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Article: Photochemical α-Cleavage Reaction of 3’,5’-Dimethoxybenzoin: A Combined Time-Resolved Spectroscopy and Computational Chemistry Study
Title | Photochemical α-Cleavage Reaction of 3’,5’-Dimethoxybenzoin: A Combined Time-Resolved Spectroscopy and Computational Chemistry Study |
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Authors | |
Keywords | photoinitiator benzoin α-cleavage transient absorption spectroscopy DFT calculation |
Issue Date | 2020 |
Publisher | Molecular Diversity Preservation International. The Journal's web site is located at http://www.mdpi.org/molecules |
Citation | Molecules, 2020, v. 25 n. 15, p. article no. 3548 How to Cite? |
Abstract | Benzoin is one of the most commonly used photoinitiators to induce free radical polymerization. Here, improved benzoin properties could be accomplished by the introduction of two methoxy substituents, leading to the formation of 3’,5’-dimethoxybenzoin (DMB) which has a higher photo-cleavage quantum yield (0.54) than benzoin (0.35). To elucidate the underlying reaction mechanisms of DMB and obtain direct information of the transient species involved, femtosecond transient absorption (fs-TA) and nanosecond transient absorption (ns-TA) spectroscopic experiments in conjunction with density functional theory/time-dependent density functional theory (DFT/TD-DFT) calculations were performed. It was found that the photo-induced α-cleavage (Norrish Type I reaction) of DMB occurred from the nπ* triplet state after a rapid intersystem crossing (ISC) process (7.6 ps), leading to the generation of phenyl radicals on the picosecond time scale. Compared with Benzoin, DMB possesses two methoxy groups which are able to stabilize the alcohol radical and thus result in a stronger driving force for cleavage and a higher quantum yield of photodissociation. Two stable conformations (cis-DMB and trans-DMB) at ground state were found via DFT calculations. The influence of the intramolecular hydrogen bond on the α-cleavage of DMB was elaborated. |
Persistent Identifier | http://hdl.handle.net/10722/300918 |
ISSN | 2023 Impact Factor: 4.2 2023 SCImago Journal Rankings: 0.744 |
PubMed Central ID | |
ISI Accession Number ID |
DC Field | Value | Language |
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dc.contributor.author | Li, Y | - |
dc.contributor.author | Zhang, X | - |
dc.contributor.author | YAN, Z | - |
dc.contributor.author | Du, L | - |
dc.contributor.author | Tang, W | - |
dc.contributor.author | Phillips, DL | - |
dc.date.accessioned | 2021-07-06T03:12:01Z | - |
dc.date.available | 2021-07-06T03:12:01Z | - |
dc.date.issued | 2020 | - |
dc.identifier.citation | Molecules, 2020, v. 25 n. 15, p. article no. 3548 | - |
dc.identifier.issn | 1420-3049 | - |
dc.identifier.uri | http://hdl.handle.net/10722/300918 | - |
dc.description.abstract | Benzoin is one of the most commonly used photoinitiators to induce free radical polymerization. Here, improved benzoin properties could be accomplished by the introduction of two methoxy substituents, leading to the formation of 3’,5’-dimethoxybenzoin (DMB) which has a higher photo-cleavage quantum yield (0.54) than benzoin (0.35). To elucidate the underlying reaction mechanisms of DMB and obtain direct information of the transient species involved, femtosecond transient absorption (fs-TA) and nanosecond transient absorption (ns-TA) spectroscopic experiments in conjunction with density functional theory/time-dependent density functional theory (DFT/TD-DFT) calculations were performed. It was found that the photo-induced α-cleavage (Norrish Type I reaction) of DMB occurred from the nπ* triplet state after a rapid intersystem crossing (ISC) process (7.6 ps), leading to the generation of phenyl radicals on the picosecond time scale. Compared with Benzoin, DMB possesses two methoxy groups which are able to stabilize the alcohol radical and thus result in a stronger driving force for cleavage and a higher quantum yield of photodissociation. Two stable conformations (cis-DMB and trans-DMB) at ground state were found via DFT calculations. The influence of the intramolecular hydrogen bond on the α-cleavage of DMB was elaborated. | - |
dc.language | eng | - |
dc.publisher | Molecular Diversity Preservation International. The Journal's web site is located at http://www.mdpi.org/molecules | - |
dc.relation.ispartof | Molecules | - |
dc.rights | This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. | - |
dc.subject | photoinitiator | - |
dc.subject | benzoin | - |
dc.subject | α-cleavage | - |
dc.subject | transient absorption spectroscopy | - |
dc.subject | DFT calculation | - |
dc.title | Photochemical α-Cleavage Reaction of 3’,5’-Dimethoxybenzoin: A Combined Time-Resolved Spectroscopy and Computational Chemistry Study | - |
dc.type | Article | - |
dc.identifier.email | Zhang, X: heeteen@hku.hk | - |
dc.identifier.email | Du, L: ailleen@hku.hk | - |
dc.identifier.email | Phillips, DL: phillips@hku.hk | - |
dc.identifier.authority | Phillips, DL=rp00770 | - |
dc.description.nature | published_or_final_version | - |
dc.identifier.doi | 10.3390/molecules25153548 | - |
dc.identifier.pmid | 32756525 | - |
dc.identifier.pmcid | PMC7435414 | - |
dc.identifier.scopus | eid_2-s2.0-85089170405 | - |
dc.identifier.hkuros | 323196 | - |
dc.identifier.volume | 25 | - |
dc.identifier.issue | 15 | - |
dc.identifier.spage | article no. 3548 | - |
dc.identifier.epage | article no. 3548 | - |
dc.identifier.isi | WOS:000559173900001 | - |
dc.publisher.place | Switzerland | - |