Preparation, Crystal Structure, Thermal Analysis, Scanning Electron Microscopy and Optical Band-Gaps of Cu2GeTe4 and Cu2SnTe4 Alloys

Polycrystalline samples (weight ~ 1g) of Cu 2 GeTe 4 and Cu 2 SnTe 4 alloys were prepared by the usual melt and anneal method and the products characterized by X-Ray Diffraction (XRD), Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM) and Optical Diffuse Reflectance UV / VIS / NIR Spectroscopytechniques. It was found that: a) Cu 2 GeTe 4 and Cu 2 SnTe 4 crystallize in an orthorhombic structure (sg Imm2; N o44) with lattice parameters a = 5.9281 (4) Å, b = 4.2211 (6) Å, c = 12.645 (5) Å and a = 6.0375 (6) Å, b = 4.2706 (3) Å, c = 12.844 (1 ) Å, respectively; b) both alloys show two thermal transitions: 762 and 636K upon heating and; 700 and 578K upon cooling for Cu 2 GeTe 4 ; 702 and 636K upon heating and; 650 and 590K upon cooling for Cu 2 SnTe 4 ; c) both alloys present large deviations of stoichiometry for the cations Cu (~ 35%), Ge (7.2%) and Sn (26.4%) and minor deviation within the experimental error, for the anion Te; and, d) the measured optical band gaps were 0.63 and 0.53 eV for Cu 2 SnTe 4 and Cu 2 GeTe 4 , respectively.Polycrystalline samples (weight ~ 1 g) of the Cu 2 GeTe 4 and Cu 2 SnTe 4 alloys were prepared by the melting and annealing method and the products characterized by the techniques of X-ray diffraction (XRD), Thermal Differential Analysis (ATD). ), Scanning Electron Microscopy (SEM) and UV / VIS / CIR diffuse optical reflectance spectroscopy. It was found that: a) Cu 2 GeTe 4 and Cu 2 SnTe 4 crystallize in an orthorhombic structure (ge Imm2; N o44) with network parameters a = 5.9281 (4) Å, b = 4.2211 (6) Å, c = 12.645 (5) Å and a = 6.0375 (6) Å, b = 4.2706 (3) Å, c = 12.844 (1) Å, respectively; b) both alloys show two thermal transitions: 762 and 636K when heating and; 700 and 578K after cooling for Cu 2 GeTe 4 ; 702 and 636K when heating and; 650 and 590K after cooling for Cu 2 SnTe 4 ; c) both alloys present important stoichiometric deviations in their cations: Cu (~ 35%), Ge (7.2%) and Sn (26.4%) and lower than the experimental error for the anion Te; and d) the optical energy gaps measured were 0.63 and 0.53 eV for Cu 2 SnTe 4 and Cu 2 GeTe 4, respectively

Design, Synthesis, and Structure of Copper Dithione Complexes: Redox‐Dependent Charge Transfer

Redox‐active ligands impart versatility in transition metal complexes, which are attractive for photosensitizers, dye sensitized solar cells, photothermal therapy, etc. Dithiolene (Dt) ligands can transition between fully reduced and fully oxidized states. Herein, we report the syntheses, characterization, crystal structures and electronic properties of four [Cu(R2Dt0)2]+/2+ (R = Me, iPr) complexes, [Cu(iPr2Dt0)2][PF6] (1a), [Cu(iPr2Dt0)2][PF6]2 (1b), and [Cu(Me2Dt0)2][PF6] (2a), [Cu(Me2Dt0)2][PF6]2 (2b), where iPr2Dt0 = N,N′‐diisopropyl‐1,2‐piperazine dithione and Me2Dt0 = N,N′‐dimethyl‐1,2‐piperazine dithione. In addition, the molecular structure of [Cu(iPr2Dt0)2][BF4]2(1c) is also reported. Complexes 1a and 2a crystallized in the triclinic, P1 space group, and 1c crystallized in the monoclinic crystal system, space group C2/c. The single‐crystal X‐ray diffraction measurements show that the Cu(I) complexes have a distorted tetrahedral geometry, whereas the Cu(II) complex exhibits a true square‐planar geometry. Cu(I) complexes exhibit a low energy charge‐transfer band (450–650 nm), which are not observed in Cu(II) complexes. Electrochemical studies of these complexes show both ligand‐ and metal‐based redox couples

Toward the Synthesis of Designed Metal-Organic Materials

Metal-Organic Materials (MOMs) are an emerging class of crystalline solids that offer the potential for utilitarian design, as one of the greatest scientific challenges is to design functional materials with foreordained properties and eventually synthesize custom designed compounds for projected applications. Polytopic organic ligands with accessible heteroatom donor groups coordinate to single-metal ions and/or metal clusters to generate networks of various dimensionality. Advancements in synthesis of solid-state materials have greatly impacted many areas of research, including, but not limited to, communication, computing, chemical manufacturing, and transportation. Design approaches based on building blocks provide a means to conquer the challenge of constructing premeditated solid-state materials. Single-metal ion-based molecular building blocks, MNx(CO2)y+x, constructed from heterochelating ligands offer a new route to rigid and predictable MOMs. Specific metal bonds are considered responsible for directing the geometry or topology of metal-organic assemblies; these bond geometries constitute the building units, MNxOy. When these building units are connected through appropriate angles, nets or polyhedra can be targeted and synthesized, such as metal-organic cubes and Kagomé lattices. MNx(CO2)y+x MBBs can result in MN2O2 building units with square planar or see-saw geometries, depending on the mode of chelation. Using a 6-coordinate metal and a heterochelating ligand with bridging functionality, TBUs can be targeted for the synthesis of valuable networks, such as Zeolite-like Metal-Organic Frameworks (ZMOFs). Zeolitic nets, constructed from tetrahedral nodes connected through ~145° angles, are valuable targets in MOMs, as they inherently contain cavities and/or channel systems and lack interpenetration. Other design approaches have been explored for the design of ZMOFs from TBUs, such as the use of hexamethylenetetramine (HMTA) as an organic TBU. When this TBU coordinates to a 2-connected metal with appropriate angles, zeolite-like nets rare to metal-organic crystal chemistry can be accessed. Additionally, MNx(CO2)y MBBs have been used to construct metal-organic polyhedra (MOPs), used as supermolecular building blocks (SBBs), that can be peripherally functionalized and ultimately extended into threedimensional ZMOFs. Rational synthesis, mainly based on building block approaches, advances bridging the gap between design and construction of solid-state materials. However, some challenges still arise for the establishment of reaction conditions for the formation of intended MBBs and thus targeted frameworks

Toward the Synthesis of Designed Metal-Organic Materials

Metal-Organic Materials (MOMs) are an emerging class of crystalline solids that offer the potential for utilitarian design, as one of the greatest scientific challenges is to design functional materials with foreordained properties and eventually synthesize custom designed compounds for projected applications. Polytopic organic ligands with accessible heteroatom donor groups coordinate to single-metal ions and/or metal clusters to generate networks of various dimensionality. Advancements in synthesis of solid-state materials have greatly impacted many areas of research, including, but not limited to, communication, computing, chemical manufacturing, and transportation. Design approaches based on building blocks provide a means to conquer the challenge of constructing premeditated solid-state materials. Single-metal ion-based molecular building blocks, MNx(CO2)y+x, constructed from heterochelating ligands offer a new route to rigid and predictable MOMs. Specific metal bonds are considered responsible for directing the geometry or topology of metal-organic assemblies; these bond geometries constitute the building units, MNxOy. When these building units are connected through appropriate angles, nets or polyhedra can be targeted and synthesized, such as metal-organic cubes and Kagomé lattices. MNx(CO2)y+x MBBs can result in MN2O2 building units with square planar or see-saw geometries, depending on the mode of chelation. Using a 6-coordinate metal and a heterochelating ligand with bridging functionality, TBUs can be targeted for the synthesis of valuable networks, such as Zeolite-like Metal-Organic Frameworks (ZMOFs). Zeolitic nets, constructed from tetrahedral nodes connected through ~145° angles, are valuable targets in MOMs, as they inherently contain cavities and/or channel systems and lack interpenetration. Other design approaches have been explored for the design of ZMOFs from TBUs, such as the use of hexamethylenetetramine (HMTA) as an organic TBU. When this TBU coordinates to a 2-connected metal with appropriate angles, zeolite-like nets rare to metal-organic crystal chemistry can be accessed. Additionally, MNx(CO2)y MBBs have been used to construct metal-organic polyhedra (MOPs), used as supermolecular building blocks (SBBs), that can be peripherally functionalized and ultimately extended into threedimensional ZMOFs. Rational synthesis, mainly based on building block approaches, advances bridging the gap between design and construction of solid-state materials. However, some challenges still arise for the establishment of reaction conditions for the formation of intended MBBs and thus targeted frameworks

Chapter 10: Chalcogenides and Non-oxides

Comprehensive Inorganic Chemistry II reviews and examines topics of relevance to today’s inorganic chemists. Covering more interdisciplinary and high impact areas, Comprehensive Inorganic Chemistry II includes biological inorganic chemistry, solid state chemistry, materials chemistry, and nanoscience. The work is designed to follow on, with a different viewpoint and format, from our 1973 work, Comprehensive Inorganic Chemistry, edited by Bailar, Emeléus, Nyholm, and Trotman-Dickenson, which has received over 2,000 citations. The new work will also complement other recent Elsevier works in this area, Comprehensive Coordination Chemistry and Comprehensive Organometallic Chemistry, to form a trio of works covering the whole of modern inorganic chemistry. Chapters are designed to provide a valuable, long-standing scientific resource for both advanced students new to an area and researchers who need further background or answers to a particular problem on the elements, their compounds, or applications. Chapters are written by teams of leading experts, under the guidance of the Volume Editors and the Editors-in-Chief. The articles are written at a level that allows undergraduate students to understand the material, while providing active researchers with a ready reference resource for information in the field. The chapters will not provide basic data on the elements, which is available from many sources (and the original work), but instead concentrate on applications of the elements and their compounds.https://nsuworks.nova.edu/cnso_chemphys_facbooks/1010/thumbnail.jp

Polymorphism in Novel Li2-II-IV-S4 Diamond-Like Semiconductors

Diamond-like semiconductors (DLSs) have structures that are derived from either the cubic or hexagonal form of diamond. The I2-II-IV-VI4 diamond-like semiconductors are particularly interesting systems for their tunable nature and technological applications in photovoltaic solar cells, spintronics, and non-linear optics, specifically second harmonic generation. Polymorphism, which may affect important physicochemical properties in these materials, has been commonly reported in binary and ternary systems, while investigations of polymorphism in quaternary DLSs have been less prevalent. Polymorphs have been observed crystallizing in the stannite (I-42m) and wurtzstannite (Pmn21) structure types, which differ in the closest-packed arrangement of the anions, cubic versus hexagonal respectively. Polymorphism may also be observed in quaternary DLSs that maintain the same anion packing, but differ only in the cation ordering arrangements within the tetahedral holes. In the hexagonally derived quaternary DLSs, the different cation ordering gives rise to at least three different structure types, wurtzstannite (Pmn21), wurtzkesterite (Pn), and cobalt (II) lithium silicate (Pna21). In this work, high-temperature solid-state synthesis in a Li2-II-IV-VI4 system lead to the discovery of two new polymorphic compounds, crystallizing in the Pna21 and Pn space groups. The two polymorphs were analyzed using single crystal X-ray diffraction, synchrotron X-ray powder diffraction, and optical diffuse reflectance UV/Vis/NIR spectroscop