| Owing to the unique optical, electrical, and properties, associated with the intriguing intramolecularπ-πinteractions, porphyrins, phthalocyanines, as well as sandwich type rare complexes, as a novel functional materials, have been expected to be widely potential application in materials science, such as in molecular electronics, molecular information storage, and nonlinear optics, etc. Phthalocyanines and porphyrins 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.Due to their fundamental importance in many biological processes, porphyrins (Pors) have been extensively studied in view of biomimetic synthetic models over the past few decades. So, in this paper, we described the synthesis of a series of new Pors and Mixed (Phthalocyaninato)(porphyrinato) Yttrium(III) Double-decker Complexes with novel photophysical properties. Our research work has been focused on the synthesis, characterization, optical properties, and photophysical properties of these macrocyclic tetrapyrrole compounds include the following four parts:1. Synthesis, Electrochemical and Spectroscopic Properties of C60-Porphyrin Dyads with Different Phenyl Ether LinkageA series of C60-porphyrin dyads, connected by phenyl ether linkage of one meso-phenyl group of the porphyrin moiety on para, meta, and ortho positions, respectively, together with their zinc complexes have been designed and synthesized. All of these compounds were characterized by means of MALDI-TOF mass spectrometry, elemental analysis, and 1H NMR. The electronic absorption spectroscopic and electrochemical studies show that there is a considerable interaction between the two chromophores in the ground state of these dyads. The fluorescence spectroscopic study reveals that the emission of porphyrin moiety is efficiently quenched by C60 moiety, and the quenching efficiency is higher when the C60 linked at the ortho position of meso-phenyl ring than that linked at para or meta positions, indicating the linkage dependence of the intramolecular interaction between the two chromophores in these dyads.2. Linkage Dependence of Intramolecular Fluorescence Quenching Process in Porphyrin-appended Mixed (Phthalocyaninato)(porphyrinato) Yttrium(III) Double-decker ComplexesThree novel mixed (phthalocyaninato)(porphyrinato) yttrium double-decker complexes appended with one metal free porphyrin chromophore at the para, meta, and ortho position, respectively, of one meso-phenyl group of the porphyrin ligand in the double-decker unit through ester linkage,3-5, have been designed, synthesized, and spectroscopically characterized. The photophysical properties of these three isomeric tetrapyrrole triads were comparatively investigated along with the model compounds metal free tetra(4-butyl)porphyrin H2TBPP (1) and mixed [1,4,8,11,15,18,22,25-octa(butyloxyl)phthalocyaninato] [tetra(4-butyl)-porphyrinato] yttrium double-decker complex HY[Pc(a-OC4H9)g](TBPP) (2) by steady-state and transient spectroscopic methods. The fluorescence of the metal free porphyrin moiety attached through ester linkage at the meta and ortho position of one meso-phenyl group of porphyrin ligand in the double-decker unit in triads 4 and 5 is effectively quenched by the double-decker unit, which takes place in several hundred femtoseconds. However, the fluorescence of the metal free porphyrin moiety attached at the para position of one meso-phenyl group of porphyrin ligand in the double-decker unit in triad 3 is only partially quenched, clearly revealing the effect of the position of porphyrin-substituent on the photophysical properties of the triads. Furthermore, the molecular structures of 3-5 were simulated using density functional theory (DFT) calculations. It was found that the relative orientation between the metal free porphyrin moiety and the double-decker unit for compound 3 is crossed, while those for compounds 4 and 5 are open- and closed-shellfish-like, respectively, which is suggested to be responsible for their different intramolecular fluorescent quenching efficiency. 3. Porphyrin Porphyrin-appended Mixed (Phthalocyaninato)(porphyrinato) Yttrium(Ⅲ) Double-decker Complexes:Effect of Connecting Position of Nonlinear Optical PropertiesThree novel mixed (phthalocyaninato)(porphyrinato) yttrium double-decker complexes appended with one metal free porphyrin chromophore at the para, meta, and ortho position, respectively, of one meso-phenyl group of the porphyrin ligand in the double-decker unit through ester linkage,1-3, as well as mixed [1,4,8,11,15,18,22,25-octa(butyloxyl)phthalocyaninato][tetra(4-butyl)-porphyrinato] yttrium double-decker complex HY[Pc(α-OC4H9)8](TBPP) (4) have been investigated by the open-aperture fs Z-scan technique. The third-order nonlinear optical (NLO) properties of these tetrapyrrole triads reveal their strong RSA properties with the nonlinear absorption shifting in the trace of RSA-SA-RSA-SA-RSA at femtosecond timescale. Interestingly, at the intensity of 7.48-8.39 GW/cm2 the triads 1 and 2 with a metal free porphyrin chromophore appended at the para and meta position, respectively, of one meso-phenyl group of the porphyrin ligand in the double-decker unit still remain at a characteristic response of RSA. In contrast, the triad 3 with a metal free porphyrin chromophore appended at the ortho position has already shown a trend of SA peak at the same intensity range, confirming the effect of the position of porphyrin-substituent on the photopysical properties of the triads..4. C60-modified Mixed (Phthalocyaninato)(porphyrinato) Yttrium(Ⅲ) Double-decker Complex:Synthesis, Characterization, and Photophysical PropertiesA novel mixed (phthalocyaninato)(porphyrinato) yttrium(Ⅲ) double-decker complex covalently linked with C60 chromophore at the para position of one meso-phenyl group of the porphyrin ligand by phenyl ether linkage has been designed and synthesized by treatment of the half-sandwich yttrium complex [YⅢ(acac)(Por)], generated in situ from [Y(acac)3]·nH2O (acac=acetylacetonate) and the C60-appended free base porphyrin (3), with 1,4,8,11,15,18,22,25-octa(butyloxyl)phthalocyanine under reflux in TCB in good yield. The photophysical properties of this novel dyad containing the C60 and mixed (phthalocyaninato)(porphyrinato) yttrium(Ⅲ) double-decker components were investigated by steady-state and transient spectroscopic methods. Comparative studies over the electronic absorption spectra document that there is no considerable electronic interaction between the C60 and mixed (phthalocyaninato)(porphyrinato) yttrium(Ⅲ) double-decker components in steady-state. Time-resolved absorption spectra of this dyad reveal a photoinduced electron transfer from the {HY[Pc(α-OC4H9)g](Por)} to C60 moiety upon irradiation at 400 nm, which excites both C60 and {HY[Pc(α-OC4H9)8](Por)} components, resulting in a charge-separated state with a lifetime longer than 1 ns. |
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