Design, Synthesis, Properties And Self-assembled Nanostructures Of Porphyrinato/Phthalocyaninato Complexes

Porphyrins are a group of organic compounds that frequently occur in nature. The porphyrin structure is the functional composition of chlorophyll, a kind of biomolecule. It is also the active site of hemoglobin, the well-known oxygen carrier protein. Phthalocyanines are analogues of porphyrins. Due to the additional 4 benzene rings on the periphery, they are more conjugated. Both series belonging to a cyclic tetrapyrrole family are able to be modified by chemical methods. At the same time, different metal atoms can also change the functions. Generally, with the help of transition metals, metal tetrapyrrole complexes can be obtained. While with large metal centers and high coordination numbers, sandwich-type double-and triple-deckers complexes can be formed. Special metal centers such as Mn and Zn can also induce axial coordination. Owing to the extraordinary optical, electrical, and magnetic properties, porphyrins, phthalocyanines, as well as their sandwich-type double-and triple-decker structures have been recently emerging as advanced molecular materials with great potential applications in the fields of molecular conductors, molecular electronics, molecular magnets, etc. In this thesis a series of porphyrin and/or phthalocyanine derivatives are designed, with their structures and properities comprehensively studied. Moreover, a new method for the synthesis of phthalocyanine was involved. Our research work has been focused on the following respects:1. Morphology-Controlled Self-Assembled Nanostructures of 5,15-Di[4-(5-acetylsulfanylpentyloxy)phenyl]porphyrin Derivatives. Effect of Metal-Ligand Coordination Bonding on Tuning the Intermolecular InteractionNovel metal free 5,15-di[4-(5-acetylsulfanylpentyloxy)phenyl]porphyrin H2[DP(CH3COSC5H10O)2P] (1) and its zinc congener Zn[DP(CH3COSC5H10O)2P] (2) were designed and fabricated into organic nanostructures by a phase-transfer method. Their self-assembling properties in MeOH and n-hexane were comparatively investigated by scanning electronic microscopy (SEM) and X-ray diffraction (XRD) technique. Inter-molecularπ-πinteraction of metal free porphyrin 1 leads to the formation of hollow nanospheres and nanoribbons in MeOH and n-hexane, respectively. In contrast, introduction of additional Zn-O coordination bond for porphyrinato zinc complex 2 induces competition with inter-molecularπ-πinteraction, resulting in nanostructures with nanorod and hollow nanosphere morphology in MeOH and n-hexane. The present result appears to represent the first effort towards controlling and tuning the morphology of self-assembled nanostructures of porphyrin derivatives via molecular design and synthesis through introduction of metal-ligand coordination bonding interaction. Nevertheless, availability of single crystal and molecular structure revealed by X-ray diffraction analysis for both porphyrin derivatives renders it possible to investigate the formation mechanism as well as the molecular packing conformation of self-assembled nanostructures of these typical organic building blocks with large conjugated system in a more confirmed manner.2. Design, Synthesis, Characterization, and OFET Properties of Amphiphilic Heteroleptic Tris(phthalocyaninato) Europium(III) Complexes. The Effect of Crown Ether Hydrophilic SubstituentsTwo amphiphilic heteroleptic tris(phthalocyaninato) europium complexes with hydrophilic crown ether heads and hydrophobic octyloxy tails [Pc(mCn)4]Eu[Pc(mCn)4]Eu[Pc(OC8H17)8] (m=12, n=4; m=18, n=6) (1,2) were designed and prepared. These novel sandwich triple-decker complexes have been characterized by a wide range of spectroscopic methods and electrochemically studied. With the help of Langmuir-Blodgett (LB) technique, these typical amphiphilic triple-decker complexes have been fabricated into organic field effect transistors (OFET) with top contact configuration on bare SiO2/Si substrate, hexamethyldisilazane (HMDS)-treated SiO2/Si substrate, and octadecyltrichlorosilane (OTS)-treated SiO2/Si substrate, respectively. The device performance is revealed to be dependent on the species of crown ether substituents and substrate surface treatment. The carrier mobility for hole as high as 0.33 cm2 V-1 s-1 and current modulation of 7.91×105 have been reached for the devices of triple-decker compound 1 deposited on the octadecyltrichlorosilane (OTS)-treated SiO2/Si substrates, indicating the effect of substrate surface treatment on the OFET performance due to the improvement on the film quality as demonstrated by the atomic force microscope (AFM) investigation results. 3. Nonperipherally Octa(butyloxy)-substituted Phthalocyanine Derivatives with Good Crystallinity. Effect of Metal-Ligand Coordination on the Molecular Structure, Internal Structure, and Dimension of Self-Assembled NanostructuresTo investigate the effect of metal-ligand coordination on the molecular structure, internal structure, dimension, and morphology of self-assembled nanostructures, two non-perpherally octa(alkoxyl)-substituted phthalocyanine compounds with good crystallinity, namely metal free 1,4,8,11,15,18,22,25-octa(butyloxy)phthalocyanine H2Pc(a-OC4H9)8 (1) and its lead complex Pb[Pc(α-OC4H9)8] (2), were designed and synthesized. Single crystal X-ray diffraction analysis reveals the distorted molecular structure with a saddle conformation for 1 and a Pb-connected pseudo-double-decker supramolecular structure with a domed conformation for 2, respectively. The formation of nanoribbons in the absence of Na+ with ca. 100 and 150 nm average width for 1 and 2, respectively, revealed the molecular structure (conformation) associated with metal-ligand (Pb-Nisoindole, Pb-Naza, and Pb-Obutyloxy) coordination on the dimension of nanostructures for 2. The formation of twisted nanoribbons in the presence of Na+ with ca.50 and 100 nm average width for 1 and 2, respectively, revealed the molecular structure (conformation) associated with additional metal-ligand (Na-Naza and Na-Obutyloxy) coordination bonds for both the compounds. Both nanoribbons and twisted nanoribbons display rich higher order refraction peaks in their XRD patterns, giving clear information about the internal structure of the nanoribbons. To the best of our knowledge, the present result represents the first self-assembled nanostructures fabricated from phthalocyanine derivatives with confirmed internal structure, controllable dimension and morphology, and high molecular ordering nature. It will be helpful for the design and preparation of phthalocyanine-based nanoelectronic and nanooptoelectronic devices with good performance due to the close relationship between molecular ordering and dimension of nanostructures and the performance and size of nanodevices.4. Bis[1,4,8,11,15,18,22,25-octa(butyloxyl)phthalocyaninato] Rare Earth Double-Decker Complexes:Synthesis, Spectroscopy, and Molecular StructureHomoleptic octa-α-substituted bis(phthalocyaninato) rare earth sandwich-type complex HMⅢ[Pc(α-OC4H9)8]2 [M=Eu(1), Y(2)] have been prepared in the presence of organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and benzo-18-crown-6/benzo-15-crown-5 in refluxing n-octanol. To the best of our knowledge, it is the first example of homoleptic non-peripherally octa(alkoxyl)-substituted bis(phthalocyaninato) rare earth complexes. Comparative studies on a series of reactions reveal the key role of DBU as catalyst and crown ether as template in the formation of homoleptic rare earth double-decker complexes with structurally highly deformed non-peripherally octa(butyloxy)-substituted phthalocyanine ligand. The molecular structure of the complex 1 has been determined by single-crystal X-ray diffraction analysis. The metal center is octa-coordinated by the isoindole nitrogen atoms of the two phthalocyaninato ligands, forming a distorted square antiprism. These two bis(phthalocyaninato) rare earth double-deckers have also been characterized by a wide range of spectroscopic methods including MS,1H NMR, UV-vis, IR, and EPR. Structural and spectroscopic studies reveals that theπ-πinteraction between the two Pc(a-OC4H9)g rings is weaker than that for the corresponding unsubstituted orβ-substituted bis(phthalocyaninato) analogues.