One-pot synthesis of unsubstituted and methyl substituted-pyrazinyl diselenides and monoselenides: structural, optical property characterization and DFT calculations

Organoselenium compounds have long been fascinated researchers owing to their wide range of applications, such as in anticancer, in catalysis, and as molecular precursors for metal selenides. In this view, herein, the one-pot synthesis of dimethyl substituted and unsubstituted dipyrazinyl monoselenides, [(2-pyz)2Se] and [(2,5-Me2-3-pyz)2Se], and the corresponding dipyrazinyl disenides, [(2-pyzSe)2] and [(2,5-Me2-3-pyzSe)2], is demonstrated by the reduction of selenium metal using sodium borohydride at room temperature and a subsequent alkylation using the corresponding pyrazinyl halide in ethanol. All the diselenides and monoselenides were characterized using IR, UV-vis, photoluminescence, and NMR (1H, 13C{1H}, and 77Se{1H}) spectroscopy. The molecular structures of the diselenides and monoselenides were unambiguously determined by single-crystal X-ray diffraction (SC-XRD). The optical properties, including absorption, excitation, emission, and quantum yield, of these organoselenium compounds were examined. Additionally, DFT calculations were performed to determine the HOMO and LUMO orbitals, band gap, and oscillator strength of these ligands.

Facile one pot synthesis of highly photoresponsive coinage metal selenides (Cu1.8Se and Ag2Se) achieved through novel Cu and Ag pyridylselenolates as molecular precursors

Copper selenide (Cu_1.8Se) and silver selenide (Ag₂Se) have garnered unprecedented attention as efficient absorber materials for cost-effective and sustainable solar cells. Phase pure preparation of these exotic materials in a nano-regime is highly desirable. This account outlines a simple and easily scalable pathway to Cu_1.8Se and Ag₂Se nanocrystals using novel complexes [Cu{2-SeC₅H₂(Me-4,6)₂N}]₄ (1), [Ag{2-SeC₅H₂(Me-4,6)₂N}]₆ (2) and [Ag{2-SeC₅H₃(Me-5)N}]₆·2C₆H₅CH₃ (3·2C₆H₅CH₃) as single source molecular precursors (SSPs). Structural studies revealed that the Cu and Ag complexes crystallize into tetrameric and hexameric forms, respectively. This observed structural diversity in the complexes has been rationalized via DFT calculations and attributed to metal-metal bond endorsed energetics. The thermolysis at relatively lower temperature in oleylamine of complex 1 afforded cubic berzelianite Cu_1.8Se and complexes 2 and 3 produced orthorhombic naumannite Ag₂Se nanocrystals. The low temperature synthesis of these nanocrystals seems to be driven by the observed preformed Cu₄Se₄ and Ag₆Se₆ core in the complexes which have close resemblance with the bulk structure of the final materials (Cu_1.8Se and Ag₂Se). The crystal structure, phase purity, morphology, elemental composition and band gap of these nanocrystals were determined from pXRD, electron microscopy (SEM and TEM), EDS and DRS-UV, respectively. The band gap of these nanocrystals lies in the range suitable for solar cell applications. Finally, these nanocrystal-based prototype photo-electrochemical cells exhibit high photoresponsivity and stability under alternating light and dark conditions.

Isolation of monomeric copper(II) phenolate selenoether complexes using chelating ortho-bisphenylselenide-phenolate ligands and their electrocatalytic hydrogen gas evolution activity

A series of novel copper(II) phenolate selenoether complexes have been synthesized and structurally characterized for the first time from copper(I) phenanthroline and various substituted ortho-bisphenylselenide-phenol chelating ligands. The synthesized complexes exhibit Jahn-Teller distortion in their geometry and varied from distorted square planar to distorted octahedral by varying the substituent in the bis-selenophenolate ligand. The synthesized complexes electrocatalyze the hydrogen evolution reaction (HER) with a faradaic efficiency of up to 89%, and it was observed that the distorted square pyramidal geometry is the optimum geometry for the maximum efficiency of these copper complexes.

Internally functionalized multifaceted organochalcogen compounds

Internally functionalized multifaceted organochalcogen compounds have been designed and their ligand chemistry has been developed. The palladium complexes show remarkable homogeneous catalytic activity.

Applications of metal selenium/tellurium compounds in materials science

Metal chalcogenides are technologically important materials. Physical, chemical, electrical and mechanical properties of these materials can be fine-tuned by manipulating their shape, size and composition. Although several methods are employed for their synthesis, single-source molecular precursor route has emerged as a versatile strategy for their synthesis and in controlling shape, size and composition of the material under moderate conditions. This chapter gives a brief coverage on the design and development of single-source molecular precursors which have been employed for the preparation of metal selenide/telluride nanocrystals and for deposition of thin films. The discussion includes synthesis of transition-, main group and f-block metal chalcogenolate and/or chalcogenide clusters as precursors and their conversion into metal chalcogenides in the form of thin films and nanostructures. Precursors for ternary metal chalcogenides are also included.

Pyridyl and pyrimidyl chalcogenolates of coinage metals and their utility as molecular precursors for the preparation of metal chalcogenides

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.

Copper complexes of arylselenolate-based ligands: synthesis and catalytic activity in azide–alkyne cycloaddition reactions

Arylselenolate-based copper complexes have been synthesized and used as pre-catalysts for azide-alkyne cycloaddition reactions.

Diverse silver(i) coordination chemistry with cyclic selenourea ligands

The reactions of cyclic selenoureas with silver(i) salts yield new coordination complexes with sterically-controlled solid state aggregation.

Hemilabile silver(i) complexes containing pyridyl chalcogenolate (S, Se) ligands and their utility as molecular precursors for silver chalcogenides

A series of silver triphenylphosphine complexes containing pyridyl chacogenolate (S, Se) ligands has been synthesized by employing [AgCl(PPh₃)₃] and [Ag₂(μ-Cl)₂(PPh₃)₄].