Direct Observation of Germyl Radicals by a Laser-Photolysis of Germyl Ketones

Mochida, Kunio; Ichikawa, Kyoko; Okui, Shuko; Sakaguchi, Yoshio; Hayashi, H.

doi:10.1246/cl.1985.1433

Cited by 17 publications

(9 citation statements)

References 7 publications

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“…[14] Radical formation upon photodecomposition has been reported in previous publications. [15,16] This phenomenon has been ascribed to an a-cleavage according to Norrish Type I mechanism, [14,17] but no studies on the initiating behavior of acrylate-based formulations were performed. In the current paper, UV-Vis absorption characteristics and photoinitiating activity under broadband irradiation and with special dental halogen and LED-based lamps were investigated.…”

Section: Communicationmentioning

confidence: 99%

New Photocleavable Structures, 4

Ganster¹,

Fischer²,

Moszner³

et al. 2007

Macromol. Rapid Commun.

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As highly reactive acylphosphine oxide‐based photoinitiators (PIs) are limited in the application for dental materials by their absorption behavior, we were interested to prepare acylgermane 1. UV‐Vis absorption maximum of the important n–π* transition was red shifted about 30 nm compared to monoacylphosphine oxides. Photo‐DSC results with a dental LED lamp showed nearly the same reactivity for 1 compared to camphorquinone (CQ), while monoacylphosphine oxides are not reactive. In broadband irradiation experiments, significantly higher reactivity compared to CQ was found. Application‐oriented tests showed sufficient storage stability of the formulation and excellent photobleaching behavior.magnified image

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Section: Communicationmentioning

confidence: 99%

New Photocleavable Structures, 4

Ganster¹,

Fischer²,

Moszner³

et al. 2007

Macromol. Rapid Commun.

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Section: Introductionmentioning

confidence: 99%

“…One class of compounds for which substitution patterns play ak ey role for photophysical properties are benzoylgermanes,w hich have been studied for the first time by Mochida et al [4,5] in the mid-1980s. Some years later,W akasa et al [6] investigated the influence of different substitution patterns on the fluorescenceb ehavior of this class of compounds.…”

Section: Introductionmentioning

confidence: 99%

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Photophysical Properties of Benzoylgermane and para‐Substituted Derivatives: Substituent Effects on Electronic Transitions

et al. 2016

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In the present study, a selection of basic substitution patterns on benzoyl(trimethyl)germane was investigated using time-dependent density-functional theory (TDDFT) to explore the influence on the stability and on the relative order of the lowest excited electronic states. The theoretical results are in agreement with absorption and fluorescence measurements. We show that electron-withdrawing groups decrease the energetic level of the lowest singlet and triplet state relative to the electron-pushing systems resulting in red-shifted radiative transitions (fluorescence). In the first triplet state electron-withdrawing groups lead to an increased dissociation barrier and a close approach with the singlet ground state before the transition state in the triplet state is reached, favoring radiationless ground-state recovery. The results are also in good agreement with empirical concepts of organic chemistry, therefore providing simple rules for synthetic strategies towards tuning the excited-state properties of benzoylgermanes.

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“…Germyl radicals formed via photolysis of monoacylgermanes Ph 3 Ge(CO)Ph and PhMe 2 Ge(CO)Ph have been observed by Mochida and Hayashi in 1985 using laser-flash photolysis (LFP). [44] The assignment of the transient absorptionb ands to the Gecentered radicals Ph 3 GeC and PhMe 2 GeC has been possible via comparison with the LFP spectra reported previously for Gecentered radicals derived from germanium hydrides( 1983 by Scaianoand Ingold as well as by Hayashi and Mochida). [45] Taraban and co-workers investigated the photocleavage of monoacylgermane Et 3 Ge(CO)Ph (benzoyltriethylgermane) via chemically-induced dynamic nuclear polarization (CIDNP) NMR spectroscopyi n1 987, confirming the formationo fE t 3 GeC and C(CO)Pha st he primary triplet radicalp air.…”

Section: Photochemistry Of Acylgermanesmentioning

confidence: 99%

Recent Advances in Germanium‐Based Photoinitiator Chemistry

Haas

Radebner

Eibel

et al. 2018

Chemistry A European J

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Acylgermanes provide an outstanding photoinduced reactivity at very useful absorption wavelengths. This encouraged multidisciplinary research groups to utilize them as highly effective and non‐toxic photoinitiators particularly for medical applications. In this Minireview, we present the most recent breakthroughs to synthesize acylgermanes. We also outline mechanistic aspects of photoinduced reactions of several acylgermane derivatives based on fundamental spectroscopic insights. These studies may aid future developments for tailor‐made photoinitiators.

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Direct Observation of Germyl Radicals by a Laser-Photolysis of Germyl Ketones

Abstract: Photochemical primary processes of benzoyltriphenylgermane and benzoylphenyldimethylgermane were studied at room temperature in cyclohexane and chloroform. The germyl radicals generated were observed directly with the aid of a laser-photolysis technique.

Cited by 17 publications

References 7 publications

New Photocleavable Structures, 4

New Photocleavable Structures, 4

Photophysical Properties of Benzoylgermane and para‐Substituted Derivatives: Substituent Effects on Electronic Transitions

Recent Advances in Germanium‐Based Photoinitiator Chemistry

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