Design, Synthesis, Organic Aggregation And NLO Properties Of Chiral Porphyrin And Phthalocycanine Compounds

As novel functional materials, porphyrins and phthalocyanines have been expected to be widely application in materials science, such as molecular electronics, molecular information storage, and nonlinear optics, etc. Recently, to obtain ordered supramolecular aggregates and nano-scale assembly, besides the expression, transmission, storage and regulation of molecular/supramolecular's chirality, have attracted increasing attentions. lit must be pointed out that self-assembly of functional molecules into a prerequisite nanostructure with desirable dimension and morphology via controlling inter-molecular interaction and the introduced chirality informations still remains a great challenge for scientists. In order to investigate the hierarchical assembly, the role of coordination bond in tuning the aggregates's morphology and the expression of chiral information at molecular/supramolecular level, in this thesis several chiral porphyrins and phthalocyanines are designed and synthesized. Our research work has been focused on the following respects:1. Helical Nano-structures Self-Assembled from Optically Active Phthalocyanine Derivatives Bearing Four Optically Active Binaphthyl Moieties:Effect of Metal-ligand Coordination on the Morphology, Dimension, and Helical Pitch of Self-Assembled Nano-structures(R)-and (S)-Enantiomers of optically active metal free tetrakis [11,12:13,14-di(1',2'-naphtho)-1,4,7,10,15,18-hexaoxacycloeicosa-2,11,13-trieno]-ph thalocyanine and their zinc complexes, (R)-and (S)-H2Pc (1) and (R)-and (S)-ZnPc (2), were prepared from the tetramerization of corresponding phthalonitriles, (R)-and (S)-2,3-(4',5'-dicyanobenzo)-11,12:13,14-di(1',2'-naphtho)-1,4,7,10,15,18-hexaoxacycloeicosa-2,11,13-triene, in the absence and presence of Zn(OAc)2·2H2O template, respectively, promoted by organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Their self-assembly behavior in the absence and presence of 4,4'-bipyridine has been comparatively investigated by electronic absorption and circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) technique, and X-ray photoelectron spectroscopy (XPS). The metal free phthalocyanine self-assembles into highly ordered fibrous nano-structures (ca.3um length,70 nm width, and 125 nm helical pitch) with left-handed and right-handed helicity for (R)-1 and (S)-1, respectively, through the hierarchical manner via one-dimensional helices with chirality determined by the optically active binaphthyl side chains. In contrast, self-assembly of the phthalocyaninato zinc analogue leads to the formation of nano-particles. However, in the presence of 4,4'-bipyridine, additionally formed metal-ligand Zn-N(4,4-bipyridine) coordination bonds between the nitrogen atoms of additive 4,4'-bipyridine molecule and the zinc center of (R)-and (S)-2 molecules together withπ-πinteraction and chiral discrimination of chiral side chains induce a right-handed and left-handed helical arrangement in a stack of (R)-and (S)-2 molecules, respectively, which further hierarchically packs into highly ordered fibrous nano-structures of average tens of micrometer length,30 nm width, and 106 nm helical pitch with the same helicity to the stack, revealing the effect of metal-ligand coordination bonding interaction on the morphology, dimension, handedness, and the helical pitch of self-assembled nano-structures.2. Synthesis, Circular Dichroism, and Third-Order Nonlinear Optical Properties of Optical Active Porphyrin Derivatives Bearing Four Meso Chiral Citronellal MoietiesA novel metal free meso-5,10,15,20-tetra-(2,6-dimethyl-5-heptenyl)porphyrin porphyrin [(R)-H2T(C9H17)4P (1)] with four chiral citronellal units attached at the meso positions of porphyrin and its zinc congener (R)-ZnT(C9H17)4P (2) have been designed, synthesized, and characterized. These two porphyrin compounds were characterized by 1HNMR, MS, third-order nonlinear optical (NLO) and various spectroscopic methods including IR, florescence, UV-vis and CD. Their florescence, UV-vis especially CD spectra changed after the formation of aggregates. Different from other porphyrin compounds containing chiral carbons, both metal free porphyrin and its zinc congener display positive CD signal in the Soret absorption region of porphyrin ligand, indicating effective chiral information transfer from the chiral citronellal tails to porphyrin chromophore at the molecular level. That's because the chiral citronellal tails were incorporated directly onto the meso positions instead of via meso-attached benzene ring. When self-assembled to aggregates, they displayed suparmolecular chirality with different directions.