Molecular metal-containing soft materials

It is a privilege to welcome the readers of Dalton Transactions to this themed issue on molecular metal-containing soft materials. In assembling the collection, we have focused on emerging trends related to metallosurfactants, metallomesogens, metallopolymers, metallorganic frameworks, supramolecular, and hierarchical materials that take advantage of the geometric, redox, and magnetic properties of 3d, 4d, 5d transition metals, lanthanides, and main group metals to build up organized and often responsive architectures based on “soft” organic scaffolds.

The articles published here represent a contribution of almost 200 researchers from over 70 top groups in more than 60 universities and research centers in East, South and Southeast Asia, Europe, North America, and Oceania, and were selected following the usual rigorous peer review advocated by the Royal Society of Chemistry. We are particularly proud to report that about 40% of the authors are female; not yet the desired 50 : 50 split, but certainly a big step in the right direction.

We have two Perspective reviews, coincidentally on molecular electronics; one by Low and collaborators on the design of molecular wires based on acetylide complexes (DOI: 10.1039/C8DT02103A), and another by Verani on molecular rectifiers based on five-coordinate metallosurfactants (DOI: 10.1039/C8DT02891E).

The topic of metallosurfactants was further presented in papers by Hallett, Dervisi, Fallis et al. investigating the cellular uptake of phosphorescent rhenium surfactants (DOI: 10.1039/C8DT00669E), Suades, Barnadas-Rodríguez et al. examining the biomedical applications of molybdenum-based metallosomes (DOI: 10.1039/C8DT01584H), and Paul, Fallis, Griffith et al. using small-angle neutron scattering to evaluate the hydrophobicity of metalloemulsions (DOI: 10.1039/C8DT02031K), whereas Brand et al. used in situ spectroelectrochemical methods to understand reduction-triggered orientation changes on LB films (DOI: 10.1039/C8DT00333E), and Verani et al. investigated the feasibility of current rectification by a bimetallic hydrophobe (DOI: 10.1039/C8DT03158D).

Metallomesogens were studied in articles by Hayami, Lindoy et al. inspecting the ferroelectric and luminescent behavior of zinc and platinum liquid crystalline species (DOI: 10.1039/C8DT01100A), and Laschat, Molard et al. examining the luminescence of columnar materials containing molybdenum clusters and crown ether derivatives (DOI: 10.1039/C8DT03254H).

Systems based on metallopolymers were investigated by Li et al. (DOI: 10.1039/C8DT01537F) and Patra, Mishra et al. (DOI: 10.1039/C8DT01818A). The first group was interested in the structure of layered zinc-based coordination polymers and their use as fluorescent sensors for amino acids, whereas the second was analyzing long-range electronic coupling between two ruthenium centers bridged by thiophene-based oligomers.

Four papers examined the development and uses of metallorganic frameworks and mixed-matrix materials. Cook, Lin et al.investigated copper, palladium, and iron nodes as fillers for mixed-matrix materials intended for membrane gas separation (DOI: 10.1039/C8DT00082D), Medishetty, Devi et al. developed metallorganic framework thin films using a new vapor–solid deposition methodology (DOI: 10.1039/C8DT00352A), Ren, Liu et al. synthesized lead-based 3D hybrid frameworks that display thermochromic luminescence (DOI: 10.1039/C8DT01469H), and Kirillov, Gu et al. investigated new cadmium-based architectures that hold promising photocatalytic properties toward the degradation of organic dye pollutants (DOI: 10.1039/C8DT02467G).

Several contributions focused on supramolecular materials; Weder et al. studied europium-based polymers capable of color switching (DOI: 10.1039/C8DT01580E), Newkome, Wesdemiotis et al. evaluated structural interconversions in triptycene-based systems (DOI: 10.1039/C7DT04571A), Sun et al. explored stereocontrolled self-assembly and transformations in lanthanide-based helicates (DOI: 10.1039/C8DT01808A), Sun, Li, Wang et al. investigated the self-assembly and host/guest interactions of terpyridine-based cages in the presence of zinc and iron (DOI: 10.1039/C8DT01044G), and Zhao, Liu, Wong et al. evaluated singlet oxygen generation triggered by energy transfer between two ionic iridium complexes (DOI: 10.1039/C8DT00720A).

The formation of hierarchical materials was examined by Stefankiewicz et al. on photoswitchable cadmium complexes with azobenzene-imines, (DOI: 10.1039/C8DT00590G), Tarakanov, Pushkarev et al. on controlled monomer dimer self-assembly (DOI: 10.1039/C8DT00384J), Lensen, Feiters, Elemans et al. on the formation of porphyrin hexamers (DOI: 10.1039/C8DT01572D), whereas Haga et al. investigated the use of ruthenium and iron-based polymers for the extraction of carbon nanotubes (DOI: 10.1039/C8DT01573B), and Hu et al. developed spherical polyelectrolyte brushes for imaging (DOI: 10.1039/C8DT01069B).

Finally, a few papers dealt with specific aspects of the reactivity and responsiveness of metal-containing soft materials, such as He, Rusling et al. who analyzed the oxidation of DNA by gold nanocatalysts on carbon (DOI: 10.1039/C8DT01966E), Biros, Werner et al. who demonstrated the feasibility of selective lanthanide extraction with tripodal ligands (DOI: 10.1039/C8DT02239A), and Orti, Housecroft et al. who studied copper complexes as luminophores in light-emitting electrochemical cells (DOI: 10.1039/C8DT01338A). A few other papers will appear in the online edition.

We are very thankful to every person who contributed to this issue, starting with the authors, and expanding to the reviewers and the dedicated staff at Dalton Transactions. Mike Andrews, Sarah Kenwright, Debora Giovanelli, Caroline Knapp, Helen Lunn, Jessica Moon and Romnik Thind along with many others are especially acknowledged. We hope the readers will enjoy this issue as much as we enjoyed working on it.

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