Acyl-1,4-Dihydropyridines as Efficient Dual-Mode Photoinitiators for Radical Polymerisation under Blue and Green Light
5 affiliations
- 1School of Chemical and Pharmaceutical Sciences, Technological University Dublin, City Campus, Dublin, Ireland, D07 ADY7
- 2Centre for Synthesis and Chemical Biology, School of Chemistry
- 3University College Dublin
- 4Centre for Industrial & Engineering Optics, School of Physics, Clinical and Optometric Sciences
- 5Technological University Dublin
Abstract
Acyl-1,4-dihydropyridines are readily accessible radical precursors, but their poten al as photoini ators has remained largely unexplored.Here we show that these easily prepared compounds are dual-mode photoini ators that operate across the visible spectrum.Under blue light (405-475 nm), they act directly as Type I photoini ators: photoinduced fragmenta on releases acyl radicals that polymerise acrylate and methacrylate monomers.In trimethylolpropane triacrylate, DHP-2-NMe₂ and DHP-5-OMe show the highest Type I ac vity, with DHP-2-NMe₂ inducing gela on in only 6 s at a loading of 0.042 wt%.Under green light (525 nm), the DHPs serve as co-ini ators in photosensi sed Type II systems.With porphyrin-, BODIPY-and xanthene-based photosensi sers, rapid photopolymerisa on is observed; DHP-5-OMe is the most consistent co-ini ator, and PdOEP gives gela on mes of 2-14 s (median 3 s).Subs tuent-dependent reac vity observed in radical-trapping experiments supports a photoinduced electron-transfer pathway that, under op mised condi ons, delivers a Giese-type adduct in 92% yield under green light.Finally, combining DHP-1-H with I2BDP in a photopolymerisable glass increases the holographic diffrac on efficiency at 532 nm from 43% to 82% and the refrac ve-index modula on from 1.43 × 10⁻³ to 2.39 × 10⁻³.Single-step synthesis, strong visible-light absorp on and complete photobleaching make acyl-DHPs a prac cal pla orm for visible-light photopolymerisa on and holographic pa erning.
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BibTeX
@misc{dvoracek2026acyl14dihydropyridines,
title = {{Acyl-1,4-Dihydropyridines as Efficient Dual-Mode Photoinitiators for Radical Polymerisation under Blue and Green Light}},
author = {Metodej Dvoracek and Pratik Avinash and Karthikeyan Manoharan and Arun Madathil and Luke Adams and Tatsiana Mikulchyk and Mikhail A. Filatov and Bartosz Bieszczad},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15009749/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009749/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Acyl-1,4-Dihydropyridines as Efficient Dual-Mode Photoinitiators for Radical Polymerisation under Blue and Green Light
AU - Metodej Dvoracek
AU - Pratik Avinash
AU - Karthikeyan Manoharan
AU - Arun Madathil
AU - Luke Adams
AU - Tatsiana Mikulchyk
AU - Mikhail A. Filatov
AU - Bartosz Bieszczad
PY - 2026
DA - 2026/10/01
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009749/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009749/v1
AB - Acyl-1,4-dihydropyridines are readily accessible radical precursors, but their poten al as photoini ators has remained largely unexplored.Here we show that these easily prepared compounds are dual-mode photoini ators that operate across the visible spectrum.Under blue light (405-475 nm), they act directly as Type I photoini ators: photoinduced fragmenta on releases acyl radicals that polymerise acrylate and methacrylate monomers.In trimethylolpropane triacrylate, DHP-2-NMe₂ and DHP-5-OMe show the highest Type I ac vity, with DHP-2-NMe₂ inducing gela on in only 6 s at a loading of 0.042 wt%.Under green light (525 nm), the DHPs serve as co-ini ators in photosensi sed Type II systems.With porphyrin-, BODIPY-and xanthene-based photosensi sers, rapid photopolymerisa on is observed; DHP-5-OMe is the most consistent co-ini ator, and PdOEP gives gela on mes of 2-14 s (median 3 s).Subs tuent-dependent reac vity observed in radical-trapping experiments supports a photoinduced electron-transfer pathway that, under op mised condi ons, delivers a Giese-type adduct in 92% yield under green light.Finally, combining DHP-1-H with I2BDP in a photopolymerisable glass increases the holographic diffrac on efficiency at 532 nm from 43% to 82% and the refrac ve-index modula on from 1.43 × 10⁻³ to 2.39 × 10⁻³.Single-step synthesis, strong visible-light absorp on and complete photobleaching make acyl-DHPs a prac cal pla orm for visible-light photopolymerisa on and holographic pa erning.
ER -