Photoactivatable Anthracenes

Abstract

Fifteen substituted maleimide cycloadducts of anthracene derivatives were synthesized in one or two steps from available precursors in yields ranging from 32 to 63%. They differ in the nature of the group on the maleimide nitrogen atom and of the substituents on the anthracene platform. In all instances, the introduction of a maleimide bridge across positions 9 and 10 of the anthracene skeleton isolates electronically its peripheral phenylene rings and suppresses its characteristic fluorescence. The cycloadducts with a 4-(dimethylamino)phenyl group on the maleimide nitrogen atom undergo retro-cycloaddition upon ultraviolet illumination with quantum yields ranging from 0.001 to 0.01. This structural transformation restores the aromatic character of the central ring of the oligoacene chromophore and activates its emission with fluorescence quantum yields ranging from 0.07 to 0.85. Thus, this particular choice of building blocks for the construction of photoresponsive compounds can translate into viable operating principles for fluorescence activation and, ultimately, lead to the realization of valuable photoactivatable fluorophores for imaging applications.

Chemically Delaminated Free‐Standing Ultrathin Covalent Organic Nanosheets

“…To address these issues, we attempted to chemically exfoliate an anthracene‐based 2D COF by incorporating N ‐hexylmaleimide molecules within the anthracene moieties of the COF layers through [4+2] cycloaddition reactions. It is well known that the 9‐ and 10‐positions of anthracene units are susceptible towards [4+2] cycloaddition reactions . The introduction of N ‐hexylmaleimide within the COF backbone disturbs the π–π stacking interactions and the planarity of the individual layers, which results in exfoliation.…”

Chemically Delaminated Free‐Standing Ultrathin Covalent Organic Nanosheets

“…To address these issues,w ea ttempted to chemically exfoliate an anthracene-based 2D COF by incorporating N-hexylmaleimide molecules within the anthracene moieties of the COF layers through [4+ +2] cycloaddition reactions.Itis well known that the 9-and 10-positions of anthracene units are susceptible towards [4+ +2] cycloaddition reactions. [11] The introduction of N-hexylmaleimide within the COF backbone disturbs the p-p stacking interactions and the planarity of the individual layers,w hich results in exfoliation. Furthermore, these exfoliated CONs easily assemble into as elf-standing thin film at an air-water interface,w hich could easily be transferred onto ag lass slide,s ilicon surface,o re ven al oop.…”

Plasmonic Acceleration of a Photochemical Replicator

“…[37] The fluorescence quantum yield of 2, reported in Table 1, is a literature value. [38] Samples were illuminated with a Luzchem Research LZC-4 V photoreactor (420 nm, 2.3 mW cm À2 ) for the experiments in Figure 2 and S2 and with the excitation source (380 nm) of the emission spectrometer for the experiments in Figure 3 and S3. A Chemat Technologies KW-4 A spin coater was used to prepare the polymer films.…”