Phenazine-Based Donor Acceptor Systems as Organic Photocatalysts for “Metal-free” C–N/C–C Cross-Coupling

Abstract

With an aim to achieve a balance between ground-state and excited-state reduction potential of donor acceptor systems for efficient C–N/C–C cross-coupling, a series of donor acceptor systems DA1–DA4 have been synthesized by varying the donor strength and connecting positions. With an increase in donor strength, systematic elevation in the ground-state reduction potential and decrease in the HOMO–LUMO gap was observed. Interestingly, all the derivatives DA1–DA4 could catalyze the C–N bond formation reaction between activated aryl halides and amines at low catalytic loading under metal-free conditions without the need of any external base upon irradiation with white LED. A balance was realized in the case of derivative DA2, which exhibits high efficiency in C–N couplings. Different control experiments support the validity of the energy as well as electron transfer pathways in the visible light-mediated C–N bond formation. This study further reveals the potential of derivative DA1 in “metal-free” Sonogashira coupling involving activated aryl halides which is attributed to its high excited-state reduction potential.

Donor–Acceptor‐Type Organic‐Small‐Molecule‐Based Solar‐Energy‐Absorbing Material for Highly Efficient Water Evaporation and Thermoelectric Power Generation

“…Dibenzo[f,h]quinoxaline and anthraquinone are common electron-withdrawing groups used for constructing long-wavelength organic light-emitting materials due to their planarity, highly conjugated backbones and strong electron-withdrawing abilities. [40,41] However, to construct organic photothermal materials with broad absorption spectra and narrow band gap, their electron-withdrawing abilities and conjugate rigid plane skeleton are not sufficient enough. Herein, by fusing two strong dibenzo[f,h]quinoxaline and anthraquinone units together, a new stronger electron-accepting core, dibenzo[a,c] naphtho[2,3-h]phenazine-8,13-dione (PDN) with conjugate rigid planar skeleton, was developed.…”

4,7-Diarylbenzo[c][1,2,5]thiadiazoles as fluorophores and visible light organophotocatalysts

“…Organic π-conjugated electron donor-acceptor (D-A) systems have firmly established themselves as a powerful design motif for applications such as organic photovoltaics, fluorophores and photocatalysts. [1][2][3][4] Among the endless combinations of donor and acceptor groups, the benzo[c] [1,2,5]thiadiazole (BTZ) motif has received appreciable attention as a strongly electron accepting moiety, primarily for use in photovoltaic applications but also as fluorescent sensors or bioimaging probes for lipid droplets, mitochondria and plasma membranes. [5][6][7][8][9][10][11][12] The BTZ group has also been researched for photocatalytic applications although this has mainly been limited to heterogeneous systems involving BTZ containing metal-organic frameworks (MOFs), [13][14][15] covalent organic frameworks (COFs), [16][17][18] and conjugated porous polymers (CPPs).…”

Stereo-electronic effect of the perfluoropropyl group on the solid-state molecular packing of isomeric dibenzo[a,c]phenazine derivatives

“…54 Moreover, dibenzo[a,c]phenazine is used as a promising n-type building block in the research and development of organic semiconductor materials, ranging from OLEDs, to solar cells, catalysts, and phototransistors. [55][56][57][58] Despite their potential applications in the organic semiconductor field, research on the crystal structure and analysis of the crystal packing of dibenzo[a,c]phenazine derivatives have been scarcely reported. 59,60 Built on the foundation of our earlier work on perfluoroalkylated polyaromatic hydrocarbons (PAHs), [51][52][53]61 we report here the synthesis, characterization, and crystal structures of three isomers of perfluoropropylated dibenzo[a, c]phenazine.…”