Themed collection Selenium & Tellurium chemistry at the beginning of the 3rd millennium: a celebration of ICCST

Vito Lippolis and Claudio Santi introduce the New Journal of Chemistry themed collection on selenium & tellurium chemistry at the beginning of the 3rd millennium: a celebration of ICCST.

The reactivity of N-heterocyclic dichalcogenides and their sodium salts towards group 10 metal phosphine precursors has been investigated.

An overview of the preparation and synthetic potentialities of functionalized organoselenium and organotellurium compounds is presented.

Synthesis of and metallophilic interactions in N-heterocyclic chalcogenolates of coinage metals have been described and their utility as molecular precursors for binary and ternary chalcogenide materials has been demonstrated.

1,4-Anhydro-4-seleno-D-talitol is an exceptional selenium-containing small molecule with significant therapeutic potential; its beneficial actions firmly establish a new therapeutic paradigm in which selenium plays a central role.

This perspective highlights the critical analysis of the challenges, in the past decade, which led to the development of organoselenium compounds and their use as versatile catalysts in organic synthesis towards the oxidation of olefins and C–H bonds. Furthermore, the emphasis here differs from previous reviews of the field by classifying the various types of catalyses and the diverse strategies.

The existence of intramolecular chalcogen bonds (IChBs) in 2,6-disubstituted arylchalcogen derivatives is determined by the substituents and the sigma hole donor behavior of the chalcogen atom in the molecule.

Key developments in the coordination chemistry of the soft, neutral chalcogenoether ligands towards hard s-, f- and early d-block ions, and their prospects for various applications are discussed.

Multidentate chalcogen-centred ligands, whose flexibility and redox-activity is manifested in their metal complexes, are generated from bis(chalcogenophosphinoyl) C-bridged anions via selenium–proton exchange or direct reaction with chalcogens.

Recent advances on transition-metal-catalyzed direct chalcogenation of C–H bonds with disulfides and diselenides are summarized.

Recent advances in the speciation and identification of tellurium metabolites in animals and plants by LC-ICP-MS and LC-ESI-MS are reviewed.

This review showcases recent work devoted to placing heavy inorganic elements within π-conjugated frameworks and the novel properties that can arise.

Key aspects for the development of a greener synthesis and the use of the organoselenium compounds.

This tutorial review elucidates the fundamental concepts necessary for an understanding of the unique structures and reactivities of tellurium compounds.

Pure thin films of metal tellurides, such as CdTe, Sb₂Te₃ and In₂Te₃, can be generated from complexes of the [TePrⁱ₂PNPPrⁱ₂Te]⁻ ligand by using the technique of aerosol-assisted chemical vapour deposition.

Cyclic selenocysteine-containing peptides were synthesized via one-pot tandem conversion of N-alkylcysteine-containing selenopeptides.

α-Fluoroalkylselenolated sulfones have been readily obtained via a visible-light promoted radical addition of fluoroalkylselenyl and tosyl groups onto unsaturated substrates.

Novel stable tellurium-containing carbohydrates are prepared; these react very rapidly with two-electron oxidants and show promise as protective agents.

A first example of Ugi 5-component 5-center reactions resulted in methionine and Se-methionine type peptide and peptoid building blocks.

The first example of a chromo-fluorogenic chemosensor containing a selenourea moiety is here described.

The first tellurocarbonyl complex with a half-sandwich structure [CpRuCl(CTe)(H₂IMes)] was synthesized and compared with its CE (E = O, S, Se) analogs.

Permanently porous hydrogen-bonded organic frameworks comprising rod-like molecules with two MIDA boronate termini have been prepared.

A non-traditional and robust probe skeleton was derivatized for chemosensing applications to investigate a potential novel mode of hypochlorite detection.

The versatile coordinating ability of a novel spirocyclic, P₂N₂-supported Te₅ dianion is exemplified by N,N′-bonding to Na⁺ ions and Te,Te′,Te′′ linkages to a Cp*Rh(III) group.

The first general approach for the biosynthesis of selenoproteins that contain photocaged selenocysteine residues at genetically-encoded positions is described.

The zirconium-mediated syntheses of pinacolboronate (BPin) appended benzo[b]tellurophenes and two phenyl/BPin substituted tellurophene isomers with different colors of emission have been achieved.

Diselenolodiselenole (C₄Se₄) derivatives are synthesized for the first time by heating substituted diaryl diynes with elemental selenium. The optical, electrochemical and structural properties of C₄Se₄-derivatives are tuned by varying end-capping aromatic substituents.

Reaction of Woollins' reagent (WR) with pyridine yields the P(V) species PhPSe₂ stabilised by pyridine coordination. Its potential as a selenation reagent under mild conditions was shown by calculations and an experimental comparison to WR.

Benzamide ring-substituted, quinine-derived ebselen analogue is synthesized which exists in selenol form upon addition of PhSH. It catalyses oxidation of PhSH with H₂O₂ faster (10³-fold) than ebselen.

Phosphorodiselenoic acid esters with a binaphthyl group were reacted with alkenes in the presence of Bu₃SnH and AIBN to give phosphonoselenoic acid esters in moderate to good yields.

[PhP(Se)(μ-Se)]2 (Woollins' reagent, WR) with disodium alkenyl-diols and dibromoalkanes are able to construct a series of unusual nine- to fifteen-membered organoselenophosphorus macrocycles bearing the O–P–Se–C_n–Se–P–O linkage or the O–P–Se–C_n–O–P–Se linkage.

Interactions between the electrode surface and the transition metal during the initial step of metal nanoparticle formation can be utilized to control the formation and size of metal nanoparticles deposited on a conducting surface.

The 15-membered rings [(^tBuN)P(μ-N^tBu)₂P(N^tBu)(μ-E–E)]₃ (E = Se, S) are comprised of planar P₆E₆ motifs stabilised by perpendicular P₂N₂ rings.

Novel photoluminescent selenospirocyclic and selenotetracyclic compounds, stabilized by intramolecular secondary Se⋯O interactions with an ortho-nitro group, have been accessed successfully through domino reactions of amines and imines, respectively.

The thermal reaction of a (dibenzobarreleneselenolato)(hydrido)platinum(II) complex gave two four-membered selenaplatinacycles by syn-hydroplatination and a vinylic C–H activation and a five-membered one by an aromatic C–H activation.

The 2 : 1 reactions between TMEDA·Li[(H)C(PPh₂Se)₂] and MCl₂ afforded the homoleptic complexes, {M[(H)C(PPh₂Se)₂]₂}, which undergo a selenium/hydrogen exchange at the carbon centre to yield the dianionic triseleno ligand in {M_n[(Se)C(PPh₂Se)₂]₂} (n = 1, M = Sn, Te; n = 2, M = Hg).

Cyclopenta[c]selenophene-(CH₂OMe)₂ has been synthesized by a new synthetic approach and successfully electrochemically polymerized. PCPS showed well-defined spectroelectrochemistry, a low band gap and good stability in the oxidized state. Calculations predicted a planar structure for PCPS.

Alkaline hydrolysis of (2-phenylazophenyl)tellurium trihalides gave an intramolecularly stabilized homometallic, heptanuclear organotellurium oxide cluster R₆Te₇O₁₁ (4) in good yield.

Alkyl and aryl substituted diazabutadiene ligands are shown to support a highly electrophilic “Se²⁺” synthon, which can be utilized in ligand exchange reactions to generate Se centred dicationic coordination complexes.

Triphenylborane adducts of benzo-2,1,3-telluradiazole are isoelectronic and isostructural analogues of N-alkyl-substituted telluradiazolyl cations.

The formally uncharged tellurium atom from the first telluroselenophosphonium cation [tBu(iPr)₂(p-TolTeSe)P]⁺ behaves as a soft acceptor towards the central tellurium atom of a diiodotellurate(II) anion [p-TolTeI₂]⁻, exhibiting a novel type of Te(anion)→ Te(cation) donor–acceptor interaction involving two orthogonal 3c–4e systems.

The first example of an undimerized π-stacked bis-1,2,3-thiaselenazolyl radical displays improved bandwidth and conductivity relative to an isostructural bis-1,2,3-dithiazolyl.

Optically active P-chiral phosphinoselenoic chlorides were successfully synthesized by reacting optically active phosphinoselenoic acid salts with oxalyl chloride. The chloride was converted to a phosphinoselenothioic acid salt with high ee.

Hexyl thiol has been transformed to hexyl selenol and related selenides and selenocyanate by substitution of the corresponding hexyldiphenylsulfonium tetrafluoroborate with selenium nucleophiles.

n-Channel OFETs using oligoselenophane- and oligothiophene-based semiconductors as active layers have been successfully fabricated, and the field-effect mobilities for the selenophane-based compounds are found to be higher than those for the thiophene analogues.

Five C_i–Se⋯O⋯Se–C_i atoms in anthraquinone and 9-(methoxy)anthracene bearing phenylselanyl groups at 1,8-positions align linearly, the origin of which is shown to be a non-bonded 5c–6e interaction of the five atoms.

Trimethylsilylselenoferrocene 1 has been prepared in good yield from sodium ferrocenylselenolate. The reagent 1 is used as for the synthesis [Cl₄Cd₄{μ₂-Se(C₅H₄)Fe(C₅H₅)}₆]²⁻2 (shown), a Cd₄Se₆ adamantoid cluster with six surface ferrocenyl groups.

Model studies on the trapping reaction of protein selenenic acids were carried out with a stable primary-alkyl model compound.

Selenophilicity, minimized dihedral angles, acidic selenols, multitarget hopping: cytosolic delivery with 1,2-diselenolanes outperforms 1,2-dithiolanes, by far.

The human body contains 25 selenoproteins, but challenges in their preparations have prevented biological characterizations thus far. Here we report the first total chemical syntheses of two human selenoproteins, selenoprotein M (SELM) and selenoprotein W (SELW).

One-electron oxidation of diaryldichalcogenides is the key to the preparation of the corresponding radical cations.

CdS/CdTe nanopencils were synthesized via anion exchange and the effect of the geometry on the carrier dynamics was investigated.

The in silico predicted Se⋯N interaction on amidoarylselenenyl iodides has been experimentally exploited for the efficient synthesis of N-substituted benzoisoselenazol-3(2H)-ones, benzoisothiazol-3(2H)-ones and ebselen, recently reported as potent antiviral agent against Sars-Cov2.

Three lead(II) bis(acylselenoureato) complexes were prepared by reaction of the respective acylselenourea compounds with Pb(OAc)₂. One of these lead complexes was converted into PbSe nano- and microstructures by microwave-assisted synthesis.

In this work, chalcogen functionalized dithiophenes, equipped on both extremities with chalcogen-bonding recognition heterocycles, have been prepared following two synthetic pathways.

The biological activity of sulfur and selenium, despite their similarity, shows some remarkable differences that have been recognized in many different scenarios.

New hybrid molecules containing benzo-2,1,3-thiadiazole, benzofuran and arylselanyl moieties were synthesized and their photophysics and biomolecule interactive studies were performed.

Various bimetallic bis- and tris-homocubane analogues of group 9 transition metals have been isolated and structurally characterized employing Li[BH₂E₃] (E = S or Se).

A novel methodology for accelerating the annulation was developed based on the reactions of selenium dihalides in the presence of alcohols.

A new electron acceptor is synthesized and reduced into its radical-anion isolated in the form of two salts with different structures and magnetic properties.

The nature of E⋯E′ in 1-RE–8-R′E′C₁₀H₆ (E/E′ = O, S, Se and Te) is clarified with the QTAIM approach and NBO analysis, after structural determinations.

An active and robust photocatalyst for water splitting.

A-ring selenation of naphthoquinones and anthraquinones is reported. The reaction proceeds in the presence of a copper source, and provides an efficient and general method for preparing selenium-based quinones with trypanocidal activity.

Formation of selenoxides improves the antioxidant activity of organoselenium compounds and should be considered as an important marker in the design of new selenium based antioxidants.

The first complex of an organotellurenium cation as a ligand with Pd(II) is reported.

Iso-tellurazole N-oxides yield a remarkable variety of structures with coinage-metal monocations.

Baking Pancakes: Dicationic products of the single-electron oxidation of phenoxatellurine.

Four diiron hexacarbonyl-complexes containing dithiolato (5), diselenolato (6), selenolato-thiolato (7) and μ²,κ³-C,O,Se-ligands (8), respectively have been prepared as [FeFe]-hydrogenase mimics.

Unusual isomorphic substitution in the crystals of [FcMe₂Te]⁺I⁻ with an admixture of Te–I ionized [FcMeTeI⁺]I⁻ supports the 3c-4e as a general, seamless bonding model for the hypervalent tellurium in both the isolated molecules and crystals.