Synthesis of Protected Benzenepolyselenols

Previously unknown benzenepolyselenols have been synthesized and isolated in their acetyl-protected form. The two molecules 1,3,5-tris­(acetylseleno)­benzene and 1,2,4,5-tetrakis­(acetylseleno)­benzene were synthesized by the reductive dealkylation in Na/NH₃ of 1,3,5-tris­(<i>tert</i>-butylseleno)­benzene and 1,2,4,5-tetrakis­(<i>tert</i>-butylseleno)­benzene, respectively. Hexakis­(<i>tert</i>-butylseleno)­benzene was also synthesized and structurally characterized by single-crystal X-ray diffraction, but it was not possible to isolate hexakis­(acetylseleno)­benzene. The synthetic methodology is likely to be useful in the synthesis of other areneselenols

3D Printed Molecules and Extended Solid Models for Teaching Symmetry and Point Groups

Tangible models help students and researchers visualize chemical structures in three dimensions (3D). 3D printing offers a unique and straightforward approach to fabricate plastic 3D models of molecules and extended solids. In this article, we prepared a series of digital 3D design files of molecular structures that will be useful for teaching chemical education topics such as symmetry and point groups. Two main file preparation methods are discussed within this article that outlines how to prepare 3D printable chemical structures. Both methods start with either a crystallographic information file (.cif) or a protein databank (.pdb) file and are ultimately converted into a 3D stereolithography (.stl) file by using a variety of commercially and freely available software. From the series of digital 3D chemical structures prepared, 18 molecules and 7 extended solids were 3D printed. Our results show that the file preparation methods discussed within this article are both suitable routes to prepare 3D printable digital files of chemical structures. Further, our results also suggest that 3D printing is an excellent method for fabricating 3D models of molecules and extended solids

3D Printed Molecules and Extended Solid Models for Teaching Symmetry and Point Groups

Tangible models help students and researchers visualize chemical structures in three dimensions (3D). 3D printing offers a unique and straightforward approach to fabricate plastic 3D models of molecules and extended solids. In this article, we prepared a series of digital 3D design files of molecular structures that will be useful for teaching chemical education topics such as symmetry and point groups. Two main file preparation methods are discussed within this article that outlines how to prepare 3D printable chemical structures. Both methods start with either a crystallographic information file (.cif) or a protein databank (.pdb) file and are ultimately converted into a 3D stereolithography (.stl) file by using a variety of commercially and freely available software. From the series of digital 3D chemical structures prepared, 18 molecules and 7 extended solids were 3D printed. Our results show that the file preparation methods discussed within this article are both suitable routes to prepare 3D printable digital files of chemical structures. Further, our results also suggest that 3D printing is an excellent method for fabricating 3D models of molecules and extended solids

Synthesis of Protected Benzenepolyselenols

Previously unknown benzenepolyselenols have been synthesized and isolated in their acetyl-protected form. The two molecules 1,3,5-tris­(acetylseleno)­benzene and 1,2,4,5-tetrakis­(acetylseleno)­benzene were synthesized by the reductive dealkylation in Na/NH₃ of 1,3,5-tris­(<i>tert</i>-butylseleno)­benzene and 1,2,4,5-tetrakis­(<i>tert</i>-butylseleno)­benzene, respectively. Hexakis­(<i>tert</i>-butylseleno)­benzene was also synthesized and structurally characterized by single-crystal X-ray diffraction, but it was not possible to isolate hexakis­(acetylseleno)­benzene. The synthetic methodology is likely to be useful in the synthesis of other areneselenols

3D Printed Molecules and Extended Solid Models for Teaching Symmetry and Point Groups

Tangible models help students and researchers visualize chemical structures in three dimensions (3D). 3D printing offers a unique and straightforward approach to fabricate plastic 3D models of molecules and extended solids. In this article, we prepared a series of digital 3D design files of molecular structures that will be useful for teaching chemical education topics such as symmetry and point groups. Two main file preparation methods are discussed within this article that outlines how to prepare 3D printable chemical structures. Both methods start with either a crystallographic information file (.cif) or a protein databank (.pdb) file and are ultimately converted into a 3D stereolithography (.stl) file by using a variety of commercially and freely available software. From the series of digital 3D chemical structures prepared, 18 molecules and 7 extended solids were 3D printed. Our results show that the file preparation methods discussed within this article are both suitable routes to prepare 3D printable digital files of chemical structures. Further, our results also suggest that 3D printing is an excellent method for fabricating 3D models of molecules and extended solids

Tuning Band Gap Energies in Pb₃(C₆X₆) Extended Solid-State Structures

A detailed plane-wave density functional theory investigation of the solid-state properties of the extended organometallic system Pb₃C₆X₆ for X = O, S, Se, and Te has been performed. Initial geometry parameters for the Pb–X and C–X bond distances were obtained from optimized calculations on molecular fragment models. The Pb₃C₆X₆ extended-solid molecular structures were constructed in the space group <i>P</i>6/<i>mmm</i> on the basis of the known structure for X = S. Ground-state geometries, band gap energies, densities of states, and charge densities were calculated with the PBE-generalized gradient exchange-correlation functional and the HSE06 hybrid exchange-correlation functional. The PBE band gap energies were found to be lower than the HSE06 values by >0.7 eV. The band energies at points of high symmetry along the first Brillouin zone in the crystal were larger than the overall band gap of the system. Pb₃C₆O₆ was predicted to be a direct semiconductor (Γ point) with a PBE band gap of 0.28 eV and an HSE06 band gap of 1.06 eV. Pb₃C₆S₆ and Pb₃C₆Se₆ were predicted to have indirect band gaps. The PBE band gap for Pb₃C₆S₆ was 0.98 eV, and the HSE06 band gap was 1.91 eV. The HSE06 value is in good agreement with the experimentally observed band gap of 1.7 eV. Pb₃C₆Se₆ has a PBE band gap of 0.56 eV and a HSE06 band gap of 1.41 eV. Pb₃C₆Te₆ was predicted to be metallic with both of the PBE and HSE06 functionals. A detailed analysis of the PBE band structure and partial density of states at two points before and after the metallic behavior reveals a change in orbital character indicative of band crossing in Pb₃C₆Te₆. These results show that the band gap energies can be fine-tuned by changing the substituent X atom

Synthesis, Characterization, and Calculated Electronic Structure of the Crystalline Metal–Organic Polymers [Hg(SC₆H₄S)(en)]_<i>n</i> and [Pb(SC₆H₄S)(dien)]_<i>n</i>

The reaction of Hg­(OAc)₂ with 1,4-benzenedithiol in ethylenediamine at 80 °C yields [Hg­(SC₆H₄S)­(en)]_<i>n</i>, while the reaction of Pb­(OAc)₂ with 1,4-benzenedithiol in diethylenetriamine at 130 °C yields [Pb­(SC₆H₄S)­(dien)]_<i>n</i>. Both products are crystalline materials, and structure determination by synchrotron X-ray powder diffraction revealed that both are essentially one-dimensional metal–organic polymers with -M-SC₆H₄S- repeat units. Diffuse reflectance UV–visible spectroscopy indicates band gaps of 2.89 eV for [Hg­(SC₆H₄S)­(en)]_<i>n</i> and 2.54 eV for [Pb­(SC₆H₄S)­(dien)]_<i>n</i>, while density functional theory (DFT) band structure calculations yielded band gaps of 2.24 and 2.10 eV, respectively. The two compounds are both infinite polymers of metal atoms linked by 1,4-benzenedithiolate, the prototypical molecule for single-molecule conductivity studies, yet neither compound has significant electrical conductivity as a pressed pellet. In the case of [Pb­(SC₆H₄S)­(dien)]_<i>n</i> calculations indicate fairly flat bands and therefore low carrier mobilities, while the conduction band of [Hg­(SC₆H₄S)­(en)]_<i>n</i> does have moderate dispersion and a calculated electron effective mass of 0.29·<i>m</i>_<i>e</i>. Hybridization of the empty Hg 6s orbital with SC₆H₄S orbitals in the conduction band leads to the band dispersion, and suggests that similar hybrid materials with smaller band gaps will be good semiconductors

Synthesis, Characterization, and Calculated Electronic Structure of the Crystalline Metal–Organic Polymers [Hg(SC₆H₄S)(en)]_<i>n</i> and [Pb(SC₆H₄S)(dien)]_<i>n</i>

The reaction of Hg­(OAc)₂ with 1,4-benzenedithiol in ethylenediamine at 80 °C yields [Hg­(SC₆H₄S)­(en)]_<i>n</i>, while the reaction of Pb­(OAc)₂ with 1,4-benzenedithiol in diethylenetriamine at 130 °C yields [Pb­(SC₆H₄S)­(dien)]_<i>n</i>. Both products are crystalline materials, and structure determination by synchrotron X-ray powder diffraction revealed that both are essentially one-dimensional metal–organic polymers with -M-SC₆H₄S- repeat units. Diffuse reflectance UV–visible spectroscopy indicates band gaps of 2.89 eV for [Hg­(SC₆H₄S)­(en)]_<i>n</i> and 2.54 eV for [Pb­(SC₆H₄S)­(dien)]_<i>n</i>, while density functional theory (DFT) band structure calculations yielded band gaps of 2.24 and 2.10 eV, respectively. The two compounds are both infinite polymers of metal atoms linked by 1,4-benzenedithiolate, the prototypical molecule for single-molecule conductivity studies, yet neither compound has significant electrical conductivity as a pressed pellet. In the case of [Pb­(SC₆H₄S)­(dien)]_<i>n</i> calculations indicate fairly flat bands and therefore low carrier mobilities, while the conduction band of [Hg­(SC₆H₄S)­(en)]_<i>n</i> does have moderate dispersion and a calculated electron effective mass of 0.29·<i>m</i>_<i>e</i>. Hybridization of the empty Hg 6s orbital with SC₆H₄S orbitals in the conduction band leads to the band dispersion, and suggests that similar hybrid materials with smaller band gaps will be good semiconductors