Green-and-Red Photoluminescence from Si-Si and Ge-Ge Bonded Network Homopolymers and Copolymers

Recently, we found pure green photoluminescence (PL) at 540 nm (2.34 eV) in a vacuum, which is characteristic of a Si-Si bonded network polymer bearing n-butyl groups (organopolysilyne, SNP). SNP was carefully isolated as an orange-yellow solid by avoidance of contact with air and water in the polymer synthesis and PL measurement. This was in contrast with previous reports that SNPs carrying alkyl groups have a blue PL band around 450-480 nm. By applying the modified technique to a soluble Ge-Ge bonded network polymer carrying n-butyl groups (organopolygermyne, GNP), with much care in synthesising the polymer and measuring the PL, we found that GNP reveals a very brilliant red-coloured PL band at 690 nm (1.80 eV) in a vacuum at 77 K. This was in contrast with a previous report that GNP carrying n-hexyl groups has a green PL band at 560 nm (2.21 eV). On the other hand, soluble Si-Ge network copolymers (SGNPs) prepared in a similar way to SNP and GNP syntheses showed green-and-red dual PL bands at 540 nm and 690 nm. Based on analyses with IR, Raman, HR-TEM, XPS, EELS, UV-Vis and PL data, the dual emission was assumed to originate from the coexistence of Si and Ge domains (1-2 nm in diameter), possibly, in the same skeleton of SGNP

Molecular properties of helical polysilylenes in solution

Sato T., Terao K., Teramoto A., et al. Molecular properties of helical polysilylenes in solution. Polymer 44, 5477 (2003); https://doi.org/10.1016/S0032-3861(03)00574-3.This article reviews recent advances in research of helical conformations of optically active polysilylenes in solution. The helical conformation induces strong circular dichroism, chain stiffness, and liquid crystallinity in polysilylene chains, and it sensitively affects electronic state in the σ-conjugated silicon backbone. The helical conformation is determined by the internal rotation potential of the silicon backbone, and it turns out that the internal potential remarkably depends on the chemical structure of side-chains bonded to polysilylenes. Interrelations among these properties, the internal potential, and the side-chain chemical structure are discussed for optically active poly(dialkylsilylene)s

Solvent and Temperature Effects on the Chiral Aggregation of Optically Active Poly(dialkylsilane)s Confined in Microcapsules

Terao K., Mori Y., Dobashi T., et al. Solvent and Temperature Effects on the Chiral Aggregation of Optically Active Poly(dialkylsilane)s Confined in Microcapsules. Langmuir, 20(2), 306-308, December 12, 2003. Copyright © 2003, American Chemical Society. https://doi.org/10.1021/la0302798

Temperature and solvent dependence of stiffness of poly{n-hexyl-[(s)-3-methylpentyl]silylene} in dilute solutions

Terao K., Terao Y., Teramoto A., et al. Temperature and solvent dependence of stiffness of poly{n-hexyl-[(s)-3-methylpentyl]silylene} in dilute solutions. Macromolecules, 34(13), 4519-4525, May 25, 2001. Copyright © 2001, American Chemical Society. https://doi.org/10.1021/ma010212w

Circular Dichroism of Optically Active Poly(dialkylsilane) Aggregates in Microcapsules

Terao K., Kikuchi N., Sato S., et al. Circular Dichroism of Optically Active Poly(dialkylsilane) Aggregates in Microcapsules. Langmuir, 22(19), 7975-7980, August 10, 2006. Copyright © 2006, American Chemical Society. https://doi.org/10.1021/la060810+

Conformational transitions in poly{n-hexyl-[(S)-3-methylpentyl]silylene) in dilute solution: Temperature and molecular weight dependence detected by circular dichroism

Terao K., Terao Y., Teramoto A., et al. Conformational transitions in poly{n-hexyl-[(S)-3-methylpentyl]silylene) in dilute solution: Temperature and molecular weight dependence detected by circular dichroism. Macromolecules, 34(18), 6519-6525, July 24, 2001. Copyright © 2001, American Chemical Society. https://doi.org/10.1021/ma0104433

Stiffness of polysilylenes depending remarkably on a subtle difference in chiral side chain structure: Poly{n-hexyl-[(S)-2-methylbutyl]silylene)} and poly{n-hexyl-[(S)-3-methylpentyl]silylene}

Terao K., Terao Y., Teramoto A., et al. Stiffness of polysilylenes depending remarkably on a subtle difference in chiral side chain structure: Poly{n-hexyl-[(S)-2-methylbutyl]silylene)} and poly{n-hexyl-[(S)-3-methylpentyl]silylene}. Macromolecules, 34(8), 2682-2685, March 16, 2001. Copyright © 2001, American Chemical Society. https://doi.org/10.1021/ma002030s

Mirror Symmetry Breaking of Silicon Polymers-From Weak Bosons to Artificial Helix

From elemental particles to human beings, matter and living worlds ill our universe are dissymmetric with respect to mirror symmetry. Since the early 19th century, the origin of biomolecular handedness has been puzzling scientists. Nature's elegant bottom-Up preference, however, sheds light oil new concepts of generating, amplifying, and switching artificial polymers, supramolecules, liquid crystals, and organic crystals that call exhibit ambidextrous circular dichroism in the UV/Visible region with efficiency in production under milder ambient conditions. In the 1920s, Kipping, who first synthesized polysilanes with phenyl groups, had much interest in the handedness of inorganic and organic substances from 1898 to 1909 in his early research life. Polysilanes-which are Soluble Si-Si bonded chain-like near-UV chromophores that carry a rich variety of organic groups-may become a bridge between animate and inanimate polymer systems. The present account focuses on several mirror symmetry breaking phenomena exemplified in polysilanes carrying chiral and/or achiral side groups, which are in isotropic dilute solution, as polymer particles dispersed in solution, and in a double layer film immobilized at the solid surface, and subtle differences in the helix, by dictating ultimately ultraweak chiral forces at subatomic, atomic, and molecular levels