Mesogenic Materials Containing Main Group Borondifluorides

  • Lai, Chung-Kung (PI)

Project Details

Description

Metallomesogens, i.e. metal-containing liquid crystals have been our research forcus during the past years. Recently, our research target has been partially shifted to liquic crystals containing Main group 13 (or IIIB) elements. Complexes or adducts containing boron difluoride (BF2) have received much attention during the past years. Many known boron difluoride complexes, widely investigated as fluorescent materials have shown the potential for application in many areas such as biological imaging, molecular probes, electroluminescent devices, photosensitizers and others. These complexes were often generated by reactions of boron trifluoride and pi-conjugated chelating ligands in non-oxygen containing solvents. Boron, a nonmetal element of Group 13 (IIIA), is considered as an electron deficient atom. It has an oxidation state of three or four (OS = 3, 4) and the resulting complexes all form a triangular or tetrahedral geometry. Many unique boron complexes have been reported and their optical properties were extensively investigated.Three common types of coordination modes, i.e. [O,O], [N,O] and [N,N0], have long been known for boron difluoride. Among the known complexes, the majority of boron complexes were coordinated with O,O-chelating ligands, such as diketonates and triketonate. Recently, much attention has been paid to such BF2-[O,O] complexes, when studied in applications of two-photo absorbing molecules, luminescent materials, sensors and near-IR probes. In contrast, rarer complexes coordinated to N,N-chelating ligands were known, such as diketiminates and formazanates. Only a few complexes were known to complex with N,O-chelating ligands, such as quinolone-ketones. These BF2-[N,O] complexes often showed interesting photophysical and photochemical properties, which might have applications in OLED, OFET, LCs and others. The diketiminate and formazanate moieties were often considered as redox-active and near-infrared dyes that showed larger Stokes shifts upon complexation to boron difluoride.In this proposal, a few series of borondifluoride complexes derived from heterocyclic compounds will be prepared, characterized and their potential mesomorphic properties are also investigated. Boron complexes containing mono-borondifluoride and bis-borondofluoride moieties will be studied. Columnar and smectic phases are expected to exhibit by these boron complexes depending the shape of the molecules. In addition, their optical properties will be also explored indetail.
StatusFinished
Effective start/end date1/08/1831/07/19

Keywords

  • Transition metals
  • coordination complexes
  • boron compounds
  • metallomesogens
  • disc-like
  • rod-like

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