Rhodium(III) and Iridium(III) Bipyricorrole Complexes: Syntheses

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Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

Rhodium(III) and Iridium(III) Bipyricorrole Complexes: Syntheses, Structures, and Properties B. Adinarayana,† Muthuchamy Murugavel,† Mainak Das, Narasinga Rao Palepu, and A. Srinivasan* National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar 752050, Odisha, India S Supporting Information *

ABSTRACT: Rhodium(III) and iridium(III) bipyricorrole complexes have been unprecedentedly reported. Single-crystal X-ray diffraction studies unambiguously evinced the molecular structures of metal complexes in octahedral geometry. The monoanionic platform of bipyricorrole effectively stabilizes metal ions in their higher oxidation states. It is worth mentioning that the fluorescence quantum yield of the rhodium(III) complex is 3-fold higher than that of free-base bipyricorrole.

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INTRODUCTION Corrole is a ring-contracted porphyrin with a direct pyrrole− pyrrole linkage that shares its π-conjugation pathway with porphyrin and its molecular skeleton with the corrin ring.1 In contrast to the porphyrin macrocycle, the trianionic core of corrole can stabilize metal ions in higher oxidation states.2 After the successful synthetic methodologies established by Gross,3a Paolesse,3b and Gryko3c and their co-workers, the research on corrole chemistry has gained more attention. Particularly, interest has increased toward the coordination chemistry of corrole4 because of its potential applications in the fields of catalysis,5 sensors,6 dye-sensitized solar cells,7 and medicinal chemistry.8 The chemistry of rhodium and iridium corroles, which is more relevant to this manuscript, was demonstrated by Gross and co-workers. The rhodium(III) corrole, [(tpfc)RhIIIP(C6H11)3] (1), where tpfc = tris(pentafluorophenyl)corrole, was obtained by the aerial oxidation of the intermediate rhodium(I) complex in the presence of excess P(C6H11)3 (Chart 1).9 On the other hand, the chemistry of iridium(III) corroles is exciting because of their intriguing photophysical properties, such as high phosphorescence quantum yield, long phosphorescence lifetime, etc. The first example of an iridium(III) corrole complex, [(tpfc)IrIII(tma)2] (2),10 where tma = trimethylamine, exhibits near-infrared phosphorescence emission at a wavelength longer than that of the cyclometalated iridium(III) complex at ambient temperature.11 Recently, iridium(III) benzonorrole, an isomer of the benzocorrole metal complex, was reported by Furuta and co-workers. This N-mutated iridium(III) corrole complex has a dramatic effect on the photophysical properties, which shows phosphorescence emission at around 900 nm.12 Very recently, we have successfully introduced a new family of corrole analogues, biphenylcorrole13a and bipyricorrole,13b © XXXX American Chemical Society

Chart 1. Chemical Structures of 1−3, 4a, and 4b

by replacing a bipyrrole unit with the biphenyl and bipyridyl units in the corrole system. In bipyricorrole, the trivalency of the corrole analogue was successfully converted into its monovalency, and it could stabilize metal ions in the 2+ oxidation states [zinc(II), nickel(II), and palladium(II)] with an axial ligand or a counteranion and be exploited for the selective sensing of Zn2+ metal ions.13b Further, the reactivity of mesofree bipyricorrole was examined by oxidative coupling with various oxidizing agents.13c Herein, we report the syntheses, Received: October 24, 2017

A

DOI: 10.1021/acs.inorgchem.7b02724 Inorg. Chem. XXXX, XXX, XXX−XXX

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insertion of metal ions in bipyricorrole 5a. The bipyridyl protons in 3 are resonated as a triplet at 9.12 ppm (H3 and H19) and as a multiplet at 8.50 ppm (H2, H20, H4, and H18; Figure 1a). The pyrrolic β-CH protons appear as a set of doublets at 7.46 ppm (H8 and H14) and 7.32 ppm (H9 and H13), and meso-phenyl protons are in the range of 7.81−7.52 ppm. In contrast to 3, the bipyridyl protons in 4a resonate as doublets at 9.10 ppm (H2 and H20) and 8.58 ppm (H4 and H18) and a triplet at 8.19 ppm (H3 and H19; Figure 1b). The pyrrolic β-CH protons are observed as a set of doublets at 7.58 ppm (H8 and H14) and 7.22 ppm (H9 and H13), and mesophenyl protons are between 7.83 and 7.53 ppm. In comparison, the 1H NMR signals of 3 and 4a are more shielded than those of 5a (Figure S5). The molecular structures of complexes 3 and 4b were unambiguously confirmed by single-crystal X-ray diffraction studies, and the structures are shown in Figure 2. Suitable

structures, and photophysical and electrochemical properties of rhodium(III) and iridium(III) complexes of bipyricorrole. As a consequence, it has been proven that bipyricorrole is a unique ligand that can stabilize metal ions in different oxidation states (2+ and 3+), even though it has monoanionic platform.

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RESULTS AND DISCUSSION The coordination chemistry of 5a was performed by treating a CH2Cl2 solution of 5a with [Rh(CO)2Cl]2 in methanol and afforded 3 (CCDC 1576275) in 45% yield. The insertion of iridium(III) was achieved by refluxing a p-xylene solution of 5a and 5b with bis(1,5-cyclooctadiene)diiridium dichloride ([Ir(cod)Cl]2; Scheme 1), and 4a and 4b (CCDC 1576274) were Scheme 1. Synthesis of 3, 4a, and 4ba

a (i) [Rh(CO)2Cl]2, CH2Cl2, CH3OH, RT; (ii) [Ir(cod)Cl]2, p-xylene, reflux.

obtained in 68% and 56% yield, respectively. In both cases, the color of the solution turns into dark green from blue. Rhodium(III) bipyricorrole (3) shows a prevalent mass peak at 687.0830, which corresponds to the chemical formula C39H25ClN4Rh (Figure S1), whereas iridium(III) bipyricorrole (4a) was identified as an adduct of two chlorine atoms and a sodium ion that matches with the mass peak at 835.0798 (C39H25Cl2IrN4Na; Figure S2). It was envisioned from the mass spectral pattern that compound 4a might have an octahedral geometry with two axially coordinated chloride ligands. The solution-state structures of 3 and 4a were deduced from 1 H NMR spectra recorded at 298 K in CDCl3 (Figure 1). The disappearance of the NH signal in 3 and 4a confirms the

Figure 2. Molecular structures of 3 and 4b: (a and c) top views; (b and d) side views. Ellipsoids are set at the 50% probability level. The meso-aryl groups are omitted for clarity in the side view.

Figure 1. 1H NMR spectra of (a) 3 and (b) 4a in CDCl3 at 298 K. B

DOI: 10.1021/acs.inorgchem.7b02724 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry crystals of 3 were grown by the slow evaporation of a CH2Cl2 solution in the presence of n-hexane. As reflected from NMR and mass analyses, rhodium(III) ion insertion and axial coordination are confirmed from the single-crystal X-ray structure (Figure 2a,b and Table S1), where the rhodium(III) ion is placed exactly at the center of the ligand. The geometry around the metal ion is octahedral with a basal plane containing four nitrogen atoms, and the axial positions are occupied by two chloride ligands. The bond lengths of Rh−N1 and Rh−N4 are 2.008(3) and 2.009(3) Å, respectively, which are moderately longer than the Rh−N2 and Rh−N3 distances, viz., 1.978(3) and 1.977(2) Å (Figure S14 and Table S2). These values are slightly longer than that of the reported rhodium(III) corrole14 and shorter than that of the rhodium(III) N-confused porphyrin,15 where the respective values are shown in Table S2. The saddling dihedral angle values of 3 are between 0.64(7)° and 9.67(9)°, which are comparable with the earlier reported bipyricorrole complexes (Figure S15 and Table S3).13b,c The presence of axial chloride ligands in the complex generates an intermolecular hydrogen-bonding interaction to form self-assembled dimers with bond distances and angles of C2−H2···Cl2 2.665(1) Å and 151.15(2)° and C19−H19···Cl1 2.828(1) Å and 153.18(2)°, respectively (Figure S16). These dimers are combined together to generate a 1D array in the solid state (Figure S17). On the other hand, the unit cell of the iridium(III) complex 4b contains two crystallographically independent molecules (Ir1 and Ir2; Figure S18), and one of the structures (Ir1) is shown in Figure 2c,d. As observed in the rhodium(III) complex 3, the axial positions are occupied by chloride ligands and the geometry around the metal ion is octahedral. The bond lengths of Ir1−N1 and Ir1−N4 are 2.021(5) and 2.019(5) Å, respectively, which are slightly longer than those of Ir1−N2 and Ir1−N3, viz., 1.992(4) and 1.997(5) Å (Table S2 and Figure S14). However, these values are higher than those of their respective iridium(III) corrole complexes.10 The saddling dihedral angles of 4b are from 0.82(2) to 5.01(2)° (Table S3). The presence of fluorine atoms in the pentafluoro unit and axial chloride ions generates a series of intermolecular hydrogenbonding interactions to form self-assembled dimers (Figure S19) and 1D arrays (Figures S20−S22). The dimers and arrays are combined together to generate a 2D supramolecular assembly in the solid state (Figure S23). In addition, the bond lengths of the bipyridine unit in 3 (1.355−1.411 Å) and 4b (1.341−1.415 Å) (Figure S14) are in the range of typical sp2−sp2 double-bond character and remain isolated from the overall macrocyclic conjugation, thus exhibiting nonaromatic character. The steady-state electronic absorption spectra of 3 and 4a were recorded in CH2Cl2 (Figure 3), and their molar extinction coefficients are listed in Table 1. In comparison to 5a (Figure S24), the high-energy band of 4a is hypsochromically shifted by a wavelength of 15 nm and the low-energy band of 4a is bathochromically shifted by 21 nm, and they appear at 356 and 686 nm, respectively. In contrast, 3 exhibits a split high-energy band at 353 and 407 nm and prominent low-energy bands at 653 and 719 nm. The spectral pattern is comparable and bathochromically shifted with respect to the split Soret and Q bands of rhodium(III) corrole.16 The molar extinction coefficients of 3 and 4a at high-energy bands are less than those of 5a. Conversely, the respective values of 3 at the lowenergy bands are higher than those of 5a and 4a. This might be explained by theoretical studies, where the electronic transition

Figure 3. Steady-state electronic spectra of 3 and 4a.

Table 1. Electronic Absorption Spectral Data of 3, 4a, 4b, and 5a Recorded in CH2Cl2 (Concentration ≈ 10−5 M) compound 3 4a 4b 5a

high-energy bands λmax/nm (log ε) 353 (4.60), 407 (4.55) 356 (4.58) 353 (4.35) 371 (4.73)

low-energy bands λmax/nm (log ε)

λem/ nm

653 (4.18), 719 (4.79) 686 (4.29) 653 (4.00) 665 (4.40)

Φf

τ/ns

740, 806

0.06

0.47

773, 731

0.02

1.1

in 3 is contributed by 94% from a highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) transition (Table S8). In addition, the experimental absorption spectra of 4a and 5a were corroborated with the simulated electronic spectra obtained by theoretical calculations (Figures S25 and S27). The steady-state and time-resolved fluorescence emissions of metal complexes 3 and 4a were examined along with those of ligand 5a (Figure 4). In contrast to 1, surprisingly, the rhodium(III) complex 3 exhibits fluorescence emission at 740 and 806 nm, where the spectral pattern is the exact mirror image of its low-energy absorption bands. The quantum yield and lifetime of 3 were calculated to be 0.06 and 0.47 ns, respectively. It is worth mentioning that the quantum yield of 3 is 3-fold higher than that of 5a (0.02). On the other hand, the iridium(III) complex 4a shows neither fluorescence nor phosphorescence emission. In general, the iridium(III) corrole 210 and iridium(III) benzonorrole12 are phosphorescent in nature; however, 4a reveals contrasting behavior and is similar to iridium(III) carbaporphyrinoids.17 The electrochemical properties of 3, 4a, and 5a have been investigated by differential pulse voltammetry in a CH2Cl2 solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte (Figure S28), and their redox potentials were tabulated (Table S10). Compound 5a exhibits five distinct oxidation potentials at −0.46, 0.03, 0.62, 0.90, and 1.08 V and one reduction potential at −1.59 V. The third, fourth, and fifth oxidation potentials of 5a are reminiscent of the oxidation potentials of free-base corrole.18 Surprisingly, the first oxidation potentials of 3 and 4a are very similar and occur at 0.42 and 0.44 V, which might be attributed to ligand-centered rather than metal-centered oxidation.19 The first reduction potentials of 3 and 4a at C

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Figure 4. (a) Fluorescence emission spectra and (b) lifetime measurements of 3 and 5a in CH2Cl2.

−1.35 and −1.42 V are positively shifted by 240 and 170 mV with respect to 5a. The second oxidation and reduction potentials of 3 appear at 0.80 and −1.73 V, and the second oxidation is perhaps due to the oxidation of rhodium(III) to rhodium(IV). The electrochemical HOMO−LUMO gaps of 3 and 4a were calculated to be 1.77 and 1.86 V, respectively, which follows a trend similar to that obtained from computational calculations. The density functional theory (DFT) calculations were carried out using Gaussian 0920 program with restricted B3LYP level, in order to support the electronic structures of 3 and 4a. All structures were fully optimized without any symmetry restriction. The frontier molecular orbitals of 3 and 4a and their energy-level diagrams are shown in Figure S31. These orbitals follow C2v symmetry, as in the case of metallocorroles,21 which are nondegenerate and well separated in their energy levels. The HOMO and LUMO of 3 and 4a are localized on the bipyricorrole moiety. There is a negligible overlap of the metal d orbital in 3 and a significant overlap of the metal d orbital in 4a with the HOMO of bipyricorrole.

measurements were recorded on an Edinburgh instrument. X-rayquality crystals of the synthesized complexes were grown by the vapor diffusion of n-hexane into a CH2Cl2 solution. Single-crystal X-ray diffraction data of 3and 4b were collected on a Bruker Kappa APEX-II CCD four-angle rotation system, with Mo Kα radiation (λ = 0.71073 Å). For collection of the data of the ϕ and ω scans, a diffraction measurement method was used for the experiment. A SQUEEZE routine was applied using the PLATON program to remove the highly disordered solvent molecules to proceed to the final refinement of the main structure.22 Electrochemical studies were carried out on a CHI 1120A instrument with a three-electrode system, which consisted of a platinum disk as the working electrode, a platinum wire as the counter electrode, and Ag/AgCl as the reference electrode. Fluorescence quantum yields were determined by using meso-tetraphenylporphyrin (TPPH2) in toluene (Φf = 0.11) as a reference. DFT calculations were carried out using the Gaussian 09 program. All structures were fully optimized without any symmetry restriction. All calculations were performed with a restricted B3LYP (Becke’s three-parameter hybrid exchange and Lee−Yang−Parr correlation functionals)23 level, employing the basis sets 6-31G(d)24 for chlorine, hydrogen, nitrogen, and fluorine atoms and LANL2DZ25 for rhodium and iridium metal atoms. Syntheses and Spectral Characterization. Synthesis of 5a.13b A mixture of 6 (0.400 g, 0.86 mol) and benzaldehyde (0.105 mL 0.86 mol) was dissolved in 300 mL of dry CH2Cl2 and stirred for 10 min in dark and under an inert atmosphere. Trifluoroacetic acid (0.39 mL, 5.16 mol) was added, stirring was continued for 3 h, and the mixture was oxidized with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (0.585 g, 2.58 mol). The compound was then purified through basic alumina column chromatography followed by silica gel (100−200 mesh) column chromatography and eluted with 0.5% CH3OH/CH2Cl2. The compound was recrystallized with CH2Cl2/n-hexane to give 5a in 15% yield. 1 H NMR (400 MHz, CDCl3): δ 10.62 (s, 1H), 9.46 (d, J = 6.5 Hz, 2H), 8.58 (t, J = 7.4 Hz, 2H), 8.06 (d, J = 7.7 Hz, 2H), 7.70−7.49 (m, 15H), 7.30 (d, J = 5.1 Hz, 2H), 7.00 (d, J = 5.2 Hz, 2H). 13C NMR (100 MHz, CD3OD): δ 155.19, 154.17, 151.84, 145.56, 138.33, 136.10, 135.06, 132.16, 131.92, 131.26, 130.62, 129.76, 129.20, 128.86, 128.65, 122.76, 108.47. UV−vis [CH2Cl2; λmax/nm (log ε)]: 371 (4.73), 665 (4.40). MS (ESI). Calcd for C39H26N4: m/z 550.2157. Found: m/z 551.2224 (M + 1). Quantum yield (Φf): 0.02. Synthesis of 3. A solution of [Rh(CO)2Cl]2 (2.81 mg, 0.007 mmol) in 2 mL of CH3OH was added to a solution of 5a (8 mg, 0.015 mmol) in 15 mL of CH2Cl2 and allowed to stir for 4 h. The compound was then extracted with CH2Cl2, and the solvent was removed by a rotary evaporator. The crude reaction mixture was subjected to neutral alumina column chromatography and eluted with 50% CH2Cl2/nhexane. The compound was recrystallized with CH2Cl2/n-hexane to give 3 in 45% yield. 1 H NMR (400 MHz, CDCl3): δ 9.12 (t, J = 4.1 Hz, 2H), 8.50 (m, 4H), 7.81 (m, 4H), 7.74 (m, 2H), 7.66−7.61 (m, 6H), 7.54−7.52 (m, 3H), 7.46 (d, J = 5.3 Hz, 2H), 7.32 (d, J = 5.3 Hz, 2H). 13C NMR (100

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CONCLUSIONS In conclusion, we have successfully demonstrated the coordination chemistry of a monoanionic bipyricorrole with rhodium and iridium salts. The core, which was effectively utilized to stabilize the metal ions in the 2+ oxidation state, is further extended to stabilize rhodium and iridium ions in the 3+ oxidation state. Spectral and structural analyses reveal that the complexes exhibit nonaromatic character. The electronic absorption spectra of these complexes are reminiscent of their corrole analogues and further supported by theoretical calculations. The bipyricorrole core is an ideal platform to stabilize the metal ion in the 1+ oxidation state, and research is currently headed in this direction in our group.

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EXPERIMENTAL SECTION

General Considerations. Reagents and materials for synthesis were used as obtained from Sigma-Aldrich chemical suppliers. All solvents were purified and dried by standard methods prior to use. NMR solvents were used as received. The NMR spectra were recorded with Bruker 400 and 700 MHz spectrometers with tetramethylsilane [Si(CH3)4] as an internal standard. High-resolution electrospray ionization mass spectrometry spectra were recorded on a Bruker micro-TOF-QII mass spectrometer. The electronic absorption and steady-state fluorescence spectra were recorded with a PerkinElmer− Lambda 750 UV−vis spectrophotometer and an Edinburgh FS5 fluorescence spectrometer, respectively. Time-resolved fluorescence D

DOI: 10.1021/acs.inorgchem.7b02724 Inorg. Chem. XXXX, XXX, XXX−XXX

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MHz, CDCl3): δ 155.67, 154.58, 149.70, 149.26, 139.59, 138.85, 137.29, 134.96, 134.22, 133.44, 133.07, 130.99, 128.65, 128.23, 127.86, 127.82, 126.08, 120.57. UV−vis [CH2Cl2; λmax/nm (log ε)]: 353 (4.60), 407 (4.55), 653 (4.18), 719 (4.79). MS (ESI). Calcd for C39H25Cl2N4Rh: m/z 722.0511. Found: m/z 687.0830 (M − Cl). Quantum yield (Φf): 0.06. Synthesis of 4a. Compound 5a was dissolved in 100 mL of dry pxylene, and anhydrous sodium acetate (6 mg, 0.01 mmol) was added to the reaction mixture and allowed to stir for 15 min. [Ir(cod)Cl]2 (30 mg, 0.046 mmol) was then added and refluxed at 140 °C under a nitrogen atmosphere for 16 h. The crude reaction mixture was subjected to neutral alumina column chromatography and eluted with 100% CH2Cl2. The compound was recrystallized with CH2Cl2/nhexane to give 4a in 68% yield. 1 H NMR (700 MHz, CDCl3): δ 9.10 (d, J = 7.5 Hz, 2H), 8.58 (d, J = 8.3 Hz, 2H), 8.19 (t, J = 8.0 Hz, 2H), 7.83 (dd, J = 7.2 and 1.7 Hz, 4H), 7.78 (dd, J = 7.5 and 1.4 Hz, 2H), 7.64 (m, 6H), 7.58 (d, J = 5.3 Hz, 2H), 7.53 (m, 3H), 7.22 (d, J = 5.3 Hz, 2H). 13C NMR (176 MHz, CDCl3): δ 157.32, 149.31, 147.85, 139.49, 139.36, 138.19, 135.44, 133.23, 133.02, 132.11, 129.80, 128.60, 128.21, 128.07, 127.81, 127.76, 119.41, 112.35. UV−vis [CH2Cl2; λmax/nm (log ε)]: 356 (4.58), 686 (4.29); MS (ESI). Calcd for C39H25Cl2N4Ir: m/z 812.1086. Found: m/ z 835.0798 (M + Na). Synthesis of 4b. Anhydrous sodium acetate was added to a solution of 5b (6 mg, 0.01 mmol) in p-xylene (100 mL) and allowed to stir for 15 min. Then [Ir(cod)Cl]2 (30 mg, 0.05 mmol) was added and refluxed for 16 h under a nitrogen atmosphere. The compound was purified through neutral alumina column chromatography with 100% CH2Cl2 and recrystallized with CH2Cl2/n-hexane to give 4b in 56% yield. 1 H NMR (700 MHz, CDCl3): δ 9.09 (d, J = 7.5 Hz, 2H), 8.56 (d, J = 8.4 Hz, 2H), 8.20 (t, J = 8.0 Hz, 2H), 7.85−7.80 (m, 4H), 7.80−7.60 (m, 6H), 7.42 (d, J = 5.2 Hz, 2H), 7.29 (d, J = 5.3 Hz, 2H). 13C NMR (176 MHz, CDCl3): δ 157.68, 156.94, 149.52, 147.42, 139.70, 138.92, 136.02, 133.12, 130.21, 130.13, 129.57, 128.85, 128.33, 119.92. UV− vis [CH2Cl2; λmax/nm (log ε)]: 353 (4.35), 653 (4.00). MS (ESI). Calcd for C33H20Cl2F5IrN4: m/z 902.0614. Found: m/z 925.0504 (M + Na).

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ACKNOWLEDGMENTS A.S. thanks NISER, DAE, for financial support. B.A. thanks CSIR and M.D. thanks NISER for SRF, and M.M. and P.N.R. thank DST-SERB for NPDF (Grants PDF/2016/003432 and PDF/2017/001568). We thank Dr. R. V. R. Reddy for computational calculations and Dr. Jitendra Kumar and Pankaj Kalita for solving the crystal structures.

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REFERENCES

(1) Paolesse, R. In The Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2000; Vol. 2, pp 201−232. (2) (a) Orłowski, R.; Gryko, D.; Gryko, D. T. Synthesis of Corroles and Their Heteroanalogs. Chem. Rev. 2017, 117, 3102−3137. (b) Guilard, R.; Barbe, J. M.; Stern, C.; Kadish, K. M. Porphyrin Handbook 2003, 18, 303. (c) Luobeznova, I.; Simkhovich, L.; Goldberg, I.; Gross, Z. Electronic Structures and Reactivities of Corrole−Copper Complexes. Eur. J. Inorg. Chem. 2004, 8, 1724−1732. (3) (a) Gross, Z.; Galili, N.; Saltsman, I. The first direct synthesis of corroles from pyrrole. Angew. Chem., Int. Ed. 1999, 38, 1427−1429. (b) Paolesse, R.; Mini, S.; Sagone, F.; Boschi, T.; Jaquinod, L.; Nurco, D. J.; Smith, K. M. 5, 10, 15-Triphenylcorrole: a product from a modified Rothemund reaction. Chem. Commun. 1999, 14, 1307−1308. (c) Koszarna, B.; Gryko, D. T. Efficient Synthesis of meso-Substituted Corroles in a H2O-MeOH Mixture. J. Org. Chem. 2006, 71, 3707− 3717. (4) Barata, J. F.; Neves, M. G. P. M. S.; Faustino, M. A. F.; Tome, A. C.; Cavaleiro, J. A. Strategies for Corrole Functionalization. Chem. Rev. 2017, 117, 3192−3253. (5) (a) Zhang, W.; Lai, W.; Cao, R. Energy-Related Small Molecule Activation Reactions: Oxygen Reduction and Hydrogen and Oxygen Evolution Reactions Catalyzed by Porphyrin- and Corrole-Based Systems. Chem. Rev. 2017, 117, 3717−3797. (b) Golubkov, G.; Bendix, J.; Gray, H. B.; Mahammed, A.; Goldberg, I.; DiBilio, A. J.; Gross, Z. High-Valent Manganese Corroles and the First Perhalogenated Metallocorrole Catalyst. Angew. Chem., Int. Ed. 2001, 40, 2132−2134. (c) Meier-Callahan, A. E.; Di Bilio, A. J.; Simkhovich, L.; Mahammed, A.; Goldberg, I.; Gray, H. B.; Gross, Z. Chromium corroles in four oxidation states. Inorg. Chem. 2001, 40, 6788−6793. (d) Gross, Z.; Simkhovich, L.; Galili, N. First catalysis by corrole metal complexes: epoxidation, hydroxylation, and cyclopropanation. Chem. Commun. 1999, 7, 599−600. (6) (a) Ding, Y.; Zhu, W.-H.; Xie, Y. Development of Ion Chemosensors Based on Porphyrin Analogues. Chem. Rev. 2017, 117, 2203−2256. (b) Santos, C. I.; Oliveira, E.; Barata, J. F.; Faustino, M. A. F.; Cavaleiro, J. A.; Neves, M. G. P.; Lodeiro, C. Corroles as anion chemosensors: exploiting their fluorescence behaviour from solution to solid-supported devices. J. Mater. Chem. 2012, 22, 13811− 13819. (7) Walker, D.; Chappel, S.; Mahammed, A.; Brunschwig, B. S.; Winkler, J. R.; Gray, H. B.; Zaban, A.; Gross, Z. Corrole-sensitized TiO2 solar cells. J. Porphyrins Phthalocyanines 2006, 10, 1259−1262. (8) (a) Teo, R. D.; Hwang, J. Y.; Termini, J.; Gross, Z.; Gray, H. B. Fighting Cancer with Corroles. Chem. Rev. 2017, 117, 2711−2729. (b) Gross, Z.; Galili, N.; Saltsman, I. The first direct synthesis of corroles from pyrrole. Angew. Chem., Int. Ed. 1999, 38, 1427−1429. (9) Simkhovich, L.; Mahammed, A.; Goldberg, I.; Gross, Z. Synthesis and characterization of germanium, tin, phosphorus, iron, and rhodium complexes of tris (pentafluorophenyl) corrole, and the utilization of the iron and rhodium corroles as cyclopropanation catalysts. Chem. Eur. J. 2001, 7, 1041−1055. (10) Palmer, J. H.; Day, M. W.; Wilson, A. D.; Henling, L. M.; Gross, Z.; Gray, H. B. Iridium corroles. J. Am. Chem. Soc. 2008, 130, 7786− 7787. (11) Palmer, J. H.; Durrell, A. C.; Gross, Z.; Winkler, J. R.; Gray, H. B. Near-IR phosphorescence of iridium (III) corroles at ambient temperature. J. Am. Chem. Soc. 2010, 132, 9230−9231.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.7b02724. Details of spectral and single-crystal X-ray analyses, electrochemical studies, and computational calculations (PDF) Accession Codes

CCDC 1576274−1576275 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Tel.: 0674-2494170. ORCID

A. Srinivasan: 0000-0001-8467-1538 Author Contributions †

These authors contributed equally.

Notes

The authors declare no competing financial interest. E

DOI: 10.1021/acs.inorgchem.7b02724 Inorg. Chem. XXXX, XXX, XXX−XXX

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DOI: 10.1021/acs.inorgchem.7b02724 Inorg. Chem. XXXX, XXX, XXX−XXX