Organic Nanostructures with Controllable Morphology Fabricated from Mixed (Phthalocyaninato)(porphyrinato) Europium Double-Decker Complexes
journal contributionposted on 28.01.2010, 00:00 by Xiaomei Zhang, Quanbo Wang, Lizhen Wu, Wei Lv, Jitao Lu, Yongzhong Bian, Jianzhuang Jiang
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The self-assembly behavior of two sandwich-type mixed (phthalocyaninato)(porphyrinato) europium double-decker complexes, namely Eu(Pc)(TClPP) [Pc = phthalocyaninate; TClPP = meso-tetrakis(4-chlorophenyl)porphyrinate] (1) and optically active (R)- and (S)-EuH[Pc(OBNP)2](TClPP)] [Pc(OBNP)2 = phthalocyaninate with two aromatic chiral binaphthayl units attached at the nonperipheral positions] (2), has been comparatively studied. In addition, a hydrophilic additive with intense adhesive ability, sodium carboxymethylcellulose (CMC), was also introduced onto the sandwich-type self-assembly systems to combine with double-decker molecules to induce additional hydrophilic/hydrophobic interaction. In the absence of the additive CMC, the double-decker molecules of 1 self-assemble into nanobelts in mixed solvent of chloroform and methanol. Introduction of two aromatic chiral binaphthayl units onto the nonperipheral positions of phthalocyanine ligand in the sandwich-type mixed double-decker complex 2 leads to the formation of tubal nanostructures. Observation of significant difference in the circular dichroism (CD) spectra of (R)- and (S)-2 in chloroform from their aggregates dispersed in methanol confirms the effective intermolecular interaction due to the interplay of π−π interaction between adjacent double-decker molecules with chiral discrimination among chiral side chains at supramolecular level. With addition of CMC, cooperation of intrinsic intermolecular π−π interaction with additionally introduced hydrophilic/hydrophobic interaction between adjacent double-decker molecules induces the formation of nanoscale hollow spheres at 45 °C during the self-assembly process of 1 and 2.