Julien Massin

Recent developments in hydrogen evolving molecular cobalt(II)–polypyridyl catalysts

The search for efficient noble metal-free hydrogen-evolving catalysts is the subject of intense research activity. A new family of molecular cobalt(II)-polypyridyl catalysts has recently emerged. These catalysts prove more robust under reductive conditions than other cobalt-based systems and display high activities under fully aqueous conditions. This review discusses the design, characterization, and evaluation of these catalysts for electrocatalytic and light-driven hydrogen production. Mechanistic considerations are addressed and structure-catalytic activity relationships identified in order to guide the future design of more efficient catalytic systems.

Covalent Design for Dye-Sensitized H2-Evolving Photocathodes Based on a Cobalt Diimine–Dioxime Catalyst

Dye-sensitized photoelectrochemical cells (DS-PECs) for water splitting hold promise for the large-scale storage of solar energy in the form of (solar) fuels, owing to the low cost and ease to process of their constitutive photoelectrode materials. The efficiency of such systems ultimately depends on our capacity to promote unidirectional light-driven electron transfer from the electrode substrate to a catalytic moiety. We report here on the first noble-metal free and covalent dye-catalyst assembly able to achieve photoelectrochemical visible light-driven H2 evolution in mildly acidic aqueous conditions when grafted onto p-type NiO electrode substrate.

Dye-sensitized PS-b-P2VP-templated nickel oxide films for photoelectrochemical applications

Moving from homogeneous water-splitting photocatalytic systems to photoelectrochemical devices requires the preparation and evaluation of novel p-type transparent conductive photoelectrode substrates. We report here on the sensitization of polystyrene-block-poly-(2-vinylpyridine) (PS-b-P2VP) diblock copolymer-templated NiO films with an organic push–pull dye. The potential of these new templated NiO film preparations for photoelectrochemical applications is compared with NiO material templated by F108 triblock copolymers. We conclude that NiO films are promising materials for the construction of dye-sensitized photocathodes to be inserted into photoelectrochemical (PEC) cells. However, a combined effort at the interface between materials science and molecular chemistry, ideally funded within a Global Artificial Photosynthesis Project, is still needed to improve the overall performance of the photoelectrodes and progress towards economically viable PEC devices.

Red Emitting Neutral Fluorescent Glycoconjugates for Membrane Optical Imaging

A family of neutral fluorescent probes was developed, mimicking the overall structure of natural glycolipids in order to optimize their membrane affinity. Nonreducing commercially available di- or trisaccharidic structures were connected to a push-pull chromophore based on dicyanoisophorone electron-accepting group, which proved to fluoresce in the red region with a very large Stokes shift. This straightforward synthetic strategy brought structural variations to a series of probes, which were studied for their optical, biophysical, and biological properties. The insertion properties of the different probes into membranes were evaluated on a model system using the Langmuir monolayer balance technique. Confocal fluorescence microscopy performed on muscle cells showed completely different localizations and loading efficiencies depending on the structure of the probes. When compared to the commercially available ANEPPS, a family of commonly used membrane imaging dyes, the most efficient probes showed a similar brightness, but a sharper pattern was observed. According to this study, compounds bearing one chromophore, a limited size of the carbohydrate moiety, and an overall rod-like shape gave the best results.

Interactions of Isophorone Derivatives with DNA: Spectroscopic Studies

Interactions of three new isophorone derivatives, Isoa Isob and Isoc with salmon testes DNA have been investigated using UV-Vis, fluorescence and circular dichroism spectroscopic methods. All the studied compounds interact with DNA through intercalative binding mode. The stoichiometry of the isophorone/DNA adducts was found to be 1:1. The fluorescence quenching data revealed a binding interaction with the base pairs of DNA. The CD data indicate that all the investigated isophorones induce DNA modifications.

Synthesis of multifunctional lipid–polymer conjugates: application to the elaboration of bright far-red fluorescent lipid probes

A new class of lipid-ended polymer conjugates presenting reactive sites regularly distributed along the polymer chain were synthesized using RAFT polymerization. The chosen modular approach enables preparation of different lipid families by tuning the nature of the phospholipid α-end, the molecular weight and the lateral functions of the polymer chain. The multiple activated ester functions of the conjugates can indeed be used for the efficient coupling of a great variety of amino-containing entities of interest. In this study, we elaborated original fluorescent lipid–polymer probes for optical microscopy by coupling along the chain a controlled number of chromophores emitting in the far-red where auto-fluorescence and light absorption by biological samples are limited. Water-soluble fluorescent lipid probes exhibiting an enhanced brightness were obtained. As a proof of concept, these probes were able to efficiently label the lipid bilayer of liposomes of various sizes. Such multifunctional lipid-ended polymers thus exhibit great potential to functionalize model and natural lipid assemblies.

Correction: Interactions of Isophorone Derivatives with DNA: Spectroscopic Studies

The following information is missing from the Funding section: Wroclaw Centre of Biotechnology, Programme, The Leading National Research Centre (KNOW) provided funding for the publication of the results of the study.