Establishing Structure–Activity Relationships in Photocatalytic Systems by Using Nickel Bis(dithiolene) Complexes as Proton Reduction Catalysts

Abstract

Herein, we present an artificial photocatalytic system for H2 evolution based on a series of proton reduction catalysts, namely [Ni{S2C2(Ph)2}2] (1), [Ni{S2C2(Ph)2}2](NEt4) (1–), [Ni{S2C2(Ph)(Ph–OCH3‐4)}2] (2), [Ni{S2C2(Ph)(Ph–OCH3‐4)}2](NEt4) (2–), [Ni{S2C2(Ph–OCH3‐4)2}2] (3) and [Ni{S2C2(Ph–OCH3‐4)2}2](NEt4) (3–), [Ni(mnt)2] (NBu4) (4–), [Ni(mnt)(S2C2(Ph)2)](NBu4) (5–). These complexes are different of both in charge and the substituents on dithiolene ligand and represent a group of active catalysts for the reduction of protons with high TONs. A series of ReI complexes, [ReBr(CO)3 (bpy)], [ReCl(CO)3(bpy)], [Re(NCS)(CO3)(bpy)], [ReBr(CO)3(amphen)] and [ReBr(CO)3 (pq)] were used as photosensitizers, in combination with triethanolamine as a sacrificial electron donor and acetic acid as a proton source. The differences of the ligands in the electron donating properties and reactivity are discussed in the light of the experimental data. We also present the physicochemical characterization of a previously reported heteroleptic monoanionic complex (5–), by UV/Vis spectroscopy, FTIR spectroscopy, cyclic voltammetry and single‐crystal X‐ray diffraction studies.

Tunable NIR Absorption Property of a Dithiolene Nickel Complex: A Promising NIR-II Absorption Material for Photothermal Therapy

“…This indicates that NiBD-Cz may form J-aggregates in the NiBD-Cz NPs aqueous solution, which is conducive to excitation by 1064 nm laser irradiation . As we know, the maximum absorption of the reported MBD PTAs is mainly located at NIR-I, ,− and that of only a few is located in the NIR-II. The strong absorption in the NIR-II means that it has better application potential in the field of biotechnology.…”

Heteroleptic nickel complexes bearing O‐methyldithiophosphate and aminodiphosphine monosulfide ligands as robust molecular electrocatalysts for hydrogen evolution

“…It is therefore essential to develop efficient and more stable catalysts for hydrogen production that contain earth‐abundant and cheap metals that are easy to synthesize with inexpensive components. [ 12–14 ] With this in mind, a great number earth‐abundant transition metal complexes, such as nickel, [ 14–20 ] cobalt, [ 21–24 ] copper, [ 21,25,26 ] and zinc, [ 21 ] have been developed recently as molecular electrocatalysts for hydrogen evolution.…”

“…[ 16 ] Koutsouri and coworker have commented that the heteroleptic complex (NBu 4 )[Ni(mnt)(S 2 C 2 Ph 2 )] (mnt = maleonitriledithiolate) as a hydrogen evolution catalyst displaying significant photocatalytic activity with turnover number (TON) of 409, which performs better than the corresponding homoleptic complexes [Ni(S 2 C 2 Ph 2 ) 2 ] and (NBu 4 )[Ni (mnt) 2 ], respectively. [ 14 ]…”

Metalloligand Nickel Bis(Dithiolene) Based Metal–Organic Frameworks for Efficient Photocurrent and Photothermal Conversion

“…The results show good electrochemical activity of [NiS 4 ] center in the ligand, in agreement with previously described complexes in the literature. 26,44,45 The presence of reversible and stable oxidation states shows the prospects of these materials in the field of electrochemistry.…”

“…The anisotropy in the electron paramagnetic resonance (EPR) spectroscopies for the solid samples of [Ni(C 2 S 2 (C 6 H 4 COOH) 2 ) 2 ] (g value = 2.038), 1 and 2 (Figure c) at room temperature implies some contribution of the d orbital of nickel in the total spin density, which is usually, in this class of materials, distributed on nickel and the dithiolene ligands. , We have further studied the cyclic voltammetry (CV) of the nickel bis(dithiolene) based MOFs, 1 and 2 (Figure S14). The results show good electrochemical activity of [NiS 4 ] center in the ligand, in agreement with previously described complexes in the literature. ,, The presence of reversible and stable oxidation states shows the prospects of these materials in the field of electrochemistry.…”