Sindt, Ammon J. published the artcileGuest Inclusion Modulates Concentration and Persistence of Photogenerated Radicals in Assembled Triphenylamine Macrocycles, Category: bromides-buliding-blocks, the main research area is macrocycle self assembly crystal guest radicals.
Substituted triphenylamine (TPA) radical cations show great potential as oxidants and as spin-containing units in polymer magnets. Their properties can be further tuned by supramol. assembly. Here, we examine how the properties of photogenerated radical cations, intrinsic to TPA macrocycles, are altered upon their self-assembly into one-dimensional columns. These macrocycles consist of two TPAs and two methylene ureas, which drive the assembly into porous organic materials. Advantageously, upon activation the crystals can undergo guest exchange in a single-crystal-to-single-crystal transformation generating a series of isoskeletal host-guest complexes whose properties can be directly compared. Photoinduced electron transfer, initiated using 365 nm light-emitting diodes, affords radicals at room temperature as observed by ESR (EPR) spectroscopy. The line shape of the EPR spectra and the quantity of radicals can be modulated by both polarity and heavy atom inclusion of the encapsulated guest. These photogenerated radicals are persistent, with half-lives between 1 and 7 d and display no degradation upon radical decay. Re-irradiation of the samples can restore the radical concentration back to a similar maximum concentration, a feature that is reproducible over several cycles. EPR simulations of a representative spectrum indicate two species, one containing two N hyperfine interactions and an addnl. broad signal with no resolvable hyperfine interaction. Intriguingly, TPA analogs without bromine substitution also exhibit similar quantities of photogenerated radicals, suggesting that supramol. strategies can enable more flexibility in stable TPA radical structures. These studies will help guide the development of new photoactive materials.
Journal of the American Chemical Society published new progress about Crystal structure. 183994-94-7 belongs to class bromides-buliding-blocks, name is 4-(Bromomethyl)-N,N-diphenylaniline, and the molecular formula is C19H16BrN, Category: bromides-buliding-blocks.
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary