Nanoscale Organization of a Platinum(II) Acetylide Cholesteric Liquid Crystal Molecular Glass for Photonics ApplicationsShow others and affiliations
2020 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 30, no 28, article id 1910562Article in journal (Refereed) Published
Abstract [en]
The fabrication, molecular structure, and spectroscopy of a stable cholesteric liquid crystal platinum acetylide glass obtained from trans-Pt(PEt3)(2)(C(sic)C-C6H5-C(sic)N)(C(sic)C-C6H5-COO-Cholesterol), are described and designated as PE1-CN-Chol. Polarized optical microscopy, differential scanning calorimetry, and wide-angle X-ray scattering experiments show room temperature glassy/crystalline texture with crystal formation upon heating to 165 degrees C. Further heating results in conversion to cholesteric phase. Cooling to room temperature leads to the formation of a cholesteric liquid crystal glass. Scanning tunneling microscopy of a PE1-CN-Chol monolayer reveals self-assembly at the solid-liquid interface with an array of two molecules arranged in pairs, oriented head-to-head through the CN groups, giving rise to a lamella arrangement. The lamella structure obtained from molecular dynamics calculations shows a clear phase separation between the conjugated platinum acetylide and the hydrophobic cholesterol moiety with the lamellae separation distance being 4.0 nm. Ultrafast transient absorption and flash photolysis spectra of the glass show intersystem crossing to the triplet state occurring within 100 ps following excitation. The triplet decay time of the film compared to aerated and deoxygenated solutions is consistent with oxygen quenching at the film surface but not within the film. The high chromophore concentration, high glass thermal stability, and long triplet lifetime in air show that these materials have potential as nonlinear absorbing materials.
Place, publisher, year, edition, pages
Wiley , 2020. Vol. 30, no 28, article id 1910562
Keywords [en]
cholesteric liquid crystals, molecular dynamics, molecular glass, nonlinear optics, platinum acetylide, triplet states
National Category
Physical Chemistry Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-300800DOI: 10.1002/adfm.201910562ISI: 000535706000001PubMedID: 32684903Scopus ID: 2-s2.0-85085614911OAI: oai:DiVA.org:kth-300800DiVA, id: diva2:1594604
Note
QC 20210915
2021-09-152021-09-152023-06-19Bibliographically approved