Ladder-Type Pyran-fused Polycyclic Conjugated Molecules:Synthesis And Physical Properties

Molecular self-assembly base on the technology that the non covalent bond interaction through the spontaneous formation.self-assembly process is the whole complex synergistic effect,In addition to ligand affect their properties, and also affected by a great deal of physical and chemical factors. Self-assembly contain functiona π-πconjugated organic molecules have attracted increasingly attention due to their potential applications in organic or supramolecular electronics. polycyclic aromatic carbonhydrates (PAHs) are the main compound and often used as building block for construction of these materials. Until now, a good number of PAHs derivatives with different geometric and electronic structures have been designed and achieved, however, synthesis and characterization of heteroatom doped-PAHs derivatives are still very rare. Introducing oxygen into the all carbon aromatic skeleton of PAHs cloud result in dramatic changes in their physicochemical or electronic properties. In recent years pyran-fused polycyclic are an important class of photochromic dyes, it has being attract lot of attention and motivate interesting research.In this paper, We designed three kinds of oxygen-doped polycyclic aromatic carbonhydrates. We analysis the crystal structure and crystal packing of compound 4a-4c.Physicochemical properties and self-assembling behaviors of these pyran-fused compounds were fully inverstigated. The physicochemical properties of PAHs were characterized by UV vis,fluorescence spectrometry, besides The UV-vis absorption spectra of pyran-fused PAHs were further calculated at TD-DFT level. DSC and TGA result indicated that oxygen-doped PAHs exhibiting show good thermal stability with a weight loss of 5% over 290 ℃. We use Scanning elelctron microscopy (SEM) and Transmission electron microscope(TEM) to observe the Self-assemble of PAHs the result that the length of chain has a crucial effect on the self-assemble. The electrochemical behaviors of pyran-fused PAHs 4a-4c were subsequently investigated by cyclic voltammetry (CV) in CH3CN, the theoretical calculations of pyran-fused PAHs have been performed based on time-dependent density functional theory.Single-crystal X-ray diffraction (XRD) and optical spectroscopies analyses revealed that the synergetic effect of π-π stacking and van der Waals interactions play a key role in controlling the morphologies of these aggregates. And the pyran-fused structures essentially generated the extended π-conjugated systems and rich optical properties.