| Phthalocyanines and porphyrins are two important classes of pigments which have found their applications in various disciplines. Both series belong to a cyclic tetrapyrrole family in which the four isoindole or pyrrole nitrogen atoms are able to complex with a range of metal ions. With large metal centers which favor octa-coordination (e.g. rare earths, actinides, group 4 transition metals, and main group elements such as In, Sn, As, Sb, and Bi), sandwich-type complexes in the form of double- and triple-deckers can be formed. Due to the intramolecularπ-πinteractions and the intrinsic nature of the metal centers, these novel complexes display characteristic features, which cannot be found in their non-sandwich counterparts, enabling them to be used in different areas. They are versatile materials for electrochromic displays, field effect transistors, gas sensors and as structural and spectroscopic models for the special pair found in the bacterial photosynthetic reaction centers.Our research work has been focused on the following respects:1. The Electron-donating or -withdrawing Nature of Substituents Revealed By the Electrochemistry of Metal-free PhthalocyaninesThe effect of substituents on the electrochemistry of metal-free phthalocyanines was examined for seventeen phthalocyanine compounds, which also provides new information about the electronic donating or withdrawing nature of various substituents, namely alkoxy. alkylthio, alkyl, alkynyl, phenyloxy, and phenylthio groups attached onto the phthalocyanine system, from the viewpoint of electrochemistry. Most of the effects of peripheral and non-peripheral substitution on the electrochemistry of metal-free phthalocyanines have been reasonably explained by considering the energy levels of frontier molecular orbitals of corresponding compounds, which were obtained by the calculations using semi-empirical PM3 method.2.Study ofπ-conjugated Systems in Ring-Fused Phthaloyanine Derivatives and Bis-(na)pthalocyaninato Double-decker ComplexesWe have prepared a series of Pc derivatives with variousπ-conjugated systems by fusing benzo rings and quantitatively characterized the electronic structures. The LUMO and HOMO were found to have a parallel relationship. The shift of the redox potentials, and the relationship between the frontier orbitals and fused benzo rings were quantitatively characterized in terms of the CV measurements and MO calculations. Moreover, the electrochemistry of homoleptic bis(naphthalocyaninato) double-decker complexes for the whole series of tervalent rare earths M(TBNc)2 has been systematically studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The half-wave potentials of all the oxidations and the first reduction for double-decker complexes are dependent on the size of the metal center. The difference between the redox potentials of the first and second reductions for MⅢ(TBNc)2, which represents the potential difference between the first oxidation and first reduction of [MⅢ(TBNc)2]-, lies in the range 1.09-0.95 V and gradually diminishes along with the lanthanide contraction, indicating increasedπ-πinteraction in the double-deckers in the same order. Comparison of electrochemical characteristics between M(TBNc)2 and M(TBPc)2 reveals that the extension on the ligand conjugated system from phthalocyanine to naphthalocyanine attenuates the ring-to-ring separation effect on the redox potentials of the double-deckers of the whole series of tervalent lanthanides.3. H2O-involved hydrogen bonds in pseudo double-decker supramolecular structure of phthalocyaninato zinc complex1,8,15,22-Tetrakis(3-pentyloxy)phthalocyaninato zinc complex Zn[Pc(α-OC5H11)4] has been prepared by treating metal-free phthalocyanine H2Pc(α-OC5H11)4 with Zn(OAc)2·2H2O in refluxing n-pentanol. X-ray single crystal analysis reveals that two water molecules exist between two Zn[Pc(α-OC5H11)4] molecules. Each H2O coordinates with one zinc cation and hydrogen bonds with an aza-nitrogen atom and its neighboring oxygen atom from the alkoxy substituent of another molecule, forming a pseudo-double-decker supramolecular structure in the crystals with a ring-to-ring separation of 3.728 A. This, to the best of our knowledge, represents the first example of phthalocyaninato transition metal complexes, for which the H2O-involved hydrogen bonds connect two phthalocyanine rings to form a pseudo-double-decker supramolecular structure {Zn[Pc(α-OC5H114]·H2O}2. To enhance understanding the existence of hydrogen bonds in the solid state crystal structure of this compound, theoretical calculations on the stabilization energy in a system composed of two Zn[Pc(α-OC5H11)4] moieties as well as in the supramolecular structure {Zn[Pc(α-OC5H11</sub>4]·H2O}2 have been performed using the density functional theoretical method. Comparison in the calculated stabilization energy between these two systems together with the nature bond orbital analysis over the later supramolecular structure reveals the dominant H2O-involved hydrogen bonding interaction over theπ-πinteraction in {Zn[Pc(α-OC5H11)4]·H2O}2.4. Synthesis, Characterization, and OFET Properties of Amphiphilic Heteroleptic Tris(phthalocyaninato) Europium(Ⅲ) Complexes with Hydrophilic Poly(oxyethylene) SubstituentsA series of amphiphilic heteroleptic tris(phthalocyaninato) europium complexes with hydrophilic poly(oxyethylene) heads and hydrophobic alkoxy tails {Pc[(OC2H4)2OCH+3]8}Eu{Pc[(OC2H4)2OCH3]8}Eu[Pc(OCnH2n+1)8] (n = 6, 8, 10, 12) (1-4) were designed and prepared from the reaction between homoleptic bis(phthalocyaninato) europium compound {Pc[(OC2H4)2OCH3]8}Eu{Pc[(OC2H4)2OCH3]8} and metal free 2,3,9,10,16,17,23,24-octakis(alkoxy) phthalocyanine H2Pc(OCnH2n+1)8 (n = 6, 8. 10,12) in the presence of Eu(acac)3·H2O (Hacac = acetylacetone) in boiling 1,2,4-trichlorobenzene (TCB). 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 unusual bottom contact configuration. The devices display good OFET performance with the carrier mobility for holes in the direction parallel to the aromatic phthalocyanine rings, which shows dependence on the length of hydrophobic alkoxy side chains, decreasing from 0.46 for 1 to 0.014 cm2 V-1 s-1 for 4 along with the increase in the carbon number in the hydrophobic alkoxy side chains. |
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