Linkage Dependence of Intramolecular Fluorescence Quenching

Sep 28, 2010 - Mixed (porphyrinato)(phthalocyaninato) rare-earth(III) double-decker complexes for broadband light harvesting organic solar cells. Yong...
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J. Phys. Chem. B 2010, 114, 13143–13151

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Linkage Dependence of Intramolecular Fluorescence Quenching Process in Porphyrin-Appended Mixed (Phthalocyaninato)(Porphyrinato) Yttrium(III) Double-Decker Complexes Xianyao Zhang,† Yong Li,‡ Dongdong Qi,§ Jianzhuang Jiang,*,†,§ Xingzhong Yan,*,‡ and Yongzhong Bian*,§ Department of Chemistry, Shandong UniVersity, Jinan 250100, China, Department of Chemistry, UniVersity of Science and Technology Beijing, Beijing 100083, China, and Center for AdVanced PhotoVoltaics, Department of Electrical Engineering and Computer Science, South Dakota State UniVersity, Brookings, South Dakota 57007, United States ReceiVed: June 30, 2010; ReVised Manuscript ReceiVed: September 14, 2010

Three 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 tetrakis(4butyl)porphyrin H2TBPP (1) and mixed [1,4,8,11,15,18,22,25-octakis(butyloxyl)phthalocyaninato][tetrakis(4butyl)porphyrinato] yttrium double-decker complex HY[Pc(R-OC4H9)8](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 mesophenyl 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 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. Introduction Porphyrins as well as their most important artificial analogues, phthalocyanines, are important classes of pigments that have fascinated chemists for many decades due to their applications in various disciplines.1 In recent years, both species have been among the most attractive building blocks for artificial photosynthetic systems due to the close similarity in their molecular and electronic structure to the bacteriochlorophyll derivative found in the photosynthetic reaction center (RC).2 In particular, sandwich-type bis(tetrapyrrole) complexes3 formed with large metal ions such as rare earth, actinide, early transition, and main group metals have been intensively investigated for the purpose of mimicking the photophysical behavior of the “special pair” in the RC. It must be pointed out that additional research interest for sandwich-type tetrapyrrole metal complexes also comes from their great potential applications in molecular electronic, photonic, and ionoelectronic devices.4 In addition to the extensive investigation over the photophysical properties of a large number of monomeric porphyrin and phthalocyanine derivatives,5 considerable efforts have been devoted to multiporphyrin arrays and heteroporphyrin-phthalocyanine arrays linked by covalent bond or supramolecular * E-mail: [email protected] (J.J). † Shandong University. ‡ South Dakota State University. § University of Science and Technology Beijing.

interactions.6-8 For example, the butadiyne-linked porphyrin arrays with ferrocene and fullerene terminals were revealed to exhibit efficient long-range charge-transfer properties.8a The windmill- and cyclic-porphyrin arrays display enhanced absorbing abilities and efficient excitation energy transfer processes between the constituent porphyrin units.8b,c Especially the photophysical studies over the heteropoprhyirn-phthalocyanine arrays have revealed that both the photoinduced electron and energy-transfer processes between the porphyrin and phthalocyanine chromophores are very efficient and can be altered by changing the structure and the environment.8d-f On the other hand, sandwich-type bis(tetrapyrrole) complexes show notable decrease of the first oxidation potentials and increase of the first reduction potentials as compared with the respective mono(tetrapyrrole) compounds.3 As a result, they can serve as potent electron donors,9a electron acceptors,9b and both roles,9c respectively, in charge-transfer materials. Covalently linked electron donor-acceptor systems involving sandwichtype bis(porphyrinate) metal unit were first reported in 1996 with a quinone9d,e or a pyromellitic imide9d chromophore as the electron-acceptor partner. In 2007, the photophysical properties for a series of porphyrin-appended bis(phthalocyaninato) europium complexes having different number of porphyrin substituents at the peripheral or nonperipheral position(s) of the phthalocyaine ligand were examined for the first time by this group.10 A rapid and efficient photoinduced electron-transfer

10.1021/jp106020t  2010 American Chemical Society Published on Web 09/28/2010

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SCHEME 1: Synthesis of the Porphyrin-Appended Mixed (Phthalocyaninato)(Porphyrinato) Yttrium(III) Double-Decker Complexes 3-5 Together with the Model Compound 2

process from the porphyrin unit(s) to [Eu(Pc)2] core was revealed. Very recently, Torres and co-workers synthesized a series of heterodyads composed of bis(phthalocyaninato) rare earth double-decker unit covalently linked to C60 and studied their photophysics.11 They found that photoexcitation of C60 leads to a rapid electrotransfer from the double-decker unit to the C60 and a charge-separated state, [REIII(Pc)(Pc′)]+-C60-, with lifetime longer than 3 ns. In the present paper, we describe in detail the synthesis and spectroscopic and photophysical properties of three novel mixed (phthalocyaninato)(porphyrinato) yttrium double-decker complexes appended with one metal-free porphyrin chromophore at the para, meta, and ortho position of one meso-phenyl group of the porphyrin ligand in the double-decker unit through ester linkage, 3-5, Scheme 1. Comparative studies clearly reveal the positional effect of the metal-free porphyrin chromophore covalently linked at one meso-phenyl group of porphyrin ligand of mixed (phthalocyaninato)(porphyrinato) yttrium(III) doubledecker unit on the photophysical processes. To the best of our knowledge, this represents the first trial toward understanding the effect of substituents at the sandwich-type bis(tetrapyrrole) metal complexes on the photophysical property based on mixed (phthalocyaninato)(porphyrinato) rare earth systems. Results and Discussion Synthesis and Characterization. As shown in Scheme 1, the synthesis of mixed (phthalocyaninato)(porphyrinato) yttrium double-decker complexes 2 and 10-12 involves the prior generation of the half-sandwich complex Y(acac)(Por) from

Y(acac)3 · nH2O and corresponding H2Por (1, 6, 7, or 8), followed by treatment with metal-free phthalocyanine H2Pc(R-OC4H9)8. In line with the previous results,12 only protonated species HY[Pc(R-OC4H9)8](Por) (2, 10-12) were isolated when nonperipherally octakis(butyloxy)-substituted phthalocyanine H2Pc(ROC4H9)8 was involved in the mixed ring rare earth double-decker complexes. Cross-condensation between the metal-free 5-(4acylchloride-phenyl)-10,15,20-tris(4-tert-butylphenyl)porphyrin (13) and protonated double-decker complexes 10-12 in chloroform in the presence of triethylamine afforded the tetrapyrrole triads 3-5 in good yields. Satisfactory elemental analysis results were obtained for all the three newly prepared tetrapyrrole triads containing protonated mixed (phthalocyaninato)(porphyrinato) yttrium doubledecker unit 3-5, Table 1. These three compounds were further characterized by MALDI-TOF mass and 1H NMR spectroscopic methods. The MALDI-TOF mass spectra of these compounds clearly showed intense signals for the protonated molecular ion ([M + H]+). The isotopic pattern closely resembled the simulated one as exemplified by the spectrum of 3 given in Figure S1 (Supporting Information). Satisfactory NMR spectra could not be obtained for either the protonated double-decker 2 or the triads containing the protonated double-decker unit 3-5 most probably due to the tautomerization of the acidic proton on the porphyrin ligand in the double-decker unit (it is worth noting that the acid proton in the protonated mixed ring doubledecker should locate on the porphyrin side according to our recent work).13 Upon addition of ca. 1% hydrazine hydrate, wellresolved spectra with virtually all the expected signals were

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TABLE 1: Analytical and Mass Spectroscopic Data for Triad Compounds 3-5 analysis (%)a compound

yield (%)

3 4 5

64 57 71

+

[M + H] (m/z)

a,b

2785.76 (2785.36) 2785.75 (2785.36) 2785.65 (2785.36)

C

H

N

76.55 (76.35) 76.45 (76.35) 76.61 (76.35)

6.88 (6.66) 6.68 (6.66) 6.52 (6.66)

8.15 (8.05) 7.98 (8.05) 8.11 (8.05)

a Calculated values given in parentheses. b By MALDI-TOF mass spectrometry. The value corresponds to the most abundant isotopic peak of the protonated molecular ion ([MH]+).

TABLE 2: Electronic Absorption Data for Compounds 1-5 in CH2Cl2 compound 1 2 3 4 5

λmax [nm] (log ε) 324 (4.84) 322 (4.95) 323 (4.84) 323 (4.92)

420 (5.83) 416 (5.35) 421 (5.68) 421 (5.66) 416 (5.61)

516 (4.50) 495 (4.79) 494 (4.85) 494 (4.73) 493 (4.75)

observed for 2-5. The IR spectra of 2-5 showed a distinct band at ca. 1325 cm-1, Figure S2 (Supporting Information), which is a characteristic signal for dianionic phthalocyaninato ligands.12,14 This result confirms the protonated nature of the double-decker unit in these complexes. Steady-State Electronic Absorption Spectra. It is worth noting that the electronic absorption spectroscopic properties of mixed (phthalocyaninato)(porphyrinato) rare earth complexes have been revealed to depend on the solvent employed.15 For the purpose of excluding the solvent effect, the electronic absorption spectra of all the triads 3-5 as well as the model compounds 1 and 2 were recorded in the same CH2Cl2 solvent, and the data are compiled in Table 2. Figure 1 compares the electronic absorption spectra of 1-3. H2TBPP (1) shows a typical electronic absorption feature of the metal-free porphyrin compounds with an intense Soret band at 420 nm and four weak Q bands at 517, 552, 592, and 649 nm, respectively. While the electronic absorption spectrum of mixed (phthalocyaninato)(porphyrinato) yttrium model compound 2 resembles those of HM[Pc(R-OC5H11)4](TClPP) [M ) Y, Sm, Eu; Pc(R-OC5H11)4

Figure 1. Electronic absorption spectra of 1 (a), 2 (b), and 3 (c) in CH2Cl2 together with the linear superimposition of the individual components of 1 and 2 (d).

552 (4.34) 567 (4.28) 556 (4.46) 554 (4.38) 555 (4.42)

591 (4.18) 623 (4.54) 622 (4.57) 623 (4.06) 623 (4.51)

648 (4.22) 647 (4.47) 645 (4.40) 648 (4.42)

951 (4.25) 951 (4.27) 951 (4.18) 952 (4.20)

) 1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninate],12 HY[Pc(ROC4H9)8](TClPP),12 and HM[Pc(OBNP)2](TClPP) (M ) Y, Eu; Pc(OBNP)2 ) binaphthyl-phthalocyaninate),15 indicating the protonated mixed ring double-decker nature of this complex, with the strong phthalocyanine and porphyrin Soret bands at 324 and 416 nm, respectively, and several Q bands in the range of 561-946 nm in addition to a band with medium intensity at 493 nm attributed to a transition involving a delocalized orbital. The electronic absorption spectrum of the triad 3 is a linear superimposition of the individual components of 1 and 2, indicating the absence of strong ground-state electronic interaction between the two components in 3. This seems also true for the remaining two isomeric triads 4 and 5, Figure S3 (Supporting Information). Photophysical Properties. Before expounding the photophysical properties of the present sandwich mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes, it appears necessary to give a very brief description over the luminescent properties of corresponding sandwich tetrapyrrole rare earth complexes. However, to the best of our knowledge, the results reported thus far on the photophyiscal properties of sandwich-type tetrapyrrole rare earth complexes still remain extremely rare most probably due to the very weak or actually lack of luminescence of such kind of compounds associated with the heavy rare earth atom effect and strong electronic interaction between the neighboring tetrapyrrole rings in the sandwich molecules. According to Holten and Yamauchi and co-workers,16a,b homoleptic bis(porphyrinato) complexes of Y and La with either octaethylporphyrin or tetraphenylporphyrin ligand gave no photoluminescence. This is also true for the unsubstituted homoleptic bis(phthalocyaninato) europium complex.10 However, weak photoluminescence was observed for either homoleptic bis[2,3,9,10,16,17,24,25-octakis(alkylthio)phthalocyaninato] rare earth complexes M[Pc(SC16H33)8]2 (M ) Eu, Lu, Tb)16c or heteroleptic bis(phthalocyaninato) rare earth species M(Pc)(Pc′) (M ) Sm, Eu, Lu).11 In the present case, no obvious emission was observed for the reference doubledecker compound HY[Pc(R-OC4H9)8](TBPP) (2) under either Soret band or Q-band excitation according to the steady-state emission measurement, indicating the presence of efficient fluorescence quenching of the porphyrin and phthalocyanine ligands in the double-decker compound. The steady-state emission spectrum of the metal-free porphyrin H2TBPP (1) is shown in Figure 2. As can be seen, upon an excitation at the Soret band around 420 nm, the metal-free porphyrin H2TBPP (1) showed two strong Q-band emission

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Figure 3. Fluorescence decay at the emission of 654 nm for 1 and 3 in CH2Cl2 with 417 nm excitation (dotted green line, IRF).

Figure 2. Steady-state fluorescence spectra of 1 and 3 in CH2Cl2 with excitation at 420 and 417 nm, respectively.

peaks.17 The fluorescence measurements on compounds 4 and 5 revealed that the fluorescence of metal-free porphyrin moiety which is connected via an ester linkage at the meta and ortho position of one meso-phenyl group of the porphyrin ligand in the double-decker unit, respectively, was completely quenched. This result is in good accordance with the studies of other covalently linked mixed porphyrin-phthalocyanine systems, in particular porphyrin-appended bis(phthalocyaninato) europium triad compounds which exhibit efficient photoinduced energy and/or electron transfer between the two subunits.8d-f,10 In the present case, intramolecular energy-transfer process from the excited porphyrin chromophore to the protonated mixed (phthalocyaninato)(porphyrianto) yttrium unit seems to be an reasonable assignment for the complete fluorescence quenching of metal-free porphyrin chromophore in the traids 4 and 5 on the basis of the good spectral overlap between the emission of H2TBPP (1) and the absoptions of HY[Pc(R-OC4H9)8](TBPP) (2). In contrast, the fluorescence measurements revealed that the emission of metal-free porphyrin chromophore covlently linked through ester linkage at the para position of one meso-phenyl group of porphyrin ligand in the double-decker unit in triad 3 was not completely quenched by the mixed (phthalocyaninato)(porphyrinato) yttrium component, Figure 2. In addition, the feature of fluorescence spectrum for this triad compound is very similar to that of metal-free porphyrin H2TBPP (1) despite the significantly decreased fluorescence intensity. Triad 3 has a relative fluorescence quantum yield (Φ/Φ0) of 0.0013 (determined by the comparative method with H2TBPP, Φ0 ) 0.12, as the standard).17e,f Comparison of the steady-state emission property of traid 3 with 4 and 5 clearly reveals the effect of the linking position of metal-free porphyrin moiety at the mixed (phthalocyaninato)(porphyirnato) yttrium double-decker unit on the fluorescence quenching process of the metal-free porphyrin moiety by the protonated mixed (phthalocyaninato)(porphyrin) double-decker unit in these triads. Time-resolved fluorescence dynamics of compounds 3-5 were studied in CH2Cl2. For comparative purpose, the model compounds 1 and 2 were also investigated, Figures 3 and 4. The time-resolved fluorescence dynamics of 4 and 5, with an excitation at 417 nm and an emission at 654 nm, revealed that

Figure 4. Fluorescence decay at the emission of 654 nm for 2, 4, and 5 in CH2Cl2 with 417 nm excitation (dotted green line, IRF).

the emission from the metal-free porphyrin moiety was completely quenched in less than 200 fs, Figure 4, indicating the ultrafast nature of this photoinduced process. Unlike the typical decay behavior of metal-free porphyrins for 1 with a long time decay component with time scale >33 ps

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Figure 5. Configuration parameter of complexes 3-5 from molecular mechanics calculations.

(which is out of the measurement range),17 a fast component with a time scale of 1.7 ps was observed in the fluorescence decay of 3 in addition to the a slow decay component with a time scale of ∼30 ps, Figures 3 and S4 (Supporting Information). The long time decay component, ∼30 ps for 3, is therefore assigned to the relaxation from Q-band to the triplet states of the metal-free porphyrin moiety in 3.8b,c,17d Further support for this point comes from the observation of the similar depolarization behavior of 1 and 3, Figure S5 (Supporting Information). The decay with a time scale of 1.7 ps suggests a fast photoinduced intramolecular energy-transfer process between the porphyrin and [HY(Pc)(Por)] chromophores. However, this photoinduced process is not as quick as the ones observed for 4 and 5 due to the different linking position of the appending metal-free porphyrin at the double-decker unit and therefore different relative orientation between the two subunits as clearly revealed by the simulated molecular configurations as detailed below. Density Functional Theory (DFT) Studies. Density functional theory (DFT) methods at the B3LYP level have proved suitable for calculating energy-minimized structures and properties of both metal-free porphyrins and (phthalocyaninato)(porphyrinato) metal double-decker complexes.18-21 The Los Alamos National Laboratory (LANL2DZ) effective core pseudopotentials were verified as appropriate for studying bis(phthalocyaninato) yttrium complexes.15,22-24 Nevertheless, B3LYP displays excellent performance in calculating the molecular systems composed of C, O, and H atoms.25 As a consequence, in the present case the molecular structures for the three triad compounds 3-5 are calculated at the level of B3LYP/ LANL2DZ for the purpose of understanding the relationship between the structure and ultrafast photodynamics. According to the calculation results, the metal-free porphyrin macrocyle employs significant different orientation and position relative to the double-decker unit in tetrapyrrole triads 3-5 due to the different binding site of metal-free porphyrin chromophore at the para, meta, and ortho position of one phenyl group of the porphyrin ligand in the double-decker subunit, Figures 5 and 6. The mean planes for the metal-free porphyrin (A) and porphyrinato yttrium (B) macrocycles are defined by their four inner N atoms of pyrrole units on the basis of previous investigation results for similar compounds.12,13,26,27 As shown in Figure 5 and Table 3, the relative orientation of the two mean macrocycle planes of A and B is basically determined by three main molecular structural parameters φ1, φ4, and φ5. In the triad 5, φ4 is close to 180°, which therefore gives almost no contribution to the dihedral angle between the two mean planes of A and B. As a result, the dihedral angle between the two mean planes of A and B (ΨAB) for 5 is mainly determined by φ1 and φ5. In contrast, φ4 is 171.9 and 122.2° in 3 and 4, respectively, indicating the significant effect of φ4 on the ΨAB for these two triads. In addition, as shown in Figure 5 and Table 3, the distance between A and B macrocycles, which is measured by the center-to-center distance (Rcc) between these two subunits, is also determined by φ1, φ4, and φ5. Calculation reveals that the dihedral angle between the two mean planes of A and B (ΨAB) for 3, 4, and 5 is 42.9, 129.1,

Figure 6. Simulated conformations at the level of B3LYP/LanL2DZ conformation of compounds 3-5.

TABLE 3: Configuration Parameter of Complexes 3-5 from Molecular Mechanics Calculations compound

φ1 (°)

φ2 (°)

φ3 (°)

φ4 (°)

φ5 (°)

Rcca (Å)

3 4 5

62.5 69.7 69.4

2.1 1.2 0.4

179.4 177.2 179.3

171.9 122.2 178.4

96.1 72.1 115.8

19.1 17.7 10.3

a

Rcc: center-to-center distance in Å.

and 44.9°, respectively, while these two macrocycles of A and B employ different form of crossed, open-shellfish-like, and closed-shellfish-like relative orientation in 3, 4, and 5, Figure 6. Despite the similar value of the ΨAB for triad compounds 3 and 5, the different relative orientation between A and B macrocyles in these two compounds appears to be responsible for their different fluorescent quenching efficiency (1 Φ/Φ0),17e low for 3 (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 was only partially quenched, Φ/Φ0 ) 0.0013) and high for 5 (the fluorescence of metal-free porphyrin connected at the meta position of one mesophenyl group of porphyrin ligand in the double-decker unit was completely quenched). This is further supported by the similar fluorescent quenching efficiency of triad 4 and 5 due to the suitable relative orientation between metal-free porphyrin (A) and HY(Pc)(Por) double-decker unit (B) in these two triads. It is also worth noting that the center-to-center distance between A and B, Rcc, seems to have an insignificant effect on the fluorescent quenching efficiency according to the calculation results as exemplified by the significant different ultrafast photodynamic properties between 3 and 4 despite their similar center-to-center distance between A and B, Table 3. These results reveal that the relative orientation for the metal-free porphyrin and double-decker unit associated with different

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connecting position appears to be the primary factor affecting the intramolecular fluorescent quenching process. Conclusion In summary, three novel porphyrin-appended mixed (phthalocyaninato)(porphyrinato) yttrium double-decker complexes have been designed, synthesized, and characterized. Comparative studies over the photophysical properties of these three isomeric tetrapyrrole triads reveal the complete quenching of the fluorescence of the metal-free porphyrin moiety attached through ester linkage at the meta and ortho position in triads 4 and 5 by the double-decker moiety but only partial quenching of the fluorescence of the metal-free porphyrin moiety attached at the para position in triad 3, clearly demonstrating the effect of the position of porphyrin substituent on the photophysical properties of the triads. The observation has been explained by the different relative orientation between the metal-free porphyrin and doubledecker unit associated with the different connecting position in these triads through DFT molecular mechanics calculations. Experimental Section General. n-Octanol was distilled from sodium under nitrogen. Column chromatography was carried out on silica gel (Merck, Kieselgel 60, 70-230 mesh) and biobeads (BIORAD S-X1, 200-400 mesh) columns with the indicated eluents. All other reagents and solvents were used as received. The compounds Y(acac)3...nH2O,28 5,10,15,20-tetrakis(4-tert-butylphenyl)porphyrin (H2TBPP) (1),29 5-(4-hydroxyphenyl)-10,15,20-tris(4-tertbutylphenyl)porphyrin (6), 5-(3-hydroxyphenyl)-10,15,20-tris(4tert-butylphenyl)porphyrin (7), 5-(2-hydroxyphenyl)-10,15,20tris(4-tert-butylphenyl)porphyrin (8),30 5-(4-carboxyphenyl)10,15,20-tris(4-tert-butylphenyl)porphyrin (9),31 and 5-(4acylchloride-phenyl)-10,15,20-tris(4-tert-butylphenyl)porphyrin (13)31 were prepared according to the published procedures,; see Supporting Information for details. 1 H NMR spectra were recorded on a Bruker DPX 300 spectrometer (300 MHz) in CDCl3, [D6]DMSO, or CDCl3/ [D6]DMSO 1:1. Spectra were referenced internally by using the residual solvent resonance (δ ) 7.26 and 2.49 ppm for CDCl3 and [D6]DMSO, respectively) relative to SiMe4 (TMS). MALDI-TOF mass spectra were taken on a Bruker BIFLEX III ultrahigh resolution Fourier transform ion cyclotron resonance (FTICR) mass spectrometer with alpha-cyano-4hydroxycinnamic acid as the matrix. Elemental analyses were performed on an Elementar Vavio El III. Electronic absorption spectra were obtained with a Hitachi U-4100 spectrophotometer. The steady-state emission spectra were measured by an Edinburgh FS920 Fluorescence Spectrophotometer or a fiber optical spectrometer from Ocean Optics. Solutions were prepared by CH2Cl2 with concentration of 1.0 µM for 1, 3.0 µM for 2, and 1.5 µM for 3-5. IR spectra were recorded on KBr-matrix pellets on a Bruker Tensor 37 spectrometer with a resolution of 2 cm-1. Density Functional Theory (DFT) Calculation. DFT methods of hybrid B3LYP functional with Becke exchange32 and Lee-Yang-Parr correlation33 were used to study the molecular structures. In all the cases, the LANL2DZ basis set34-36 was employed. The Berny algorithm using redundant internal coordinates37 was utilized in energy minimization, and the default cutoffs were used throughout. The molecular orbital surface isovalue is 0.02. All calculations were carried out using the Gaussian 03 program38 on an IBM P690 system housed at

Zhang et al. Shandong Province High Performance Computing Center. The measurements of average plane are defined by the Mercury 2.2 program.39 Fluorescence Upconversion Measurement. Time-resolved fluorescence measurements for 1-5 in solution were carried out by using a femtosecond upconversion technique. The solutions were prepared with anhydrous, deoxygenated CH2Cl2 at a concentration of ∼0.5 mg/mL. The femtosecond fluorescence upconversion system used in this work is a FOG 100 system (CDP, Russia) with a mode-locked Ti-sapphire laser (Tsunami, Spectra Physics) light source pumped by a 10 W CWNd:YVO4 laser (Millennia, Spectra-Physics). Briefly, samples were excited by the second harmonic light generated by doubling the fundamental light at a wavelength of ∼834 nm from a modelocked Ti-sapphire laser with a pulse width of ∼57 fs and a pulse repetition rate of 86 MHz. The output spectrum of the laser radiation was monitored with a spectrum analyzer (Ocean Optics), which was used as a probe to ensure pure mode-locking regime of the femtosecond laser. The polarization of the excitation beam for the anisotropy measurements was controlled with a Berek’s plate. A rotating sample cell was used to avoid possible photodegradation and other accumulative effects. The fluorescence emitted from the sample was collected with an achromatic lens and directed onto a β-barium borate nonlinear crystal. The fundamental light passes through a motorized optical delay line and then mixes with the sample emission in the nonlinear crystal to generate sum frequency light. The sum frequency light is dispersed using a monochromator and detected by a photomultiplier tube (Hamamatsu R1527P). The instrument response function (IRF) was estimated to be 188 fs at full width at half-maximum (fwhm).40 Fluorescence anisotropy (γ) can be given by the equation below

γ ) (Fpar - G · Fper)/(Fpar + 2G · Fper) where Fpar and Fper are the fluorescence intensity for the parallel and perpendicular polarization, respectively; the G factor was calibrated by measuring the polarized fluorescence decay of perylene in toluene, which gives equal polarized fluorescence intensity after a complete rotation diffusion in tens of picoseconds. In order to extract out the decay or increase parameters from the original data for fluorescence (anisotropy) dynamics, a decay model has been suggested for processing the data n

R(t) ) A +

∑ Bie-t/τ

i

i)1

where A is the constant for illustrating the detecting background; Bi, the amplitude which can be negative or positive, is related to the analytic sample and data acquisition (a negative value indicates an increase, while a positive demonstrates a decay of the detected signal); τi is the lifetime; R(t) is a approximate description of the dynamics, which cannot illustrate intrinsic features including the statistic noise and instrument response (sample excitation) from the original data. Especially for the lifetime measurements within a short time scale, the decay model has to be modified with an instrumental response function [E(t′)]. The acquired signal [X(t)] can be given by

Porphyrin Yttrium Double-Decker Complexes

X(t) )

∫0t E(t′)R(t - t′) dt′

A real decay process has to be deconvoluted from X(t). This deconvolution process was carried out with the IRF by using the vFit program (CDP, Russia). The smallest residual value was controlled during the fitting and simulation. Preparation of HY[Pc(r-OC4H9)8](TBPP) (2). A mixture of Y(acac)3 · nH2O (25 mg, ca. 0.05 mmol) and H2TBPP (1) (42 mg, 0.05 mmol) in n-octanol (4 mL) was heated to reflux under nitrogen for ca. 4 h. The mixture was cooled to room temperature and then treated with H2Pc(R-OC4H9)8 (55 mg, 0.05 mmol) under reflux for another 4 h. After a brief cooling, the mixture was evaporated under reduced pressure and the residue was chromatographed on a silica gel column. A small amount of unreacted H2TBPP was separated by using CHCl3/hexanes (4:1) as eluent, and then the column was eluted with CHCl3. A small green band containing the metal-free phthalocyanine followed by another green band containing the protonated double-decker was developed. The latter fraction was collected and chromatographed again using CHCl3/MeOH (98:2) as eluent. The nonprotonated counterpart was not detected during chromatography. Then the product was loaded onto a biobeads column with CHCl3 as the eluent, and the first fraction was collected and evaporated. The product was further purified by recrystallization from CHCl3/MeOH (68 mg, 67%): 1H NMR (300 MHz, CDCl3/[D6]DMSO (1:1) with ca. 1% hydrazine hydrate, 295.9 K, TMS): δ 1.11-1.16 (t, 24H, J ) 7.5), 1.68 (s, 36H), 1.71-1.87 (m, 16H), 2.17-2.58 (m, 16H), 5.03-5.24 (m, 16H), 6.40 (s, 4H), 7.15-7.24 (m, 8H), 7.52 (s, 8H), 7.61 (s, 4H), 7.76-7.91 (m, 8H). Anal. Calcd. (%) for C125H140N11O8Y: C 74.57, H 7.01, N 7.65. Found: C 74.55, H 7.22, N 7.54. Preparation of HY[Pc(r-OC4H9)8](Por) (10-12). By using the above procedure with 5-(4-hydroxyphenyl)-10,15,20-tris(4tert-butylphenyl)porphyrin (6), 5-(3-hydroxyphenyl)-10,15,20tris(4-tert-butylphenyl)porphyrin (7), or 5-(2-hydroxyphenyl)10,15,20-tris(4-tert-butylphenyl)porphyrin (8) instead of H2TBPP (1) as the starting material, the target double-decker complexes 10-12 were isolated in relatively good yield of 72%, 56%, or 66%, respectively. Again the nonprotonated counterpart was not detected during chromatography. For 10: MS (MALDI-TOF): an isotopic cluster peaking at m/z 1976.3 [Calcd. for (MH)+ 1976.3]. Anal. Calcd. (%) for C120H132N12O9Y: C 72.96, H 6.74, N 8.51. Found: C 72.88, H 6.93, N 8.42. 1H NMR (300 MHz, CDCl3/[D6]DMSO (1:1) with ca. 1% hydrazine hydrate, 295.9 K, TMS): δ 1.12-1.16 (t, 24H, J ) 6), 1.60 (s, 27H), 1.71-1.84 (m, 16H), 2.17-2.24 (m, 16H), 5.02-5.21 (m, 16H), 5.22 (s, -OH), 6.34-6.62 (m, 4H), 7.08-7.14 (m, 8H), 7.50-7.54 (m, 8H), 7.63-7.71 (s, 4H), 7.81-7.93 (m, 8H). For 11: MS (MALDI-TOF): an isotopic cluster peaking at m/z 1976.3 [Calcd. for (MH)+ 1976.3]. Anal. Calcd. (%) for C120H132N12O9Y: C 72.96, H 6.74, N 8.51. Found: C 72.98, H 6.79, N 8.67. 1H NMR (300 MHz, CDCl3/[D6]DMSO (1:1) with ca. 1% hydrazine hydrate, 295.9 K, TMS): δ 1.14-1.18 (t, 24H, J ) 6), 1.61 (s, 27H), 1.74-1.85 (m, 16H), 2.19-2.25 (m, 16H), 5.09 (s, br, 16H), 5.19 (s, -OH), 6.41 (s, br, 4H), 6.78-6.86 (m, 8H), 7.14-7.27 (m, 8H), 7.50-7.56 (m, 12H). For 12: MS (MALDI-TOF): an isotopic cluster peaking at m/z 1976.3 [Calcd. for (MH)+ 1976.3]. Anal. Calcd. (%) for C120H132N12O9Y: C 72.96, H 6.74, N 8.51. Found: C 72.86, H 6.64, N 8.48. 1H NMR (300 MHz, CDCl3/[D6]DMSO (1:1) with ca. 1% hydrazine hydrate, 295.9 K, TMS): δ 1.12-1.16 (t, 24H,

J. Phys. Chem. B, Vol. 114, No. 41, 2010 13149 J ) 6), 1.67 (s, 27H), 1.76-1.84 (m, 16H), 2.19-2.26 (m, 16H), 5.09-5.17 (m, 16H), 5.21 (s, -OH), 6.45-6.64 (m, 4H), 7.02-7.05 (m, 3H), 7.12-7.17 (m, 8H), 7.38-7.41 (s, br, 1H), 7.74-7.90 (m, 8H), 7.94-9.97 (m, 8H). Preparation of Tetrapyrrole Triads 3-5. According to the reported procedure,31 suspension of 5-(4-carboxyphenyl)10,15,20-tris(4-tert-butylphenyl)porphyrin (9) (26 mg, 0.01 mmol) in thionyl chloride (2 mL) was refluxed for 12 h. The resulting mixture was then concentrated under reduced pressure to afford 5-(4-acylchloride-phenyl)-10,15,20-tris(4-tert-butylphenyl)porphyrin (13). This crude product was dissolved in chloroform (10 mL) which was added to a stirred solution containing intermediate double-decker HY[Pc(R-OC4H9)8](Por) (10-12) (19.8 mg, 0.01 mmol) and triethylamine (100 mg, 0.1 mmol) in chloroform (10 mL) at room temperature. After further reaction at room temperature for another 10 h under stirring, the mixed solution was concentrated under reduced pressure and the residue was dissolved in toluene (50 mL). The organic phase was washed with water (3 × 10 mL) and then brine (10 mL), and dried over sodium sulfate. Upon removal of the solvent under reduced pressure, the crude product was loaded onto a biobeads column with CHCl3 as the eluent. The desired tetrapyrrole triad products were developed as the first fraction which was further purified by repeated chromatography on biobeads column followed by recrystallization from CHCl3 and MeOH. 3: 18 mg, 64% yield. 4: 16 mg, 57% yield. 5: 20 mg, 71% yield. For 3: 1H NMR (300 MHz, CDCl3/[D6]DMSO (1:1) with ca. 1% hydrazine hydrate, 295.9 K, TMS). δ 1.11-1.15 (t, 24H, J ) 6), 1.55 (s, 27H), 1.60 (s, 27H), 1.77-1.82 (m, 16H), 2.19 (s, br, 16H), 5.09-5.16 (m, 16H), 6.39-6.41 (m, 8H), 6.85-6.95 (m, 16H), 7.14-7.24 (m, 8H), 7.74-7.90 (m, 8H), 7.77-7.82 (m, 8H), 7.90-7.95 (m, 16H). For 4: 1H NMR (300 MHz, CDCl3/[D6]DMSO (1:1) with ca. 1% hydrazine hydrate, 295.9 K, TMS). δ 1.08-1.13 (t, 24H, J ) 7.5), 1.54 (s, 27H), 1.68 (s, 27H), 1.70-1.77 (m, 16H), 2.15-2.20 (m, 16H), 5.04-5.20 (m, 16H), 6.33-6.60 (m, 8H), 7.06-7.20 (m, 16H), 7.48-7.57 (m, 8H), 7.71-7.77 (m, 8H), 7.96-7.99 (m, 16H). For 5: 1H NMR (300 MHz, CDCl3/[D6]DMSO (1:1) with ca. 1% hydrazine hydrate, 295.9 K, TMS). δ 1.10-1.15 (t, 24H, J ) 7.5), 1.59 (s, 27H), 1.68 (s, 27H), 1.75-1.80 (m, 16H), 2.19-2.21 (m, 16H), 5.08-5.21 (m, 16H), 6.44 (s, br, 2H), 6.61-6.64 (m, 1H), 6.71 (s, 1H), 7.02-7.04 (m, 2H), 7.09-7.12 (m, 5H), 7.15-7.17 (m, 5H), 7.22-7.24 (m, 4H), 7.27-7.38 (m, 16H), 7.80-7.86 (m, 10H), 7.90-8.17 (m, 10H). Acknowledgment. Financial support from the Natural Science Foundation of China, the Fundamental Research Funds for the Central Universities, Beijing Natural Science Foundation, USTB, and SDU is gratefully acknowledged. Supporting Information Available: Details of the synthesis, the 1H NMR spectra, and results of elemental analysis of 5,10,15,20-tetrakis(4-tert-butylphenyl)porphyrin H2TBPP (1), 5-(4-hydroxyphenyl)-10,15,20-tris(4-tert-butylphenyl)porphyrin (6), 5-(3-hydroxyphenyl)-10,15,20-tris(4-tert-butylphenyl)porphyrin (7), 5-(2-hydroxyphenyl)-10,15,20-tris(4-tert-butylphenyl)porphyrin (8), and 5-(4-carboxyphenyl)-10,15,20-tris(4-tertbutylphenyl)porphyrin (9); experimental and simulated isotopic patterns for the molecular ion of double-decker complex 3; IR spectra of 2-5; electronic absorption spectra of 4 and 5; fluorescence decay in short-time scale of 1 and 3 at the emission of 654 nm in CH2Cl2 with 417 nm excitation; anisotropy decay of fluorescence for 1 and 3 at the emission of 654 nm in CH2Cl2

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with 417 nm excitation. This material is available free of charge via the Internet at http://pubs.acs.org. References and Notes (1) (a) Porphyrins and Metalloporphyrins; Smith, K. M., Ed.; Elsevier: Amsterdam, 1975. (b) The Porphyrins; Dolphin, D., Ed.; Academic Presss: New York, 1978. (c) Phthalocyanines: Properties and Applications; Leznoff, C. C., Lever, A. B. P., Eds.; VCH Publishers: New York, 1989-1996; Vol. 1-4. (d) Mckeown, N. B. Phthalocyanine Materials: Synthesis, Structure and Function; Cambridge University Press: Cambridge, U.K., 1998. (e) Jiang, J.; AdVances in Functional Phthalocyanine Materials; In Structure and Bonding; Mingos, D. M. P., Ed.; Springer-Verlag: Heidelberg, Germany, 2010; Vol. 135. (f) The Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2000, Vols. 1-10; 2003; Vols. 11-20. (2) (a) Deisenhofer, J.; Epp, O.; Miki, K.; Huber, R.; Michel, H. J. Mol. Biol. 1984, 180, 385–398. (b) Deisenhofer, J.; Epp, O.; Miki, K.; Huber, R.; Michel, H. Nature 1985, 318, 618–624. (c) Deisenhofer, J.; Michel, H. Science 1989, 245, 1463–1473. (d) Allen, J. P.; Feher, G.; Yeates, T. O.; Rees, D. C.; Deisenhofer, J.; Michel, H.; Huber, R. Proc. Natl. Acad. Sci. U.S.A. 1986, 83, 8589–8593. (e) Barber, J.; Andersson, B. Nature 1994, 370, 31–34. (f) Xiong, J.; Fischer, W. M.; Inoue, K.; Nakahara, M.; Bauer, C. E. Science 2000, 289, 1724–1730. (3) (a) Ng, D. K. P.; Jiang, J. Chem. Soc. ReV. 1997, 26, 433–442. (b) Jiang, J.; Kasuga, K.; Arnold, D. P. In Supramolecular Photo-SensitiVe and ElectroactiVe Materials; Nalwa, H. S., Ed.; Academic Press: New York, 2001; pp 113-210. (c) Jiang, J.; Bao, M.; Rintoul, L.; Arnold, D. P. Coord. Chem. ReV. 2006, 250, 424–448. (d) Jiang, J.; Ng, D. K. P. Acc. Chem. Res. 2009, 42, 79–88. (e) Buchler, J. W.; Ng, D. K. P. In The Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2000; Vol. 3, pp 245-294. (f) Weiss, R.; Fischer, J. In The Porphyrin Handbook.; Kadish, K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2003; Vol. 16, pp 171-246. (4) (a) Liu, Z.; Yasseri, A. A.; Lindsey, J. S.; Bocian, D. F. Science 2003, 302, 1543–1545. (b) Shirk, J. S.; Lindle, J. R.; Bartoli, F. J.; Boyle, M. E. J. Phys. Chem. 1992, 96, 5847–5852. (c) Mendonca, C. R.; Gaffo, L.; Misoguti, L.; Moreira, W. C.; Oliveira, O. N., Jr.; Zilio, S. C. Chem. Phys. Lett. 2000, 323, 300–304. (d) Chen, Y.; Su, W.; Bai, M.; Jiang, J.; Li, X.; Liu, Y.; Wang, L.; Wang, S. J. Am. Chem. Soc. 2005, 127, 15700– 15701. (e) Bai, M.; Bao, M.; Ma, C.; Arnold, D. P.; Choi, M. T. M.; Ng, D. K. P.; Jiang, J. J. Mater. Chem. 2003, 13, 1333–1339. (5) (a) Chou, J. H.; Nalwa, H. S.; Kosal, M. E.; Rakow, N. A.; Suslick, K. S. In The Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2000; Vol. 6, pp 43-132. (b) Flow, S. R. In The Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2003; Vol. 19, pp 179190. (c) De la Torre, G.; Bottari, G.; Hahn, U.; Torres, T. In Structure Bonding (Berlin), Mingos, D. M. P., Ed.; Springer-Verlag: Heidelberg, Germany, 2010; Vol. 135, pp 1-44. (d) Li, X.; Wang, H.; Wu, H. In Structure Bonding (Berlin); Mingos, D. M. P., Ed.; Springer-Verlag: Heidelberg, Germany, 2010; Vol. 135, pp 229-274. (6) (a) Gust, D.; Moore, T. A. In The Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard, R. , Eds.; Academic Press: San Diego, CA, 2000; Vol. 8, pp 153-190. (b) Gust, D.; Moore, T. A.; Moore, A. L. Acc. Chem. Res. 2001, 34, 40–48. (c) Aratani, N.; Kim, D.; Osuka, A. Acc. Chem. Res. 2009, 42, 1922–1934. (d) Wasielewski, M. R. Acc. Chem. Res. 2009, 42, 1910–1921. (e) De la Escosura, A.; Martinez-Diaz, M. V.; Guldi, D. M.; Torres, T. J. Am. Chem. Soc. 2006, 128, 4112–4118. (f) D’Souza, F.; Subbaiyan, N. K.; Xie, Y.; Hill, J. P.; Ariga, K.; Ohkubo, K.; Fukuzumi, S. J. Am. Chem. Soc. 2009, 131, 16138–16146. (g) Holten, D.; Bocian, D. F.; Lindsey, J. S. Acc. Chem. Res. 2002, 35, 57–69. (h) Kim, D.; Osuka, A. Acc. Chem. Res. 2004, 37, 735–745. (i) Guo, M.; Yan, X.; Goodson, T., III. AdV. Mater. 2008, 20, 4167–4171. (7) (a) Lo, P. C.; Leng, X.; Ng, D. K. P. Coord. Chem. ReV. 2007, 251, 2334–2353. (b) Soares, A. R. M.; Martinez-diaz, M. V.; Bruckner, A.; Pereira, A. M. V. M.; Tome, J. P. A.; Alonso, C. M. A.; Faustino, M. A. F.; Neves, M. G. P. M. S.; Tome, A. C.; Silva, A. M. S.; Cavaleiro, J. A. S.; Torres, T.; Guldi, D. M. Org. Lett. 2007, 19, 1557–1560. (c) Kameyama, K.; Satake, A.; Kobuke, Y. Tetrahedron Lett. 2004, 45, 7617– 7620. (d) Tome, J. P. C.; Pereira, A. M. V. M.; Alonso, C. M. A.; Neves, M. G. P. M. S.; Tomes, A. C.; Silva, A. M. S.; Cavaleiro, J. A. S.; Martinezdiaz, M. V.; Torres, T.; Rahman, G. M. A.; Ramey, J.; Guldi, D. M. Eur. J. Org. Chem. 2006, 257–267. (e) Ali, H.; van Lier, J. E. Tetrahedron Lett. 2009, 50, 1113–1116. (8) (a) Winters, M. U.; Dahlstedt, E.; Blades, H. E.; Wilson, C. J.; Frampton, M. J.; Anderson, H. L.; Albinsson, B. J. Am. Chem. Soc. 2007, 129, 4291–4297. (b) Cho, H. S.; Rhee, H.; Song, J. K.; Min, C. K.; Takase, M.; Aratani, N.; Cho, S.; Osuka, A.; Joo, T.; Kim, D. J. Am. Chem. Soc. 2003, 125, 5849–5860. (c) Peng, X.; Aratani, N.; Takagi, A.; Matsumoto, T.; Kawai, T.; Hwang, I. W.; Ahn, T. K.; Kim, D.; Osuka, A. J. Am. Chem. Soc. 2004, 126, 4468–4469. (d) Li, X.; Ng, D. K. P. Eur. J. Inorg. Chem. 2000, 1845–1848. (e) Li, X.; Zhou, Q. F.; Tian, H. J.; Xu, H. J. Chin.

Zhang et al. J. Chem. 1998, 16, 97–108. (f) Li, L.; Shen, S.; Yu, Q.; Zhou, Q.; Xu, H. J. Chem. Commun. 1991, 619–620. (9) (a) Capobianchi, A.; Ercolani, C.; Paoletti, A. M.; Pennesi, G.; Rossi, G.; Chiesi-Villa, A.; Rizzoli, C. Inorg. Chem. 1993, 32, 4605–4611. (b) Galmiche, L.; Mentec, A.; Pondaven, A.; L’Her, M. New J. Chem. 2001, 25, 1148–1151. (c) Collman, J. P.; Kendall, J. L.; Chen, J. L.; Collins, K. A.; Marchon, J. C. Inorg. Chem. 2000, 39, 1661–1667. (d) Girolami, G. S.; Hein, C. L.; Suslick, K. S. Angew. Chem., Int. Ed. Engl. 1996, 35, 1223– 1225. (e) Buchler, J. W.; Heinz, G. Chem. Ber. 1996, 129, 1073–1081. (10) Bian, Y.; Chen, X.; Wang, D.; Choi, C.-F.; Zhou, Y.; Zhu, P.; Ng, D. K. P.; Jiang, J.; Weng, Y.; Li, X. Chem.sEur. J. 2007, 13, 4169–4177. (11) Ballesteros, B.; Torre, G.; Sharer, A.; Hausmann, A.; Herranz, M. ´ .; Guldi, D. M.; Torres, T. Chem.sEur. J. 2010, 16, 114–125. A (12) Wang, R.; Li, R.; Li, Y.; Zhang, X.; Zhu, P.; Lo, P C.; Ng, D. K. P.; Pan, N.; Ma, C.; Kobayashi, N.; Jiang, J. Chem.sEur. J. 2006, 12, 1475– 1485. (13) Zhang, Y.; Cai, X.; Yao, P.; Xu, H.; Bian, Y.; Jiang, J. Chem.sEur. J. 2007, 13, 9503–9514. (14) Bao, M.; Bian, Y.; Rintoul, L.; Wang, R.; Arnold, D. P.; Ma, C.; Jiang, J. Vib. Spectrosc. 2004, 34, 283–291. (15) Zhang, X.; Muranaka, A.; Lv, W.; Zhang, Y.; Bian, Y.; Jiang, J.; Kobayashi, N. Chem.sEur. J. 2008, 14, 4667–4674. (16) (a) Yan, X.; Holten., D. J. Phys. Chem. 1988, 92, 409–414. (b) Ishii, K.; Ohba, Y.; Iwaizumi, M.; Yamauchi., S. J. Phys. Chem. 1996, 100, 3839–3846. (c) Yoshinoand, K.; Lee, S. B.; Sonoda, T.; Kawagishi, H.; Hidayat, R.; Nakayama, K.; Ozaki, M.; Ban, K.; Nishizawa, K.; Ohta, K.; Shirai, H. J. Appl. Phys. 2000, 88, 7137–7143. (17) (a) Murov, S. L.; Carmichael, I.; Hug, G. L. Handbook of Photochemistry, 2nd ed.; Marcel Dekker: New York, 1993. (b) Tsuchiya, S. Chem. Phys. Lett. 1990, 169, 608–610. (c) Gentemann, S.; Medforth, C. J.; Forsyth, T. P.; Nurco, D. J.; Smith, K. M.; Fajer, J.; Holten, D. J. Am. Chem. Soc. 1994, 116, 7363–7368. (d) Yan, X. Z.; Goodson III, T.; Imaoka, T.; Yamamoto, K. J. Phys. Chem. B. 2005, 109, 9321–9329. (e) Xu, W.; Chen, H.; Wang., Y.; Zhao, C.; Li, X.; Wang, S.; Weng, Y. ChemPhysChem 2008, 9, 1409–1415. (f) Seybold, P. G.; Gouterman, M. J. Mol. Spectrosc. 1969, 31, 1–13. (18) Zhang, Y.; Zhang, X.; Liu, Z.; Bian, Y.; Jiang, J. J. Phys. Chem. A. 2005, 109, 6363–6370. (19) Cai, X.; Zhang, Y.; Qi, D.; Jiang, J. J. Phys. Chem. A. 2009, 113, 2500–2506. (20) Qi, D.; Zhang, Y.; Cai, X.; Jiang, J.; Bai, M. J. Mol. Graph. Mod. 2009, 27, 693–700. (21) Ma, R.; Guo, P.; Cui, H.; Zhang, X.; Nazeeruddin, M. K.; Grtzel, M. J. Phys. Chem. A 2009, 113, 10119–10124. (22) Zhang, Y.; Cai, X.; Qi, D.; Yao, P.; Bian, Y.; Jiang, J. ChemPhysChem. 2008, 9, 781–792. (23) Zhang, Y.; Cai, X.; Zhou, Y.; Zhang, X.; Xu, H.; Liu, Z.; Li, X.; Jiang, J. J. Phys. Chem. A. 2007, 111, 392–400. (24) Zhang, Y.; Cai, X.; Qi, D.; Bian, Y.; Jiang, J. J. Phys. Chem. C. 2008, 112, 14579–14588. (25) Sousa, S. F.; Fernandes, P. A.; Ramos, M. J. J. Phys. Chem. A 2007, 111, 10439–10452. (26) Bian, Y.; Li, L.; Wang, D.; Choi, C.; Cheng, Y. Y. D.; Zhu, P.; Li, R.; Dou, J.; Wang, R.; Pan, N.; Ng, D. K. P.; Kobayashi, N.; Jiang, J. Eur. J. Inorg. Chem. 2005, 2612–2618. (27) Zhu, P.; Pan, N.; Li, R.; Dou, J.; Zhang, Y.; Cheng, D. Y. Y.; Wang, D.; Ng, D. K. P.; Jiang, J. Chem.sEur. J. 2005, 11, 1425–1432. (28) Stites, J. G.; McCarty, C. N.; Quill, L. L. J. Am. Chem. Soc. 1948, 70, 3142–3143. (29) Barnett, G. H.; Hudson, M. F.; Smith, K. M. J. Chem. Soc., Perkin. Trans. 1 1975, 1401–1403. (30) (a) Little, R. G. J. Heterocycl. Chem. 1978, 15, 203. (b) Lu, G.; Chen, Y.; Zhang, Y.; Bao, M.; Bian, Y.; Li, X.; Jiang, J. J. Am. Chem. Soc. 2008, 130, 11623–11630. (31) (a) Luo, C.; Guldi, D. M.; Imahori, H.; Tamaki, K.; Sakata, Y. J. Am. Chem. Soc. 2000, 122, 6535–6551. (b) Imahori, H.; Tamaki, K.; Araki, Y.; Sekiguchi, Y.; Ito, O.; Sakata, Y.; Fukuzumi, S. J. Am. Chem. Soc. 2002, 124, 5165–5174. (32) Lee, C.; Yang, W.; Parr, R. G. Phys. ReV. B 1988, 37, 785–789. (33) Dunning, J, T. H.; Hay, P. J. In Modern Theoretical Chemistry; Schaefer, H. F., III., Ed.; Plenum: New York, 1976; Vol. 3, pp 1-28. (34) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 270–283. (35) Wadt, W. R.; Hay, P. J. J. Chem. Phys. 1985, 82, 284–298. (36) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 299–310. (37) Peng, C.; Ayala, P. Y.; Schlegel, H. B.; Frisch, M. J. J. Comput. Chem. 1996, 17, 49–56. (38) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.; Adamo, C.;

Porphyrin Yttrium Double-Decker Complexes Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson,

J. Phys. Chem. B, Vol. 114, No. 41, 2010 13151 B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian03, revision B.05; Gaussian, Inc.: Pittsburgh, PA, 2003. (39) Mercury 2.2, Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, England. (40) Wang, Q.; Li, Y.; Yan, X. Z.; Rathi, M.; Ropp, M.; Galipeau, D.; Jiang, J. Appl. Phys. Lett. 2008, 93, 073303–073305.

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