Self-Assembly of Optical Molecules with Supramolecular Concepts

Fabrication of nano-sized objects is one of the most important issues in nanoscience and nanotechnology. Soft nanomaterials with flexible properties have been given much attention and can be obtained through bottom-up processing from functional molecules, where self-assembly based on supramolecular chemistry and designed assembly have become crucial processes and techniques. Among the various functional molecules, dyes have become important materials in certain areas of nanotechnology and their self-assembling behaviors have been actively researched. In this short review, we briefly introduce recent progress in self-assembly of optical molecules and dyes, based mainly on supramolecular concepts. The introduced examples are classified into four categories: self-assembly of (i) low-molecular-weight dyes and (ii) polymeric dyes and dye self-assembly (iii) in nanoscale architectures and (iv) at surfaces

Self-assembly of tripodal squaraines: cation-assisted expression of molecular chirality and change from spherical to helical morphology

Let's do the twist: Tripodal squaraines self-assemble from acetonitrile to form hollow spheres, the complexation of which with Ca<SUP>2+</SUP> or Mg<SUP>2+</SUP> results in extended networks. An analogous chiral dye exhibits a bisignate CD couplet and a helical morphology upon Ca<SUP>2+</SUP> binding (see figure). Thus, the molecular chirality of a functional dye is expressed through specific cation binding and manifested in the form of supramolecular helicity

Squaraine dyes: a mine of molecular materials

This feature article highlights the recent developments in the field of squaraine chemistry. Attempts have been made to address the relevance of squaraine dyes as a class of functional organic materials useful for electronic and photonic applications. Due to the synthetic access of a variety of squaraine dyes with structural variations and due to the strong absorption and emission properties which respond to the surrounding medium, these dyes have been receiving significant attention. Therefore, squaraine dyes have been extensively investigated in recent years, from both fundamental and technological viewpoints

Aligned 1‑D Nanorods of a π‑Gelator Exhibit Molecular Orientation and Excitation Energy Transport Different from Entangled Fiber Networks

Linear π-gelators self-assemble into entangled fibers in which the molecules are arranged perpendicular to the fiber long axis. However, orientation of gelator molecules in a direction parallel to the long axes of the one-dimensional (1-D) structures remains challenging. Herein we demonstrate that, at the air–water interface, an oligo­(<i>p</i>-phenylenevinylene)-derived π-gelator forms aligned nanorods of 340 ± 120 nm length and 34 ± 5 nm width, in which the gelator molecules are reoriented parallel to the long axis of the rods. The orientation change of the molecules results in distinct excited-state properties upon local photoexcitation, as evidenced by near-field scanning optical microscopy. A detailed understanding of the mechanism by which excitation energy migrates through these 1-D molecular assemblies might help in the design of supramolecular structures with improved charge-transport properties