Macrocyclic Photoinitiator Based on Prism[5]arene Matching LEDs Light with Low Migration

Abstract

In this work, a naphthalene-based macrocycle prism[5]arene (NP 5 OCH 3 ) is developed as a novel kind of photoinitiator. When NP 5 OCH 3 is irradiated under light, the bond between methylene and naphthalene can be quickly broken owning to the existence of ring tension. The macrocycle is cleaved to linear oligomer biradicals, which can effectively initiate the free radical photopolymerization of acrylate monomers. Compared with conventional photoinitiators, NP 5 OCH 3 has strong light absorption in the wavelength range of 365-405 nm, so it can well match the environment-friendly light-emitting diodes (LEDs) light source to realize highly efficient initiation. In addition, there is no small molecule fragment generated during NP 5 OCH 3 fracture, and the resulted linear oligomer biradicals can be immobilized in the polymer after initiating polymerization, so NP 5 OCH 3 photoinitiators show much lower migration rate and cytotoxicity. Cleavable macrocycle prismarene may provide a new idea for the design of safe and efficient photoinitiators matching long wavelength light.

Nondiffusion-Controlled Photoelectron Transfer Induced by Host–Guest Complexes to Initiate Cationic Photopolymerization

“…31−33 Second, the macrocyclic P6/NP5 exhibited a much lower migration rate and cytotoxicity than other small-molecule photosensitizers, owing to the absence of small molecular fragment generation. 34,35 In addition, the host−guest complex extended the initiating wavelength of Iod from ultrashort ultraviolet to nearultraviolet, which could better match the environment-friendly LED light source. In this way, it would be proven that the supraphotoinitiators with a nondiffusion-controlled photoelectron transfer process could be developed for highly efficient photopolymerization.…”

“…At the same time, the newly presented peaks (H a , H b , H c , and H d ) on the 1 H NMR spectra proved that P6 would be broken to a straight chain (P6OC2H5-α/β-chain), which had been studied in our previous work. 34,35 The characteristic peaks of iodobenzene and other photodegradation products recovered from the round and wideshaped peaks to sharp and narrow peaks showed that the photodegradation products were released from the cavity of macrocycles and escaped from the reaction cage. NP5-Iod was shown to undergo similar light reactions under light irradiation in Figure S12.…”

“…First, in our paper, a photosensitizer (P6/NP5) and iodonium salt (Iod) are used to form a host–guest complex by supramolecular interaction. Thus, P6/NP5 could donate electrons to Iod under nondiffusion control, endowing a higher photopolymerization rate and epoxy resin final conversion than the multicomponents reaction process. − Second, the macrocyclic P6/NP5 exhibited a much lower migration rate and cytotoxicity than other small-molecule photosensitizers, owing to the absence of small molecular fragment generation. , In addition, the host–guest complex extended the initiating wavelength of Iod from ultrashort ultraviolet to near-ultraviolet, which could better match the environment-friendly LED light source. In this way, it would be proven that the supra-photoinitiators with a nondiffusion-controlled photoelectron transfer process could be developed for highly efficient photopolymerization.…”

Synthesis, conformational properties, and molecular recognition abilities of novel prism[5]arenes with branched and bulky alkyl groups

“…18 As a result of these appealing properties, prismarenes have attracted significant interest in the scientific community over the last three years. [20][21][22][23][24][25][26] An intriguing aspect of prismarenes pertains to their chirality. Like pillararenes, [27][28][29] prism[n] arenes exhibit planar chirality (Fig.…”

Charge-transfer inclusion complex formation of the tropylium cation with prism[6]arenes

“…Among various supramolecular host molecules, macrocyclic compounds embody excellent host–guest properties due to their specific cavity structures that endow them with efficient molecular recognition for different kinds of guests. 1 Prismarenes, 2–8 as one novel kind of macrocyclic host reported in 2020 by Gaeta and his colleagues, have one π-electron-rich aromatic cavity originating from the naphthalene ring repeating units. Structural features of prismarenes have afforded them outstanding properties to selectively complex with a variety of electron-deficient guests.…”