Hydrogen bonded dimers of ketocoumarin in the solid state and alcohol:water binary solvent: fluorescence spectroscopy, crystal structure and DFT investigation

Ramamurthy, K.; Malar, E. J. Padma; Selvaraju, Chellappan

doi:10.1039/c9nj01053j

Cited by 11 publications

(9 citation statements)

References 63 publications

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“…The photophysical and photochemical properties of KCs were largely investigated . For example, the study of the photophysical properties of KCs in different solvents and alcohol: water binary mixture and solid state has been accomplished using steady‐state, fluorescence spectroscopy and other techniques . Williams and co‐authors have studied different 3‐KCs with alkoxy or dialkylamino substituents in the 7‐position as photoinitiators (PIs).…”

Section: Introductionmentioning

confidence: 99%

Keto‐coumarin scaffold for photoinitiators for 3D printing and photocomposites

Abdallah

Dumur

Hijazi

et al. 2020

Journal of Polymer Science

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The purposes of this paper are moving toward (a) the development of a new series of photoinitiators (PIs) which are based on the keto-coumarin (KC) core, (b) the introduction of light-emitting diodes (LEDs) as inexpensive and safe sources of irradiation, (c) the study of the photochemical mechanisms through which the new PIs react using different techniques such as Fourier transform infrared, UV-visible or fluorescence spectroscopy, and so on, (d) the use of such compounds (presenting good reactivity and excellent photopolymerization initiating abilities) for two specific and high added value applications: 3D printing (@405 nm) and preparation of thick glass fiber photocomposites with excellent depth of cure, and finally (e) the comparison of the performance of these KC derivatives versus other synthesized coumarin derivatives. In this study, six well-designed KC derivatives (KC-C, KC-D, KC-E, KC-F, KC-G, and KC-H) are examined as high-performance visible-light PIs for the cationic polymerization of epoxides as well as the free-radical polymerization of acrylates upon irradiation with LED@405 nm. Excellent polymerization rates are obtained using two different approaches: a photooxidation process in combination with an iodonium (Iod) salt and a photoreduction process when associated with an amine (N-phenylglycine or ethyl 4-(dimethylamino)benzoate). High final reactive conversions were obtained. A full picture of the involved photochemical mechanisms is provided. K E Y W O R D S keto-coumarin, light-emitting diode, photocomposite, photoinitiator, photopolymerization, 3D printing resin

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Section: Introductionmentioning

confidence: 99%

Keto‐coumarin scaffold for photoinitiators for 3D printing and photocomposites

Abdallah

Dumur

Hijazi

et al. 2020

Journal of Polymer Science

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“…As far as near-UV photoinitiators are concerned, a large series of coumarins and keto-coumarins have been described in previous papers (some examples can be found in refs − and references herein). Some of them have been evaluated as photoredox catalysts and used for the preparation of hydrogels paving the way toward photopolymerization in water using a water-soluble photoinitiator .…”

Section: Introductionmentioning

confidence: 99%

In Silico Design of Nitrocoumarins as Near-UV Photoinitiators: Toward Interesting Opportunities in Composites and 3D Printing Technologies

Abdallah

Hijazi

Graff

et al. 2020

ACS Appl. Polym. Mater.

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In this work, the in-silico rational design of new photoinitiators by molecular modeling for specific wavelength (here 405 nm) and specific applications (3D printing, composites) is reported. A large number of (keto)coumarin derivatives were investigated by molecular modeling and their synthesis and more detailed photochemical investigations are based on obtaining structures having both excellent predicted light absorption properties @405 nm and high excited state energy levels (to ensure high photochemical reactivity). More particularly, four new families of coumarins were designed (4 of the 19 proposed coumarins were never synthesized (N2,M6,T1,T6)): the first family is based on Nitrocoumarins (N1-N6), the second one on Methoxybenzene-based coumarins and Ethoxycoumarins (M1-M6), the third one on Thiophene-based coumarins (T1-T6) and the last family studied concerns Alkyne-based coumarin (A1). The purpose of this work concerns the study of the photoinitiating ability of these compounds in different monomers for different polymerization processes (free radical, cationic) using FTIR technique. The different compounds reported in this work are very efficient to initiate the free radical polymerization of (meth)acrylates but also the cationic polymerization of epoxides upon mild irradiation conditions using a Light 2 Emitting Diode (LED) at 405 nm as visible light source. Nitrocoumarins were identified as the best candidates for photoinitiation among the different families of coumarins investigated in this work. More precisely, nitrocoumarins are characterized by very good polymerization profiles, great final reactive function conversions (FC) and also high rates of polymerization (Rp). The electrochemical and photochemical properties of the different compounds were also studied to get a deeper insight into the photochemical mechanisms supporting the initiation process. A full picture of the involved photochemical mechanisms is provided. Thanks to the astounding polymerization initiating ability of these coumarins, their use in 3D printing applications can be worthwhile. Remarkably, using these compounds, the preparation of photocomposites was possible even in difficult light penetration conditions resulting from the presence of fibers inside the resins.

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“…Noticeably, C4 proved to be more efficient than C3, resulting from a more favorable electron transfer from the coumarin to the metallocene. [196] These results were confirmed in another study in which polymethyl-substituted ferrocenes were used as additives. [197] Scheme 1.…”

Section: Introduction Of the Type I Moietymentioning

confidence: 56%

Recent advances on coumarin-based photoinitiators of polymerization

Dumur

2022

European Polymer Journal

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During the past decades, a breakthrough has been obtained in the development of photoinitiators activable under low light intensity and in the visible range. In the search for new structures, biosourced or bioinspired molecules have been examined as potential candidates for photoinitiation. In this field, coumarins that can be found in numerous flowers, fruits, vegetables and plant species were determined as highly efficient photoinitiators of polymerization. Especially, these structures were determined as acting as efficiency photoinitiators in Type I and Type II initiating systems. In this review, an overview of the recent development on visible light coumarin-based photoinitiators of polymerization is provided. To evidence the interest of these structures, comparisons with reference photoinitiating systems will be provided.

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Hydrogen bonded dimers of ketocoumarin in the solid state and alcohol:water binary solvent: fluorescence spectroscopy, crystal structure and DFT investigation

Abstract: Fluorescence emission spectrum of ketocoumarin dimers in an alcohol:water binary mixture and the solid state.

Cited by 11 publications

References 63 publications

Keto‐coumarin scaffold for photoinitiators for 3D printing and photocomposites

Keto‐coumarin scaffold for photoinitiators for 3D printing and photocomposites

In Silico Design of Nitrocoumarins as Near-UV Photoinitiators: Toward Interesting Opportunities in Composites and 3D Printing Technologies

Recent advances on coumarin-based photoinitiators of polymerization

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