: 10.1021/jacs.5b01053] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cyanobacterial aldehyde-deformylating oxygenase (cADO) converts long-chain fatty aldehydes to alkanes via a proposed diferric-peroxo intermediate that carries out the oxidative deformylation of the substrate. Herein, we report that the synthetic iron(III)-peroxo complex [Fe(III)(η(2)-O2)(TMC)](+) (TMC = tetramethylcyclam) causes a similar transformation in the presence of a suitable H atom donor, thus serving as a functional model for cADO. Mechanistic studies suggest that the H atom donor can intercept the incipient alkyl radical formed in the oxidative deformylation step in competition with the oxygen rebound step typically used by most oxygenases for forming C-O bonds.
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Affiliation(s)
- Alireza Shokri
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
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28
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Primary photochemical dynamics of metal carbonyl dimers and clusters in solution: Insights into the results of metal–metal bond cleavage from ultrafast spectroscopic studies. Inorganica Chim Acta 2015. [DOI: 10.1016/j.ica.2014.07.064] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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29
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Bastos EL, da Silva SM, Baader WJ. Solvent Cage Effects: Basis of a General Mechanism for Efficient Chemiluminescence. J Org Chem 2013; 78:4432-9. [DOI: 10.1021/jo400426y] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Erick L. Bastos
- Departamento de Quı́mica Fundamental, Instituto de Quı́mica, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Sandra M. da Silva
- Departamento de Quı́mica Fundamental, Instituto de Quı́mica, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Wilhelm J. Baader
- Departamento de Quı́mica Fundamental, Instituto de Quı́mica, Universidade de São Paulo, São Paulo, SP, Brazil
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30
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Onyeozili EN, Mori-Quiroz LM, Maleczka RE. [1,2]- and [1,4]-Wittig Rearrangements of α-Alkoxysilanes: Effect of Substitutions at both the Migrating Benzylic Carbon and the Terminal sp 2 Carbon of the Allyl Moiety. Tetrahedron 2013; 69:849-860. [PMID: 23459008 PMCID: PMC3580876 DOI: 10.1016/j.tet.2012.10.091] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Substituted α-alkoxysilanes can be deprotonated by alkyllithium bases and made to undergo Wittig rearrangements to afford the #x0005B;1,4]- and [1,2]-rearranged products in varying ratios. Substitution at the benzylic migrating carbon and/or at the allylic carbon of the allyl moiety impacts the rearrangement reaction, influencing the reactivity as well as the [1,4]-/[1,2]-selectivity. Diastereomeric α-alkoxysilanes show different reactivities with the syn diastereomer being the more reactive isomer.
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Affiliation(s)
- Edith N. Onyeozili
- Department of Chemistry, Florida A&M University, Tallahassee, FL 32307 USA
| | - Luis M. Mori-Quiroz
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824 USA
| | - Robert E. Maleczka
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824 USA
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31
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Cobalt(III) complexes of unsaturated carboxylic acids: synthesis, characterization, and photochemical studies in aqueous medium. RESEARCH ON CHEMICAL INTERMEDIATES 2012. [DOI: 10.1007/s11164-012-0850-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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32
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Wang HL, Wang G, Shen BJ, Xu CM, Gao JS. Upgrading Residue by Carbon Rejection in a Fluidized-Bed Reactor and Its Multiple Lump Kinetic Model. Ind Eng Chem Res 2011. [DOI: 10.1021/ie201597y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hong-liang Wang
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
| | - Gang Wang
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
| | - Bao-jian Shen
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
| | - Chun-ming, Xu
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
| | - Jin-sen Gao
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
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33
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Xu H, Bernskoetter WH. Mechanistic Considerations for C–C Bond Reductive Coupling at a Cobalt(III) Center. J Am Chem Soc 2011; 133:14956-9. [DOI: 10.1021/ja2072548] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hongwei Xu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Wesley H. Bernskoetter
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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34
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Movassaghi M, Ahmad OK, Lathrop SP. Directed heterodimerization: stereocontrolled assembly via solvent-caged unsymmetrical diazene fragmentation. J Am Chem Soc 2011; 133:13002-5. [PMID: 21761893 PMCID: PMC3157567 DOI: 10.1021/ja2057852] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A general strategy for the directed and stereocontrolled assembly of carbon-carbon linked heterodimeric hexahydropyrroloindoles is described. The stepwise union of complex amines in the form of mixed diazenes followed by photoexpulsion of dinitrogen in a solvent cage provides completely guided assembly at challenging C(sp(3))-C(sp(3)) and C(sp(3))-C(sp(2)) connections.
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Affiliation(s)
- Mohammad Movassaghi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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35
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Jin JC, Zhang YN, Wang YY, Liu JQ, Dong Z, Shi QZ. Syntheses and Crystal Structures of a Series of Coordination Polymers Constructed From C2-Symmetric Ligand 1,3-Adamantanedicarboxylic Acid. Chem Asian J 2010; 5:1611-9. [DOI: 10.1002/asia.200900751] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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36
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Kliegman S, McNeill K. Reconciling disparate models of the involvement of vinyl radicals in cobalamin-mediated dechlorination reactions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:8961-8967. [PMID: 19943673 DOI: 10.1021/es902267j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Inner-sphere (nonradical) and outer-sphere (radical-based) mechanisms have been suggested for cobalamin-mediated dechlorination of tetrachloroethylene (PCE) and trichloroethylene (TCE). In this study, the role of free vinyl radicals was investigated using deuterated radical traps: d(8)-isopropanol and d(8)-tetrahydrofuran. For both substrates, addition of trap resulted in production of deuterated dechlorination products, and higher concentrations of trap resulted in increased amounts of deuterated products. However, only a finite proportion of the products were trappable: 8% of the PCE-derived products and 86% of the TCE-derived products result from free radicals. The data show that the reaction does not proceed solely by either an inner-sphere or an outer-sphere mechanism and led to the hypothesis that caged radical intermediates were involved in the mechanism. The untrappable fraction of products are hypothesized to result from in-cage reactions. This hypothesis was investigated using d(5)-glycerol as a radical trap and viscogen. Although increased viscosity resulted in decreased formation of free-radical-derived products, consistent with the cage hypothesis, these data were inconclusive. The role of d(8)-isopropanol in enhancing the production of radicals in this system via an acetone ketyl radical chain mechanism was also investigated, and no evidence for such an effect was found.
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Affiliation(s)
- Sarah Kliegman
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA
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37
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Stickrath AB, Carroll EC, Dai X, Harris DA, Rury A, Smith B, Tang KC, Wert J, Sension RJ. Solvent-Dependent Cage Dynamics of Small Nonpolar Radicals: Lessons from the Photodissociation and Geminate Recombination of Alkylcobalamins. J Phys Chem A 2009; 113:8513-22. [DOI: 10.1021/jp9017986] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Andrew B. Stickrath
- Department of Chemistry, Department of Physics, and Program in Applied Physics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - Elizabeth C. Carroll
- Department of Chemistry, Department of Physics, and Program in Applied Physics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - Xiaochuan Dai
- Department of Chemistry, Department of Physics, and Program in Applied Physics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - D. Ahmasi Harris
- Department of Chemistry, Department of Physics, and Program in Applied Physics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - Aaron Rury
- Department of Chemistry, Department of Physics, and Program in Applied Physics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - Broc Smith
- Department of Chemistry, Department of Physics, and Program in Applied Physics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - Kuo-Chun Tang
- Department of Chemistry, Department of Physics, and Program in Applied Physics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - Jonathan Wert
- Department of Chemistry, Department of Physics, and Program in Applied Physics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - Roseanne J. Sension
- Department of Chemistry, Department of Physics, and Program in Applied Physics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
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38
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Yen CW, Mahmoud MA, El-Sayed MA. Photocatalysis in gold nanocage nanoreactors. J Phys Chem A 2009; 113:4340-5. [PMID: 19271721 DOI: 10.1021/jp811014u] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The photodegradation of methyl orange was found to take place very efficiently using hollow Au nanocages which are known to have remaining Ag on their interior walls which can be oxidized to Ag(2)O. The degradation rate is found to be more efficient than photodegradation reaction using semiconductor nanomaterials, such as TiO(2) and ZnO. The reaction rate is found to increase by increasing the degree of Ag oxidation on the interior wall of the nanocages prior to the reaction and is a function of the nanocavity size and the pore density of the nanocage walls. As the cage size varies, it is found that the photocatalytic rate increases and then decreases with a maximum rate at nanoparticle size of 75 nm with a medium pore density in the walls. All these results suggest that the catalysis is occurring inside the cavity, whose interior walls are covered with the Ag(2)O catalysts. Similar to the mechanism proposed in the degradation by the other semiconductors, we propose that the photodegradation mechanism involves the formation of the hydroxyl radical resulting from the photoexcitation of the Ag(2)O semiconductor. The observed results on the rate are discussion in terms of (1) the surface area of the inner wall covered with Ag (Ag(2)O), (2) the density and size of the pores in the walls, and (3) the cavity size of the nanoparticles.
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Affiliation(s)
- C W Yen
- Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA
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39
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Oelkers AB, Tyler DR. Radical cage effects: a method for measuring recombination efficiencies of secondary geminate radical cage pairs using pump-probe transient absorption methods. Photochem Photobiol Sci 2008; 7:1386-90. [PMID: 18958326 DOI: 10.1039/b804399j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A method is reported for measuring the recombination efficiency of secondary geminate radical cage pairs. The procedure involves measuring the recombination efficiency for primary geminate recombination (F(c1)) using pump-probe laser methods and measuring the "apparent" (or net) recombination efficiency (F(cP)) for all geminate pairs (primary and secondary) using steady-state irradiation methods. A mathematical relationship between F(cP), F(c1), and F(c2) (where F(c2) is the recombination efficiency for secondary geminate recombination) is derived and demonstrated using the photolysis reactions of the [(CpR)Mo(CO)(3)](2) molecules, where CpR = eta(5)-C(5)H(4)CH(3) and eta(5)-C(5)H(4)(CH(2))(2)C(O)NCH(3)(CH(2))(n)CH(3) (n = 3, 8, 13, 18). As an example of the results obtained using the new method, it was found that F(c1) = 0.43 and F(c2) = 0.68 for the molecule with CpR = eta(5)-C(5)H(4)CH(2)CH(2)N(CH(3))C(O)(CH(2))(18)CH(3). The value of F(c2) decreased as the side-chain on the Cp ring got shorter; F(c2) is equal to 0.0 for the molecules with n = 3 and for CpR = eta(5)-C(5)H(4)CH(3). It is hypothesized that a longer side-chain prevents facile diffusion of the radicals out of the secondary cage, whereas the smaller side-chains permit more facile diffusion apart of the radicals. A general conclusion is that the reactions of large radicals in particular may be especially impacted by secondary geminate cage recombination.
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Affiliation(s)
- Alan B Oelkers
- Department of Chemistry, University of Oregon, Eugene, Oregon 97403, USA
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40
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Wang H, Wang YY, Yang GP, Wang CJ, Wen GL, Shi QZ, Batten SR. A series of intriguing metal–organic frameworks with 3,3′,4,4′- benzophenonetetracarboxylic acid: structural adjustment and pH-dependence. CrystEngComm 2008. [DOI: 10.1039/b805727c] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Oelkers AB, Schutte EJ, Tyler DR. Solvent cage effects: the influence of radical mass and volume on the recombination dynamics of radical cage pairs generated by photolysis of [CpCH2CH2N(CH3)C(O)(CH2)nCH3Mo(CO)3]2(n = 3, 8, 13, 18) (Cp = η5-C5H4) complexes. Photochem Photobiol Sci 2008; 7:228-34. [DOI: 10.1039/b709005f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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42
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43
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Oelkers AB, Scatena LF, Tyler DR. Femtosecond Pump−Probe Transient Absorption Study of the Photolysis of [Cp‘Mo(CO)3]2 (Cp‘ = η5-C5H4CH3): Role of Translational and Rotational Diffusion in the Radical Cage Effect. J Phys Chem A 2007; 111:5353-60. [PMID: 17552498 DOI: 10.1021/jp064849z] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Femtosecond pump-probe studies of the photodissociation and subsequent radical cage pair recombination dynamics of the organometallic dimer [Cp'Mo(CO)3]2 (Cp' = eta5-C5H4CH3) are reported. The dynamics following photodissociation were studied in numerous noncoordinating hydrocarbon solvents. The results indicate that primary geminate recombination occurs on an ultrafast time scale (tau approximately 5 ps) and the efficiency of cage escape is inversely proportional to solvent viscosity. Investigation of the time-dependent anisotropy in this system allowed for an estimate of the rotational correlation time of the radical fragments (tau approximately 5-25 ps). Comparison of the rates of rotational motion with the population kinetics shows that the primary solvent cage dynamics and recombination efficiency are controlled by radical diffusion and not by radical rotation.
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Affiliation(s)
- Alan B Oelkers
- Department of Chemistry, University of Oregon, Eugene, OR 97403, USA
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44
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45
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Leung DH, Bergman RG, Raymond KN. Scope and Mechanism of the C−H Bond Activation Reactivity within a Supramolecular Host by an Iridium Guest: A Stepwise Ion Pair Guest Dissociation Mechanism. J Am Chem Soc 2006; 128:9781-97. [PMID: 16866535 DOI: 10.1021/ja061412w] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A chiral self-assembled supramolecular M(4)L(6) assembly has been shown to be a suitable host for a series of reactive monocationic half-sandwich iridium guests 1, 3, and 4 that are capable of activating C-H bonds. Upon encapsulation, selective C-H bond activation of organic substrates occurs. Precise size and shape selectivity are observed in the C-H bond activation of aldehydes and ether substrates. The reactions exhibit significant kinetic diastereoselectivities. Thermodynamic studies have shown that the iridium starting materials and products are bound strongly by the host assembly. The encapsulation process is largely entropy-driven. Kinetic investigations with water-soluble phosphine traps and added salts have provided evidence for a unique stepwise mechanism of guest dissociation for [4 subset Ga(4)L(6)]. Iridium guest 4 first dissociates from the host cavity to form an ion pair with the host exterior. This species then fully dissociates from the host exterior into the bulk solution. Model ion pair intermediates were characterized directly with (1)H NMR NOESY techniques. The rate of iridium guest dissociation is slower than the rate observed for the C-H bond activation processes, indicating that the selective C-H bond activation reactivity occurs within the cavity of the supramolecular host.
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Affiliation(s)
- Dennis H Leung
- Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
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46
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Frija LMT, Khmelinskii IV, Cristiano MLS. Mechanistic Investigations into the Photochemistry of 4-Allyl-tetrazolones in Solution: A New Approach to the Synthesis of 3,4-Dihydro-pyrimidinones. J Org Chem 2006; 71:3583-91. [PMID: 16626145 DOI: 10.1021/jo060164j] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photolysis (lambda = 254 nm) of 4-allyl-tetrazolones 2a-c was carried out in methanol, 1-propanol, 1-hexanol, acetonitrile, and cyclohexane. The sole primary photochemical process identified was molecular nitrogen elimination, with formation of pyrimidinones 6a-c. Following the primary photocleavage, secondary reactions were observed in acetonitrile and cyclohexane, leading to phenyl-isocyanate (7), aniline (9), and 1-phenylprop-1-enyl-isocyanate (10a). In alcoholic solutions, the primary products, 6a-c, remained photostable even under extended irradiation, making possible the isolation of 3,4-dihydro-pyrimidinones as stable compounds in very high yields. The observed photostability of pyrimidinones 6a-c in alcohols is ascribed to the excited state quenching via reversible proton transfer, facilitated by the solvent cage stabilization due to formation of hydrogen bonds. The viscosity of alcohols is directly related to the cage effects observed. The photocleavage of 4-allyl-tetrazolones leads probably to a caged triplet radical pair. This hypothesis is confirmed by the solvent viscosity effect on the photolysis quantum yields. Additionally, dissolved molecular oxygen sensitizes the formation of pyrimidinones, as should be expected for a triplet intermediate that can only form the product molecule after T-S conversion, which is accelerated by oxygen.
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Affiliation(s)
- Luís M T Frija
- CCMAR, Universidade do Algarve, Campus de Gambelas, 8005-039 Faro, Portugal
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47
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Huang KW, Han JH, Cole AP, Musgrave CB, Waymouth RM. Homolysis of weak Ti-O bonds: experimental and theoretical studies of titanium oxygen bonds derived from stable nitroxyl radicals. J Am Chem Soc 2005; 127:3807-16. [PMID: 15771515 DOI: 10.1021/ja044512f] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Titanium-oxygen bonds derived from stable nitroxyl radicals are remarkably weak and can be homolyzed at 60 degrees C. The strength of these bonds depends sensitively on the ancillary ligation at titanium. Direct measurements of the rate of Ti-O bond homolysis in Ti-TEMPO complexes Cp2TiCl(TEMPO) (3) and Cp2TiCl(4-MeO-TEMPO) (4) (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl, 4-MeO-TEMPO = 2,2,6,6-tetramethyl-4-methoxypiperidine-N-oxyl) were conducted by nitroxyl radical exchange experiments. Eyring plots gave the activation parameters, deltaH++ = 27(+/- 1) kcal/mol, deltaS++ = 6.9(+/- 2.3) eu for 3 and deltaH++ = 28(+/- 1) kcal/mol, deltaS++ = 9.0(+/- 3.0) eu for 4, consistent with a process involving the homolysis of a weak Ti-O bond to generate the transient Cp2Ti(III)Cl and the nitroxyl radical. Thermolysis of the titanocene TEMPO complexes in the presence of epoxides leads to the Cp2Ti(III)Cl-mediated ring-opening of the epoxide followed by trapping by the nitroxyl radical. The X-ray crystal structure of the Ti-TEMPO derivative, Cp2TiCl(4-MeO-TEMPO) (4), is reported. DFT (B3LYP/6-31G*) calculations and experimental studies reveal that the strength of the Ti-O bond decreases dramatically with the number of cyclopentadienyl groups on titanium. The calculated Ti-O bond strength of the monocyclopentadienyl complex 2 is 43 kcal/mol, whereas that of the biscyclopentadienyl complex 3 is 17 kcal/mol, a difference of 26 kcal/mol. These studies reveal that the strength of these Ti-O bonds can be tuned over an interesting and experimentally accessible temperature range by appropriate ligation on titanium.
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Affiliation(s)
- Kuo-Wei Huang
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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48
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García F, García JM, Rubio F, de la Peña JL, Guzmán J, Riande E. Reaction kinetics and gel effect on the polymerization of 2-ethoxyethyl methacrylate and 2(2-ethoxyethoxy) ethyl methacrylate. ACTA ACUST UNITED AC 2002. [DOI: 10.1002/pola.10480] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Braden DA, Parrack EE, Tyler DR. Photochemical studies as a function of solvent viscosity. A new photochemical pathway in the reaction of (eta5-C5H4Me)2Mo2(CO)6 with CCl4. Photochem Photobiol Sci 2002; 1:418-20. [PMID: 12856710 DOI: 10.1039/b202112a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper reports the results of a study that used systematic changes in the solvent viscosity to probe the photochemical reactivity of the Cp'2Mo2(CO)6 (Cp' = eta5-C5H4CH3) molecule. The quantum yields for photolysis of Cp'2Mo2(CO)6 in the presence of CCl4 were studied as a function of solvent viscosity. The quantum yields did not decrease to zero with increasing solvent viscosity but rather leveled off at a constant, non-zero value. This result cannot be explained by any of the previously reported radical or Mo-CO dissociation photochemical pathways for this molecule, and therefore an additional photochemical pathway is suggested to be operating in the reaction. The new pathway may involve a reactive isomer of Cp'2Mo2(CO)6 or possibly electron transfer between the excited state of Cp'2Mo2(CO)6 and CCl4.
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Affiliation(s)
- Dale A Braden
- Department of Chemistry, University of Oregon, Eugene, OR 97403-1253, USA
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