Directional Building Blocks Determine Linear and Cyclic Silicon Architectures

Abstract

Silicon nanomaterials combine earth abundance and biodegradability with exceptional electronic properties. Strategic synthesis promises access to novel architectures with well-defined surface structure, size, and shape. Herein, we describe a five-step synthesis of functional macrocyclic polysilanes. Comparison of the materials isolated from isomeric building blocks provides evidence that building block directionality controls the shape of the resulting nanomaterial. Infrared (IR) and H andSi NMR spectroscopies, coupled to computational data, provide evidence of a well-defined Si-H and Si-Me terminated structure. The intrinsic porosity and the polarization arising from the hydridic character of the Si-H bond suggest applications in lithium-ion batteries, which are supported by quantum chemical calculations.

Functional Polymeric Materials Based on Main‐Group Elements

“…[19] Homo-catenation of the electron-deficient Group 13 elements into linear oligomeric chains of more than 2atoms has proved very challenging because of the relatively weak EÀ Eb ond strengths compared to the neighboring Group 14 elements (BÀB, AlÀAl, GaÀGa, and InÀIn BDEs:2 93, 188, 113, and 100 kJ mol À1 ) [5] and the strong tendency to form small cycles or clusters supported by organic ligands. [16].C opyright 2018 AmericanC hemical Society. Theu se of borylene units turned out essential for obtaining the elusive B 4 chain in the Fe complex 12 ( Figure 3) prepared by Braunschweig et al [21] Recently,t his group also disclosed acycliccatenated compounds (13), which consist of coupled borylborene pairs supported by N-heterocyclic carbenes (NHCs).…”

“…Theu se of borylene units turned out essential for obtaining the elusive B 4 chain in the Fe complex 12 ( Figure 3) prepared by Braunschweig et al [21] Recently,t his group also disclosed acycliccatenated compounds (13), which consist of coupled borylborene pairs supported by N-heterocyclic carbenes (NHCs). An exception is the spontaneous ring-opening of arsenomethane,( MeAs) 5 (16), which produces an insoluble purple solid with semiconducting properties.E xperimental and theoretical studies attributed the low solubility to ab ackbone structure consisting of aladder of two stacked poly(methylarsine) linear chains (19,Scheme 3,top). Top: Structures of oligosilanes with and without conformational constraints, UV-visible absorption maxima, and X-ray crystal structure of 8 (n = 2);adapted with permissionf rom Ref.…”

Funktionelle polymere Materialien auf der Basis von Hauptgruppen‐Elementen

“…[10] Alle diese verketteten Polymere weisen eine s-Konjugation auf,w as zu interessanten optischen und elektronischen Eigenschaften führt, einschließlich Halbleitereigenschaften nach Dotierung oder Photobestrahlung. [16] Anwendungen dieser Materialtypen sind in elektronischen Geräten denkbar,w obei die halbleitenden Eigenschaften genutzt werden. Der Konjugationseffekt wird in der Regel anhand der bathochromen Verschiebungen in den Absorptionsspektren bei Kettenverlängerung bewertet.…”

“…B. durch Boran-katalysierte Hydrosilylierung von Alkinen. Eine Ausnahme bildet die spontane Ringçffnung von Arsenomethan (MeAs) 5 (16), die einen unlçslichen violetten Feststoff mit halbleitenden Eigenschaften erzeugt. Diese Oligomere erwiesen sich als makrocyclisch, wie detaillierte Schwingungsund NMR-spektroskopische Analysen zeigten.…”

“…Diese Oligomere erwiesen sich als makrocyclisch, wie detaillierte Schwingungsund NMR-spektroskopische Analysen zeigten. [16] Anwendungen dieser Materialtypen sind in elektronischen Geräten denkbar,w obei die halbleitenden Eigenschaften genutzt werden. Die relativ geringe Stärke von E-E-Bindungen (E = Si, Ge,S n) kann auch in Photoresist-Technologien genutzt werden.…”