Two-Coordinate Coinage Metal Complexes as Solar Photosensitizers

Abstract

Generating sustainable fuel from sunlight plays an important role in meeting the energy demands of the modern age. Herein, we report two-coordinate carbene-metal-amide (cMa, M = Cu­(I) and Au­(I)) complexes that can be used as sensitizers to promote the light-driven reduction of water to hydrogen. The cMa complexes studied here absorb visible photons (εvis > 103 M–1 cm–1), maintain long excited-state lifetimes (τ ∼ 0.2–1 μs), and perform stable photoinduced charge transfer to a target substrate with high photoreducing potential (E +/* up to −2.33 V vs Fc+/0 based on a Rehm–Weller analysis). We pair these coinage metal complexes with a cobalt–glyoxime electrocatalyst to photocatalytically generate hydrogen and compare the performance of the copper- and gold-based cMa complexes. We also find that the two-coordinate complexes herein can perform photodriven hydrogen production from water without the addition of the cobalt–glyoxime electrocatalyst. In this “catalyst-free” system, the cMa sensitizer partially decomposes to give metal nanoparticles that catalyze water reduction. This work identifies two-coordinate coinage metal complexes as promising abundant metal, solar fuel photosensitizers that offer exceptional tunability and photoredox properties.

Intra- and Intermolecular Charge-Transfer Dynamics of Carbene–Metal–Amide Photosensitizers

“…This degradation is unsurprising as the cyclic voltammogram (CV) trace reveals a nonreversible oxidation wave for the compound, leading to a lifetime too short for the cation to recombine with MePI – to form the stable neutral state. As the oxidative nonreversibility in Au Cz MAC is attributed to the polymerization of the unsubstituted 3- and 6- positions in the carbazole ligand, consistent with irreversible oxidation of bare Cz, our approach has been to make substitutions at these locations with tert -butyl groups in Au BCz MAC to impart reversibility, which is observed in its CV. , …”

“…In this paper, we fully investigate the establishment of the TADF equilibrium and intermolecular charge-transfer dynamics. Two of the materials studied here (i.e., Cu BCz MAC and Au BCz MAC ; Figure ) have been used in a photoelectrocatalytic cycle as a photosensitizer, as illustrated in Figure . Here, we generate a full picture of the charge-transfer dynamics of a series of cMa complexes necessary to understand the photocatalysis, utilizing a range of spectroscopic techniques.…”

Two-Coordinate Thermally Activated Delayed Fluorescence Coinage Metal Complexes: Molecular Design, Photophysical Characters, and Device Application

“…Apart from emissive dopants in EL application, TADF cMa complexes have recently demonstrated their potential as sensitizers to promote water reduction to H 2 . 285 Applications of these chromophores to make full use of both singlet and triplet excitons will also interest researchers in the such fields as organic lasers, photocatalysis, solar energy conversion, chemical sensor, and bioimaging.…”

“…Manipulating the excited states associated with different nature will bring in impressive, innovative, and distinguished emissive mechanisms and properties by the rational molecular design. Apart from emissive dopants in EL application, TADF cMa complexes have recently demonstrated their potential as sensitizers to promote water reduction to H 2 . Applications of these chromophores to make full use of both singlet and triplet excitons will also interest researchers in the such fields as organic lasers, photocatalysis, solar energy conversion, chemical sensor, and bioimaging.…”

Advancing Evidence-Based Data Interpretation in UV–Vis and Fluorescence Analysis for Nanomaterials: An Analytical Chemistry Perspective

“…Another important step in mitigating ambiguous UV–vis data analysis is to report the as-acquired UV–vis spectra with clearly labeled spectral intensities, rather than solely relying on normalized UV–vis data or simply ignore the scale of the UV–vis intensity. In nano science literature, it has been quite common to present normalized or arbitrarily scaled and/or baseline-offset spectra obtained from materials of varying sizes, concentrations, and compositions in the same figure. − While these approaches might be effective to highlight spectral differences among the samples, it can obscure potential issues in data reliability as UV–vis spectra can be highly distorted even when the sample UV–vis intensity is within the instrument LDR. − To promote evidence-based spectral interpretation, we believe it is imperative to avoid reporting the processed UV–vis spectra without the as-acquired spectra either in the Supporting Information or in the main text.…”