Molecular Tectonics: Design of Enantiopure Luminescent

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Molecular Tectonics: Design of Enantiopure Luminescent Heterometallic Ir(III)−Cd(II) Coordination Network Chaojie Xu, Aurélie Guenet,* Nathalie Kyritsakas, Jean-Marc Planeix,* and Mir Wais Hosseini* Molecular Tectonics Laboratory, UMR UDS-CNRS 7140, icFRC, University of Strasbourg, F-67000 Strasbourg, France S Supporting Information *

ABSTRACT: With the aim of combining luminescence and chirality in heterometallic Ir(III)−Cd(II) coordination networks, synthetic strategies for the formation of new Ir(III)-based chiral metallatectons ([Ir(dFppy)2(1)][PF6]), both as a racemic mixture of Δ and Λ enantiomers (rac-[Ir(dFppy)2(1)][PF6]) and as enantiopure complexes (Δ-[Ir(dFppy)2(1)][PF6] and Λ-[Ir(dFppy)2(1)][PF6]), were developed. The final compounds were characterized both in solution and in the crystalline phase. Notably, their crystal structures were determined by single crystal X-ray diffraction, and their photophysical properties in solution and in the solid state were investigated. Combination of the cationic linear metallatecton with Cd2+ iodide salt ([CdI3]−), behaving as an anionic two-connecting node, leads to the formation of 1D chiral and neutral heterometallic Ir(III)−Cd(II) luminescent coordination networks both as a racemic mixture and as enantiomerically pure infinite architectures. The latter have been structurally studied in the solid state by X-ray diffraction both on single crystals and on microcrystalline powders. The infinite coordination networks display phosphorescence in the solid state at ca. 600 nm upon excitation at 400 nm.

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INTRODUCTION Over the past two decades, coordination polymers (CPs) or coordination networks (CNs), also called metal−organic frameworks (MOFs), have received growing interest due to their synthetic versatility as well as their wide spectrum of applications, ranging from gas storage to biomedical imaging or drug delivery.1 These infinite periodic architectures in the crystalline phase are formed, under self-assembly conditions, upon combination of bridging coordinating tectons2 and metal centers or complexes as connecting nodes. Among many types of coordination networks, luminescent MOFs3 are of particular interest for their applications in chemical sensing or explosive detection, for example.4 Other appealing applications are mimicry of photosynthesis5 and photocatalysis.6 Although most of the luminescent MOFs described so far are based on conjugated organic linkers and/or lanthanide ions inducing mainly ligand-centered (LC) emission or sharp lanthanide emission, some recent examples dealing with heterometallic luminescent MOFs (or mixed metal−organic frameworks, M’MOFs) based on combination of metallatectons with metal centers have been reported.7 Metallatectons (or metalloligands),8 coordination complexes, bearing at their periphery secondary coordinating groups, behave as bridging ligands in the presence of metal centers or complexes, offering at least two divergently oriented coordination sites. The luminescent heterometallic M’MOFs described so far are based on either Ru(II),9 Os(II),9b−d Ir(III),10 or Pt(II)11 metalloligands as well as Zn(II) porphyrins,12 dipyrrins,13 and polypyridine complexes.14 The use of transition metal complexes as metallatectons offers at least two advantages over purely organic tectons: (i) light absorption over the entire visible spectrum © XXXX American Chemical Society

may be achieved, (ii) phosphorescent metal complexes (e.g., Ir, Ru, Os, Pt) exhibit metal-to-ligand-charge transfer (MLCT) excited states enabling harvest of triplet excitons. In particular, iridium(III) complexes are well-known triplet emitters15 possessing interesting photophysical properties, such as high photoluminescence quantum yields (PLQY), long-lived emission, good photostability, and emission color tunability.16 The incorporation of cationic or neutral Ir(III) luminescent complexes into MOF-type materials has been achieved either by doping,17 encapsulation of the metal complex within the pores,18 or using them as linkers.10 Besides their luminescent properties, octahedral iridium complexes bearing at least two bidentate ligands also exhibit intrinsic metal-centered chirality of the (Λ, Δ) type. Thus, for a bis-cyclometalated Iridium complex bearing one neutral ligand such as a 2,2′-bipyridyl chelate, two stereoisomers may be formed. In order to generate enantiopure coordination complexes, different strategies19,20 have been explored, even though their asymmetric synthesis remains a synthetic challenge. A direct approach is the use of chiral organic ligand to drive the formation of only one diastereoisomer or to separate the pairs of diastereoisomers formed.21 In this approach, the chirality of the ligand is transferred to the metal center. For cationic metal complexes, the use of chiral anions22 leading to the formation of pairs of diastereoisomers that can be separated by chromatography or by solubility differences has been reported.23 Another approach is based on a two-step procedure starting with the binding of an auxiliary enantiopure organic ligand such as oxazoline- or Received: August 19, 2015

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DOI: 10.1021/acs.inorgchem.5b01910 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry

Scheme 1. Synthetic Route for the Preparation of the Racemic Complex rac-[Ir(dFppy)2(1)][PF6] (top) and the Enantiopure Ir Complex Δ-[Ir(dFppy)2(1)][PF6] (bottom)a,b

The same route was followed to obtain Λ-[Ir(dFppy)2(1)][PF6] except that D-serine was used instead of L-serine. rac corresponds to the racemic mixture of both Δ and Λ enantiomers. bConditions: (i) (1) 5,5′-Dibromo-2,2′-bipyridine (2), CH2Cl2/CH3OH 1/1, 60 °C, (2) KPF6, H2O, 70 °C; (ii) 4-ethynylpyridine, Pd(PPh3)4, CuI, toluene/CH3CN/iPr2NH 2/0.15/0.8, 70 °C. (iii) (1) L-serine, NaOMe, MeOH, 40 °C, 16 h; (2) 1 M HCl, MeOH, RT, 10 min. a

been used for the formation of homochiral coordination networks. MacDonnell and co-workers used two substituted enantiopure ruthenium complexes to generate luminescent homometallic coordination oligomers through the formation of C−N covalent bonds.26 However, the oligomers composed of up to 15 Ru units were only characterized in solution. Following another approach, Cohen and co-workers used an enantiopure Co(III) dipyrrin as metallatecton. However, they failed to obtain homochiral heterometallic architectures.27 It is also worth noting that all the reported examples of heterometallic CPs incorporating Ir-based metallatectons have been obtained as racemic mixtures. The generation of crystalline homochiral phosphorescent heterometallic coordination networks remains thus a challenge, in particular when using enantiopure chiral-at-metal metallatectons. In order to address this issue, i.e. combining luminescence with metalcentered chirality, we have designed enantiomerically pure Ir(III)-based complexes bearing two peripheral coordinating sites. Enantiopure solid-state porous materials based on an extended chiral-at-metal architecture may be of interest for

serine-derivatives to generate and subsequently separate the two diastereoisomers. The second step is based on the replacement of the labile chiral ligand by one achiral bidentate or two achiral monodentate ligands.24 It should be noted that, compared to other metal centers with octahedral coordination geometry such as Ru(II) complexes, the decisive advantage of chiral enantiopure Iridium complexes bearing polypyridyl bidentate ligands is their configurational inertness, i.e. the absence of racemization of the enantiopure metal complexes in solution under usual conditions. Thus, they appear to be ideal entities for the design of metallatectons, leading to the formation of enantiopure heterometallic coordination networks. While a number of chiral homometallic CPs are known,25 fewer examples of chiral heterometallic CPs have been described. The reported architectures are based on the incorporation of BINAP-, BINOL-, or chiral salen-based linkers via direct synthesis or postsynthetic transformations and have been designed mainly for asymmetric catalysis.25e To the best of our knowledge, their luminescent properties have not been studied. Furthermore, only two chiral-at-metal complexes have B


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Inorganic Chemistry

Figure 1. Portions of the crystal structure of the racemic mixture (rac-[Ir(dFppy)2(1)][PF6]) showing the disposition of the two enantiomers Δ and Λ in the lattice (ORTEP47 view, 50% probability level) (a) and the alternate packing of enantiomers leading to π−π interactions (b and c). H atoms, PF6− anions, and solvent molecules are omitted for clarity. The C atoms of the organic ligands 1 and dFppy are differentiated by color.

bis-cyclometalated Ir(III) complexes bearing as a third ligand a bipyridine unit is based on the reaction between the dichlorobridged dimer [Ir(dFppy) 2(μ-Cl) 2] and the bipyridine moiety. 30 Unfortunately, the fluorinated complex [Ir(dFppy)2(1)][PF6] could not be obtained following this synthetic route. Indeed, this strategy afforded a mixture of fluorinated Iridium complexes, as evidenced by 19F NMR spectroscopy. The mixture could not be purified by standard methods. The desired Ir complex rac-[Ir(dFppy)2(1)][PF6] was successfully obtained using another strategy based on Pdcatalyzed Sonogashira31 coupling reactions using Ir(III) complexes as substrates. It should be noted that such an approach has been previously developed for Pd-catalyzed Suzuki coupling reactions in which cationic tris-bidentate28b,32 or bis-tridentate33 cyclometalated Iridium(III) complexes were used as substrates. This route requires the synthesis of 5,5′dibromo-2,2′-bipyridine (2). The latter was prepared in 69% yield by a Stille coupling reaction using 5-bromo-2-iodopyridine (Scheme 1 top).34 Using a slightly modified reported procedure,28c the dibromo Ir complex rac-[Ir(dFppy)2(2)][PF6] was obtained in 60% yield as a 1/1 mixture of both enantiomers upon reaction of the dichloro-bridged dimer rac[Ir(dFppy)2(μ-Cl)]235 with the dibromo 2,2′-bipyridine ligand 2 in a mixture of CH2Cl2 and CH3OH followed by precipitation with an aqueous KPF6 solution (Scheme 1 top). Finally, a Pd-catalyzed Sonogashira coupling reaction between rac-[Ir(dFppy)2(2)][PF6] and 4-ethynylpyridine36 afforded the desired complex rac-[Ir(dFppy)2(1)][PF6] as a mixture of enantiomers in 46% yield. In addition to classical characterizations (see Supporting Information), rac-[Ir(dFppy)2(1)][PF6] was also structurally studied in the crystalline phase by Xray diffraction on a single crystal (see Supporting Information for crystallographic data). Crystals of rac-[Ir(dFppy)2(1)][PF6] were obtained by vapor diffusion of Et2O into a CH3CN solution of the Ir complex (Figure 1). Owing to the disorder of solvent molecules, the structure was solved using the SQUEEZE command.37 rac-[Ir(dFppy)2(1)][PF6] crystallizes in the triclinic system with P-1 as the space group, and it exhibits similar geometrical parameters as those reported for

sensing chiral molecules, for separating mixtures of enantiomers, or for chemical transformation in chiral space. Furthermore, the luminescent nature, resulting from the use of Ir(III) complexes, of extended architectures formed in the presence of connecting metallic nodes may be explored for optical sensing mentioned above. It may also be noted that the strategy proposed here is more efficient, since the chirality is centered on the metal and thus does not require tedious synthesis of enantiopure ancillary ligands. Herein, we report the synthesis and characterization, both in solution and in the solid state, of the new luminescent cyclometalated Ir(III) cationic metallatecton as a racemate (rac[Ir(dFppy)2(1)]+) as well as enantiopure species (Δ-[Ir(dFppy)2(1)]+ and Λ-[Ir(dFppy)2(1)]+) (Scheme 1) and their combinations with Cd2+ cation as a connecting node, leading to the formation of 1D chiral coordination networks.

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RESULTS AND DISCUSSION Design of Ir(III)-based luminescent metallatectons. The design of the organometallic cationic metallatecton is based on an Ir(III) cyclometalated complex using two 2-(2,4difluorophenyl)pyridine (dFppy) units and a third neutral and achiral 2,2′-bipyridine-type chelate (bpy). The latter is connected to two 4-ethynylpyridyl moieties at positions 5 and 5′, leading thus to [Ir(dFppy)2(1)]+ complex (Scheme 1). The ethynyl spacer connecting the two peripheral pyridyl units to the central bipyridyl moiety was chosen in order to allow coplanarity between the peripheral and central units and to further extend the conjugation. The other two bidentate dFppy ligands completing the coordination sphere of the Ir center were introduced in order to obtain a luminescent metallatecton. The rationale behind the introduction of fluorine atoms on the 2-phenylpyridyl (ppy) scaffold was to induce a hypsochromic shift of the emission28 when compared to its nonfluorinated analogue [Ir(ppy)2(1)]+,29 thus ensuring emission in the visible range. This metallatecton [Ir(dFppy)2(1)]+ was designed to behave as a linear bridging unit. Synthesis and characterization of the Ir complex as a racemate. The usual method for the formation of heteroleptic C


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Inorganic Chemistry

dichroism (CD, Figure 2). As expected, the enantiomers exhibit mirror image CD spectra. Pairs of enantiomers also show

iridium(III) complexes containing two dFppy ligands and one unsubstituted bpy38 or 5,5′-substituted bpy39 ligand (average bond lengths and angles: Ir−Cppy 2.011 Å; Ir−Nppy 2.041 Å; Ir−Nbpy 2.136 Å; Nppy−Ir−Nppy 171.71°; Nppy−Ir−Cppy 80.65°; Nbpy−Ir−Nbpy 76.81°). Within the crystal, two crystallographically nonequivalent Ir complexes are present (Figures 1b and 1c). Both Ir centers adopt a slightly distorted octahedral coordination geometry with the expected trans-arrangement of the N donor atoms and cis-arrangement of the C atoms of the cyclometalated ligand.15a,40 The bipyridyl moiety is almost planar, and the ethynyl junctions between the central bipyridyl and terminal pyridyl groups are almost linear (C−C−C angles in the 174.37−180.00° range). The terminal pyridyl units are almost coplanar to the central bpy unit (dihedral angles ranging from −11.84° to 4.92°). Both Δ and Λ enantiomers are present in the lattice (Figure 1a), leading thus to an achiral space group. The length of the metallatecton, i.e. the distance between the two N atoms of the terminal pyridyl units, is ca. 20.6 Å. π−π interactions between two substituted bpy ligands belonging to two neighboring Δ (or Λ) enantiomers are observed (shortest C−C distances of 3.55 and 3.59 Å for the two types of Ir complexes; Figures 1b and 1c respectively). The purity of the microcrystalline phase obtained was investigated by powder xRay diffraction (PXRD), which revealed a good match between the recorded and simulated patterns using the single crystal data (see Supporting Information). Synthesis and characterization of the enantiopure complexes. The strategy used for the synthesis of enantiopure Δ-[Ir(dFppy)2(1)][PF6] and Λ-[Ir(dFppy)2(1)][PF6] complexes was based on chiral resolution of the iridium dimer rac-[Ir(dFppy)2(μ-Cl)]2 (Scheme 1 bottom). Using the procedure reported for the nonfluorinated analogue [Ir(ppy)2(μ-Cl)],24a the resolution was achieved using L- or Dserine as chiral auxiliaries. The treatment of the racemic mixture with L-serine afforded the diastereoisomers Δ-[Ir(dFppy)2(Lserine)] and Λ-[Ir(dFppy)2(L-serine)]. The same holds when D-serine is used. For each couple ([Δ,L-serine], [Λ,L-serine] or [Δ,D-serine], [Λ,D-serine]), the diastereoisomers were separated by column chromatography on silica gel. The acid (HCl) treatment of [Δ,L-serine] or [Λ,D-serine] afforded the enantiopure ΔΔ- or ΛΛ-[Ir(dFppy)2(μ-Cl)]2 dimers, respectively, in 40 and 37% overall yields. The latter are slightly lower than those reported for the nonfluorinated analogue. This may result from a more tedious chromatographic separation of the intermediate serine-based diastereomeric complexes. Indeed, for the [Δ,L-serine], [Λ,L-serine] couple, the first eluting diastereoisomer [Δ,L-serine] could be obtained analytically pure, whereas the slower eluting diastereoisomer corresponding to [Λ,L-serine] was found to be always contaminated with [Δ,Lserine]. Interestingly, when using D-serine, the first eluting band which could be isolated as a pure compound was the [Λ,Dserine] complex. As described above for the racemic mixture of complexes, the bipyridine ligand 2 was then combined with the enantiopure dimer (ΔΔ or ΛΛ) to obtain the enantiopure Δor Λ-[Ir(dFppy)2(2)][PF6] complexes in 60% and 55% yield, respectively. Again, a Sonogashira coupling reaction with 4ethynylpyridine afforded the enantiopure Δ- and Λ-[Ir(dFppy) 2 (1)][PF6] complexes in 46% and 45% yield, respectively. It should be noted that the dibromo intermediate as well as the final cationic Ir complexes could only be isolated as their PF6 salts, as purification of their chloride salts was not possible. All chiral complexes were characterized by standard techniques (see Supporting Information), including circular

Figure 2. Circular dichroism spectra of ΔΔ-[Ir(dFppy)2(μ-Cl)]2 (black solid) and ΛΛ-[Ir(dFppy)2(μ-Cl)]2 (black, dashed) in CH2Cl2 and of Δ-[Ir(dFppy)2(1)][PF6] (blue, solid) and Λ[Ir(dFppy)2(1)][PF6] (blue, dashed) in CH3CN at RT.

opposite specific rotation ([α]D, see Supporting Information). It is important to note that the configuration of the metal center (Δ or Λ) is retained during the coupling reaction. Unfortunately, we were not able to grow suitable crystals of the two enantiomers Δ-[Ir(dFppy)2(1)][PF6] and Λ-[Ir(dFppy)2(1)][PF6] for structural studies by X-ray diffraction on a single crystal. However, the structure of the intermediate dibromo complex Δ-[Ir(dFppy)2(2)]+ could be determined (Figure 3). Single crystals were obtained upon slow diffusion of

Figure 3. Crystal structure of the enantiopure complex Δ-[Ir(dFppy)2(2)][PF6] (ORTEP47 view, 50% probability level). H atoms and PF6− anions are omitted for clarity.

Et2O into a CH3CN solution containing the complex Δ[Ir(dFppy)2(2)][PF6]. Again, owing to the disorder of solvent molecules, the structure was solved using the SQUEEZE command.37 As expected, Δ-[Ir(dFppy)2(2)][PF6] crystallizes in a chiral space group (orthorhombic, C2221). The Ir(III) center adopts a distorted octahedral coordination geometry and is surrounded by one bipyridine 2 and two dFppy moieties displaying the expected cis-arrangement of the C atoms and trans-arrangement of the N atoms. The average bond lengths and angles around the Ir center (Ir−Cppy 1.996 Å; Ir−Nppy 2.041 Å; Ir−Nbpy 2.136 Å; Nppy−Ir−Nppy 173.98°; Nppy−Ir− D


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Inorganic Chemistry

Figure 4. Portions of the X-ray structure of rac-[Ir(dFppy)2(1)]·[CdI3] showing the formation of infinite homochiral chains (a for the Δ enantiomer). Short F−F and F−Cl distances are highlighted with dashed lines. Each plane is composed of homochiral 1D networks (Δ or Λ) packed in a parallel mode. Consecutive homochiral planes are of opposite chirality, with the packing depicted along the 1D direction (b) and along the c axis (c). The Δ enantiomers are depicted in blue while the Λ enantiomers are colored in red. The chlorinated solvent molecules are depicted in yellow. EtOH solvent molecules and H atoms have been omitted for clarity.

Cppy 77.38°; Nbpy−Ir−Nbpy 80.67°) are similar to those observed for the racemic iridium complex discussed above. Synthesis of racemic and enantiopure Ir(III)−Cd(II) heterometallic coordination networks. The formation of coordination networks was first attempted by combining the racemic mixture of enantiomers rac-[Ir(dFppy)2(1)][PF6] as metallatectons with different metallic centers. As a metallic node, CdI2 salt was chosen because Cd(II) may adopt an octahedral geometry with the two apical positions occupied by the two I− anions. Diffusion of an EtOH solution of CdI2 through a EtOH/Cl2CHCHCl2 buffer layer containing two drops of trifluoroethanol and 4,4,4-trifluorobutanol into a solution of rac-[Ir(dFppy)2(1)][PF6] in 1,1,2,2-tetrachloroethane led to the formation of orange single crystals within 2 weeks. Although for the combination of rac-[Ir(dFppy)2(1)]+ behaving as a linear bis-monodentate metallatecton with CdI2 one would expect the formation of a 2D grid-type architecture,13,25j,41 the structural study revealed another type of architecture. The crystal (space group C2/c) is composed of the iridium complex [Ir(dFppy)(1)]+, Cd2+ cations, I− anions, and solvent molecules (EtOH, Cl2CHCHCl2) (Figure 4). It is worth noticing that solvent molecules were not disordered and could all be localized. It appears that the PF6− anion was exchanged with iodide ion during the crystallization process. This observation is interesting, since one of the drawbacks when using a cationic metallatecton for the generation of coordination networks is the presence of the counterion, often occupying the empty space within the lattice. It is also worth noting that, even though the two fluorinated solvents, i.e. pentafluoroethanol and trifluorobutanol, were found to be indispensable for the formation of crystals, they are not present in the crystal lattice. The iridium center adopts a

distorted octahedral coordination geometry with bond lengths and angles (Ir−Cppy 2.013(7) Å; Ir−Nppy 2.048(6) Å; Ir−Nbpy 2.130(4) Å; Nppy−Ir-Nppy 175.3(3)°; Nppy−Ir-Cppy 80.8(3)°; Nbpy−Ir-Nbpy 77.1(2)°) close to those observed for the discrete metallatecton. While the dFppy ligands are almost planar (dihedral angle Nppy−Cppy−Cppy−Cppy 2.05°), the two pyridyl moieties of the bipyridyl units are not coplanar (dihedral angle Nbpy−Cbpy−Cbpy−Nbpy 8.16°). The ethynyl spacers are not linear but bent (CC−Cbpy 171.0(8)° and Cpy-CC 176.4(8)°). Consequently, the bpy ligand is slightly curved and the tilt angle between the terminal and central pyridyl units of the bpy moiety (dihedral angles ranging from 16.45° to 21.09°) is slightly more pronounced than that for the discrete metallatecton. Within the coordination network rac-[Ir(dFppy)2(1)]·[CdI3], the Cd center adopts a trigonal bipyramidal coordination geometry with the two terminal pyridyl moieties of two metallatectons occupying the apical positions (Cd−N 2.463(5) Å; N−Cd−N 172.0(3)°) and three iodide atoms located at the trigonal base (Cd−I 2.7635(9) Å and 2.8114(6) Å; I−Cd−I 117.33(3)° and 121.337(15)°). Thus, the [CdI3]− complex behaves as a two-connecting node and bridges two consecutive metallatectons, leading thus to an infinite 1D network (Figure 4a). The distance between two consecutive Cd2+ cations is 25.26 Å. The linear chains are packed in a parallel mode and slightly staggered. A rather short Cl···F distance of ca. 2.92 Å is observed between the chlorinated solvent molecules and the F atom in position 4 belonging to the dFppy moieties. Furthermore, two neighboring dFppy moieties display a short F−F distance (atoms in position 2) of ca. 2.94 Å (Figure 4a). The packing of 1D chiral networks leads to homochiral planes (Δ or Λ). Consecutive planes are of opposite chirality and packed in a parallel fashion, E


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Inorganic Chemistry

Figure 5. Portions of the X-ray structure of Λ-[Ir(dFppy)2(1)]·[CdI3] showing: the formation of infinite chains along the b axis and their packing in two different sheets A (a) and B (b), and the packing of consecutive homochiral A and B sheets along the N−Cd−N axis (c) of the chains and along the c axis (d), leading to the formation of the chiral crystal. For the sake of clarity, consecutive sheets are differentiated by color (gray for A and red for B). MeOH solvent molecules and H atoms have been omitted for clarity.

cyclometallating unit are almost coplanar (dihedral angle in the range −2.031 to 1.221°). The ethynyl spacers are also slightly bent and the terminal pyridyl units tilted with respect to the bidentate central bpy chelate (dihedral angles ranging from −21.84° to 20.33°). The geometry around the Cd atom is again trigonal bipyramidal with three iodine atoms occupying the trigonal base (Cd−I 2.7734(13) Å; 2.7824(12) Å; 2.7879(8) Å and 2.8100(8) Å; I−Cd−I 119.80(2)°; 119.58(2)°; 120.41(4)° and 120.85(4)°) and two nitrogen atoms belonging to the terminal pyridyl units of two distinct metallatectons in axial positions (Cd−N 2.485(6) Å and 2.465(6) Å; N−Cd−N 174.0(3)° and 173.1(4)°). The bridging of two consecutive enantiopure Ir metallatectons by Cd atoms leads to the formation of infinite chiral chains with a distance of 25.32 Å between two consecutive Cd(II) metallic nodes (Figures 5a and 5b). The parallel packing of consecutive chains leads to two different types of sheets A and B differing by the orientation of the dFppy units with respect to the plane defined by the three I− anions around the Cd2+ cation and the degree of staggering. Within sheet A, a short F−F distance of 3.12 Å between the F atoms at position 2 of the dFppy is detected (Figure 5a and gray layer on Figures 5c and 5d), whereas for sheet B (Figure 5b and red layer in Figures 5c and 5d), the F−F distance is substantially larger, precluding thus any F−F interaction. It is worth noting that, because of the use of the SQUEEZE command related to the disorder of solvent molecules, in particular Cl2CHCHCl2 molecules, the latter could not be localized. Consequently, the presence of possible Cl−F interactions between chlorinated solvent molecules and dFppy units, as observed in the case of the rac-[Ir(dFppy)2(1)]·[CdI3] coordination network, cannot be ruled out. The formation of the crystal results from the packing of A and B sheets in an alternate fashion (see Figures 5c and 5d). Finally, the experimental PXRD pattern of microcrystalline

leading thus to the formation of the crystal (Figures 4b and 4c). The tetrachloroethane solvent molecules occupy the empty spaces within each sheet. Between consecutive sheets, a rather short distance of 3.44 Å between F atoms and the dFppy centroids is observed. Again, the purity of microcrystalline powder was ascertained by PXRD, which revealed a good match between patterns simulated from single crystal and experimental data (see Supporting Information). Under the same self-assembly conditions, the enantiopure Λ[Ir(dFppy)2(1)][PF6] complex was combined with CdI2 salt. Diffusion of a solution of CdI2 in EtOH through a EtOH/ Cl2CHCHCl2 buffer layer with two drops of trifluoroethanol and 4,4,4-trifluorobutanol into a solution of the enantiopure Ir metallatecton in 1,1,2,2-tetrachloroethane afforded also within 2 weeks orange single crystals. The structural investigation by single crystal X-ray diffraction again revealed the formation of infinite 1D networks Λ-[Ir(dFppy)2(1)]·[CdI3] (Figure 5). As in the case of the racemic mixture discussed above, again, during the self-assembly process, the PF6− counterions have been exchanged with iodide anions. The crystal (chiral space group C2) contains the enantiopure Λ-[Ir(dFppy)2(1)]+ tectons, [CdI3]− anions, and methanol molecules. It should be noted that, owing to the disorder of other solvent molecules, the structure was refined using data generated by the SQUEEZE algorithm.37 For that reason, one cannot exclude the presence of halogenated solvent molecules within the crystal. Within the enantiomerically pure 1D coordination network, the bond lengths and angles for the Λ-Ir metallatecton moiety (average distances and angles: Ir−Cppy 2.010 Å; Ir−Nppy 2.065 Å; Ir−Nbpy 2.132 Å; Nppy−Ir−Nppy 176.0°; Nppy−Ir−Cppy 81.4°; Nbpy−Ir-Nbpy 77.1°) are similar to those observed for rac[Ir(dFppy)2(1)]·[CdI3] (racemic mixture) discussed above. As in the latter case, the two central pyridyl rings of the bpy ligand are not coplanar, exhibiting a dihedral angle of ca. 8.67°, while the difluorophenyl and pyridyl moieties belonging to the F


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Inorganic Chemistry powder matches the simulated pattern, confirming thus the purity of the phase (see Supporting Information). Luminescent properties of the discrete Ir complex and of the two heterometallic coordination polymers. The photophysical properties of the discrete Ir(III) complex rac-[Ir(dFppy)2(1)][PF6] as a racemate were studied both in solution (Figures 6a and 7a) and in the solid state (Figure 6b).

Figure 7. (a) Emission (solid lines, λexc = 360 nm) and excitation (dotted lines, λem = 607 nm) spectra of rac-[Ir(dFppy)2(1)][PF6] in aerated (black) and degassed (red) THF solutions at room temperature. (b) Emission spectrum (λexc = 400 nm) of rac[Ir(dFppy)2(1)][PF6] in the solid state.

observed for rac-[Ir(dFppy)2(1)][PF6]. This may be attributed to delocalization of the bipyridine π system, stabilizing its LUMO. This is supported by similar behavior in solution reported for ppy-cyclometalated Ir complexes bearing 2,2′bipyridine ligand substituted in positions 5 and 5′ with aryl rings43 or oligo(arylene ethynylene) units.44 It should also be noted that, in solution, the emission lifetimes are similar for rac[Ir(dFppy)2(1)]+ (τ = 1.97 and 0.49 μs in degassed and aerated THF, respectively; τ = 1.52 and 0.36 μs in degassed and aerated CH3CN, respectively) and for [Ir(dFppy)2(bpyH2)]+ (τ = 1.50 μs, degassed CH3CN).28b Finally, at room temperature, the complex rac-[Ir(dFppy)2(1)][PF6] exhibits in degassed THF and in the solid state quantum yields (QY) of 19% and 2%, respectively. As described above for rac-[Ir(dFppy)2(1)][PF6], the presence of π−π interactions (Figure 1) may account for the low solid-state QY. It should be noted that the PXRD study (see Supporting Information) of the sample used for the luminescence measurements in the solid state showed that the phase was pure. The solid-state photophysical properties of the two heterometallic coordination networks discussed above were investigated (Figure 8). The absorption properties of both selfassembled architectures are similar to those observed for the discrete Ir complex in the solid state. Dealing with the luminescence of the racemic and the enantiopure coordination networks, coordination of the Cd2+ cation to the peripheral pyridyl coordinating sites of the metallatecton 1 does not quench the Ir-centered luminescence. Indeed, a structured emission band is observed in both cases with two maxima at ca. 575 and 620 nm. As expected, the emission bands are slightly red-shifted with respect to the discrete Ir complex (Δλ = 15 nm for the emission band maximum). This can be explained assuming that the lowest excited state has a ligand-centered

Figure 6. (a) Absorption spectra of rac-[Ir(dFppy)2(2)][PF6] in CH3CN (blue), rac-[Ir(dFppy)2(1)][PF6] in CH3CN (solid line, black) and in THF (dashed dotted line, gray). (b) Diffuse reflectance spectrum of rac-[Ir(dFppy)2(1)][PF6] (black) in the solid state.

In CH3CN, the mixture of enantiomers exhibits intense absorption bands between 240 and 400 nm (Figures 6b and 7b). These bands can be attributed to spin-allowed ligandcentered (LC) transitions involving the dFppy and the bpy moieties with a weak contribution of MLCT and LLCT (ligand-to-ligand charge transfer) transitions as described previously.28b The relatively intense absorption band between 300 and 360 nm is probably due to conjugation over the bpy moieties, as evidenced by the absence of this band in the absorption spectrum of rac-[Ir(dFppy)2(2)][PF6] (Figure 6a) and as previously reported for Ir(III) complexes bearing pphenylene substituted bpy ligands.28b In the solid state, a strong absorption band between 250 and 700 nm, arising from LC, MLCT, and LLCT transitions, is observed for rac-[Ir(dFppy)2(1)][PF6] (Figure 6b). The emission spectra recorded in degassed THF (Figure 7a) and in the solid state (Figure 7b) show a structured band with two maxima at ca. 570 and 605 nm. In both cases, in a first approximation, the emission could be attributed to a mixture of 3 MLCT (Ir → bpy) and 3LLCT (ppy → bpy) transitions,42 as described for its analogous compound [Ir(dFppy)2(bpyH2)]+ (bpyH2 = unsubstituted 2,2′-bipyridine) (λem = 534 nm, RT, degassed CH3CN).28b However, for rac-[Ir(dFppy)2(1)][PF6], owing to the structured emission, an increased ligand-centered character may be assumed for the lowest excited state. When compared to [Ir(dFppy)2(bpyH2)]+, a bathochromic shift is G


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coordination networks, selective recognition of fluorinated guest molecules within the pores is also foreseen.

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EXPERIMENTAL SECTION

General. NMR spectra were recorded on Bruker Avance AV300 (300 MHz for 1H, 282 MHz for 19F, 75 MHz for 13C), Bruker Avance AV400 (400 MHz for 1H, 100 MHz for 13C) or Bruker Avance AV500 (500 MHz for 1H, 125 MHz for 13C) spectrometers at 20 °C. Chemicals shifts (in ppm) were determined relative to residual undeuterated solvent as internal reference (CDCl3: 7.26 ppm for 1H and 77.2 ppm for 13C; CD3CN: 1.94 ppm for 1H and 118.3 and 1.3 ppm for 13C). Spin multiplicities are given with the following abbreviations: s (singlet), br s (broad singlet), d (doublet), dd (doublet of doublet), t (triplet), q (quadruplet), m (multiplet) and coupling constants (J) quoted in Hz. 1H NMR spectra were assigned by standard methods combined with COSY and NOESY/ROESY experiments. 13C NMR spectra were assigned by standard methods combined with DEPT, HMQC and HMBC experiments. Mass spectrometry was performed at the Service Commun d’Analyses, Université de Strasbourg. Low and high-resolution mass spectra (positive and negative mode ESI: Electro Spray Ionization) were recorded on Thermoquest AQA Navigator with time-of-flight detector. Elemental analyses were performed on a Thermo Scientific Flash 2000 by the “Service Commun de Microanalyses” of the University of Strasbourg. X-ray crystal structure data were collected on a Bruker SMART CCD diffractometer with Mo−Kα radiation. The structures were solved and refined using the Bruker SHELXTL Software Package using SHELXS-97 (Sheldrick, 2014) and refined by full matrix least-squares on F2 using SHELXL-97 (Sheldrick, 2014) with anisotropic thermal parameters for all non-hydrogen atoms.48 The hydrogen atoms were introduced at calculated positions and not refined (riding model). Powder X-ray diffraction (PXRD) patterns were recorded on a Bruker D8 AV diffractometer using Cu−Kα radiation (λ = 1.5406 Å) operating at 40 kV and 40 mA with a scanning range between 3.8 and 50° by a scan step size of 2°/min. For comparison, simulated patterns were calculated using the Mercury software. CCDC 1413070− 1413073 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/ cif. UV/vis absorption spectra in solution and in the solid state were recorded on a PerkinElmer Lambda 650S spectrophotometer (spectra in the solid state recorded in the reflection mode, using a 150 mm integrating sphere and Spectralon as light spectral reference for the reflection corrections). Wavelengths are given in nm and molar absorption coefficients (ε) are given in M−1.cm−1. Steady-state emission spectra in solution were recorded on a HORIBA JobinYvon IBH FL-322 Fluorolog 3 spectrometer equipped with a 450 W xenon arc lamp, double grating excitation and emission monochromators (2.1 nm mm−1 dispersion; 1200 grooves mm−1) and a Hamamatsu R928 photomultiplier tube. Steady-state emission spectra in the solid state were recorded on a PerkinElmer LS55 spectrometer equipped with a Hamamatsu R928 photomultiplier tube. Emission and excitation spectra were corrected for source intensity (lamp and grating) and emission spectral response (detector and grating) by standard correction curves. Emission quantum yields in solution were measured using the method of Crosby and Demas45 using [Ru(bpy)3][Cl]2 in degassed acetonitrile as the standard (Φ = 0.06).46 Luminescence quantum yields in the solid state were performed by using an absolute photoluminescence quantum yield spectrometer Quantaurus C11347-11 (Hamamatsu, Japan) exciting the samples from 300 to 500 nm. Time-resolved measurements were performed using the PicoHarp 300 equipped with time correlated single photon counting (TCSPC) system on the Fluoro Time 300 (PicoQuant), where a laser source 375 nm (LDH-P-C-375) was applied to excite the samples. The laser was mounted directly on the sample chamber at 90° and collected by a PMA-C 192 M single-photon-counting detector. Signals were collected using EasyTau software, and data analysis was

Figure 8. Diffuse reflectance (a) and emission (b) spectra of the coordination polymers, rac-[Ir(dFppy)2(1)]·[CdI3] (black) and Λ[Ir(dFppy)2(1)]·[CdI3] (red) in the solid state. For the two emission spectra, λexc = 400 nm.

character. The binding of Cd2+ cation by the pyridyl units should slightly affect the electronic properties of the bpy ligand, thus modifying the LUMO energy level of the complex. The solid-state QY value for both infinite architectures appeared to be less than 1%, which is lower than the QY measured for the discrete Ir complex rac-[Ir(dFppy)2(1)][PF6]. Although the presence of iodide ions might be responsible for this decrease, the possible reason for the lower QY cannot be discussed further, since it might originate either from partial quenching of the emission within the solid-state architecture or from the low precision of the quantum yield measurements.

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CONCLUSIONS In conclusion, synthetic strategies for the formation of octahedral tris(chelate) Ir(III)-based chiral metallatectons, both as a racemic mixture of Δ and Λ enantiomers and as enantiopure complexes bearing only achiral bidentate ligands, have been developed. Combination of the cationic linear metallatecton with Cd2+ iodide salt ([CdI3]−) behaving as an anionic two-connecting node was shown to lead to the formation of 1D chiral heterometallic Ir(III)−Cd(II) luminescent coordination networks both as a racemic mixture and as enantiomerically pure infinite architectures. The novelty of the work presented here lies in the use of an enantiopure chiral-atmetal Ir(III)-based metallatecton for the formation, under selfassembly conditions, of homochiral networks in the presence of [CdI3]− anion. Furthermore, the Ir(III)-based organometallic metallatecton displays phosphorescence. Interestingly, the luminescent property is maintained in the presence of Cd2+ cation used as the connecting node for the formation of the infinite architectures. Efforts toward the formation of porous crystalline enantiopure and luminescent materials using other metallic nodes and/or other peripheral coordination sites are underway. Because of the presence of fluorine atoms within the H


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Inorganic Chemistry

Cl)]2 were obtained as yellow solids (30 mg and 28 mg) in 40% and 37% yields, respectively. ΔΔ-[Ir(dFppy)2(μ-Cl)]2: 1H NMR, 13C NMR and 19F NMR spectra were identical to rac-[Ir(dFppy)2(μ-Cl)]2. [αD] (20 °C, 0.063 g/100 mL, CH2Cl2): + 205°. UV−visible (CH2Cl2): λ (nm) (ε ×10−3 (M−1·cm−1)) 254 (73.2), 297 (29.9), 338 (12.7), 382 (6.7). ΛΛ-[Ir(dFppy)2(μ-Cl)]2: 1H NMR, 13C NMR and 19 F NMR spectra were identical to rac-[Ir(dFppy)2(μ-Cl)]2. [αD] (20 °C, 0.060 g/100 mL, CH2Cl2): −183°. UV−visible (CH2Cl2): λ (nm) (ε ×10−3 (M−1·cm−1)) 254 (70.9), 297 (28.7), 338 (12.5), 382 (6.5). Δ- and Λ-[Ir(dFppy)2(2)][PF6]. Synthesis of the Δ- and Λcomplexes follow the same procedure as for the parent racemic complex starting from the enantiopure Iridium dimers (ΔΔ and ΛΛ[Ir(dFppy)2(μ-Cl)]2 respectively). Yellow solids (31 mg for Δ[Ir(dFppy)2(2)][PF6] and 28 mg for Λ-[Ir(dFppy)2(2)][PF6]) were obtained by recrystallization from acetonitrile (3 mL) and Et2O (20 mL) in 60% and 55% yield, respectively. Δ-[Ir(dFppy)2(2)][PF6]: Single crystals of Δ-[Ir(dFppy)2(2)][PF6] suitable for X-ray diffraction were obtained by slow diffusion of Et2O into a CH3CN solution of the desired complex. 1H NMR, 19F NMR and 13C NMR were identical to rac-[Ir(dFppy)2(2)][PF6]. [α]D (20 °C, 0.049 g/100 mL, CH3CN) −314°. UV−visible (CH3CN): λ (nm) (ε ×10−3 (M−1·cm−1)) 244 (47.6), 266 (47.5), 314 (30.4), 328 (26.4), 364 (7.0). Λ-[Ir(dFppy)2(2)][PF6]: 1H NMR, 19F NMR and 13C NMR were identical to rac-[Ir(dFppy)2(2)][PF6]. [α]D (20 °C, 0.047 g/100 mL, CH3CN) + 311° UV−visible (CH3CN): λ (nm) (ε ×10−3 (M−1·cm−1)) 244 (46.3), 266 (47.7), 314 (29.3), 328 (25.1), 364 (7.4). Δ- and Λ-[Ir(dFppy)2(1)][PF6]. The enantiopure Δ- and Λcomplexes were obtained through a Sonogashira coupling reaction following the procedure described above for the racemic compound rac-[Ir(dFppy)2(1)][PF6] starting from Δ- and Λ-[Ir(dFppy)2(2)][PF6] (42 mg, 0.041 mmol and 45 mg, 0.041 mmol respectively) to afford yellow powders after recrystallization in acetonitrile/Et2O in 46% and 45% yield, respectively. Δ-[Ir(dFppy)2(1)][PF6]: 1H, 13C and 19F NMR spectra were identical to rac-[Ir(dFppy)2(1)][PF6]. [α]D (20 °C, 0.068 g/100 mL, CH3CN): −209°. UV−visible (CH3CN): λ (nm) (ε ×10−3 (M−1·cm−1)) 243 (49.8), 303 (40.0), 356 (48.2). Λ-[Ir(dFppy)2(1)][PF6]: 1H, 13C and 19F NMR spectra were identical to rac-[Ir(dFppy)2(1)][PF6]. [α]D (20 °C, 0.069 g/100 mL, CH3CN): + 213°. UV−visible (CH3CN): λ (nm) (ε ×10−3 (M−1· cm−1)) 243 (47.6), 303 (39.8), 356 (47.5). General procedure for the formation of rac-[Ir(dFppy)2(1)]·[CdI3] or Λ-[Ir(dFppy)2(1)]·[CdI3]. In a test tube, a tetrachloroethane (1 mL) solution of complex rac-[Ir(dFppy)2(1)][PF6] (or Λ-[Ir(dFppy)2(1)][PF6]) (4 mg) was layered with a EtOH (1 mL) solution of CdI2 (2 mg) separated by a Cl2CHCHCl2/EtOH (1/1, 0.5 mL, containing one drop of 2,2,2-trifluoroethanol and one drop of 4,4,4-trifluorobutanol) buffer layer. Orange crystals of rac-[Ir(dFppy)2(1)]·[CdI3] (or Λ[Ir(dFppy)2(1)]·[CdI3]) were obtained after 2 weeks.

performed using the commercially available FluoFit software (PicoQuant GmbH, Germany). All solvents were spectrometric grade. Measurements in solution were performed on optically dilute solutions (Aλexc < 0.10). Deaerated samples were prepared by the freeze−pump−thaw technique. Circular dichroism was performed on a JASCO J-810 spectropolarimeter. Data was collected over a wavelength range of 200−600 nm, at a scan speed of 100 nm/min, bandwidth of 1 nm and data pitch of 0.1 nm. Samples were measured at RT (23 °C) and at given concentrations using a 10 mm path length cuvette (Starna Ltd.). Polarimetric measurements were performed on a PerkinElmer (model 341) instrument at a wavelength of 589 nm (Na). The [α]D values are given in 10−1 deg·cm2·g−1 and concentrations are given in g/100 mL. Synthesis. The synthetic procedures for compounds 2,34 dFppyH,35 rac-[Ir(dFppy)2(μ-Cl)2] and rac-[Ir(dFppy)2(2)][PF6] are detailed in the Supporting Information. Labeling of H and C atoms for complex rac-[Ir(dFppy)2(1)][PF6] is given in the Supporting Information. All air sensitive and anhydrous reactions were carried out under argon. Light sensitive reactions were protected from light by covering with aluminum foil. The glassware was ovendried at 100 °C and cooled under argon flow. Commercially available chemicals were used without further purification. 4-ethynylpyridine was synthesized as previously described.36 Anhydrous di-isopropylamine, toluene, chloroform, dichloromethane and THF were used as supplied by commercial sources without further purification. Methanol was dried and distilled with magnesium methoxide under argon. rac-[Ir(dFppy)2(1)][PF6]. To a solution of rac-[Ir(dFppy)2(2)][PF6] (0.108 g, 0.096 mmol) in a mixture of toluene/iPr2NH/CH3CN (20 mL/8 mL/1.5 mL) was added 4-ethynylpyridine (0.025 g, 0.24 mmol). After degassing the resulting yellow solution, Pd(PPh3)4 (10 mg, 0.0086 mmol) and CuI (5 mg, 0.026 mmol) were added. The solution was heated at 70 °C overnight. Then the yellow mixture was filtrated over Celite, washed with CH2Cl2 (3 × 5 mL) and concentrated to dryness. The yellow powder was purified by chromatography (Al2O3, MeOH/CH2Cl2 0% to 2%) and recrystallized from acetonitrile (2 mL) and diethyl ether (20 mL) to afford the product rac-[Ir(dFppy)2(1)][PF6] as an orange solid (0.055 g, 46%). Single crystals were obtained by vapor diffusion of Et2O (15 mL) into an acetonitrile solution containing the desired product (5 mg in 1 mL). 1H NMR (CD3CN, 400 MHz) δ (ppm): 8.62 (dd, 4H, 3JH−H = 4.4 Hz, 4JH−H = 1.5 Hz, H3′), 8.59 (d, 2H, 3J = 8.4 Hz, H3), 8.36−8.30 (m, 4H, H4, Ha/d), 8.11 (d, 2H, 4J = 1.7 Hz, H6), 7.93 (ddd, 2H, 3JH−H = 8.6 Hz, 3JH−H = 7.3 Hz, 4JH−H = 1.3 Hz, Hb/c), 7.71 (dd, 2H, 3JH−H = 5.8 Hz, 4JH−H = 0.9 Hz, Ha/d), 7.41 (dd, 4H, 3JH−H = 4.4 Hz, 4JH−H = 1.6 Hz, H2′), 7.12 (ddd, 2H, 3JH−H = 7.5 Hz, 3JH−H = 5.9 Hz, 4JH−H = 1.3 Hz, Hb/c), 6.71 (ddd, 2H, 3JH−F = 12.6 Hz, 3JH−F = 9.5 Hz, 4JH−H = 2.4 Hz, Hh), 5.71 (dd, 2H, 3JH−F = 8.7 Hz, 4JH−H = 2.3 Hz, HJ). 19F NMR (CD3CN, 282 MHz) δ (ppm): −72.91 (d, 6F, 1JF−F = 706.2 Hz, PF6), −107.78 (d, 2F, 4JF−F = 10.8 Hz), −109.75 (d, 2F, 4JF−F = 10.28 Hz). 13C NMR (CD3CN, 125 MHz) δ (ppm): 164.4 (dd, 1JC−F = 255.4 Hz, 3JC−F = 12.5 Hz, Ci), 164.4 (d, JC−F = 6.9 Hz, Ce/f), 162.2 (dd, 1JC−F = 259.9 Hz, 3JC−F = 12.7 Hz, Cg), 155.3 (C5), 153.9 (C6), 153.7 (d, JC−F = 6.0 Hz, C2, Ce/f), 151.1 (C3′), 150.9 (Ca/d), 143.2 (C4), 140.6 (Cb/c), 130.0 (C1′), 128.9 (Ck), 126.3 (C2′), 126.2 (C3), 125.1 (C2), 124.9 (Ca/b/c/d), 124.8 (Ca/b/c/d), 114.7 (d, 3JC−F = 17.8 Hz, CJ), 100.1 (d, 3JC−F = 27.2 Hz, Ch), 94.6 (C8), 88.3 (C7). UV− visible (CH3CN): λ (nm), (ε ×10−3 (M−1.cm−1)) 243 (49.8), 303 (37.5), 356 (42.4). UV−visible (THF): λ (nm), (ε ×10 −3 (M −1 .cm −1 )) 362 (45.2). MS (ESI + ): calcd for [M-PF 6 ] + C46H26F4Ir1N6 931.1782, found 931.1702. ΔΔ- and ΛΛ-[Ir(dFppy)2(μ-Cl)]2. The enantiopure iridium dimers were obtained adapting the procedure described by Lusby and coworkers24a for their nonfluorinated analogue with slight modifications. The crude products obtained after reaction of the racemic dimer with L- or D-serine respectively were purified by column chromatography (SiO2) using a mixture of CH2Cl2/CH3OH/NEt3 as eluent with a gradient elution of 99:0:1 to 97:3:1 (instead of CH2Cl2/CH3OH/NEt3 96:3:1 only). Starting from rac-[Ir(dFppy)2(μ-Cl)]2 (150 mg, 0.123 mmol) and L- or D-serine respectively (26 mg, 0.246 mmol), the enantiopure dimers ΔΔ-[Ir(dFppy)2(μ-Cl)]2 and ΛΛ-[Ir(dFppy)2(μ-

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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.5b01910. Synthetic procedures for compounds 2, dFppyH, rac[Ir(dFppy)2(μ-Cl)2], and rac-[Ir(dFppy)2(2)][PF6]; analytical (1H, 19F, 13C NMR spectra, CD spectra, singlecrystal crystallographic data, and PXRD patterns) data (PDF) Crystallographic data for rac-[Ir(dFppy)2(1)][PF6], Δ[Ir(dFppy)2(2)][PF6], rac-[Ir(dFppy)2(1)]·[CdI3], and Λ-[Ir(dFppy)2(1)]·[CdI3] (CIF)

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. I


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Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This contribution is part of an international research project, Chiranet, funded by the European Regional Development Fund (ERDF) under the INTERREG IV Upper Rhine Programme and as part of the Science Offensive of the Trinational Upper Rhine Metropolitan Region. Financial support from the University of Strasbourg, the International Centre for Frontier Research in Chemistry (FRC), and the LabEx CSC Strasbourg, the Institut Universitaire de France, the CNRS, is acknowledged. Elena Longhi is gratefully acknowledged for her help with luminescence measurements.

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