Noncovalent Functionalization of Thiopyridyl Porphyrins with

DOI: 10.1002/cplu.201500005

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Noncovalent Functionalization of Thiopyridyl Porphyrins with Ruthenium Phthalocyanines Leandro M. O. LourenÅo,[a] Anita Hausmann,[b] Christina Schubert,[b] Maria G. P. M. S. Neves,[a] Jos¦ A. S. Cavaleiro,[a] Toms Torres,*[c, d] Dirk M. Guldi,*[b] and Jo¼o P. C. Tom¦*[a, e] heterochromophore structures evidences the electron-donating/-accepting communication between the two dyes in the supramolecular hybrids. These structural hybrids were investigated physicochemically by means of their ground and excited state reactivities. Photophysical investigation by time-resolved transient absorption, mainly fluorescence and femtosecond spectroscopy, evidenced efficient intermolecular energy transfer from the photoexcited central porphyrin to the peripheral phthalocyanines in the supramolecular multichromophore ensembles. The findings may give impetus for the design of interesting materials for solar-light-converting systems.

Preconditions for the design of efficient organic solar-light-converting systems are strong absorptions across the visible region, the capacity to funnel excited state energy by intermolecular energy transfer, and alternative association processes in the photoinduced electron transfer. In this context, thiopyridyl porphyrins (PorSPy) and ruthenium phthalocyanines (RuPcs) proved to be versatile building blocks for the construction of novel supramolecular Por–Pc hybrid systems (PorSPy–RuPc) by axial coordination at ruthenium. The thiopyridyl groups placed at the bay region of the porphyrins coordinate the RuPc dye. A notable redistribution of the electron density in the new

Introduction The crucial topic of artificial photosynthesis is a series of lightinduced energy- and electron-transfer reactions.[1] In this context, aromatic compounds that undergo light-harvesting and reactive processes can comprise light-absorbing chromophores, which arise as antenna molecules, excited-state electron donors, and additionally electron acceptors.[2] Donor–acceptor ensembles also play key roles in molecular photovoltaic devices,[3–5] where energy is stored in the photogenerated radical ion pair states and then converted into electrical power.

Supramolecular interactions between complementary dye molecules give rise in many cases to interesting absorption properties which can cover a broader region of the visible spectrum.[6–10] As promising electron donors, porphyrins (Pors) and phthalocyanines (Pcs) have been studied in different electronic applications.[11–18] Their electronic potential depends mostly on their absorption and emission performances, which can be driven by self-assembly coordination processes. In this context, certain researchers have constructed noncovalent multi-dye systems, for example those involving different pyridyl-dye derivatives and tert-butyl ruthenium phthalocyanines (RuPcs).[19] Due to association properties, it is possible to obtain electronic transitions between the two compounds. It has been well documented that different supramolecular electron-donor and -acceptor building blocks, such as perylenebisimide[20] and perylenediimide[21] containing pyridyl units, undergo axial coordination to the ruthenium(II) metal centers of two or four RuPc units, depending on the available pyridyl groups. Recently, a series of supramolecular Por–Pc assemblies have been prepared by the D’Souza group presenting the axial coordination of (ortho-, meta-, or para-) imidozylphenyl-substituted freebase Pors to RuPc dyes.[22] On the other hand, pyridyl Pors have been reported by Cook and co-workers that allow electron donor–acceptor hybrids with pronounced design flexibility.[23] Zinc Pors are also known to form self-assembled supramolecular dyads and triads through metal–ligand coordination with pyridyl-fullerene (Py-C60) derivatives and by crown-ether inclusion, ion pairing, hydrogen bonding, and p–p stacking interactions.[24] The supramolecular heterochromophore ensem-

[a] Dr. L. M. O. LourenÅo, Dr. M. G. P. M. S. Neves, Prof. J. A. S. Cavaleiro, Dr. J. P. C. Tom¦ QOPNA and Department of Chemistry University of Aveiro 3810-193 Aveiro (Portugal) E-mail: [email protected] [b] Dr. A. Hausmann, C. Schubert, Prof. D. M. Guldi Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials Friedrich-Alexander-Universitt 91058 Erlangen (Germany) E-mail: [email protected] [c] Prof. T. Torres Departamento de Qumica Orgnica Universidad Autûnoma de Madrid Cantoblanco, 28049 Madrid (Spain) E-mail: [email protected] [d] Prof. T. Torres IMDEA-Nanociencia c/Faraday, 9, Cantoblanco, 28049 Madrid (Spain) [e] Dr. J. P. C. Tom¦ Department of Organic and Macromolecular Chemistry Ghent University, 9000 Gent (Belgium) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cplu.201500005.

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Ó 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Papers of RuPc (see the Experimental Section).[26] The reaction of H2PorF16SPy4 with RuPc was carried out in dichloromethane overnight at room temperature under nitrogen atmosphere. The compounds were purified by gel permeation chromatography (Bio-Beads S-X1) using dichloromethane as eluent to yield blue solids 1 (71 %) and 2 (91 %). Supramolecular assembly 2 was further reacted with zinc acetate at reflux in a mixture of CH2Cl2/MeOH (9:1) in order to get the zinc complex 3 (90 %). This procedure proves to be an exceptional methodology to prepare the supramolecular ensembles 1–3. The new assemblies were characterized by 1H and 19F NMR spectroscopy, UV/Vis spectroscopy, and mass spectrometry. The absorption spectra of 1–3 are summarized in Figure 2 and their profiles were compared with those of the individual

bles present an energy transfer from the periphery to the central core of these multichromophore systems. These interesting properties brought us to synthesize and study Por–Pc electron donor–acceptor assemblies based on noncovalent linkages. We report here that the mono- and tetrathiopyridyl Pors, previously described by our research group,[25] coordinate with one or four RuPc unit(s) to form the supramolecular assemblies 1–3 (Figure 1). It is noteworthy that the synthesis requires rigorous

Figure 2. Room-temperature absorption spectra of 1–3 in toluene.

components. The absorption spectrum of tetrathiopyridyl Por (H2PorF16SPy4) compares quite well with that of the tetraphenylporphyrin (H2Por) reference with a dominating Soret band absorption that maximizes at 415 nm and a series of weaker Q-band absorptions in the region of 500–650 nm (Table 1). Similarly, the absorption spectrum of zinc tetrathiopyridyl Por (ZnPorF16SPy4) closely resembles the absorption spectrum of

Figure 1. Multichromophore arrays 1–3.

control of the reaction conditions due to the possibility of obtaining incomplete axial derivatization of the RuPc by pyridyl groups of the Por derivatives.[25, 26] Fluorescence and femtosecond time-resolved transient absorption spectra indicate the efficiency of the intermolecular energy transfer from the photoexcited central porphyrin to the peripheral phthalocyanines in the supramolecular multichromophore ensembles. The findings may give impetus for the design of interesting materials for solar-light-converting systems.

Table 1. Wavelengths of the Soret band and the fluorescence maxima (lmax,em.), fluorescence quantum yields (fF), and fluorescence lifetimes of H2PorF19SPy1, H2PorF16SPy4, ZnPorF16SPy4, and arrays 1–3. Compound

Soret band [nm]

H2Por ZnPor RuPc 300–400 H2PorF19SPy1 412 H2PorF16SPy4 415

Results and Discussion

ZnPorF16SPy4 1 2 3

Synthesis and characterization New supramolecular conjugates 1 and 2 (Figure 1) were prepared by the noncovalent modification of H2PorF19SPy1 and H2PorF16SPy4[25] with the corresponding number of equivalents ChemPlusChem 2015, 80, 832 – 838

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423 418 422 430

Q bands [nm]

lmax,em.[a] fF[b] [nm]

500–650 705 500–650 655 650 670 505, 536, 581, – 634 507, 537, 581, 640 633 552, 586 600 587, 650 663 587, 650 655 586, 650 658

t

0.10 0.04 0.01 –

– – – –

0.06

–

0.03 0.01 0.003 0.0002

2.1 ns – < 100 ps (112 10) ps

[a] Excitation at 420 nm, except for RuPc which was excited at 610 nm. [b] H2Por and ZnPor used as references.

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Full Papers (Figure 3 bottom) and ZnPor[28] reveal maxima at 600 and 655 nm and quantum yields of 0.03 and 0.04, respectively. The energies of the triplet excited states of H2Por and ZnPor are known from the literature as 1.43 and 1.53 eV, respectively.[28] For H2PorF16SPy4 and ZnPorF16SPy4 we expect their triplet excited states at the same energy levels. Finally, for RuPc an emission maximum at 670 nm and a quantum yield of 0.01 evolves. Furthermore, the phosphorescence spectrum of RuPc features a maximum at 968 nm. For the latter, the energy of the triplet excited state is estimated as (1.33 0.01) eV. In the case of 3, the porphyrin-based fluorescence is notably quenched upon photoexcitiation at 420 nm, with a value of around 0.007 (Figure 3). Similarly, the ZnPorF16SPy4-based fluorescence lifetime is in 3 much shorter ((112 10) ps) than that seen in the absence of RuPc (2.1 ns). These are considered as first proof for electronic communication in the form of either energy or electron transfer between the light-harvesting ZnPorF16SPy4 and RuPc units. Despite the exclusive excitation of ZnPorF16SPy4, RuPc-centered fluorescence emerges at 657 nm with a quantum yield of 0.0002. Implicit in such a finding is the thermodynamically driven transduction of singlet excited state energy from the higher lying singlet exited state of ZnPorF16SPy4 (2.05 eV) to the lower lying singlet excited state of RuPc (1.85 eV). To confirm the energy-transfer hypothesis we measured an excitation spectrum for ZnPorF16SPy4 at the newly evolving RuPc fluorescence. It resembles the ground state absorption showing the absorption features of ZnPorF16SPy4 (430, 500–600 nm), on the one hand, and of RuPc (300–400, 650 nm), on the other hand. All of the aforementioned effects are even more pronounced upon photoexciting 2 and H2PorF16SPy4 at 420 nm and comparing their fluorescence features; fluorescence quenching is observed (Figure 3). In fact, the fluorescence quantum yield of 2 is much lower (0.003) than that of H2PorF16SPy4 (0.06) and H2Por (0.1). Also in the case of 2, RuPc fluorescence evolves at 658 nm, which, again, is at the expense of the H2PorF16SPy4 fluorescence. For comparison we measured the excitation spectrum of RuPc; its fluorescence corroborates with the H2PorF16SPy4 and RuPc-sensitized fluorescence with maxima at 422, 500–600, and 300–400/650 nm, respectively. More importantly, it also confirms the energy transfer between the H2PorF16SPy4 singlet excited state (1.95 eV) and the RuPc singlet excited state (1.85 eV). Like what has been seen before for 3, the H2PorF16SPy4 fluorescence lifetime is in 2 very short with a value below the time resolution of 100 ps. Interesting is the fact that in 1 the fluorescence quenching is weaker than in 2 with a quantum yield of nearly 0.01. Notably, besides the ZnPorF16SPy4 (2.05 eV), H2PorF16SPy4/H2PorF19SPy1 (1.95 eV), and RuPc (1.85 eV) fluorescence no additional features are seen. In further experiments, all of the RuPc-containing systems 1–3 were excited at 610 nm. Here, the exclusive RuPc excitation results only in the fluorescence of the latter without giving rise to any appreciable ZnPorF16SPy4 or H2PorF16SPy4/ H2PorF19SPy1 fluorescence and without any notable RuPc fluorescence quenching. Moreover, the corresponding maxima in these 610 nm excitation experiments match those seen for

zinc(II) tetraphenylporphyrin (ZnPor)[27] comprising a dominant Soret band absorption with a maximum at 423 nm and weak Q-band absorptions in the region of 500–600 nm (Table 1). However, when one compares the latter Pors with RuPc,[26] notable differences emerge, with RuPc showing a weak Soret band in the region of 300–400 nm and a strong Q-band maximum at 650 nm, which matches quite well with the absorption features seen for related ruthenium carbonyl phthalocyanines. The UV/Vis spectra of 1 and 2 show the features of the respective constituents H2PorF19SPy1 and H2PorF16SPy4, along with those of RuPc (Figure 2 and Table 1). In particular, the spectra show the Soret bands at 418 and 422 nm for 1 and 2, respectively, as well as the characteristic Q-bands of RuPc at 650 nm. By the same token, compound 3 features the absorption characteristics of the ZnPorF16SPy4, with a Soret band that maximizes at 430 nm, and of RuPc, with a strong Q-band at 650 nm that remained unchanged. The Soret band of 1 is blue-shifted compared to that of 2, appearing at 418 and 422 nm, respectively. We measured steady-state and time-resolved fluorescence spectra and Table 1 summarizes the fluorescence maxima, fluorescence quantum yields, and fluorescence lifetimes. H2PorF16SPy4, H2Por, ZnPorF16SPy4, and ZnPor were all photoexcited at 420 nm, while RuPc was photoexcited at 610 nm. The fluorescence spectra of H2PorF16SPy4 (Figure 3 top) and H2Por[28] feature maxima at 640 and 705 nm and quantum yields of 0.06 and 0.10, respectively. In contrast, ZnPorF16SPy4

Figure 3. Top: Room-temperature fluorescence spectra of H2PorF16SPy4 (black spectrum) in dichloromethane and 2 (red spectrum) in toluene with identical absorption at the 420 nm excitation wavelength. Bottom: Roomtemperature fluorescence spectra of ZnPorF16SPy4 (black spectrum) in dichloromethane and 3 (red spectrum) in toluene with identical absorption at the 420 nm excitation wavelength.

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Full Papers 1 (663 nm), 2 (655 nm), and 3 (658 nm) in 430 nm excitation experiments. In order to shed more light onto the interactions in the excited state of 1–3 and of their references, the femtosecond transient absorptions were probed. Here, either excitation of ZnPorF16SPy4/H2PorF16SPy4 at 420 nm or excitation of RuPc at 656 nm stood at the forefront of the investigations. The excitation of ZnPorF16SPy4 at 420 nm gives rise to the direct formation of the singlet excited state with maxima at 531, 575, and 623 nm and minima at 552, 595, and 652 nm; a similar excitation of H2PorF16SPy4 affords maxima at 494, 535, 571, and 622 nm and minima at 515, 550, 592, and 648 nm (Figure 4). The singlet excited state decays by intersys-

Figure 5. Top: Differential absorption spectra (visible and near-infrared) obtained upon femtosecond pump probe experiments (656 nm) of RuPc in toluene with time delays between 0.1 and 6749.9 ps at room temperature. Bottom: Time absorption profiles of the spectra shown in the upper part at 515 (red spectrum), 915 (black spectrum), and 590 nm (gray spectrum) monitoring the excited state decay.

presence of ruthenium, intersystem crossing to the corresponding triplet excited state is fast and efficient yielding a 1 ms lived transient maximum at 515 nm. In the case of 3, which was also excited at 420 nm, the spectral features of the ZnPorF16SPy4 singlet excited state (vide supra) are seen. Most notable are the minimum at 560 nm and the maxima at 465, 605, and 695 nm (Figure 6). The presence of the RuPc evokes a significant shortening of the ZnPorF16SPy4 singlet excited state lifetimes to namely (130 20) ps. Concomitant with the latter decay we note the formation of a new transient state. The new transient features are characteristic minima at 590 and 650 nm, which resemble those seen for RuPc. In other words, in the case of 3 an intramolecular energy transfer transduces singlet excited state energy from the initially excited ZnPorF16SPy4 to RuPc. As a matter of fact, the current finding compares well with the conclusions from the steady-state and time-resolved fluorescence experiments. On the nanosecond timescale the decay of the triplet excited state features of RuPc leads to a lifetime of (8.3 1) ms. Turning again to 2, right after the 420 nm excitation of the H2PorF16SPy4 singlet ground states, its singlet excited state is formed (Figure 7). Evidence for the latter stems from monitoring ground state bleaching at 510 nm and transient maxima at

Figure 4. Top: Differential absorption spectra (visible and near-infrared) obtained upon femtosecond pump probe experiments (420 nm) of H2PorF16SPy4 in dichloromethane with time delays between 0.1 and 6749.9 ps at room temperature. Bottom: Differential absorption spectra (visible and near-infrared) obtained upon femtosecond pump probe experiments (420 nm) of ZnPorF16SPy4 in dichloromethane with time delays between 0.1 and 6749.9 ps at room temperature.

tem crossing (ISC), with lifetimes of about (2.1 0.5) ns and (9.8 0.5) ns for ZnPorF16SPy4 and H2PorF16SPy4, respectively, featuring maxima at 840 nm (ZnPorF16SPy4) as well as 780 nm (H2PorF16SPy4). The triplet lifetimes are 80 ms for ZnPorF16SPy4 and 1 ms for H2PorF16SPy4. Immediately after excitation of RuPc at 656 nm its singlet excited state features are evident in the form of a bleaching at around 590 and 650 nm (Figure 5). The latter features a lifetime of (7.5 2.5) ps. Owing to the ChemPlusChem 2015, 80, 832 – 838


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Figure 6. Top: Differential absorption spectra (visible and near-infrared) obtained upon femtosecond pump probe experiments (420 nm) of 3 in toluene with time delays between 0.1 and 6749.9 ps at room temperature. Bottom: Time absorption profiles of the spectra shown in the upper part at 510 (red spectrum), 650 (black spectrum), and 610 nm (gray spectrum) monitoring the excited state energy transfer.

Figure 7. Top: Differential absorption spectra (visible and near-infrared) obtained upon femtosecond pump probe experiments (420 nm) of 2 in toluene with time delays between 0.1 and 6749.9 ps at room temperature. Bottom: Time absorption profiles of the spectra shown in the upper part at 510 (red spectrum) and 650 nm (black spectrum) monitoring the excited state energy transfer.

460, 615, and 690 nm. In analogy to the observation made with 3 (vide supra) an intramolecular energy transfer sets in shortly after the formation of the H2PorF16SPy4 singlet excited state. In fact, the RuPc singlet excited minima at 590 and 650 nm grows in with (21 7) ps, which matches the decay of the H2PorF16SPy4 singlet excited state. On the nanosecond timescale, the decay of the triplet excited state features of RuPc is discernable, which give rise to a lifetime of (4.0 0.5) ms. A quantitatively similar picture evolves for 1 with an intramolecular energy transfer that takes (150 50) ps (Figure 8). In complementary experiments, when 1–3 are excited at 656 nm only the features of RuPc are observed. No appreciable H2PorF19SPy1-, H2PorF16SPy4-, and ZnPorF16SPy4-based features are seen at any time during the time evolution due to the dominating absorptions of RuPc.

measurements, in general, and fluorescence and femtosecond transient absorption spectroscopy, in particular, corroborate intramolecular energy transfer from the pyridyl Por(s) to the RuPcs in all three cases. In the case of hybrid 1 a unidirectional energy transfer occurs, while for hybrids 2 and 3 energy transfer directs the excited state energy from the core to the periphery. This was demonstrated by RuPc-centered excited state features evolving upon photoexcitation of the pyridyl Por(s), which gave rise lower fluorescence quantum yields, shorter fluorescence lifetimes, and shorter singlet excited state lifetimes than the corresponding references. These results may prove to be important for the design of new Por–Pc electron donor/electron acceptor hybrids for use as building blocks in solar-light-converting systems.

Experimental Section

Conclusion

Synthesis of 5-[2,3,5,6-tetrafluoro-4-(4-pyridylsulfanyl)phenyl]-10,15,20-tris(pentafluorophenyl)porphyrin (H2PorF19SPy1)

Three novel supramolecular heterochromophore structures 1– 3 have been prepared to probe photoinduced energy- and/or electron-transfer processes. In particular, pyridyl-substituted porphyrins were coordinated with RuPc to promote electronic communication between these electron donors/electron acceptors. Photophysical investigation by means of time-resolved ChemPlusChem 2015, 80, 832 – 838


The reaction of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPPorF20, 222.1 mg, 0.228 mmol) and 4-mercaptopyridine (17.1 mg, 0.154 mmol, 0.7 equiv) using 1 mL of diethylamine was accomplished in 3 mL of DMF during 1 h at room temperature. After reaction, DMF was evaporated under reduced pressure and

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Full Papers nm (e): 423 (5.63), 552 (4.31), 586 (3.40). MALDI-TOF-MS: m/z 1401 [M + H] + .

Synthesis of 1 A mixture of H2PorF19SPy1 (14.8 mg, 0.014 mmol) and RuPc (13.2 mg, 0.015 mmol, 1.1 equiv) was stirred in 5 mL of CH2Cl2 overnight at room temperature. After concentration under reduce pressure, the products were purified by molecular exclusion chromatography column (Bio-Beads S-X1) using CH2Cl2 as the eluent. The main fraction was dried and the solid product 1 was obtained in 71 % yield. 1H NMR (300 MHz, CDCl3): d = ¢3.02 (s, 2 H, NH), 1.79 (s, 36 H, tBu-H), 6.99–7.13 (m, 4 H, Por b-H), 8.18 (d, J = 8.1 Hz, 4 H, RuPc b-H), 8.62 (d, J = 4.6 Hz, 2 H, SPy-o-H), 8.80 (d, J = 4.6 Hz, 2 H, SPy-m-H), 8.90 (s, 4 H, Por b-H), 9.30–9.47 (m, 8 H, RuPc a-H). 19 F NMR (282 MHz, CDCl3): d = ¢184.89 to ¢184.68 (m, 6 F, Ar-o-F), ¢174.74 to ¢174.51 (m, 3 F, Ar-p-F), ¢160.09 to ¢159.91 (m, 6 F, Ar-m-F), ¢157.62 (dd, J = 24.3, 11.9 Hz, 2F, SPyAr-F), ¢153.97 (dd, J = 24.3, 11.9 Hz, 2F, SPyAr-F). ESI-MS: m/z 1931 [M] + .

Synthesis of 2 A mixture of H2PorF16SPy4 (15.0 mg, 0.011 mmol) and RuPc (51.3 mg, 0.056 mmol, 5 equiv) was stirred in 5 mL of CH2Cl2 overnight at room temperature. After reaction, the products were purified by molecular exclusion chromatography column (Bio-Beads SX1) using CH2Cl2 as the eluent. The main fraction was dried and the obtained blue solid 2 was obtained in 91 % yield. 1H NMR (300 MHz, CDCl3): d = ¢3.39 to ¢3.35 (m, 2 H, NH), 1.60 (s, 144 H, tBu-H), 5.27 (d, J = 6.6 Hz, 8 H, SPy-o-H), 8.06 (d, J = 8.0 Hz, 16 H, RuPc b-H), 8.36 (s, 8 H, Por b-H), 9.25–9.39 (m, 40 H, RuPc a-H and SPy-m-H). 19F NMR (282 MHz, CDCl3): d = ¢134.18 to ¢133.96 (m, 8F, Ar-o-F), ¢130.45 to -¢130.29 (m, 8F, Ar-m-F). ESI-MS: m/z 4803 [M] + .

Figure 8. Top: Differential absorption spectra (visible and near-infrared) obtained upon femtosecond pump probe experiments (420 nm) of 1 in toluene with time delays between 0.1 and 6749.9 ps at room temperature. Bottom: Time absorption profiles of the spectra shown in the upper part at 510 (red spectrum) and 650 nm (black spectrum) monitoring the excited state energy transfer.

the residue was subjected to flash chromatography, using CH2Cl2 and CH2Cl2/MeOH (98:2) as eluents. The product was crystallized from CH2Cl2/MeOH (98:2)/hexane as a purple solid in 22 % yield. 1 H NMR (300 MHz, CDCl3): d = ¢2.97 (s, 2 H, NH), 7.29 (dd, J = 4.6, 1.5 Hz, 2 H, SPy-o-H), 8.58 (dd, J = 4.6, 1.5 Hz, 2 H, SPy-m-H), 8.87– 8.89 (m, 8 H, b-H). 19F NMR (282 MHz, CDCl3): d = ¢184.87 to ¢184.67 (m, 6F, Ar-o-F), ¢174.75 to ¢174.51 (m, 3F, Ar-p-F), ¢160.02 (dd, J = 23.1, 7.8 Hz, 6F, Ar-m-F), ¢158.15 (dd, J = 24.8, 12.5 Hz, 2F, SPyAr-F), ¢154.30 (dd, J = 24.8, 12.5 Hz, 2F, SPyAr-F). MALDI-TOF-MS: m/z 1066 [M + H] + .

Synthesis of 3 A mixture of 2 (15.0 mg, 0.003 mmol) and zinc acetate (0.57 mg, 0.003 mmol, 1 equiv) was stirred in 5 mL of CH2Cl2/MeOH (9:1) for 3 h at reflux. After that, the reaction product was purified by molecular exclusion to afford the corresponding zinc complex 3 in 90 % yield, isolated as a deep blue solid. 1H NMR (300 MHz, CDCl3): d = 1.59 (s, 144 H, tBu-H), 5.22 (d, J = 18.9 Hz, 8 H, SPy-o-H), 7.96 (br s, 24 H, RuPc b-H and Por b-H), 8.40 (d, J = 18.9 Hz, 8 H, Ar-m-H), 9.04–9.38 (m, 40 H, Por b-H and RuPc a-H). 19F NMR (282 MHz, CDCl3): d = ¢157.95 to ¢157.15 (m, 8F, Ar-o-F), ¢155.07 to ¢153.39 (m, 8F, Ar-m-F). UV/Vis (C6H5CH3), lmax. nm (e): 430 (5.93), 552 (5.06), 587 (5.48), 650 (6.14).

Synthesis of 5,10,15,20-tetrakis[2,3,5,6-tetrafluoro-4-(4-pyridylsulfanyl)phenyl]porphyrinato zinc(II) (ZnPorF16SPy4)

Acknowledgements

A mixture of Por H2PorF16SPy4 (31.6 mg, 0.024 mmol) and zinc acetate (23.7 mg, 0.13 mmol, 5 equiv) were heated in 5 mL of CHCl3/ MeOH (9:1) at reflux. The reaction was monitored by thin-layer chromatographs and was complete after stirring for 3 h under nitrogen atmosphere. By precipitation from a mixture of CHCl3/ MeOH (98:2)/hexane, the product was obtained as a purple solid and washed several times with water in order to remove the excess zinc acetate. Compound ZnPorF16SPy4 was obtained in 96 % yield. 1H NMR (300 MHz, CDCl3): d = 7.23 (d, J = 5.7 Hz, 8 H, SPy-o-H), 8.07 (d, J = 5.7 Hz, 8 H, SPy-m-H), 8.95 (s, 8 H, b-H). 19 F NMR (282 MHz, CDCl3): d = ¢154.93 (dd, J = 24.5, 11.8 Hz, 8F, Aro-F), ¢151.46 (dd, J = 24.5, 11.8 Hz, 8F, Ar-m-F). UV/Vis (CH2Cl2), lmax. ChemPlusChem 2015, 80, 832 – 838


Thanks are due to Aveiro, Erlangen and Autonoma Universities, FCT (Portugal), European Union, QREN, COMPETE and FEDER for funding QOPNA Research Unit (Project PEst-C/QUI/UI0062/2013; FCOMP-01–0124-FEDER-037296), the Portuguese National NMR Network, and the grant PTDC/CTM/101538/2008 to J. Tom¦. Leandro M. O. LourenÅo thanks FCT for his PhD grant (SFRH/BD/ 64526/2009). Financial help is also acknowledged from the Spanish MICINN (CTQ2011–24187/BQU), the Comunidad de Madrid, Spain (S2013/MIT-2841, FOTOCARBON), the EU (“SO2S” FP7837


Full Papers PEOPLE-2012-ITN, no.: 316975), and The “Solar Technologies Go Hybrid” initiative of the state of Bavaria. Keywords: donor–acceptor systems · phthalocyanines porphyrins · ruthenium · supramolecular chemistry

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Received: January 7, 2015 Published online on February 12, 2015

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