New platinum and ruthenium Schiff base complexes for water splitting reactions

Abstract

New platinum(ii) and ruthenium(ii) mononuclear complexes with naphthalene-based Schiff base ligands L1 (H2-selnaph) and L2 (H2-selnaph-COOH) were synthesized: Pt-selnaph (), Pt-selnaph-COOH (), Ru-selnaph(4-picoline)2 (), and Ru-selnaph(isoquinoline)2 (). The complexes were characterized by NMR spectroscopy, matrix-assisted laser desorption/ionization time-of-flight spectrometry, and elemental analysis, and their electrochemical and photophysical properties were investigated. The luminescent complexes and were used as photosensitizers for visible-light driven hydrogen production reactions in the presence of sacrificial electron donor triethylamine and cocatalyst precursor K2PtCl4 aqueous solution. When complex was attached to the surface of TiO2 by a carboxyl group, enhanced hydrogen photogeneration was achieved compared with complex alone, with turnover numbers of about 84 after 12 h irradiation. Calculations based on electrochemical and spectroscopic data also confirmed the feasibility of electron injection through the carboxyl group of complex into the conduction band of TiO2 for hydrogen production reactions. Complexes and were found to be efficient stable water oxidation (NH4)2Ce(NO3)6-driven catalysts with a first-order reaction behavior. A turnover frequency of 5.34 min(-1) was achieved for complex , while complex exhibited an enhanced turnover frequency of 11.9 min(-1) in pH 1.0 aqueous solution. Turnover numbers up to 1400 and 2060 were obtained after 6.5 h of reaction for and , respectively. Unique mechanistic information for water splitting is also presented through electrochemical, spectroscopic and ESI-MS high-valent ruthenium-oxo intermediate investigations.

Impact of Anchoring Groups on the Photocatalytic Performance of Iridium(III) Complexes and Their Toxicological Analysis

“…Additionally, a comprehensive analysis of the Ir(III) complexes was performed utilizing a combination of LC-ESI-Q-TOF MS and 1H NMR spectroscopy. A distinct peak observed between approximately 8.74 to 9.28 ppm in the 1 H NMR spectra is attributed to the ortho proton of isoquinoline [ 11 ]. These spectroscopic findings corroborate the anticipated molecular structures of the complexes.…”

“…Photocatalytic technology enables the effective harnessing and conversion of this energy type into various forms of power [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Particularly, the solar-driven photocatalytic water splitting technique offers an easy procedure for producing hydrogen fuel [ 11 , 12 ], a concept initially introduced in 1972 by Fujishima and Honda by utilising a TiO 2 photoanode [ 13 ]. After this study, the technology for hydrogen production through water splitting has evolved significantly [ 14 , 15 ].…”

Crystal structure oftrans-bis{4-bromo-N-[(pyridin-2-yl)methylidene]aniline-κ2N,N′}dichloridoruthenium(II)

“…Their complexes have found utility in a wide range of applications (Rezaeivala & Keypour, 2014;Gupta & Sutar, 2008). In particular, ruthenium(II) complexes of Schiff bases have been shown to display a variety of structural features and exhibit interesting biological and catalytic reactivities (Li et al, 2015;Wang et al, 2015;Drozdzak et al, 2005). Herein, we report the synthesis and crystal structure of a ruthenium(II) complex with the bidentate Schiff base ligand of 4-bromo-N-(2 0 -pyridylmethylene)aniline (PM-BrA), [RuCl 2 (C 12 H 9 BrN 2 ) 2 ], (I).…”

Photochemical transformation of a perylene diimide derivative beneficial for the in situ formation of a molecular photocatalyst of the hydrogen evolution reaction

“…In spite of the fact that platinum complexes seem to be a route to the most efficient and relatively economic “green” H 2 production, examples of their use in the role of photocatalyst itself are surprisingly scarce. 21 A few reported examples include Pt complexes with Schiff bases, although there is evidence of considerable problems with photostability, HER efficiency 22 and solubility in aqueous solutions. 23 The nature of the ligand ( e.g.…”