Optically actuating ultra-stable radicals in a large π-conjugated ligand constructed photochromic complex

Abstract

Producing ultra-stabilized radicals via light irradiation has raised considerable concern but remains a tremendous challenge in functional materials. Herein, optically actuating ultra-stable radicals are discovered in a sterically encumbered and large πconjugated tri(4-pyridyl)-1,3,5-triazine (TPT) ligands constructed photochromic compound Cu 3 (H-HEDP) 2 TPT 2 •2H 2 O (QDU-12; HEDP=hydroxyethylidene diphosphonate). The photogeneration of TPT• radicals is the photoactive behavior of electron transfer from HEDP motifs to TPT units. The ultra-long-lived radicals are contributed from strong interchain π-π interactions between the large π-conjugated TPT components, with the radical lifetime maintained for about 18 months under ambient conditions. Moreover, the antiferromagnetic couplings between TPT • radicals and Cu 2+ ions plummeted the demagnetization to 35% of its original state after light irradiation, showing the largest room temperature photodemagnetization in the current radicalbased photochromic materials.

Quadruple Photoresponsive Functionality in a Crystalline Hybrid Material: Photochromism, Photomodulated Fluorescence, Magnetism and Nonlinear Optical Properties

“…[19][20][21][22][23][24][25][26][27][28][29][30] Besides the CHPMs based on photodeformable or photoresponsive ligands, the conjugated N-heterocycle moieties as potential electron acceptors (EAs) are also desirable units for yielding CHPMs. [41][42][43][44][45][46][47][48][49][50] The assembly of various EAs moieties, electron donors (EDs) species, and metal ions generates assorted CHPMs driven by photoinduced electron-transfer (ET) between EDs and EAs, [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] and the resulting CHPMs feature additional fascinating photoresponsive functionality like photomagnetism, photocurrent, sensor for X-ray, etc. [41][42][43][44][45][46][47][48][49][50]…”

“…[41][42][43][44][45][46][47][48][49][50] The assembly of various EAs moieties, electron donors (EDs) species, and metal ions generates assorted CHPMs driven by photoinduced electron-transfer (ET) between EDs and EAs, [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] and the resulting CHPMs feature additional fascinating photoresponsive functionality like photomagnetism, photocurrent, sensor for X-ray, etc. [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] Reviewing literature implies that the explored photoresponsive functionality in reported CHPMs mainly concentrate on dyad combination. For example, photochromism and photomagnetism was observable in 3d-4f hexacyanoferrate.…”

“…The closest distance (2.795 Å) between the N phen and O carboxylate around Dy 3 + ions is favourable for ET with the assistance of coordinate bond. [45][46][47][48][49][50]70] After irradiation, the energy of phen is given to adjoining BTA 3À , resulting in the ET from O carboxylate to N phen . Thus, the photocoloration of 1 can be interpreted as photoinduced ligand-toligand ET, which also determines the photochromism of other reported CHPMs.…”

“…Thus, the photocoloration of 1 can be interpreted as photoinduced ligand-toligand ET, which also determines the photochromism of other reported CHPMs. [45][46][47][48][49][50][51][52][53] To assure the adequate photoactivation for ET for the following characterisations, the irradiation time was enlarged to 120 min for obtaining the colored sample (1P). Notably, time-variable UV-Vis spectra of 1P shows that the photogenerated radicals could be stable for 6 day at ambient conditions (Figure S7).…”

Two fluorescent copper phosphonate complexes for sensing antibiotics, ketones and Fe3+ in water

“…[9][10][11][12][13][14] As hybrid materials, metal phosphonate complexes have feasible applications in the fields covering ion exchange, proton conductivity, intercalation chemistry, photochemistry, catalysis, gas storage and separation. [15][16][17][18][19][20] The hybrid properties endowed by the metal and ligand also make it a promising candidate as fluorescence sensors to detect specific species. [21][22][23][24] In the past several years, our research group has been working on bifunctional anionic units as building blocks to construct new complexes with fascinating structures and intriguing properties.…”