and Excited-State Properties of Ruthenium(II ... - ACS Publications

Oct 10, 2016 - energy FC state was assigned as ILCT in nature for all compounds ...... (31) Barnsley, J. E.; Shillito, G. E.; Larsen, C. B.; van der S...
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Effect of Bridge Alteration on Ground- and Excited-State Properties of Ruthenium(II) Complexes with Electron-Donor-Substituted Dipyrido[3,2‑a:2′,3′‑c]phenazine Ligands Georgina E. Shillito, Christopher B. Larsen, James R. W. McLay, Nigel T. Lucas,* and Keith C. Gordon* Department of Chemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand S Supporting Information *

ABSTRACT: A series of Ru(II) 2,2′-bipyridine (bpy) complexes with an electron-accepting dipyrido[3,2-a:2′,3′-c]phenazine (dppz) ligand coupled to an electron-donating triarylamine (TAA) group have been investigated. Systematic alteration of a bridging unit between the dppz and TAA allowed exploration into how communication between the donor and acceptor is perturbed by distance, as well as by steric and electronic effects. The effect of the bridging group on the electronic properties of the systems was characterized using a variety of spectroscopic methods, including Fourier transform−Raman (FT-Raman) spectroscopy, resonance Raman spectroscopy, and transient resonance Raman (TR2) spectroscopy. These methods were used in conjunction with ground- and excited-state absorption spectroscopy, electrochemical studies, and DFT calculations. The ground-state electronic absorption spectra show distinct variation with the bridging group, with the wavelength observed for the lowest energy electronic transition ranging from 449 nm to 522 nm, accompanied by large changes in the molar absorptivity. The lowest-energy Franck−Condon state was determined to be intra-ligand charge transfer (ILCT) in nature for most compounds. The presence of higher-energy metal-to-ligand charge transfer (MLCT) Ru(II) → bpy and Ru(II) → dppz transitions was also confirmed via resonance Raman spectroscopy. The TR2 spectra showed characteristic dppz• − and TAA• + vibrations, indicating that the THEXI state formed was also ILCT in nature. Excited-state lifetime measurements reveal that the rate of decay is in accordance with the energy gap law and is not otherwise affected by the nature of the bridging unit.

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INTRODUCTION Ruthenium(II) polypyridyl complexes have attracted considerable interest, because of their versatile and manipulable photophysical properties, making them potential candidates for a range of commercial applications, including use as solar dyes, sensors, molecular encoders, and catalysts.1−4 A detailed understanding of these properties is important in order to develop effective materials. Systematic structural modification and subsequent analysis of the resulting electronic changes can further our understanding of these systems. The unusual excited-state properties of [Ru(bpy)2dppz]2+ were discovered by Friedman et al. in 1990.2 It was found that, in protic solvents, the complex was nonemissive; however, in the presence of nonprotic solvents or upon intercalation into DNA, strong luminescence was observed. Brennaman et al. showed that this observed light switch effect is a result of a dynamic equilibrium between population of the lower energy enthalpically favored dark metal-to-ligand charge transfer (MLCT) phenazine (phz) state and the entropically favored bright MLCT phenanthroline (phen) state.5,6 The nature and energies of the electronic transitions that occur in metal polypyridyl systems can be altered by direct substitution onto the chromophoric ligands, alteration of the ancillary ligands, or by changing the transition-metal center.1,4,6−19 There has been considerable research into how © XXXX American Chemical Society

the MLCT transition of Ru(II) dppz complexes can be tuned through alteration of the relative energies of the phen and phz molecular orbitals (MOs).1,4,6,7,11−13,16,20−25 The complexity of these systems can be increased by the addition of electron-donating substituents, introducing the possibility of an intraligand charge transfer (ILCT) transition. Fraser et al. investigated a series of sulfur-substituted dppz ligands and their Re(I) complexes.8 The lowest energy state of the complex was characterized as a mixed MLCT and ILCT state, from S → dppz (phz). Similarly, Jia et al. showed that when the strong electron-donor tetrathiafulvalene (TTF) was appended to dppz, the lowest energy state corresponds to an intramolecular charge-transfer (CT) state from the TTF donor to the dppz acceptor.26 Goze et al. used the same TTF-dppz ligand and coordinated it to a Ru(II) center with two ancillary bpy ligands.9 The lowest energy state was characterized as an ILCT state. Ru(II) → dppz and Ru(II) → bpy MLCT states were also observed at higher energies, resulting in an intense, broad electronic absorption spectrum.9 Further examination of ILCT transitions occurring in donor-substituted dppz systems has been conducted by Larsen et al.14 The properties of Re(I) dppz complexes with appended amine donors such as TAA Received: July 27, 2016

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DOI: 10.1021/acs.inorgchem.6b01810 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry

exchange with NH4PF6, afforded [Ru(bpy)2(dppz-R)](PF6)2 in 67%−86% yield. Identity and purity of the ligands and complexes were confirmed by 1H and 13C NMR spectroscopies, mass spectrometry, and elemental analysis. Ground-State Vibrational Spectroscopy. Density functional theory (DFT) calculations using the CAM-B3LYP functional and the 6-31G(d) basis set were used to generate the lowest energy optimized geometries of the complexes. The predicted Raman vibrational modes of the complexes were also calculated and comparison with ground-state vibrational spectra provided a means to validate the predicted geometry. The harmonic frequencies predicted by DFT calculations are usually larger than the experimentally observed frequencies. A significant proportion of this error arises from anharmonicity effects.32,33 The errors involved have a tendency to be relatively uniform;32,33 thus, a scale factor can be applied in order to achieve a closer correlation with experimental spectra.34 In this work, the scale factor is optimized in order to achieve the lowest mean absolute deviation (MAD) value for each compound. The MAD value provides a means to quantify the correlation between calculated and experimental Raman spectra. A MAD value of 570 nm, which may be due to the presence of dppz• − radical anion9,11,16,54−56 or TAA• +, suggesting population of a 3ILCT state.57 The spectrum for [Ru(bpy)2(dppz-Thio-TAA)]2+ shows a distinctly different transient absorption spectrum, compared to the other complexes. This is possibly attributed to a more active involvement of the thiophene bridge in formation of the excited state, as a result of the more significant distribution of electron delocalization over bridge. Implying that the donor and acceptor are less electronically isolated than in the other complexes. The ΔA values are very small and a wide bleach is observed, extending out to ∼450 nm. As the excited state was not strongly absorbing, this presented difficulties in establishing a sufficient excited-state population to obtain resonance Raman scattering from the excited state. Despite the differences in the transient absorption data, TR2 data suggests that the THEXI state of [Ru(bpy)2(dppz-ThioTAA)]2 is still 3ILCT in nature (vide inf ra). Figure 9 shows the relationship between ln(1/τ) and the driving force, −ΔG, obtained electrochemically, analogous to

delocalization over the bridge, than [Ru(bpy)2(dppz-TrzTAA)]2+, where the H-1 is less involved (7%). When the TD-DFT-predicted HOMO−LUMO energy gap is compared to ΔE (see Figure S7), a more linear correlation is obtained. This suggests that the predicted HOMO and LUMO reflect the energetics of oxidation and reduction, respectively, but the optical transitions do not correlate, because of the differing ΔQ values that are associated with the noninnocent nature of some of the bridging units. Transient Absorption Spectroscopy. The complexes possess microsecond-scale lifetimes and show strong sensitivity to 3O2, suggesting that a triplet state is being measured. Intersystem crossing from the initially populated singlet state occurs rapidly, to an extent that the presence of the singlet state was not observed, since all compounds showed only monoexponential decay curves. The total rate of decay of the excited state (k) is given by k = k nr + k r

where knr and kr are the nonradiative and radiative decay rates, respectively. As knr is generally far greater than kr, one can then assume that k ≈ knr = 1/τ. The transient absorption lifetimes are given in Table 3. Uncertainties were calculated from the deviation between multiple measurements. Table 3. Transient Absorption Lifetimes τ (ns)

compound 2+

[Ru(bpy)2(dppz-CC-TAA)] [Ru(bpy)2(dppz-NPh2)]2+ [Ru(bpy)2(dppz-OMe2-TAA)]2+ [Ru(bpy)2(dppz-Ph-TAA)]2+ [Ru(bpy)2(dppz-Thio-TAA)]2+ [Ru(bpy)2(dppz-TAA)]2+ [Ru(bpy)2(dppz-Trz-TAA)]2+

4050 6600 2240 1390 2340 3670 897

± ± ± ± ± ± ±

1110 257 473 175 468 1180 11

rate, k × 10−4 (s−1) 24.7 15.2 44.6 71.9 42.7 27.2 113.8

± ± ± ± ± ± ±

6.8 0.6 9.4 9.1 8.5 8.8 1.4

The transient absorption spectra were similar for all compounds, except that of [Ru(bpy)2(dppz-Thio-TAA)]2+ (Figure 8). In general, a bleach was observed below 375 nm and between ∼475 nm and ∼570 nm, which corresponds to absorption of the ground-state species. A strong positive signal

Figure 9. Relationship between ln(1/τ) (where τ is the experimentally measured lifetime) and −ΔG. With −ΔG obtained from electrochemical data (red) and TD-DFT calculations (blue). Lines are included only as guides to the eye.

ΔE and from the TD-DFT-predicted HOMO−LUMO energy gap. A qualitative trend is observed where the lifetime increases with increasing −ΔG; hence, the deactivation rate is decreased. This is in accordance with the energy gap law, which states that the rate of nonradiative decay decreases as the energy difference between the two states increases.58−60 The excited-state lifetimes of [Ru(bpy)2(dppz-NPh2)]2+, [Ru(bpy)2(dppz-TAA)]2+, and [Ru(bpy)2(dppz-Ph-TAA)]2+ are 6600, 3670, and 1390 ns, respectively, revealing a decrease in excited-state lifetime as the D−A distance is increased. The rate of electron transfer between the donor and acceptor decreases as the driving force to return to the ground state increases. The D−A distance plays a significant role in the ground-state properties of these complexes; however, upon formation of the excited state, the lifetime is primarily governed by the energy gap law. Similarly, increasing the donor−acceptor angle results in a decrease in the lifetime of the excited state species. With recorded lifetimes of 4050, 3670, and 2240 ns for [Ru(bpy)2(dppz-CC-TAA)]2+, [Ru(bpy)2(dppz-TAA)]2+, and [Ru(bpy)2(dppz-OMe2-TAA)]2+, respectively. A perturba-

Figure 8. Representative transient absorption spectrum of [Ru(bpy)2(dppz-TAA)]2+ (red) and [Ru(bpy)2(dppz-Thio-TAA)]2+ (blue), taken 1000 ns after excitation. G

DOI: 10.1021/acs.inorgchem.6b01810 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry tion in the connectivity between the donor and the acceptor caused by ring twisting may contribute to a higher energy excited state and a decrease in the lifetime. Once again, incorporation of steric factors influences the ground-state processes but the rate of return to the ground state is in accordance with the energy gap law. Similarly, in the case where the electronic nature of the bridge is changed from a conducting thiophene to a phenyl to an insulating triazole, the lifetimes are 2340, 1390, and 897 ns, respectively. For all compounds studied, the driving force for excited-state formation has a negative linear relationship to ln(1/τ) and hence decay to the ground state is governed by the energy gap law and not directly by the bridging unit. Transient Resonance Raman Spectroscopy. Transient absorption data are useful for providing excited-state lifetimes of complexes; however, in this case, the information obtained is not sufficient to conclusively characterize the nature of the excited-state species. However, transient resonance Raman (TR2) spectroscopy can be used to do so.10,44,61−64 TR2 spectroscopy is a single color experiment, where the same laser wavelength is used to pump the molecules into an excited state and then probe the subsequent excited-state scattering. The leading edge of the pulse rapidly establishes an excited state in a significant proportion of the molecules in the irradiated volume, while the trailing edge probes the excited state.65 TR2 spectra of the samples were recorded at three different laser powers, in order to establish that a single state was being measured. The photon-to-molecule ratio is ∼16 for the highest amount of energy per pulse. [Calculated by comparison of the number of photons in a single pulse to the number of molecules present in the irradiated sample. Using a laser spot size of 300 μm, a penetration depth of 1 mm and a concentration of ∼10 mM, gives ∼4.2 × 1014 molecules. A 355 nm laser with 3.9 mJ per pulse equates to ∼6.9 × 1015 photons, which gives a photon/molecule ratio of at least 16.] These analyses show that even the low power is sufficient to induce sufficient population of the excited state. The groundstate resonance Raman spectra are markedly different from the 355 nm TR2 data, indicating that the measured Raman scattering was obtained from the excited state. The only compound to not exhibit this behavior was [Ru(bpy)2(dppzThio-TAA)]2+, which is likely due to a lack of absorbance by the excited state at 355 nm, which is consistent with the TA data. The 355 nm TR2 spectrum of [Ru(bpy)2(dppz-TAA)]2+ was compared with an analogous, previously reported Re(I) complex, [Re(CO)3Cl(dppz-TAA)], and the unbound ligand dppz-TAA.14 The spectra of the ligand and that of the corresponding Ru(II) and Re(I) complexes are almost identical (see Figure 10). The isolated ligand has been previously studied and has been shown to have an ILCT-based THEXI state.14 This provides strong evidence for the presence of an ILCT THEXI state in the Ru(II) complex, as the type or, indeed, presence of a metal center or different ancillary ligands has an inconsequential effect on the spectra. Further evidence is gained through assignment of spectral features associated with the radical charged species formed in the ILCT transition, namely, TAA• + and dppz• −. dppz• − modes were assigned by comparison with TR2 studies of [Ru(bpy)2dppz]2+ conducted by McGarvey and co-workers.66−68 and a spectroelectochemical and DFT study of dppz, its deuterated analogues, and associated Re(I) complexes

Figure 10. 355 nm TR2 spectra of (a) dppz-TAA, (b) Re(CO)3Cl(dppz-TAA), and (c) [Ru(bpy)2(dppz-TAA)]2+. Solvent bands marked with an asterisk (*).

conducted by Matthewson et al.69 where dppz• − bands were observed at 1597, 1580, 1491, 1456, 1383, and 1357 cm−1. The TR2 spectrum of the ligand showed a broad band at 1595 cm−1 likely containing both the 1597 and 1580 cm−1 modes. The bands at 1471 and 1352 cm−1 may correspond to those of 1456 and 1357 cm−1, with the shift in frequency being caused by conjugation to the TAA moiety. DFT vibrational frequency calculations of the positively charged and neutral ligand were also performed, and the structural distortion observed is consistent with the positive charge being localized on the TAA group.69 The ligand vibrations at 1575, 1538, and 1172 cm−1 are associated with the TAA• + moiety and were identified using DFT calculations and previously published spectroelectochemical studies by Oyama et al.70−72 The TR2 spectra of all the [Ru(bpy)2(dppz-R)]2+ complexes except [Ru(bpy)2(dppzThio-TAA)]2+ are very similar to that of the ligand (see Figures S8 and S9), which indicates that an ILCT state is formed in each case. Population of the excited state of [Ru(bpy)2(dppz-ThioTAA)]2+ is more successful at 532 nm, because of the increased excited-state absorbance at this wavelength. The 532 nm TR2 spectrum of [Ru(bpy)2(dppz-Thio-TAA)]2+ (Figure 11) shows a mixture of ground-state and excited-state features, with the excited state bands become more predominant as the energy per laser pulse is increased, corresponding to an increase in excited-state population. Correspondingly, ground-state features, such as the band at 1442 cm−1 decrease in intensity with increasing laser power. Spectral features associated with dppz• − are seen at 1598 and 1353 cm−1. Possible TAA• + bands can also be seen at 1176 and 1576 cm−1, which may be coincident with other dppz• − vibrations. This indicates that the THEXI state of [Ru(bpy)2(dppz-Thio-TAA)]2+ is also an ILCT state. Signals at 1494 and 1270 cm−1 likely correspond to neutral bpy vibrations, with no suggestion of the presence of bpy• −, where one would expect to see features at 1211 and 1285 cm−1.44 The excited-state band appearing at 1091 cm−1 is likely attributed to the thiophene bridge. In summary, the 355 nm TR2 spectra of [Ru(bpy)2(dppzTAA)]2+, Re(CO)3Cl(dppz-TAA), and the dppz-TAA ligand were almost identical. This implies that the compounds share the same type of THEXI state. The presence of a different H

DOI: 10.1021/acs.inorgchem.6b01810 Inorg. Chem. XXXX, XXX, XXX−XXX

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most readily oxidized TAA moiety and the LUMO centered on dppz, which is most readily reduced. The nature of the THEXI state was determined using TA and TR2 spectroscopy. The similarity between the TR2 spectra of the Ru(II) complexes and that of the dppz-TAA ligand and an analogous Re(I) complex provided strong evidence for the formation of an 3ILCT THEXI state. The presence of characteristic signals associated with dppz• − and TAA• + also supported this assignment for all the compounds studied. Systematic alteration of the bridging group in the Ru(II) complexes studied revealed that the bridge between the donor and the acceptor had an appreciable effect on the ground-state properties of the complexes. However, once the excited state is formed, the subsequent rate of decay is primarily governed by the energy gap law and is not directly affected by the nature of the bridging unit.

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EXPERIMENTAL SECTION

Synthesis. The substituted benzo[c][1,2,5]thiadiazoles31 and [RuCl2(bpy)2]73 was prepared using literature procedures. Commercially available reagents and solvents were used as received. Spectroscopic- or HPLC-grade solvents were used for all spectroscopic measurements. Spectral data was analyzed using GRAMS A/I (ThermoScientific) and OriginPro v9.0 (Origin Lab Corporation). 1 H NMR spectra were recorded at 500 MHz and 13C at 126 MHz on a Varian 500AR spectrometer. All samples were recorded at 25 °C in 5-mm-diameter tubes. Chemical shifts were referenced internally to residual non-perdeuterated solvent using δ values, as reported by Gottlieb et al.74 Coupling constants are rounded to the nearest 0.1 Hz. Assignment of signals was assisted through the use of two-dimensional (2D) nuclear magnetic resonance (NMR) techniques (COSY, NOESY, 1H−13C HSQC, and 1H−13C HMBC), recorded on a Varian 500AR spectrometer using standard pulse sequences. Ligand and complex numbering schemes are included in Figure S10. HR-ESI-MS was performed on a Bruker MicrOTOF-Q mass spectrometer operating in positive mode. Values are quoted as m/z ratio, with an instrumental uncertainty of m/z ±0.003. Analysis of elemental composition was made by the Campbell Microanalytical Laboratory at the University of Otago, using a Carlo Erba Model 1108 CHNS combustion analyzer. The estimated error is the measurements in ±0.4%. General Procedure for the dppz Ligand Syntheses. A mixture of 5-substituted benzo[c][1,2,5]thiadiazole (∼1 mmol) and LiAlH4 (∼9 mol equiv) in dry THF (20 mL) was stirred at room temperature (rt) overnight, under an argon atmosphere. The reaction mixture was cooled to 0 °C, then water (0.5 mL) was added dropwise with stirring, followed by NaOH (1 mL, 10%) and then more water (1.5 mL). Solids were removed using a Celite plug (CHCl3), and the product extracted into CHCl3, and washed with water. The organic extract was dried over MgSO4, and the solvent removed under reduced pressure. 1,10-Phenanthroline-5,6-dione (∼0.93 mol equiv) and EtOH (150 mL) were then added and the mixture heated at reflux for 16 h. The reaction mixture was allowed to cool, and the solvent removed under reduced pressure. The residue was purified using preparative column chromatography (basic Al2O3, 1% MeOH in CHCl3) to afford the corresponding dppz ligand. 11-Diphenylaminodipyrido[3,2-a:2′,3′-c]phenazine (dppz-NPh2). Following the general procedure with 5-diphenylaminobenzo[c][1,2,5]thiadiazole (0.623 g, 2.05 mmol), dppz-NPh2 (0.319 g, 38%) was isolated as an orange solid. 1H NMR (500 MHz, CDCl3): δ 9.54 (dd, J = 8.1, 1.8 Hz, 1H, H1/8), 9.48 (dd, J = 8.1, 1.8 Hz, 1H, H1/8), 9.21 (m, 2H, H3,6), 8.09 (dd, J = 9.3, 0.4 Hz, 1H, H13), 7.74 (dd, J = 8.1, 4.4 Hz, 1H, H2/7), 7.70 (dd, J = 8.1, 4.5 Hz, 1H, H2/7), 7.68 (dd, J = 9.2, 2.6 Hz, 1H, H12), 7.64 (dd, J = 2.6, 0.4 Hz, 1H, H10), 7.40 (dd, J = 8.5, 7.5 Hz, 4H, H3′), 7.29 (dd, J = 8.5, 1.1 Hz, 4H, H2′), 7.22 (tt, J = 7.4, 1.2 Hz, 2H, H4′) ppm. 13C NMR (126 MHz, CDCl3): δ 152.40 (C3/6), 151.90 (C3/6), 150.10 (C9a/11), 148.49 (C4a/4b), 147.84 (C4a/4b), 146.66 (C1′), 144.31 (C9a/11), 141.39 (C8b/14a), 139.65

2

Figure 11. TR spectra (obtained at a wavelength of 532 nm) of [Ru(bpy)2(dppz-Thio-TAA)]2+ at (a) 5.4 mJ, (b) 2.4 mJ, (c) 0.8 mJ, and (d) ground-state 532 nm resonance Raman.

metal center or ancillary ligands had no effect on the spectra; therefore, the THEXI state must be ILCT in nature. The 355 nm TR2 spectra of the other compounds, with the exception of [Ru(bpy)2(dppz-Thio-TAA)]2+, were also similar to that of [Ru(bpy)2(dppz-TAA)]2+ indicating that they also possess an ILCT THEXI state. Further evidence was gained by identification of features associated with dppz• − and TAA• + in all compounds studied. Examination of the 532 nm TR2 spectrum of [Ru(bpy)2(dppz-Thio-TAA)]2+ showed excitedstate features, which are also consistent with an ILCT THEXI state. These results show that, regardless of the nature of the bridge used, the THEXI state formed is consistently ILCT in nature.

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CONCLUSIONS A series of [Ru(bpy)2(dppz-R)]2+ complexes are reported. Variation of the bridging group caused significant changes to the intensity and energy of the electronic transitions. Increasing the donor−acceptor (D−A) distance caused a blue shift in the lowest energy absorbance and increased the intensity of the transition. When communication between the donor and acceptor was reduced either sterically or electronically, the oscillator strength was significantly depleted and caused a blue shift in the transition wavelength. Time-dependent density functional theory (TD-DFT) calculations successfully model the trends displayed by the complexes and predict the lowestenergy FC state to be an ILCT state. Resonance Raman spectra revealed the presence of ligand centered states between 355 and 375 nm. A Ru(II) → bpy MLCT state was also present, characterized through enhancement of bpy modes at 448 nm. A second MLCT transition, Ru(II) → dppz, was also observed, with the wavelength of maximum enhancement ranging from 448 nm for the compounds with lower connectivity to 488 nm, for compounds with greater D−A communication. The lowestenergy FC state was assigned as ILCT in nature for all compounds, except [Ru(bpy)2(dppz-Trz-TAA)]2+ and [Ru(bpy)2(dppz-Ph-TAA)]2+, where there was too great an overlap of electronic transitions to fully characterize the lowest energy state. However, electrochemical and TD-DFT data also support assignment of an ILCT state, with the HOMO located over the I

DOI: 10.1021/acs.inorgchem.6b01810 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

9.60 (m, 2H, H1,8), 9.29 (m, 2H, H3,6), 8.63 (s, 1H, H10), 8.58 (d, J = 8.9 Hz, 1H, H13), 8.51 (d, J = 9.1 Hz, 1H, H12), 8.42 (s, 1H, H5′), 7.84 (d, J = 8.4 Hz, 2H, H2″), 7.81 (m, 2H, H2,7), 7.30 (t, J = 7.7 Hz, 4H, H3‴), 7.19 (d, J = 8.8 Hz, 2H, H3″), 7.17 (d, J = 7.9 Hz, 4H, H2‴), 7.08 (t, J = 7.3 Hz, 2H, H4‴) ppm. 13C NMR (126 MHz, CDCl3): δ 153.23 (C3/6), 153.11 (C3/6), 149.17 (C4′), 148.84 (C4a/4b), 148.69 (C4a/4b), 148.62 (C4″), 147.56 (C1‴), 142.50 (C8b/14a), 142.46 (C9a), 141.88 (C8b/14a), 141.83 (C13a), 138.08 (C11), 134.03 (C1/8), 134.00 (C1/8), 131.79 (C12), 129.55 (C3‴), 127.43 (C8a/14b), 127.27 (C8a/14b), 127.03 (C2″), 124.95 (C2‴), 124.48 (C2/7), 124.46 (C2/7), 123.75 (C13), 123.54 (C1″), 123.53 (C4‴), 123.50 (C3″), 118.22 (C10), 116.69 (C5′) ppm. HRMS (ESI) calcd for C38H25N8 ([M + H]+): m/z 593.220. Found: m/z 593.215. Elemental analysis calcd for C38H24N8·H2O: C, 74.74; H, 4.29; N, 18.35. Found: C, 74.43; H, 4.10; N, 18.22. 11-(4-Diphenylamino-2,6-dimethoxyphenyl)dipyrido-[3,2-a:2′,3′c]phenazine (dppz-OMe2-TAA). Following the general procedure with 5-(4-diphenylamino-2,6-dimethoxyphenyl)benzo[c][1,2,5]thiadiazole (0.212 g, 0.481 mmol), dppz-OMe2-TAA (0.083 g, 30%) was isolated as a yellow solid. 1H NMR (500 MHz, CDCl3): δ 9.63 (m, 2H, H1,8), 9.24 (m, 2H, H3,6), 8.39 (s, 1H, H10), 8.31 (d, J = 8.7 Hz, 1H, H13), 7.98 (d, J = 8.7 Hz, 1H, H12), 7.76 (m, 2H, H2,7), 7.33 (t, J = 7.3 Hz, 4H, H3″), 7.24 (d, J = 7.6 Hz, 4H, H2″), 7.09 (t, J = 6.8 Hz, 2H, H4″), 6.43 (s, 2H, H3′), 3.63 (s, 6H, OMe) ppm. 13C NMR (126 MHz, CDCl3): δ 158.24 (C2′), 152.37 (C1/8), 152.32 (C1/8), 149.66 (C4′), 148.39 (C4a/4b), 148.32 (C4a/4b), 147.52 (C1″), 142.65 (C9a), 141.84 (C13a), 140.88 (C8b/14a), 140.63 (C8b/14a), 137.53 (C11), 135.51 (C12), 133.87 (C3/6), 133.78 (C3/6), 131.37 (C10), 129.45 (C3″), 128.00 (C13), 127.95 (C8a/14b), 127.94 (C8a/14b), 125.08 (C2″), 124.16 (C2/7), 124.13 (C2/7), 123.54 (C4″), 112.40 (C1′), 99.93 (C3′), 56.05 (OMe) ppm. HRMS (ESI) calcd for C38H28N5O2 ([M + H]+): m/z 586.224. Found: m/z 586.219. Elemental analysis calcd for C38H27N5O2·CHCl3: C, 66.44; H, 4.00; N, 9.93. Found: C, 66.28; H, 4.39; N, 9.90. General Procedure for Ruthenium Complexations. A mixture of ligand (∼0.2 mmol) and [RuCl2(bpy)2] (1.1 mol equiv) in DMF (20 mL) were heated at reflux for 18 h. The reaction mixture was allowed to cool to rt, aqueous NH4PF6 was added, and the resultant suspension was diluted with water (200 mL). The precipitate was filtered and washed with water. The product was dried under high vacuum to afford the title compound. Bis(2,2′-bipyridine)(11-diphenylaminodipyrido[3,2-a:2′,3′-c]phenazine)ruthenium(II) hexafluorophosphate ([Ru(bpy)2(dppzNPh2)])(PF6)2. Following the general procedure for ruthenium complexations with dppz-NPh2 (0.0912 g, 0.203 mmol), the title compound (0.187 g, 80%) was isolated as a purple solid. 1H NMR (500 MHz, (CD3)2CO): δ 9.56 (d, J = 8.1 Hz, 1H, H1/8), 9.51 (d, J = 8.1 Hz, 1H, H1/8) 8.86 (d, J = 8.0 Hz, 2H, Hbpy‑3/bpy‑3′), 8.83 (d, J = 8.2 Hz, 2H, Hbpy‑3/bpy‑3′), 8.47 (d, J = 5.1 Hz, 1H, H3/6), 8.45 (d, J = 5.2 Hz, 1H, H3/6), 8.26 (t, J = 7.6 Hz, 2H, Hbpy‑4/4′), 8.20 (d, J = 9.7 Hz, 1H, H13), 8.16 (m, 4H, Hbpy‑4/bpy‑4′,bpy‑5/bpy‑5′), 8.07 (m, 2H, Hbpy‑5/bpy‑5′), 7.97 (m, 2H, H2,7), 7.77 (d, J = 9.5 Hz, 1H, H12), 7.71 (m, 1H, H10), 7.64 (m, 2H, Hbpy‑6/bpy‑6′), 7.53 (t, J = 7.3 Hz, 4H, H3′), 7.42 (m, 2H, Hbpy‑6/bpy‑6′), 7.41 (d, J = 7.3 Hz, 4H, H2′), 7.36 (t, J = 7.1 Hz, 2H, H4′) ppm. 13C NMR (126 MHz, (CD3)2CO): δ 158.33 (Cbpy‑1/bpy‑1′), 158.13 (Cbpy‑1/bpy‑1′), 154.47 (C3/6), 153.80 (C3/6), 153.05 (Cbpy‑5/bpy‑5′), 152.93 (Cbpy‑5/bpy‑5′), 152.28 (C11), 151.29 (C4a/4b), 150.39 (C4a/4b), 146.76 (C1′), 145.46 (C9a), 141.06 (C8b/14a), 140.41 (C13a), 139.08 (Cbpy‑4/bpy‑4′), 138.98 (Cbpy‑4/bpy‑4′), 137.82 (C8b/14a), 134.47 (C1/8), 133.77 (C1/8), 131.93 (C8a/14b), 131.55 (C8a/14b), 131.08 (C3′), 130.97 (C13), 128.79 (Cbpy‑6,bpy‑6′), 128.64 (C12), 128.33 (C2/7), 128.14 (C2/7), 127.61 (C2′), 127.03 (C4′), 125.37 (Cbpy‑3/bpy‑3′), 125.30 (Cbpy‑3/bpy‑3′), 112.93 (C10) ppm. 19F (376 MHz, CDCl3): δ −72.46 (d, J = 708 Hz, PF6) ppm. 31P (162 MHz, CDCl3): δ −144.36 (sept, J = 708 Hz, PF6) ppm. HRMS (ESI) calcd for C50H35N9Ru ([M]2+): m/z 431.603. Found: m/z 431.604. Elemental analysis calcd for C50H35N9RuP2F6·H2O: C, 51.29; H, 3.18; N, 10.77. Found: C, 50.97; H, 3.33; N, 11.05. Bis(2,2′-bipyridine)(11-(4-diphenylaminophenyl)dipyrido[3,2a:2′,3′-c]phenazine)ruthenium(II) hexafluorophosphate ([Ru(bpy)2(dppz-TAA)])(PF6)2. Following the general procedure for

(C13a), 138.84 (C8b/14a), 133.73 (C1/8), 133.23 (C1/8), 129.97 (C3′), 129.91 (C13), 128.03 (C8a/14b), 127.73 (C12), 127.71 (C8a/14b), 126.60 (C2′), 125.19 (C4′), 124.12 (C2/7), 124.01 (C2/7), 115.32 (C10) ppm. HRMS (ESI) calcd for C30H19N5Na ([M + Na]+): m/z 472.153. Found: m/z 472.152. Elemental analysis calcd for C30H19N5: C, 80.16; H, 4.26; N, 15.58. Found: C, 80.20; H, 4.41; N, 15.56. 11-(4-Diphenylaminophenyl)ethynyldipyrido[3,2-a:2′,3′-c]phenazine (dppz-CC-TAA). Following the general procedure with 5-(4-diphenylaminophenyl)ethynylbenzo[c][1,2,5]thiadiazole (0.249 g, 0.618 mmol), dppz-CC-TAA (0.118 g, 41%) was isolated as an orange solid. 1H NMR (500 MHz, CDCl3): δ 9.60 (m, 2H, H1,8), 9.26 (m, 2H, H3,6), 8.45 (d, J = 1.5 Hz, 1H, H10), 8.26 (d, J = 8.8 Hz, 1H, H13), 7.96 (dd, J = 8.8, 1.8 Hz, 1H, H12), 7.78 (m, 2H, H2,7), 7.48 (d, J = 8.8 Hz, 2H, H2″), 7.31 (dd, J = 8.5, 7.4 Hz, 4H, H3‴), 7.16 (dd, J = 8.5, 1.1 Hz, 4H, H2‴), 7.10 (tt, J = 7.4, 1.1 Hz, 2H, H4‴), 7.06 (d, J = 8.8 Hz, 2H, H3″) ppm. 13C NMR (126 MHz, CDCl3): δ 152.80 (C3/6), 152.73 (C3/6), 148.78 (C4″), 148.59 (C4a/4b), 148.53 (C4a/4b), 147.15 (C1‴), 142.48 (C9a), 142.13 (C13a), 141.83 (C8b/14a), 141.10 (C8b/14a), 133.97 (C1/8), 133.91 (C1/8), 133.57 (C12), 133.01 (C2″), 131.90 (C10), 129.63 (C13), 129.59 (C3‴), 127.66 (C8a/14b), 127.63 (C8a/14b), 126.47 (C11), 125.42 (C2‴), 124.33 (C2,7), 124.04 (C4‴), 122.00 (C3″), 115.11 (C1″), 94.27 (C2′), 88.40 (C1′) ppm. HRMS (ESI) calcd for C38H24N5 ([M + H]+): m/z 550.203. Found: m/z 550.198. Elemental analysis calcd for C38H23N5: C, 83.04; H, 4.22; N, 12.74. Found: C, 82.98; H, 4.37; N, 12.66. 11-(4-(4-Diphenylaminophenyl)phenyl)dipyrido[3,2-a:2′,3′-c]phenazine (dppz-Ph-TAA). Following the general procedure with 5(4-(4-diphenylaminophenyl)phenyl)benzo[c][1,2,5]thiadiazole (0.525 g, 1.15 mmol), dppz-Ph-TAA (0.378 g, 56%) was isolated as an orange solid. 1H NMR (500 MHz, CDCl3): δ 9.69 (m, 2H, H1,8), 9.29 (m, 2H, H3,6), 8.63 (d, J = 1.8 Hz, 1H, H10), 8.45 (d, J = 8.9 Hz, 1H, H13), 8.28 (dd, J = 8.9, 2.1 Hz, 1H, H12), 7.95 (d, J = 8.4 Hz, 2H, H2′), 7.83 (m, 2H, H2,7), 7.79 (d, J = 8.3 Hz, 2H, H3′), 7.59 (d, J = 8.6 Hz, 2H, H2″), 7.30 (dd, J = 8.4, 7.4 Hz, 4H, H3‴), 7.19 (d, J = 8.7 Hz, 2H, H3″), 7.17 (dd, J = 8.5, 0.9 Hz, 4H, H2‴), 7.07 (tt, J = 7.3, 1.0 Hz, 2H, H4‴) ppm. 13C NMR (126 MHz, CDCl3): δ 152.15 (C3/6), 151.98 (C3/6), 147.85 (C4″), 147.70 (C1‴), 146.83 (C4a/4b), 146.70 (C4a/4b), 143.34 (C11), 143.04 (C9a), 142.17 (C13a), 141.19 (C8b/14a), 141.13 (C4′), 140.47 (C8b/14a), 137.61 (C1′), 134.79 (C1,8), 133.91 (C1″), 130.94 (C12), 130.05 (C13), 129.49 (C3‴), 128.13 (C8a/14b), 128.10 (C2′), 128.06 (C8a/14b), 127.85 (C2″), 127.47 (C3′), 126.33 (C10), 124.78 (C2‴), 124.74 (C2,7), 123.79 (C3″), 123.33 (C4‴) ppm. HRMS (ESI) calcd for C42H28N5 ([M + H]+): m/z 602.234. Found: m/z 602.232. Elemental analysis calcd for C42H27N5: C, 83.84; H, 4.52; N, 11.64. Found: C, 83.51; H, 4.76; N, 11.34. 11-(5-(4-Diphenylaminophenyl)thien-2-yl)dipyrido[3,2-a:2′,3′-c]phenazine (dppz-Thio-TAA). Following the general procedure with 5(5-(4-diphenylaminophenyl)thien-2-yl)benzo[c][1,2,5]thiadiazole (0.448 g, 0.971 mmol), dppz-Thio-TAA (0.552 g, 95%) was isolated as a purple solid. 1H NMR (500 MHz, CDCl3): δ 9.54 (m, 2H, H1,8), 9.24 (m, 2H, H3,6), 8.38 (d, J = 1.2 Hz, 1H, H10), 8.22 (d, J = 8.7 Hz, 1H, H13), 8.12 (dd, J = 8.7, 1.1 Hz, 1H, H12), 7.74 (m, 2H, H2,7), 7.54 (m, 3H, H3′,2″), 7.30 (t, J = 7.7 Hz, 4H, H3‴), 7.28 (d, J = 3.8 Hz, 1H, H4′), 7.16 (d, J = 7.6 Hz, 4H, H2‴), 7.11 (d, J = 8.4 Hz, 2H, H3″), 7.08 (t, J = 7.4 Hz, 2H, H4‴) ppm. 13C NMR (126 MHz, CDCl3): δ 152.68 (C3/6), 152.50 (C3/6), 148.54 (C4a/4b), 148.33 (C4a/4b), 148.03 (C4″), 147.48 (C1‴), 146.19 (C5′), 142.99 (C9a), 142.06 (C13a), 141.74 (C8b/14a), 140.83 (C2′), 140.58 (C8b/14a), 136.55 (C11), 133.80 (C1/8), 133.67 (C1/8), 129.98 (C13), 129.55 (C3‴), 128.91 (C12), 127.72 (C1″), 127.70 (C8a/14b), 127.58 (C8a/14b), 126.71 (C2″), 126.47 (C3′), 124.92 (C2‴), 124.22 (C2/7), 124.20 (C2/7), 123.67 (C10,4′), 123.55 (C4‴), 123.41 (C3″) ppm. HRMS (ESI) calcd for C40H26N5S ([M + H]+): m/z 608.190. Found: m/z 608.186. Elemental analysis calcd for C40H25N5S·CHCl3: C, 67.73; H, 3.60; N, 9.63. Found: C, 67.36; H, 3.91; N, 9.68. 11-(4-(4-Diphenylaminophenyl)-1,2,3-triazol-1-yl)dipyrido[3,2a:2′,3′-c]-phenazine (dppz-Trz-TAA). Following the general procedure with 5-(4-(4-diphenylaminophenyl)-1,2,3-triazol-1-yl)benzo[c][1,2,5]thiadiazole (0.497 g, 1.11 mmol), dppz-Trz-TAA (0.159 g, 28%) was isolated as a yellow solid. 1H NMR (500 MHz, CDCl3): δ J

DOI: 10.1021/acs.inorgchem.6b01810 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

132.96 (C12), 131.90 (C8a/14b), 131.83 (C8a/14b), 131.08 (C13), 130.39 (C3‴), 129.07 (C2′), 128.84 (Cbpy‑6/bpy‑6′), 128.67 (Cbpy‑6/bpy‑6′), 128.56 (C 2,7,2″ ), 128.11 (C 3′ ), 126.71 (C 10 ), 125.53 (C 2‴ ), 125.42 (Cbpy‑3/bpy‑3′), 125.35 (Cbpy‑3/bpy‑3′), 124.33 (C4‴), 124.24 (C3″) ppm. 19 F (376 MHz, CDCl3): δ −72.63 (d, J = 708 Hz, PF6) ppm. 31P (162 MHz, CDCl3): δ −144.31 (sept, J = 708 Hz, PF6) ppm. HRMS (ESI) calcd for C62H43N9Ru ([M]2+): m/z 507.634. Found: m/z 507.637. Elemental analysis calcd for C62H43N9RuP2F12: C, 57.06; H. 3.32; N, 9.66. Found: C, 57.18; H, 3.21; N, 9.64. Bis(2,2′-bipyridine)(11-(5-(4-diphenylaminophenyl)thien-2-yl)dipyrido[3,2-a:2′,3′-c]phenazine)ruthenium(II) hexafluorophosphate ([Ru(bpy)2(dppz-Thio-TAA)]) (PF6)2. Following the general procedure for ruthenium complexations with dppz-Thio-TAA (0.119 g, 0.196 mmol), the title compound (0.221 g, 86%) was isolated as a purple solid. 1H NMR (500 MHz, (CD3)2CO): δ 9.75 (d, J = 8.1 Hz, 1H, H1/8), 9.70 (d, J = 8.0 Hz, 1H, H1/8), 8.88 (d, J = 8.2 Hz, 2H, Hbpy‑3/bpy‑3′), 8.85 (d, J = 8.2 Hz, 2H, Hbpy‑3/bpy‑3′), 8.56 (s, 1H, H10), 8.55 (d, J = 8.2 Hz, 1H, H13), 8.54 (m, 2H, H3,6), 8.47 (d, J = 8.8 Hz, 1H, H12), 8.27 (m, 2H, Hbpy‑4/bpy‑4′), 8.19 (m, 2H, Hbpy‑5/bpy‑5′), 8.18 (m, 2H, Hbpy‑4/bpy‑4′), 8.12 (m, 2H, Hbpy‑5/bpy‑5′), 8.02 (m, 2H, H2,7), 7.93 (d, J = 3.9 Hz, 1H, H3′), 7.69 (d, J = 8.6 Hz, 2H, H2″), 7.66 (m, 2H, Hbpy‑6/bpy‑6′), 7.53 (d, J = 3.9 Hz, 1H, H4′), 7.44 (m, 2H, Hbpy‑6/bpy‑6′), 7.37 (t, J = 7.5 Hz, 4H, H3‴), 7.15 (d, J = 8.3 Hz, 4H, H2‴), 7.14 (t, J = 7.5 Hz, 2H, H4‴), 7.07 (d, J = 8.6 Hz, 2H, H3″) ppm. 13 C NMR (126 MHz, (CD3)2CO): δ 158.37 (Cbpy‑1/bpy‑1′), 158.16 (Cbpy‑1/bpy‑1′), 154.86 (C3/6), 154.61 (C3/6), 153.22 (Cbpy‑5/bpy‑5′), 152.99 (Cbpy‑5/bpy‑5′), 151.70 (C4a/4b), 151.40 (C4a/4b), 149.15 (C4″), 148.19 (C1‴), 147.57 (C5′), 144.23 (C9a), 143.19 (C13a), 141.67 (C8b/14a), 140.67 (C2′), 140.35 (C8b/14a), 139.15 (Cbpy‑4/bpy‑4′), 139.06 (Cbpy‑4/bpy‑4′), 138.82 (C11), 134.62 (C1/8), 134.42 (C1/8), 131.80 (C8a/14b), 131.67 (C8a/14b), 131.29 (C13), 131.21 (C12), 130.46 (C3‴), 129.10 (C3′), 128.84 (Cbpy‑6/bpy‑6′), 128.68 (Cbpy‑6/bpy‑6′), 128.53 (C2,7), 128.07 (C1″), 127.49 (C2″), 125.78 (C2‴), 125.42 (Cbpy‑3/bpy‑3′), 125.36 (Cbpy‑3/bpy‑3′), 125.17 (C4′), 124.64 (C4‴), 123.78 (C10), 123.67 (C3″) ppm. 19F (376 MHz, CDCl3): δ −72.52 (d, J = 708 Hz, PF6) ppm. 31P (162 MHz, CDCl3): δ −144.33 (sept, J = 708 Hz, PF6) ppm. HRMS (ESI) calcd for C60H41N9RuS ([M]2+): m/z 510.612. Found: m/z 510.614. Elemental analysis calcd for C60H41N9SRuP2F12·CHCl3: C, 51.22; N, 2.96; N, 8.81. Found: C, 51.18; H, 3.12; N, 8.70. Bis(2,2′-bipyridine)(11-(4-(4-diphenylaminophenyl)-1,2,3-triazol1-yl)dipyrido[3,2-a:2′,3′-c]phenazine)ruthenium(II) hexafluorophosphate ([Ru(bpy)2(dppz-Trz-TAA)])(PF6)2. Following the general procedure for ruthenium complexations with dppz-Trz-TAA (0.120 g, 0.202 mmol), the title compound (0.176 g, 67%) was isolated as a purple solid. 1H NMR (500 MHz, (CD3)2CO): δ 9.76 (m, 2H, H1,8), 9.37 (s, 1H, H5′), 8.95 (s, 1H, H10), 8.86 (m, 5H, H13,bpy‑3,bpy‑3′), 8.71 (d, J = 8.1 Hz, 1H, H12), 8.58 (m, 2H, H3,6), 8.29 (m, 2H, Hbpy‑4/bpy‑4′), 8.19 (m, 4H, Hbpy‑4/bpy‑4′,bpy‑5/bpy‑5′), 8.13 (m, 4H, H2,7,bpy‑5/bpy‑5′), 7.94 (d, J = 8.4 Hz, 2H, H2″), 7.66 (m, 2H, Hbpy‑6/bpy‑6′), 7.44 (m, 2H, Hbpy‑6/bpy‑6′), 7.36 (t, J = 7.6 Hz, 4H, H3‴), 7.14 (m, 8H, H3″,2‴,4‴) ppm. 13 C NMR (126 MHz, (CD3)2CO): δ 158.40 (Cbpy‑1/bpy‑1′), 158.17 (Cbpy‑1/bpy‑1′), 155.16 (C3/6), 155.01 (C3/6), 153.24 (Cbpy‑5/bpy‑5′), 153.01 (Cbpy‑5/bpy‑5′), 152.00 (C4a/4b), 151.81 (C4a/4b), 149.43 (C4′), 149.20 (C4″), 148.42 (C1‴), 143.74 (C9a), 142.72 (C13a), 142.20 (C8b/14a), 141.41 (C8b/14a), 140.09 (C11), 139.18 (Cbpy‑4/bpy‑4′), 139.08 (Cbpy‑4/bpy‑4′), 134.69 (C1/8), 134.64 (C1/8), 132.70 (C13), 131.67 (C8a/14b), 131.53 (C8a/14b), 130.42 (C3‴), 128.86 (Cbpy‑6/bpy‑6′), 128.70 (C2/7,bpy‑6/bpy‑6′), 128.66 (C2/7), 127.61 (C2″), 125.82 (C12), 125.56 (C2‴), 125.43 (Cbpy‑3/bpy‑3′), 125.37 (Cbpy‑3/bpy‑3′), 125.36 (C1″), 124.40 (C3″), 124.08 (C4‴), 119.09 (C5′), 118.54 (C10) ppm. 19F (376 MHz, CDCl3): δ −72.58 (d, J = 708 Hz, PF6) ppm. 31P (162 MHz, CDCl3): δ −144.32 (sept, J = 708 Hz, PF6) ppm. HRMS (ESI) calcd for C58H40N12Ru ([M]2+): m/z 503.127. Found: m/z 503.129. Elemental analysis calcd for C58H40N12RuP2F12·0.5H2O: C, 53.38; H, 3.17; N, 12.88. Found: C, 53.42; H, 3.14; N, 12.96. Bis(2,2′-bipyridine)(11-(2,6-dimethoxy-4-diphenylaminophenyl)dipyrido[3,2-a:2′,3′-c]phenazine)ruthenium(II) hexafluorophosphate ([Ru(bpy)2(dppz-OMe2-TAA)])(PF6)2. Following the general procedure for ruthenium complexations with dppz-OMe2-TAA (0.121 g, 0.207 mmol), the title compound (0.216 g, 81%) was isolated as a

ruthenium complexations with dppz-TAA (0.105 g, 0.200 mmol), the title compound (0.204 g, 83%) was isolated as a purple solid. 1H NMR (500 MHz, (CD3)2CO): δ 9.73 (m, 2H, H1,8), 8.93 (d, J = 8.2 Hz, 2H, Hbpy‑3/bpy‑3′), 8.90 (d, J = 8.2 Hz, 2H, Hbpy‑3/bpy‑3′), 8.63 (s, 1H, H10), 8.55 (m, 4H, H3,6,12,13), 8.27 (m, 2H, Hbpy‑4/bpy‑4′), 8.18 (m, 2H, Hbpy‑5/bpy‑5′), 8.17 (m, 2H, Hbpy‑4/bpy‑4′), 8.12 (m, 2H, Hbpy‑5/bpy‑5′), 8.09 (m, 2H, H2,7), 7.96 (d, J = 8.7 Hz, 2H, H2′), 7.65 (m, 2H, Hbpy‑6/bpy‑6′), 7.43 (m, 2H, Hbpy‑6/bpy‑6′), 7.40 (t, J = 7.5 Hz, 4H, H3″), 7.20 (m, 6H, H3′,2″), 7.17 (t, J = 7.4 Hz, 2H, H4″) ppm. 13C NMR (126 MHz, (CD3)2CO): δ 158.17 (Cbpy‑1/bpy‑1′), 158.04 (Cbpy‑1/bpy‑1′), 154.79 (C3/6), 154.50 (C3/6), 153.17 (Cbpy‑5/bpy‑5′), 153.09 (Cbpy‑5/bpy‑5′), 151.26 (C4a/4b), 151.00 (C4a/4b), 149.76 (C4′), 147.95 (C1″), 144.39 (C11), 143.62 (C9a), 142.46 (C13a), 140.81 (C8b/14a), 139.73 (C8b/14a), 139.10 (Cbpy‑4/bpy‑4′), 139.04 (Cbpy‑4/bpy‑4′), 134.30 (C1/8), 134.00 (C1/8), 132.30 (C12/13), 131.78 (C1′), 131.36 (C8a/14b), 131.25 (C8a/14b), 130.65 (C12/13), 130.51 (C3″), 129.14 (C2′), 128.81 (Cbpy‑6/bpy‑6′), 128.73 (Cbpy‑6/bpy‑6′), 128.50 (C2/7), 128.41 (C2/7), 126.04 (C2″), 125.35 (Cbpy‑3,bpy‑3′), 124.98 (C10), 124.90 (C3′), 123.07 (C4″) ppm. 19F (376 MHz, CDCl3): δ −72.58 (d, J = 708 Hz, PF6) ppm. 31P (162 MHz, CDCl3): δ −144.32 (sept, J = 708 Hz, PF6) ppm. HRMS (ESI) calcd for C56H39N9Ru ([M]2+): m/z 469.619. Found: m/z 469.618. Elemental analysis calcd for C56H39N9RuP2F12·0.5H2O: C, 54.33; H, 3.26; N, 10.18. Found: C, 54.42; H, 3.16; N, 10.35. Bis(2,2′-bipyridine)(11-(4-diphenylaminophenylethynyl)dipyrido[3,2-a:2′,3′-c]phenazine)ruthenium(II) hexafluorophosphate ([Ru(bpy)2(dppz-CC-TAA)])(PF6)2. Following the general procedure for ruthenium complexations with dppz-CC-TAA (0.111 g, 0.202 mmol), the title compound (0.192 g, 76%) was isolated as a purple solid. 1H NMR (500 MHz, (CD3)2CO): δ 9.64 (m, 2H, H1,8), 8.84 (m, 4H, Hbpy‑3,bpy‑3′), 8.54 (m, 3H, H3,6,10), 8.38 (d, J = 7.8 Hz, 1H, H13), 8.26 (m, 2H, Hbpy‑4/bpy‑4′), 8.21 (d, J = 8.0 Hz, 1H, H12), 8.17 (m, 4H, Hbpy‑4/bpy‑4′,bpy‑5/bpy‑5′), 8.11 (m, 2H, Hbpy‑5/bpy‑5′), 8.06 (m, 2H, H2,7), 7.64 (m, 2H, Hbpy‑6/bpy‑6′), 7.53 (d, J = 8.2 Hz, 2H, H2″), 7.43 (m, 2H, Hbpy‑6/bpy‑6′), 7.39 (t, J = 7.8 Hz, 4H, H3‴), 7.17 (m, 6H, H2‴,4‴), 7.02 (d, J = 8.3 Hz, 2H, H3″) ppm. 13C NMR (126 MHz, (CD3)2CO): δ 158.27 (Cbpy‑1/bpy‑1′), 158.07 (Cbpy‑1/bpy‑1′), 154.95 (C3/6), 154.80 (C3/6), 153.16 (Cbpy‑5/bpy‑5′), 153.11 (Cbpy‑5/bpy‑5′), 151.84 (C4a/4b), 151.67 (C4a/4b), 149.95 (C4″), 147.69 (C1‴), 143.68 (C9a), 142.19 (C13a), 141.58 (C8b/14a), 141.24 (C8b/14a), 139.11 (Cbpy‑4/bpy‑4′), 139.03 (Cbpy‑4/bpy‑4′), 136.52 (C12), 134.63 (C1/8), 134.54 (C1/8), 133.86 (C2″), 132.37 (C10), 131.53 (C8a/14b), 131.46 (C8a/14b), 130.78 (C13), 130.54 (C3‴), 128.80 (Cbpy‑6/bpy‑6′), 128.68 (C2/7), 128.65 (Cbpy‑6/bpy‑6′), 128.63 (C2/7), 127.00 (C11), 126.37 (C2‴), 125.37 (Cbpy‑3/bpy‑3′), 125.31 (Cbpy‑3/bpy‑3′), 125.21 (C4‴), 121.90 (C3″), 114.98 (C1″), 96.51 (C2′), 88.55 (C1′) ppm. 19F (376 MHz, CDCl3): δ − 72.49 (d, J = 708 Hz, PF6) ppm. 31P (162 MHz, CDCl3): δ − 144.34 (sept, J = 708 Hz, PF6) ppm. HRMS (ESI) calcd for C58H39N9Ru ([M]2+): m/z 481.619. Found: m/z 481.621. Elemental analysis calcd for C58H39N9RuP2F12·CHCl3: C, 51.64; H, 2.94; N, 9.19. Found: C, 52.01; H, 2.68; N, 8.99. Bis(2,2′-bipyridine)(11-(4-(4-diphenylaminophenyl)phenyl)dipyrido[3,2-a:2′,3′-c]phenazine)ruthenium(II) hexafluorophosphate ([Ru(bpy)2(dppz-Ph-TAA)])(PF6)2. Following the general procedure for ruthenium complexations with dppz-Ph-TAA (0.123 g, 0.204 mmol), the title compound (0.195 g, 73%) was isolated as a purple solid. 1H NMR (500 MHz, (CD3)2CO): δ 9.80 (m, 2H, H1,8), 8.90 (d, J = 8.2 Hz, 2H, Hbpy‑3/bpy‑3′), 8.86 (d, J = 8.1 Hz, 2H, Hbpy‑3/bpy‑3′), 8.79 (d, J = 1.7 Hz, 1H, H10), 8.64 (dd, J = 8.9, 1.9 Hz, 1H, H12), 8.60 (d, J = 8.9 Hz, 1H, H13), 8.57 (m, 2H, H3,6), 8.29 (m, 2H, Hbpy‑4/bpy‑4′), 8.20 (m, 2H, Hbpy‑5/bpy‑5′), 8.19 (m, 2H, Hbpy‑4/bpy‑4′), 8.13 (m, 6H, H2,7,2′,bpy‑5/bpy‑5′), 7.94 (d, J = 8.4 Hz, 2H, H3′), 7.75 (d, J = 8.7 Hz, 2H, H2″), 7.67 (m, 2H, Hbpy‑6/bpy‑6′), 7.44 (m, 2H, Hbpy‑6/bpy‑6′), 7.36 (t, J = 7.8 Hz, 4H, H3‴), 7.16 (d, J = 8.4 Hz, 2H, H3″), 7.15 (d, J = 7.6 Hz, 4H, H2‴), 7.12 (t, J = 7.6 Hz, 2H, H4‴) ppm. 13 C NMR (126 MHz, (CD3)2CO): δ 158.42 (Cbpy‑1/bpy‑1′), 158.19 (Cbpy‑1/bpy‑1′), 154.85 (C3/6), 154.71 (C3/6), 153.24 (Cbpy‑5/bpy‑5′), 153.02 (Cbpy‑5/bpy‑5′), 151.76 (C4a/4b), 151.60 (C4a/4b), 148.81 (C4″), 148.48 (C1‴), 145.11 (C9a), 144.05 (C11), 143.13 (C13a), 141.99 (C4′), 141.51 (C8b/14a), 140.76 (C8b/14a), 139.16 (Cbpy‑4/bpy‑4′), 139.05 (Cbpy‑4/bpy‑4′), 137.83 (C1′), 1346.4 (C1/8), 134.59 (C1/8), 134.35 (C1″), K

DOI: 10.1021/acs.inorgchem.6b01810 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry purple solid. 1H NMR (500 MHz, (CD3)2CO): δ 9.76 (m, 2H, H1,8), 9.23 (m, 4H, Hbpy‑3,bpy‑3′), 8.58 (m, 2H, H3,6), 8.43 (s, 1H, H10), 8.42 (d, J = 7.5 Hz, 1H, H13), 8.26 (m, 2H, Hbpy‑4/bpy‑4′), 8.18 (m, 5H, H12,bpy‑4/bpy‑4′,bpy‑5/bpy‑5′), 8.12 (m, 2H, H2,7), 7.76 (m, 2H, Hbpy‑5/bpy‑5′), 7.66 (m, 2H, Hbpy‑6/bpy‑6′), 7.42 (m, 2H, Hbpy‑6/bpy‑6′), 7.39 (t, J = 7.4 Hz, 4H, H3‴), 7.23 (d, J = 8.5 Hz, 4H, H2″), 7.15 (t, J = 7.4 Hz, 2H, H4″), 6.49 (s, 2H, H3′), 3.65 (s, 6H, OMe) ppm. 13C NMR (126 MHz, (CD 3 ) 2 CO): δ 159.10 (C 2′ ), 158.40 (C bpy‑1/bpy‑1′ ), 158.18 (Cbpy‑1/bpy‑1′), 154.64 (C3/6), 154.55 (C3/6), 153.18 (Cbpy‑5/bpy‑5′), 153.13 (Cbpy‑5/bpy‑5′), 151.50 (C4a/4b), 151.38 (C4a/4b), 151.05 (C4′), 148.19 (C1″), 143.51 (C9a), 142.71 (C13a), 140.76 (C8b/14a), 140.39 (C8b/14a), 140.35 (C11), 139.13 (Cbpy‑4/bpy‑4′), 139.03 (Cbpy‑4/bpy‑4′), 138.17 (C12), 134.60 (C1/8), 134.50 (C1/8), 131.94 (C8a/14b), 131.91 (C8a/14b), 131.87 (C10), 130.38 (C3″), 128.83 (Cbpy‑6/bpy‑6′), 128.67 (Cbpy‑6/bpy‑6′), 128.58 (C13), 128.50 (C2/7), 128.46 (C2/7), 125.98 (C2″), 125.41 (Cbpy‑3/bpy‑3′), 125.34 (Cbpy‑3/bpy‑3′), 124.69 (C4″), 112.22 (C1′), 100.14 (C3′), 56.24 (OMe) ppm. 19F (376 MHz, CDCl3): δ −72.68 (d, J = 708 Hz, PF6) ppm. 31P (162 MHz, CDCl3): δ −144.35 (sept, J = 708 Hz, PF6) ppm. HRMS (ESI) calcd for C58H43N9O2Ru ([M]2+): m/z 499.629. Found: m/z 499.632. Elemental analysis calcd for C58H43N9O2RuP2F12·H2O: C, 53.30; H, 3.47; N, 9.64. Found: C, 53.01; H, 3.72; N, 9.29. Electrochemistry. The electrochemical cell for cyclic voltammetry (CV) analysis was composed of a 1-mm-diameter platinum rod working electrode embedded in a KeL-F cylinder with a platinum auxiliary electrode and a Ag/AgCl reference electrode. The potential of the cell was controlled by an ADI Powerlab 4SP potentiostat. Solutions were typically ∼10 −3 M in CH2 Cl2 with 0.1 M tetrabutylammonium hexafluorophosphate (NBu4PF6) as a supporting electrolyte, and were purged with argon for ∼5 min prior to measurement. The scanning rate was 100 mV s−1, and the cyclic voltammograms were calibrated against the decamethylferrocenium/ decamethylferrocene (DMFc+/DMFc) couple (−0.012 V in CH2Cl2) and are reported relative to the saturated calomel electrode (SCE) for comparison with other data by subtracting 0.045 V.51 Spectroscopy. Spectroscopic-grade dichloromethane (DCM, Sigma−Aldrich) was used for all spectroscopic measurements. The data were processed using GRAMS spectroscopy software (Thermo Fisher Scientific) v9.2 and OriginPro v8.0 (OriginLab corporation). Electronic absorption spectra were recorded at room temperature using an OceanOptics USB2000 UV-vis spectrophotometer. Extinction coefficients were determined in DCM by measuring a dilution series of five samples ranging between 10−5 mol L−1 and 10−7 mol L−1. Spectra were recorded in a 1 cm quartz cell at rt. FT-Raman spectra were measured on solid samples in KBr disks, using a Bruker Optics MultiRAM spectrometer and a liquid-nitrogen-cooled Model D418T germanium detector. The system was controlled by Bruker Opus v7.5 software. A 1064 nm Nd:YAG laser was used with a power of 150 mW. Spectra were measured with 500 scans and a spectral resolution of 4 cm−1. Resonance Raman spectra using excitation wavelengths of 350.7, 406.7, and 413.1 nm were obtained using a Kr-ion laser (Innova I-302, Coherent, Inc.). Excitation at 457.9, 488.0, and 514.5 nm wavelengths was provided by an argon-ion laser (Innova Sabre 20, Coherent, Inc.). Diode lasers (CrystaLaser) gave excitations at 375, 448 and 532 nm. The resonance Raman setup utilized has been described previously.41,61,75−77 In summary, the laser beam was focused on a spinning NMR tube in a 135° backscattering geometry with a 50 μm entrance slit of an Acton Research SpectraPro 500i spectrograph. Laser radiation was rejected before the spectrograph via the use of longpass filters (Semrock, Inc.) or narrow band-line rejection filters (Kaiser Optical). The beam was dispersed using a 1200 grooves mm−1 grating onto a Spec-10:100B CCD, cooled with liquid nitrogen to −100 °C. Winspec/32 software v2.5.23 was used to control the CCD equipment. Spectra were calibrated at each excitation wavelength, using reference peaks of a 1:1 mixture of toluene and acetonitrile.78 The excited-state absorption and emission transients were obtained using a LP920 K system (Edinburgh Instruments). A third harmonic 354.7 nm pump pulse from a Brilliant (Quantel) Nd:YAG pulse laser was used to generate the excited state of the compounds. The laser was run at 1 Hz with a pulse width of ∼6 ns. For transient absorption

spectra, the probe pulse was generated from a 450 W Model Xe900 xenon arc lamp. Photons were dispersed with a TMS300-A monochromator using an 1800 grooves mm−1 grating onto a R928 photomultiplier (Hamatsu) then recorded on a TDS3012C oscilloscope (Tektronix). The temperature of the sample was maintained at 25 °C using a Quantum Northwest instrument. The system was controlled using LS900 v6.9.1 software (Edinburgh Instruments). The samples were degassed with argon for a minimum of 15 min prior to measurement. Excited-state lifetimes were determined by fitting an exponential decay curve to the transient signal. Transient resonance Raman (TR2) measurements of the complexes were taken using a 354.7 nm Brilliant (Quantel) pulse laser and a 532.0 nm Brilliant (Quantel) pulse laser in the second harmonic mode. The lasers operated at 10 Hz and the TR2 spectra were taken at three different energy outputs of 2.2, 2.9, and 3.9 mJ per pulse for the 354.7 nm laser and 0.8, 2.4, and 5.7 mJ per pulse for the 532.0 nm laser. The power was measured using an EnergyMax USB (J-50MB-YAG) meter and the value recorded was the average energy per pulse. The scattered photons were focused onto an Acton SpectraPro 2500i spectrograph (Princeton Instruments) and dispersed by a 1200 grooves mm−1 grating into a PI-MAX intensified camera (Princeton Instruments), which had a Peltier-cooled CCD30-11 (E2 V) CCD with a controller (Princeton Instruments, Model ST-133). Narrow band-line rejection filters (Kaiser Optical Systems) for 355 nm and or 532 nm were used. WinSpec/32 software (Roper Scientific) was used to run the system. The samples were degassed with argon for 15 min before analysis and were ∼10−3 mol L−1. Computational Methods. DFT was used to calculate the optimized structures and the vibrational spectra of the compounds. TD-DFT was then used to examine the predicted electronic transitions of the compounds and the nature of the molecular orbitals (MOs) involved. The calculations were performed using Gaussian 09 software (Gaussian Inc.).79 The CAM-B3LYP functional and 6-31G(d) basis set were used with a LANL2DZ effective core potential for the Ru centers. A dichloromethane solvent field was modeled using the self-consistent reaction field (SCRF) method, with the integral equation formalism polarization continuum (IEFPCM) model.79 The output frequencies were examined using GaussSum v2.2.5 software80 and scaled to give the lowest mean absolute deviation (MAD) value of the calculated frequency, compared to experimental observations. This is calculated by measuring the mean difference between the wavenumbers of experimental bands with intensity ≥20% of the highest intensity band and the wavenumber of the predicted transition.11,14,35 The vibrational modes and MOs were visualized using Molden81 and GaussView v5.0.8 (Gaussian Inc.), respectively.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.6b01810. MAD values and scale factors, measurement of donor− acceptor (D−A) distance, time-dependent density functional theory (TD-DFT) calculated FMOs, measurement of D−A angle, TD-DFT predicted transitions, resonance Raman spectra, plots of relative Raman intensity against excitation wavelength, calculated vs electrochemical HOMO−LUMO energy gap, 355 nm TR2 spectra, synthesis and physical measurements (PDF)

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (N. T. Lucas). *E-mail: [email protected] (K. C. Gordon). Notes

The authors declare no competing financial interest. L

DOI: 10.1021/acs.inorgchem.6b01810 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

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ACKNOWLEDGMENTS Support from the University of Otago and the MacDiarmid Institute for Advanced Materials and Nanotechnology.

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