A series of highly fluorescent liquid-crystalline perylenebisimide molecules having amide or ester linkage and end-capped by phenyl, monododecyloxy phenyl, or tridodecyloxy phenyl units have been synthesized and fully characterized. The amide-functionalized series self-organized to form H type aggregates regardless of their end-capping in organic solvents like tetrahydrofuran (THF), toluene, and dichloromethane. On the other hand, only the monododecyloxy phenyl end-capped molecule in the ester series showed a tendency to self-organize with a typical J type aggregation in toluene. In both series, the highest aggregation tendency was shown by the one having monododecyloxy phenyl end-capping, with the transition temperature from aggregated to molecularly dissolved species occurring at 60 °C for the amide and 50 °C for the ester molecule. At higher concentrations in toluene, the fluorescence spectra of the monododecyloxy phenyl and tridodecyloxy phenyl terminal-substituted amide derivatives showed the formation of a new peak corresponding to excimer emission at 670 nm. Thin drop cast films of the perylenebisimide ester and amide series gave only excimer emission ∼670 nm upon excitation. Thermal analysis using differential scanning calorimetry (DSC), polarized light microscopy (PLM), and powder X-ray diffraction measurements were utilized to study the liquid-crystalline (LC) characteristics of the molecules. Scanning electron micrograph (SEM) of thin drop-cast samples that were annealed in toluene showed the formation of supramolecular rods several micrometers in length, especially for the amide derivatives. The ester derivative, on the other hand, showed a leaflike morphology thus differentiating it from the amide series, which have both hydrogen bonding and π-π interactions to support self-organization.
アミドやエステルでつながり末端がphenyl基やmonododecyloxy phenyl基およびtridodecyloxy phenyl基で置換された高蛍光性液晶のperylenebisimide分子を合成し、同定を行った。アミド置換の分子は末端がアミドにもかかわらず、有機溶媒中においてH型会合体を形成する。一方で、エステル基の方はトルエン中でJ型会合体を形成する。いずれも場合も末端がmonododecyloxy phenyl基のものが最もよく会合し、会合体から溶解する転移温度はアミドで60°C、エステルで50°Cである。monododecyloxy phenyl基やtridodecyloxy phenyl基で置換されたアミド誘導体の高濃度トルエン溶液の蛍光スペクトルは、670 nmにエキシマー発光に相当する新たなピークが見られる。perylenebisimideエステルやアミド誘導体の薄膜では670nmより短波長のエキシマー発光のみが見られる。示差走査熱や偏光顕微鏡や粉末X線回折を用いた熱分析は分子の液晶性を研究するのに有用である。トルエン中でアニールされた薄膜のSEM観察では、特にアミド誘導体の場合で数μmの長さの超分子ロッドが見られた。一方、エステル誘導体では、水素結合やπ-π相互作用の両方によって自己集合が促進されるアミド誘導体とは異なり、葉状の形状が見られる。