Design of Near-Infrared Luminescent Lanthanide Complexes

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

pubs.acs.org/IC

Design of Near-Infrared Luminescent Lanthanide Complexes Sensitive to Environmental Stimulus through Rationally Tuning the Secondary Coordination Sphere Yingying Ning, Yi-Wei Liu, Yin-Shan Meng, and Jun-Long Zhang* Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China S Supporting Information *

ABSTRACT: The design of near-infrared (NIR) emissive lanthanide (Ln) complexes sensitive to external stimulus is fundamentally important for the practical application of Ln materials. Because NIR emission from Ln is extremely sensitive to X−H (X = C, N and O) bond vibration, we herein report to harness the secondary coordination sphere to design NIR luminescent lanthanide sensors. Toward this goal, we designed and synthesized two isomeric [(η5-C5H5)Co{(D 3 CO) 2 P = O} 3 ]-Yb(III)-7,8,12,13,17,18-hexafluoro5,10,15,20-tetrakis(pentafluorophenyl)porpholactol NIR emitters, Yb-up and Yb-down, based on the stereoisomerism of porphyrin peripheral β-hydroxyl group. Yb-up, in which β-OH is at the same side of Yb(III) center, can form an intramolecular hydrogen bond with the axial Kläui ligand, whereas Yb-down cannot because its β-OH is opposite to Yb(III) center. X-ray crystal structures and photophysical studies suggested that the intramolecular hydrogen bond plays important roles on the NIR luminescence of ytterbium(III), which shortens the distance between β-OH and Yb(III) and facilitates the nonradiative deactivation of Ln excited state. Importantly, Yb-up/down were demonstrated to be highly sensitive toward temperature and viscosity. The PMMA polymer using Yb-up as the dopant NIR emitter showed thermosensitivity up to 6.0% °C−1 in the wide temperature range of 77−400 K, higher than that of Yb-down (3.8% °C−1). These complexes were also explored as the first NIR viscosity sensor, revealing their potential applications as optical sensors without visible light interference. This work demonstrates the importance of secondary coordination sphere on designing NIR Ln luminescent functional materials.

■

INTRODUCTION Near-infrared emissive lanthanides attract increasing attention for their promising applications in energy conversion,1 biomedical imaging2 and optical materials.3 To circumvent the forbidden f-f transition, creating appropriate microenvironment, consisting of either inorganic matrix4 or organic ligand5 with good light-harvesting abilities, became an effective approach to sensitize the NIR emissive lanthanides.6 Modulation of the primary coordination sphere,7 including coordination geometry and atoms8 and the excited states of antenna ligand,9 and modification of the outer sphere known as “the two component approach”,6,10 have been extensively applied to design luminescent Ln sensors. Quenching effect arising from the high energy X−H bond vibration (X= C, N and O) in the secondary coordination sphere acutely suppresses the luminescence of NIR Ln. Therefore, for NIR emissive lanthanides, replacement of C−H bond with C−D11 or C-X (X = F, Cl, Br) bonds12 is often used to enhance the NIR emission intensity and elongate the decay lifetime, especially when the primary structure was set up. However, functionalization in the secondary coordination sphere has much less been recognized in designing NIR Ln sensors. As the © XXXX American Chemical Society

secondary coordination sphere often impacts the primary coordination sphere with electronic perturbation and its noncovalent interaction with the environment is generally weak and always relegated to solvation quenching effect,13 it is challenging to design the NIR Ln sensors from modulation on the secondary coordination sphere. Recently, D. Parker and coworkers reported the systematical study on the NMR pseudocontact shifts and solvent effects of a series of C3symmetric lanthanide complexes.14 Their results revealed that minor environmental and structural changes have significant influence on their magnetic susceptibility tensor. These results have important influence on the analysis and design of novel NIR magnetic resonance shift probes. However, design of novel NIR functional lanthanide sensor based on the tuning of secondary coordination sphere is still urgently to be explored. Herein, we report a proof of concept work to design NIR ytterbium(III) sensors by harnessing the stereoisomerism of high energy vibration bond O−H in the secondary coordination sphere, which provides a novel access to systematic Received: October 27, 2017

A

DOI: 10.1021/acs.inorgchem.7b02750 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

Figure 1. A graphical representation of the coordination sphere of isomeric luminescent ytterbium(III) porpholactol complexes with Kläui ligand and their applications as thermometer and viscosity sensor in the NIR region.

Scheme 1. Synthetic Procedures of Yb-up/down and Yb-up/down-D/CD3a

a

Reaction conditions: (a) DIBAL-H, THF, rt, 1 h; (b) D2O exchange; (c) BF3·Et2O, CH2Cl2, rt, 24 h.

porphyrin periphery, whose OH group could be a H-bond donor close to Ln center. Tridentate Kläui ligand ([(η5C5H5)Co{(D3CO)2P = O}3]−)16 was used as ancillary ligand, because the oxygen atom of the P = O moiety is within the distance of hydrogen bond interaction with the porphyrin peripheral and could act as a H-bond acceptor. In order to minimize the interference of C−H bond vibration from ligands, we used perfluorinated porpholactone17 and deuterated alkyl Kläui ligand16b as starting materials. Stereoisomerism of the βOH group helps us to systematically investigate the effect of secondary coordination sphere on the luminescence of NIR Ln

investigation of the secondary coordination sphere on Ln photophysical properties. Given that high energy O−H bond vibration is extremely sensitive to some environmental stimulus such as temperature and viscosity, we envisioned to introduce an O−H bond in the secondary coordination sphere. As decreasing temperature and enhancing viscosity should slow down the O−H bond vibration, it may result in enhanced NIR emission, and therefore thermosensitive and viscosity-responsive NIR luminescent Ln would be achieved. In this work, we choose porpholactol ligand15 featured with a β-hemiacetal moiety on B


Article

Inorganic Chemistry

Figure 2. Single X-ray crystal structures (left), stick models (top right) and deviation of the skeletal heavy atoms from the N4 mean plane defined by the four pyrrolic nitrogen atoms (bottom right) of (a) Yb-up and (b) Yb-down. Four pentafluorophenyl groups were omitted for clarity in the balland-stick model.

{(D 3 CO) 2 P = O} 3 ]-Yb(III)-7,8,12,13,17,18-hexafluoro5,10,15,20-tetrakis(pentafluorophenyl)porpholactol products, which could be isolated by silica gel chromatography. According to the different orientation of the β-hydroxyl group, we termed the isomer in which the OH group and Yb(III) center are at the same side as Yb-up (21% yield), and another as Yb-down (55% yield). Gadolinium(III) complexes Gd-up and Gd-down were synthesized to determine the triplet state of ligands by their phosphorescence, for the excited state of Gd(III) is high lying to the triplet states of ligand. For systematical comparison of the quenching effects of β-OH and β-CH groups on the NIR emission of Yb(III), we also synthesized deuterated hydroxyl (Yb-up-D, Yb-down-D) and methylated complexes (Yb-up-CD3, Yb-down-CD3) as controls. Detailed synthetic procedures and full characterizations for all compounds were listed in the Experimental Section and Supporting Information (Figures S1−S30). Single crystals of Yb-up/down (CCDC: 1566734 and 1566733, respectively) were obtained by diffusion of n-hexane into the CHCl3 solution of Yb-up/down respectively (Table S1). As shown in Figure 2, both of the central Yb(III) ion are seven coordinated, sandwiched between the porphyrin ring and tripodal Kläui ligand. For Yb-up, the β-peripheral OH group points to the oxygen atom of Kläui ligand and the distance is 3.386−3.654 Å, within a weak hydrogen bond interaction range.22 The Yb−O4 distance is measured to be 4.753 Å. In Ybdown, the OH group is downward and distal to the Yb(III) center, with the O1−O5 and Yb−O1 distances of 5.432 and 5.691 Å respectively, much longer than that in Yb-up. The P4 = O5 bond length (1.484 Å) in Yb-down is slightly 0.027 Å shorter than that in Yb-up (P4 = O15:1.511 Å). Ytterbium(III) ion is located 1.181 and 1.300 Å above the N4 porphyrin mean plane for Yb-up and Yb-down, respectively. Moreover, distortion of the porphyrin plan derived from the different

by comparison of the isomers’ photophysical properties. X-ray crystal structures and photophysical studies showed that intramolecular hydrogen bond between the porphyrin periphery β-OH group and the axial Kläui ligand lowered the emission intensity and shortened the decay lifetime of Yb(III), compared to the counterpart without hydrogen bond. However, incorporation of OH to porphyrin periphery resulted in thermosensitive and viscosity-responsive emission from Yb(III) in the NIR region, demonstrating the effectiveness of OH vibration on modulation of NIR emission. Most importantly, the Yb(III) complex with intramolecular hydrogen bond displays much higher thermo-sensitivity (6.0% °C−1 in PMMA film) than the counterpart (3.8% °C−1), which reveals the perspective of design NIR emissive Ln materials by finetuning of secondary coordination sphere (Figure 1).

■

RESULTS AND DISCUSSION Synthesis and Characterization. Porphyrinates are wellknown ligands to sensitize NIR emissive lanthanides for their good coordination ability, suitable energy levels of lowest triplet state and tunable molecular structures.18 Modification of porphyrin to porpholactone, in which pyrrole ring was replaced by β-dioxazolone moieties, was a representative strategy to mimic natural tetrapyrrole pigments15,19 and modulate the excited triplet state of porphyrinates.20 Porpholactone21 and perfluoroporpholactone17 have also showed attractive properties in the design of functional NIR lanthanide materials. On the basis of previoulsy reported perfluorinated ytterbium(III) porpholactone,17 the Yb(III) porpholactol complex was synthesized through one-step reduction by diisobutyl aluminum hydride (DIBAL-H), as shown in Scheme 1. Surprisingly, for the sandwiched ytterbium(III) ion between porpholactol and the axial Kläui ligand, stereoisomerism of the β-hemiacetal on porphyrin periphery gave two isomeric [(η5-C5H5)CoC


Article

Inorganic Chemistry orientation of β-OH is opposite and the root-mean-square (rms) displacement values of the porphyrin macrocycle of 0.465 and 0.381 were obtained for Yb-up/down, respectively, as shown in Figure 2 (right). Thus, the stereoisomerism of βperipheral OH renders the formation of intramolecular hydrogen bond and simultaneously modulate the distance between Yb(III) ion and O−H/C−H oscillators. The 1H NMR spectra for Yb-up/down in CDCl3 displayed three proton signals, belonging to cyclopentadienyl, β-CH and OH groups. As shown in Figure 3, when D2O was added, the

down exhibited 2 times higher quantum yield (4.5%) and longer lifetime (41(1) μs) than Yb-up (ΦLYb = 2.4%, τobs = 20(1) μs), as shown in Figure 4a, with the reference of

Figure 3. 1H NMR spectrum (400 MHz) of Yb-up (pink) and Ybdown (blue) in CDCl3 and those after addition of D2O were shown as black.

proton signals at δ = 38.21 (s, 1H, Yb-up) and 9.74 (s, 1H, Ybdown) ppm disappeared and were assigned to the β-OH signal. Deviation of the proton chemical shift from Yb-up to Yb-down were calculated as cyclopentadienyl protons (Δ = 0.30 ppm) < β-CH (Δ = 6.31 ppm) < β-OH (Δ = −28.47 ppm). For the paramagnetism of Yb(III), deviation of the proton chemical shift in Yb(III) complexes could reflect the change of magnetic properties in some extent.14 The results indicated that minor structure variation of the β-OH group significantly influences their magnetic susceptibility tensor. Effect of Intramolecular Hydrogen Bond on NIR Emission. The UV−vis absorption of Yb-up/down are identical and both of them display intense Soret band at ca. 406 nm and Q bands in the range 550−700 nm (Figure S2 and Table S2). Compared to perfluorinated Yb(III) porpholactone, their Qy(0,0) bands are much intense and red-shifted to ca. 616 nm, similar to previously reported metalloporpholactol.15c The triplet state energy levels were estimated by the phosphorescence spectra of the corresponding Gd(III) complexes Gdup/down. No obvious difference was observed in their phosphorescence (Figure S31), which were centered at λmax = 870 nm (τ = 20(1) μs) with shoulder extended to ca. 1200 nm. The lowest energy zero phonon (ν0−0) band of the triplet state was estimated by spectral deconvolution of the luminescence signal into a series of overlapping Gaussian functions. The obtained similar triplet state energy level for Gd-up and Gddown (ca. 11 494 cm−1, Figure S31) indicated that the stereoisomerism of β-OH group does not change the lowest triplet state of porphyrinates. Upon excitation at Soret or Q-band, characteristic emission at ca. 900−1200 nm derived from the 2F5/2 → 2F7/2 transition of Yb(III) was observed in the Yb(III) complexes. The NIR emission quantum yields (ΦLYb) and lifetimes (τobs) of the Yb(III) complexes were determined and summarized in Table S2. The estimated uncertainties of ΦLYb are 15%.23 Notably, Yb-

Figure 4. (a) Luminescence intensity and decay lifetime monitored at 974 nm of Yb-up and Yb-down in CH2Cl2 at room temperature (λex = 406 nm, A406 nm = 0.1). (b) Decay lifetime of Yb-up-X referred to Ybdown-X (X = H, D, CD3) monitored at 974 nm in CH2Cl2 at room temperature.

5,10,15,20-tetraphenylporphyrin-Yb(III)-[(cyclopentadienyl)tris(di(ethyl)phosphito)cobaltate] (YbTPP(LOEt)), ΦΔ = 0.024).24 The control experiments were performed using the deuterated hydroxyl (Yb-up-D, Yb-down-D) and methylated complexes (Yb-up-CD3, Yb-down-CD3). As shown in Figure 4b and S32, the lifetime ratios of Yb-up-D/Yb-down-D and Yb-up-CD3/Yb-down-CD3 are close to 1, suggesting that O− H vibration, not the C−H bond on β-hemicacetal moiety, is the main factor for the different NIR emission of Yb-up/down. In addition, decay lifetimes of the deuterated hydroxyl (58(1) and 66(2) μs for Yb-up-D and Yb-down-D, respectively) and methylated complexes (86(2) and 85(2) μs for Yb-up-CD3 and Yb-down-CD3, respectively) were also obviously longer than that of Yb-up and Yb-down. Their NIR quantum yields (6.2%, 6.8%, 9.1%, 9.2% for Yb-up-D, Yb-down-D, Yb-up-CD3 and Yb-down-CD3, respectively) are also higher than Yb-up/down (Table S2 and Figure S33), revealing the quenching effect of OH group on NIR emission. Obvious solvent effect on the NIR emission of Yb-up/down was observed. In hydrogen bond acceptor solvents such as dimethyl sulfoxide (DMSO), methanol and water, Yb-up/ down displayed identical NIR emission intensity and lifetimes (Table S3), in contrast to the above observation in aprotic solvents such as CH2Cl2, C6H6 and n-hexane (Figure S34− S36). To exclude the effect of inner-sphere solvent molecule, we also carried out a comparative analysis of the lifetimes of Ybup/down in H2O and D2O (Table S3),25 and near zero hydration number (q = −0.2 for both Yb-up/down) were D


Article

Inorganic Chemistry

Figure 5. (a) NIR luminescent images of Yb-up under different temperature (400−77 K) in PMMA film (λex = 405 nm laser, 3.5 mW cm−2). (b) NIR emission spectra and lifetime monitored at 974 nm recorded for Yb-up under different temperature (400−77 K) in PMMA thin film (λex = 406 nm, A406 nm = 0.1). (c) Emission intensity ratio normalized according to that at 400 K and thermosensitivity (inset) of Yb-up (pink), Yb-down (blue), Yb-up-CD3 (green) and Yb-down-CD3 (orange) in PMMA thin film (400−77 K) (λex = 406 nm, A406 nm = 0.1).

decay lifetimes (ca. 89(1) μs for both Yb-up and Yb-down, Figure S37), probably due to slowing down the O−H stretching vibrations to the same extent at 77 K. We also found that Yb-up/down in PMMA thin film (1%) exhibited remarkable oxygen-independent thermosensitive emission and lifetime within a wide range of temperature (400−77 K), as shown in Figure 5 and Figure S38. Taking Ybup as an example, with the decreasing of temperature, its NIR luminescent intensity significantly enhanced (Figure 5a). Interestingly, Yb-up exhibited higher thermosensitivity (6.0% °C−1) than Yb-down (3.8% °C−1) based on the change of emission intensity, revealing the key role of the intramolecular hydrogen bond on the sensitivity of NIR emission of Yb(III). In addition, the high thermo-sensitivity was also observed in degassed solution (3.5% °C−1 for Yb-up and 2.8% °C−1 for Ybdown, Figure S39). This excludes the possibility of enhancing fluorescence only due to decreasing O2 concentration at lower temperature. As controls, we tested the thermosensitivity of Ybup/down-CD3 and found negligible change of their NIR emission (Figure S40−S41), indicating the high correlation of NIR emission to O−H vibration (Figure 5c). Moreover, Ybup/down displayed good reversibility (Figure S42), which holds the promise as potential thermosensitive dopant NIR emitters in optical device and fabrication. This is different from the previously reported strategy based on tuning the energy transfer process from the ligands’ excited states to the emitting levels of lanthanides or between different lanthanide ions, such as Eu and Tb complexes,29 and Ln doped up-conversion luminescent materials.30 This not only enriches the repertoire of thermosensitive materials also extend the optical window from visible to NIR region. Viscosity-Responsive NIR Emission. To test the generality of this approach to design NIR luminescent Ln materials related to O−H vibration, we chose the measurement of fluid viscosity (Figure S43) because of the sensitivity of OH vibration to fluid viscosity.31 We applied Yb-up/down as NIR emissive viscosity sensor to reduce the interference of visible light, which might be useful in the diagnosis of a variety of diseases such as blood and plasma viscosity changes in diabetes, hypertension, and aging.32 Taking Yb-up as an example, the emission intensity of Yb(III) enhanced with increasing solvent viscosity (Figure 6a). The decay lifetime increased from ca.

obtained. Combing with the experimental results from crystal structures and 1H NMR spectra, we ascribed the solvent effect to the formation of an intramolecular hydrogen bond in Yb-up. Locating at the same side of Yb(III), the β-OH of Yb-up forms hydrogen bond with the Kläui’s ligand and shortens the distance between β-OH and Yb(III) center due to its flexibility. This hydrogen bond might be interrupted by hydrogen bond acceptor solvents and thus the quenching effect arising from the β-OH vibration became identical for Yb-up/down. According to Ermolaev and Sveshnikova’s model,26 the nonradiative deactivation of Ln excited state is highly dependent on the distance (r) between Ln and the quenching center (knr ∝ r−6). Thus, we estimated the different nonradiative quenching effect derived from the β-OH group between Yb-up and Yb-down using the ratio of knr(Yb-up)/ knr(Yb-down). The value of 2.7 was obtained, close to the ratio of their emission intensity and decay lifetime (∼2). Moreover, vibration of the third overtones of hydroxyl group could efficiently couple with the Yb(III) excited state (10 250 cm−1) and quench the NIR emission. Therefore, we ascribed the distinctive nonradiative deactivation of Ln excited state to different distances (average value: 4.816 Å in Yb-up vs 5.691 Å in Yb-down) between β-OH quencher and Yb(III) ion. Thermosensitive NIR Emission. Thermosensitive luminescent Ln materials are emerging materials, allowing noninvasive and accurate measurement of temperature by optical remote detection system in fluid dynamics, material and life science.27 Despite the tremendous progress made in the emitters in the visible region,28 NIR emitters still remained underexplored. Recently, we reported a temperature sensitive back energy transfer process from Yb(III) to the lowest triplet state of cis-porphodilactone ligand,21b which opens a new access to thermosensitive NIR emitter. However, this thermosensitive NIR emission is dependent on the triplet state of ligand and oxygen, and thus optimizing this approach to work under a more general operating condition is highly desirable. Since tuning of NIR emission through the secondary coordination sphere was demonstrated, we further investigated the NIR thermosensitivity to test our hypothesis of designing thermosensitive NIR luminescent functional material. First, we measured the NIR emission of Yb-up/down at low temperature (77 K). As expected, they displayed similar elongated E


Article

Inorganic Chemistry

Figure 6. (a) NIR luminescent images of Yb-up in methanol/glycerol mixtures of different viscosity (λex = 405 nm laser, 3.5 mW cm−2). (b) NIR emission spectra and lifetime monitored at 974 nm recorded for Yb-up in methanol/glycerol mixtures of different viscosity (λex = 406 nm, A406 nm = 0.1). (c) Emission intensity ratio normalized according to that in methanol of Yb-up (pink), Yb-down (blue), Yb-up-CD3 (green) and Yb-downCD3 (orange) in methanol/glycerol mixtures of different viscosity (λex = 406 nm, A406 nm = 0.1).

18(1) μs in methanol to 55(2) μs in glycerol (Figure 6b). Similarly, Yb-down also exhibited enhanced luminescent intensity and prolonged lifetime in high viscous solution (Figure 6c and Figure S44). It is worthy to note that the viscosity responsive properties were also observed in degassed condition (Figure S45), which excludes the possibility of enhancing fluorescence arising from decreasing O2 concentration in high viscosity solution. However, negligible viscosity sensitivity was observed for the controls Yb-up-CD3 and Ybdown-CD3 (Figure 6c and Figure S46). As in low-viscosity environment, O−H bond should vibrate freely to produce the luminescence quenching of lanthanide. Therefore, increasing the media viscosity restricted the vibration of O−H bond, preventing the nonradiative relaxation of the emitting state of Yb(III). This is an alternative approach to monitor fluid viscosity based on “molecular rotors” design33 and enriches the practical applications of Ln NIR emitters.

spectra were recorded on a Bruker VECTOR22 FT-IR spectrometer as KBr pellets. Mass spectra were recorded on Bruker APEX IV FT-ICR mass spectrometer (ESI) or AB Sciex MALDI-TOF mass spectrometer. 1H and 19F NMR spectra were recorded on a Bruker ARX400 400 MHz spectrophotometer. Emission, excitation spectra and lifetime were measured on an Edinburgh Analytical Instruments FLS980 lifetime and steady state spectrometer equipped with a 450 W Xe lamp, a 60 W microsecond flash lamp, PMT R928 for visible emission spectrum, HAMAMATSU R5509−73 PMT with C9940−02 cooler for NIR emission spectrum and luminescence lifetime. Excitation and emission spectra were corrected for instrumental functions (including the correction for detector, gratings etc.). All luminescence decays were exponentially tail-fitted by monoexponential functions without deconvolution for the negligible instrumental reference function in NIR region. Low temperature spectra were recorded on frozen glasses of solutions of Gd complexes (MeOH/ EtOH 1:1, v/v) using a dewar cuvette filled with liquid N2 (T = 77 K). The temperature-dependent experiments were recorded on the Edinburgh Analytical Instruments FLS980 equipped with an Oxford Optistat DN2 cryostat. NIR luminescent images was obtained by the Workpower WP-US146 M NIR fluorescence camera. For the optical measurements in liquid solution, spectroscopicgrade CH3OH, dimethyl sulfoxide (DMSO), D2O, n-hexane, and C6H6 were used as purchased from Alfa-Aesar. Anhydrous CH2Cl2 was distilled from calcium hydride. For the optical measurements at 77 K, the methanol:ethanol = 1:1 glassing solvent was used. Anhydrous 1,2,4-trichlorobenzene (TCB), diisobutyl aluminum hydride (DIBALH), tetrahydrofuran (THF) and CD3OD were purchased from J&K Scientific and used as received. β-Hexafluorinated porpholactone 7,8,12,13,17,18-hexafluoro5,10,15,20- tetrakis(pentafluorophenyl)porphyrin (F26TPPL),17 sodium [(cyclopentadienyl)tris(di(methyl-d3)phosphito) cobaltate] (NaLOCD3)16b (D atom >99%) were synthesized according to literature methods. Synthesis of Ln-up/down (Ln = Yb, Gd). Ln-up/down were synthesized from Ln β-hexafluorinated porpholactones, which were synthesized according to previous studies.17 Generally, free base F26TPPL (50 mg, 0.05 mmol), lanthanide acetylacetonate hydrate (Ln(acac)3·3H2O, 0.5 mmol) (Ln = Yb or Gd) and TCB were added to a Schlenk tube and refluxed overnight. After cooling to room temperature, the reaction mixtures were transferred to a silica column, TCB was first eluted by petroleum ether, and then the unreacted free base ligand was eluted by CH2Cl2, corresponding Ln complexes was obtained by using CH2Cl2/CH3OH (v/v = 5:1) as eluent and used directly to the next step. The obtained Ln complexes (acac as ancillary ligand) and 3 equiv NaLOCD3 were dissolved in mixing solvent of CHCl3/CH3OH (v/v = 1:1, 5 mL). The mixture was refluxed for 8 h.

■

CONCLUSIONS Taken together, we designed and synthesized the sandwiched Yb(III) complexes from perfluorinated porpholactol and Kläui ligands, and first demonstrated the importance of secondary coordination sphere on the modulation of NIR Ln emission. Stereoisomerism of β-OH group on porphyrin periphery renders the formation of an intramolecular hydrogen bond in Yb-up, which shortens the distance between β-OH and Yb(III) center and thus weaker NIR emission compared to Yb-down. This is consistent to the experimental results of crystal structures and 1H NMR spectra. More importantly, due to the sensitivity of O−H vibration toward temperature and viscosity, we demonstrated the potential application of Yb-up/ down as optical thermometer and viscosity sensor in the NIR region. Thus, insights achieved here should open a new access to tuning the lanthanide luminescence properties and assist the future design of NIR emissive functional materials through the modification of secondary coordination sphere.

■

EXPERIMENTAL SECTION

General Materials and Methods. Unless otherwise stated, all reactions were performed under an inert atmosphere of nitrogen. UV− vis spectra were recorded on an Agilent 8453 UV−vis spectrometer equipped with an Agilent 89090A thermostat (±0.1 °C) at 25 °C. IR F


Article

Inorganic Chemistry

J = 19.4 Hz, 1F), −160.60 (t, J = 19.3 Hz, 1F), −160.96 (t, J = 21.2 Hz, 1F), −161.12 (t, J = 20.3 Hz, 1F). MALDI-TOF m/z [M]: Calcd for C54H6D19CoF26N4O11P3Yb 1744.02, found 1742.74 ([Yb-up], as deuterium atom is easily to be exchanged to hydrogen atom in the experiment, only peaks of Yb-up was obtained even in the MALDITOF). UV−vis (CH2Cl2, 25 °C): λmax (log ε): 406 (5.59), 511(4.19), 574(4.41), 617(5.17). Complex Yb-down-D. Yield: 90%; 1H NMR (400 MHz, CDCl3) δ −5.82(s, 5H) 27.84 (s, 1H). 19F NMR (377 MHz, Chloroform-d) δ −127.98 (d, J = 18.7 Hz, 1H), −128.30 (d, J = 19.3 Hz, 1H), −128.79 (d, J = 21.5 Hz, 1H), −130.97 (d, J = 20.1 Hz, 1H), −134.63 (d, J = 22.7 Hz, 1H), −136.17(s, 1H), −138.16 (d, J = 23.4 Hz), −138.81(s, 1H), −139.93 (s, 1H), −142.15 (d, J = 23.2 Hz, 1H), −143.37 (d, J = 24.2 Hz, 1H), −144.79(s, 1H), −146.84(s, 1H), −149.67 (t, J = 20.4 Hz, 1H), −150.66 (t, J = 20.5 Hz, 1H), −150.87 (t, J = 18.6 Hz, 1H), −150.97 (t, J = 19.1 Hz, 1H), −158.36 (t, J = 19.7 Hz, 1H), −159.44 (dt, J = 52.9, 23.6 Hz, 3H), −159.69 (t, J = 22.0 Hz, 1H), −160.60 (t, J = 21.3 Hz, 1H), −161.94 (t, J = 21.1 Hz, 1H), −162.45 (t, J = 21.3 Hz, 1H). MALDI-TOF m/z [M]: Calcd for C54H6D19CoF26N4O11P3Yb 1744.02, found 1742.75 ([Yb-down], as deuterium atom is easily to be exchanged to hydrogen atom in the experiment; only peaks of Ybdown was obtained even in the MALDI-TOF). UV−vis (CH2Cl2, 25 °C): λmax (log ε): 406 (5.52), 511(4.06), 574(4.35), 617(5.17). Synthesis of Yb-up/down-CD3. The synthetic procedures for Ybup-CD3 and Yb-down-CD3 are similar. Taking Yb-up-CD3 as example, Yb-up (50 mg, 0.025 mmol) was dissolved in dry CH2Cl2 (10 mL) and few drops of BF3·Et2O was added. The reaction was allowed to stir for 24 h at room temperature. Then the reaction solution was evaporated to dryness and Yb-up-CD3 was obtained by using CH2Cl2/petroleum ether (v/v = 1:2) as eluent. Complex Yb-up-CD3. Yield: 55%; 1H NMR (400 MHz, CDCl3) δ −5.39 (s, 5H), 19.02 (s, 1H). 19F NMR (377 MHz, CDCl3) δ −127.52 (d, J = 20.8 Hz, 1F), −127.84 (s, 1F), −128.55 (d, J = 19.8 Hz, 1F), −129.51(s, 1F), −130.50 (d, J = 24.1 Hz, 1F), −135.73 (s, 1F), −136.35 (d, J = 22.6 Hz, 1F), −136.84 (d, J = 23.5 Hz, 1F), −138.29 (s, 1F), −138.82 (s,1F), −142.44(t, J = 21.0 Hz,1F), −140.02(s, 1F), −146.82 (s, 1F), −150.04 (t, J = 21.3 Hz, 1F), −151.11 (t, J = 22.0 Hz, 2F), −158.53 (t, J = 18.4 Hz, 1F), −160.04(t, J = 23.1 Hz, F), −162.3 (m, 3F). HR-MS (ESI + ) m/z [M + H] + : Calcd for C55H7D21CoF26N4O11P3Yb 1761.0591, found 1761.0558. UV−vis (CH2Cl2, 25 °C): λmax (log ε): 406 (5.31), 511(4.02), 572(4.22), 617(5.01). Complex Yb-down-CD3. Yield: 52%; 1H NMR (400 MHz, CDCl3) δ −5.63 (s, 5H), 27.92 (s, 1H). 19F NMR (377 MHz, CDCl3) δ −127.83 (d, J = 20.8 Hz, 1F), −128.44 (d, J = 20.6 Hz, 1F), −128.71 (d, J = 24.1 Hz, 1F), −131.06 (d, J = 21.1 Hz, 1F), −135.04 (d, J = 21.1 Hz, 1F), −135.59 (s, 1F), −137.70 (d, J = 23.4 Hz, 1F), −138.68 (s, 1F), −139.08 (s, 1F), −139.38 (s, 1F), −141.81 (d, J = 25.5 Hz, 1F), −143.24 (d, J = 18.5 Hz, 1F), −144.98 (s, 1F), −146.90 (s, 1F), −149.85 (t, J = 20.4 Hz, 1F), −150.57 (q, J = 20.0 Hz, 2F), −151.04 (t, J = 20.6 Hz, 1F), −158.26 (t, J = 20.6 Hz, 1F), −159.11 (t, J = 20.3 Hz, 1F), −159.27 to −159.88 (m, 3F), −160.54 (t, J = 22.3 Hz, 1F), −161.81 (t, J = 21.7 Hz, 1F), −162.47 (t, J = 21.2 Hz, 1F). HR-MS (ESI+) m/z [M + H]+: Calcd for C54H7D19CoF26N4O11P3Yb 1761.0591, found 1761.0597. UV−vis (CH2Cl2, 25 °C): λmax (log ε): 406 (5.42), 511(4.10), 572(4.33), 617(5.08). X-ray Crystallography. Complete data sets for Yb-up and and Yb-down were collected. Single crystals suitable for X-ray analysis were coated with Paratone-N oil, suspended in a small fiber loop, and placed in a gaseous nitrogen stream on a Bruker D8 VENTURE X-ray diffractometer at 180(10) K and 298(2) K for Yb-up and Yb-down respectively. Diffraction intensities were measured using graphite monochromated Mo Kα radiation (λ = 0.71073 Å). Data collection, indexing, initial cell refinements, frame integration, and final cell refinements were accomplished using the program APEX2.34 Absorption corrections were applied using SADABS.35 Scattering factors and anomalous dispersion corrections were taken from the International Tables for X-ray Crystallography. The structure was solved by direct methods using SHELXS36 and refined against F2 on all

After cooling to room temperature, the reaction mixtures were transferred to a silica column, the product was obtained by using CH2Cl2/petroleum ether (v/v = 1:1) as eluent and used directly to the next step. The Ln β-hexafluorinated porpholactone (50 mg, 0.025 mmol) was dissolved in dry THF (10 mL) and the solution is cooled to 78 °C. DIBAL-H (20% in hexane, 0.2 mL, 7.0 equiv) was added by syringe15c and the reaction mixture was warmed to room temperature and allowed to stir for an additional hour. The reaction was then quenched by addition of a few drops of H2O and evaporated to dryness. The two products were obtained in the polarity of Ln-down < Ln-up, by using CH2Cl2/petroleum ether (v/v = 2:1) as eluent. Complex Yb-up. Yield: 15% (over three steps, based on the amount of free base porpholactone); 1H NMR (400 MHz, CDCl3) δ −5.43 (s, 5H), 21.47 (s, 1H), 38.21 (s, 1H, D2O exchangeble). 19F NMR (377 MHz, CDCl3) δ −129.16 (d, J = 21.4 Hz, 1F), −130.29 (s, 1F), −131.84 (d, J = 21.7 Hz, 1F), −132.31(s, 1F), −133.65 (d, J = 26.2 Hz, 1F), −134.41 (d, J = 21.6 Hz, 1F), −137.16 (d, J = 23.7 Hz, 1F), −137.50 (d, J = 22.3 Hz, 1F), −138.26 (d, J = 24.3 Hz,1F), −138.38 (d, J = 23.5 Hz,1F), −139.07(s, 1F), −140.92(s, 1F), −148.02 (s, 1F), −149.88 (t, J = 20.4 Hz, 1F), −150.49 (t, J = 20.5 Hz, 1F), −150.68 (t, J = 20.4 Hz, 1F), −150.82(s, 1F), −151.50 (t, J = 20.5 Hz, 1F), −158.87 (t, J = 18.4 Hz, 1F), −159.57 (t, J = 21.6 Hz, 1F), −160.17 (t, J = 19.7 Hz, 1F), −160.64 (t, J = 19.3 Hz, 1F), −160.80 (t, J = 21.0 Hz, 1F), −160.96 (t, J = 21.2 Hz, 1F), −161.14 (t, J = 20.7 Hz, 1F). HR-MS (ESI+) m/z [M + H]+: Calcd for C54H8D18CoF26N4O11P3Yb 1744.0246, found 1744.0191. UV−vis (CH2Cl2, 25 °C): λmax (log ε): 406 (5.49), 511(4.12), 572(4.32), 616(5.12). Complex Yb-down. Yield: 28% (over three steps, based on the amount of free base porpholactone); 1H NMR (400 MHz, CDCl3) δ −5.73(s, 5H), 9.74 (s, 1H, D2O exchangeble), 27.78 (s, 1H). 19F NMR (377 MHz, Chloroform-d) δ −127.98 (d, J = 18.8 Hz, 1H), −128.30 (d, J = 19.3 Hz, 1H), −128.81 (d, J = 22.3 Hz, 1H), −130.98 (d, J = 20.1 Hz, 1H), −134.65 (d, J = 22.8 Hz, 1H), −136.17(s, 1H), −138.18 (d, J = 23.4 Hz), −138.81(s, 1H), −139.93 (s, 1H), −142.14 (d, J = 23.2 Hz, 1H), −143.39 (d, J = 24.2 Hz, 1H), −144.79(s, 1H), −146.84(s, 1H), −149.67 (t, J = 20.5 Hz, 1H), −150.66 (t, J = 20.5 Hz, 1H), −150.87 (t, J = 18.6 Hz, 1H), −150.97 (t, J = 18.4 Hz, 1H), −158.35 (t, J = 19.7 Hz, 1H), −159.45 (dt, J = 52.9, 23.6 Hz, 3H), −159.68 (t, J = 22.0 Hz, 1H), −160.60 (t, J = 21.3 Hz, 1H), −161.94 (t, J = 21.1 Hz, 1H), −162.45 (t, J = 21.3 Hz, 1H). HR-MS (ESI+) m/z [M + H]+: Calcd for C54H8D18CoF26N4O11P3Yb 1744.0246, found 1744.0309. UV−vis (CH2Cl2, 25 °C): λmax (log ε): 406 (5.52), 511(4.22), 572(4.45), 616(5.22). Complex Gd-up. Yield: 13% (over three steps, based on the amount of free base porpholactone); HR-MS (ESI+) m/z [M + H]+: Calcd for C54H8D18CoF26N4O11P3Gd 1728.0099, found 1728.0100. UV−vis (CH2Cl2, 25 °C): λmax (log ε): 407 (5.54), 511(4.13), 573(4.35), 618(5.15). Complex Gd-down. Yield: 21% (over three steps, based on the amount of free base porpholactone); HR-MS (ESI+) m/z [M + H]+: Calcd for C54H8D18CoF26N4O11P3Gd 1728.0099, found 1728.0093. UV−vis (CH2Cl2, 25 °C): λmax (log ε): 407 (5.52), 511(4.09), 573(4.30), 618(5.12). Synthesis of Yb-up/down-D. The synthetic procedures for Ybup-D and Yb-down-D are similar. Taking Yb-up-D as example, Yb-up (20 mg, 0.010 mmol) was dissolved in 2 mL deuterated acetone and 1 mL D2O was added. Then the solution was evaporated to remove the acetone and then centrifuged. The precipitate was collected and dried to give the product Yb-up-D. Complex Yb-up-D. Yield: 85%; 1H NMR (400 MHz, CDCl3) δ −5.56 (s, 5H), 21.47 (s, 1H). 19F NMR (377 MHz, CDCl3) δ −129.16 (d, J = 21.4 Hz, 1F), −130.29(s, 1F), −131.84 (d, J = 21.7 Hz, 1F), −132.31(s, 1F), −133.68 (d, J = 26.0 Hz, 1F), −134.41 (d, J = 21.6 Hz, 1F), −137.16 (d, J = 23.7 Hz, 1F), −137.50 (d, J = 22.3 Hz, 1F), −138.26 (d, J = 24.3 Hz,1F), −138.38 (d, J = 23.5 Hz,1F), −139.07(s, 1F), −140.92(s, 1F), −148.02 (s, 1F), −149.88 (t, J = 20.4 Hz, 1F), −150.49 (t, J = 20.5 Hz, 1F), −150.71 (t, J = 20.2 Hz, 1F), −150.82(s, 1F), −151.50 (t, J = 20.5 Hz, 1F), −158.87 (t, J = 18.4 Hz, 1F), −159.57 (t, J = 21.6 Hz, 1F), −160.17 (t, J = 19.7 Hz, 1F), −160.21 (t, G


■

Inorganic Chemistry data by full-matrix least-squares with SHELXL-2016 following established refinement strategies.37 Yb-up crystallized in monoclinic space group C2/c. Yb-down crystallized in monoclinic space group P21/m, with one cocrystallized methanol solvent molecule. Disorder of the atoms in the axial [(η5C5H5)Co{(D3CO)2P = O}3] ligand and the β-hemiacetal moieties were observed, but no improvement was observed after further refinements or recrystallization in different solvents or at low temperature. This phenomenon widely exists in the metalloporpholactone systems before.20a,21b,38 All non-hydrogen atoms were refined anisotropically. The carbon and oxygen atoms of the β-hemiacetal moieties in Yb-up and Yb-down, as well as the carbon atoms in the axial ligand, can not be added hydrogen atoms for the highly distortion of the moieties. Details of the data quality and a summary of the residual values of the refinements are listed in Table S1. Quantum Yields Determination. Quantum yields in solution were determined using comparative method and the equation: Φs/Φr = (Gs/Gr)(ηs2/ηr2),39 where the subscripts r and s denote reference and sample respectively, Φ is the quantum yield, G is the slope from the plot of integrated emission intensity vs absorbance, and η is the refractive index of the solvent. The reference was 5,10,15,20tetraphenylporphyrin-Yb(III)-[(cyclopentadienyl)tris(di(ethyl)phosphito)cobaltate] in CH2Cl2 (YbTPP(LOEt), Φr = 0.024).24 For the quantum yield measured in air-saturated CH2Cl2, YbTPP(LOEt) and solutions of corresponding Yb(III) complex with 4 different concentration was first prepared in anhydrous CH2Cl2. The absorbance of all the solutions at 406 nm were recorded on an Agilent 8453 UV−vis spectrometer equipped with an Agilent 89090A thermostat (±0.1 °C) and NIR emissions were recorded on an Edinburgh Analytical Instruments FLS980 with the excitation wavelength at 406 nm under an identical condition. According to the ratio of the slope GYb/Gr, the relative quantum yield of Yb(III) complex could be obtained according to the equation described above. The absorbance of all the samples and references are below 0.15 and absorbance values undergo background correction by subtracting average over range from 800 to 820 nm. The integrated emission intensity which integrate from 880 to 1150 nm have been subtracting the blank (integrated emission intensity with the only pure CH2Cl2 under an identical condition). Preparation of PMMA Film. PMMA thin films for the thermosensitivity measurements were prepared by dispensing PMMA solution (10% PMMA in CH2Cl2) of the complex (0.1%, referred to the weight of solution) on glass substrates and remonving the residue solvent by additional vacuum annealing at 50 °C for 20 min. Calculation of the Nonradiative Quenching Constant. According to Ermolaev and Sveshnikova’s model,26 the nonradiative deactivation of lanthanide excited state is dependent on the distance (r) between lanthanide and the quenching center (knr ∝ r−6, eq 1).

k nr =

9000 ln(10)k rκ 2 128π 2n 4NAr 6

∫ Iem(ν)̃ εvib(ν)̃ ν−̃ 4 dν ̃

A = 1.0 μs, B = 0.2 μs−1

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.7b02750. Detailed characterization, photophysical and crystallographic data (PDF) Accession Codes

CCDC 1566733−1566734 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Jun-Long Zhang: 0000-0002-5731-7354 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS We acknowledge financial support from support from National Key Basic Research Support Foundation of China (NKBRSFC) (2015CB856301) and National Scientific Foundation of China (Grants No. 21778002 and 21571007). Mr. M. Chen in Peking University is gratefully thanked for the help with quantum yield measurements. Prof. H. Su and Dr. X. Dai in Beijing Normal University are gratefully thanked for discussion of photophysical data.

■

REFERENCES

(1) Huang, X.; Han, S.; Huang, W.; Liu, X. Enhancing Solar Cell Efficiency: The Search for Luminescent Materials as Spectral Converters. Chem. Soc. Rev. 2013, 42, 173−201. (2) (a) Zhang, T.; Zhu, X.; Cheng, C. C.; Kwok, W. M.; Tam, H. L.; Hao, J.; Kwong, D. W.; Wong, W. K.; Wong, K. L. Water-Soluble Mitochondria-Specific Ytterbium Complex with Impressive NIR Emission. J. Am. Chem. Soc. 2011, 133, 20120−20122. (b) FoucaultCollet, A.; Gogick, K. A.; White, K. A.; Villette, S.; Pallier, A.; Collet, G.; Kieda, C.; Li, T.; Geib, S. J.; Rosi, N. L. Lanthanide Near Infrared Imaging in Living Cells with Yb3+ Nano Metal Organic Frameworks. Proc. Natl. Acad. Sci. U. S. A. 2013, 110, 17199−17204. (c) Liu, Q.; Feng, W.; Li, F. Water-Soluble Lanthanide Upconversion Nanophosphors: Synthesis and Bioimaging Applications in Vivo. Coord. Chem. Rev. 2014, 273, 100−110. (d) Sy, M.; Nonat, A.; Hildebrandt, N.; Charbonnière, L. J. Lanthanide-Based Luminescence Biolabelling. Chem. Commun. 2016, 52, 5080−5095. (e) Bui, A. T.; Beyler, M.; Grichine, A.; Duperray, A.; Mulatier, J.-C.; Guyot, Y.; Andraud, C.; Tripier, R.; Brasselet, S.; Maury, O. Near Infrared Two Photon Imaging Using a Bright Cationic Yb (III) Bioprobe Spontaneously Internalized into Live Cells. Chem. Commun. 2017, 53, 6005−6008. (f) Martinić, I.; Eliseeva, S. V.; Nguyen, T. N.; Foucher, F.; Gosset, D.; Westall, F.; Pecoraro, V. L.; Petoud, S. Near-Infrared Luminescent Metallacrowns for Combined in Vitro Cell Fixation and Counter Staining. Chem. Sci. 2017, 8, 6042−6050. (3) (a) Kuriki, K.; Koike, Y.; Okamoto, Y. Plastic Optical Fiber Lasers and Amplifiers Containing Lanthanide Complexes. Chem. Rev. 2002, 102, 2347−2356. (b) Montgomery, C. P.; Murray, B. S.; New, E. J.; Pal, R.; Parker, D. Cell-Penetrating Metal Complex Optical Probes: Targeted and Responsive Systems Based on Lanthanide Luminescence. Acc. Chem. Res. 2009, 42, 925−937. (c) Ye, H.; Li, Z.; Peng, Y.;

(1)

kr is the rate constant of the electric dipole radiation; n is the refractive index of the medium; and κ2 = 2/3 is the orientational factor; r is the distance between the lanthanide ion and the accepting molecular group; Iem(ν̃) is the luminescence spectrum normalized to the unit area; εvib(ν̃) is the spectrum of the molar decimal vibration absorption coefficient of the molecular group. The values of other factors except for r in the equation are equal for the two complexes. Calculation of the Hydration Number. The hydration/solvation number was obtained by using an empirical eq 2, which was developed by Beeby et al.25 In this formula, q is the number of water molecules bound to Yb(III) ion in the first sphere of coordination; τH and τD are the rate constants of excited states of lanthanide ion in H2O and D2O, respectively. A is a proportionality constant related to the sensitivity of the Yb(III) ion to vibrational quenching by O−H oscillators, B is the correction factor for outer sphere water molecules.

q = A(1/τH − 1/τD − B)

Article

(2) H


Article

Inorganic Chemistry

Eur. J. 2007, 13, 6308−6320. (d) Hu, J.-Y.; Ning, Y.; Meng, Y.-S.; Zhang, J.; Wu, Z.-Y.; Gao, S.; Zhang, J.-L. Highly Near-IR Emissive Ytterbium (III) Complexes with Unprecedented Quantum Yields. Chem. Sci. 2017, 8, 2702−2709. (e) Pizzoferrato, R.; Francini, R.; Pietrantoni, S.; Paolesse, R.; Mandoj, F.; Monguzzi, A.; Meinardi, F. Effects of Progressive Halogen Substitution on the Photoluminescence Properties of an Erbium-Porphyrin Complex. J. Phys. Chem. A 2010, 114, 4163−4168. (13) (a) Puntus, L. N.; Lyssenko, K. A.; Antipin, M. Y.; Bünzli, J. C. Role of Inner- and Outer-Sphere Bonding in the Sensitization of Eu(III)-Luminescence Deciphered by Combined Analysis of Experimental Electron Density Distribution Function and Photophysical Data. Inorg. Chem. 2008, 47, 11095−11107. (b) Puntus, L. N.; Lyssenko, K. A.; Pekareva, I. S.; Bünzli, J.-C. G. Intermolecular Interactions as Actors in Energy-Transfer Processes in Lanthanide Complexes with 2,2’-Bipyridine. J. Phys. Chem. B 2009, 113, 9265− 9277. (14) (a) Vonci, M.; Mason, K.; Suturina, E. A.; Frawley, A. T.; Worswick, S. G.; Kuprov, I.; Parker, D.; Mcinnes, E. J. L.; Chilton, N. F. Rationalization of Anomalous Pseudocontact Shifts and Their Solvent Dependence in a Series of C3-Symmetric Lanthanide Complexes. J. Am. Chem. Soc. 2017, 139, 14166−141721. (b) Mason, K.; Rogers, N. J.; Suturina, E. A.; Kuprov, I.; Aguilar, J. A.; Batsanov, A. S.; Yufit, D. S.; Parker, D. Parashift Probes: Solution NMR and X-Ray Structural Studies of Macrocyclic Ytterbium and Yttrium Complexes. Inorg. Chem. 2017, 56, 4028−4038. (15) (a) McCarthy, J. R.; Perez, J. M.; Brückner, C.; Weissleder, R. Polymeric Nanoparticle Preparation That Eradicates Tumors. Nano Lett. 2005, 5, 2552−2556. (b) Brückner, C.; Ogikubo, J.; McCarthy, J. R.; Akhigbe, J.; Hyland, M. A.; Daddario, P.; Worlinsky, J. L.; Zeller, M.; Engle, J. T.; Ziegler, C. J. Meso-Arylporpholactones and Their Reduction Products. J. Org. Chem. 2012, 77, 6480−6494. (c) Ke, X. S.; Tang, J.; Chen, J. J.; Zhou, Z. Y.; Zhang, J. L. β-Ionic Conjugated Chlorin-Type Photosensitizers Based on Porpholactone: Synthesis, Photophysical Properties, and Photodynamic Activity. ChemPlusChem 2015, 80, 237−252. (d) Brückner, C. The Breaking and Mending of Meso-Tetraarylporphyrins: Transmuting the Pyrrolic Building Blocks. Acc. Chem. Res. 2016, 49, 1080−1092. (16) (a) Kläui, W. The Coordination Chemistry and Organometallic Chemistry of Tridentate Oxygen Ligands with Π-Donor Properties. Angew. Chem., Int. Ed. Engl. 1990, 29, 627−637. (b) Allen, K. J.; Nicholls-Allison, E. C.; Johnson, K. R.; Nirwan, R. S.; Berg, D. J.; Wester, D.; Twamley, B. Lanthanide Complexes of the KläUi Metalloligand, CpCo(P = O(OR)2)3: An Examination of Ligand Exchange Kinetics between Isotopomers by Electrospray Mass Spectrometry. Inorg. Chem. 2012, 51, 12436−12443. (17) Hu, J.-Y.; Wu, Z.-Y.; Chai, K.; Yang, Z.-S.; Meng, Y.-S.; Zhang, J.; Zhang, J.-L. β-Fluorinated Porpholactones and Metal Complexes: Synthesis, Characterization and Some Spectroscopic Studies. Inorg. Chem. Front. 2017, 4, 1539−1545. (18) (a) Zhu, X.; Wong, W. K.; Wong, W. Y.; Yang, X. Design and Synthesis of Near-Infrared Emissive Lanthanide Complexes Based on Macrocyclic Ligands. Eur. J. Inorg. Chem. 2011, 2011, 4651−4674. (b) Bulach, V.; Sguerra, F.; Hosseini, M. W. Porphyrin Lanthanide Complexes for NIR Emission. Coord. Chem. Rev. 2012, 256, 1468− 1478. (c) He, H. Near-Infrared Emitting Lanthanide Complexes of Porphyrin and Bodipy Dyes. Coord. Chem. Rev. 2014, 273, 87−99. (19) Ke, X.-S.; Chang, Y.; Chen, J.-Z.; Tian, J.; Mack, J.; Cheng, X.; Shen, Z.; Zhang, J.-L. Porphodilactones as Synthetic Chlorophylls: Relative Orientation of β-Substituents on a Pyrrolic Ring Tunes NIR Absorption. J. Am. Chem. Soc. 2014, 136, 9598−9607. (20) (a) Ke, X.-S.; Zhao, H.; Zou, X.; Ning, Y.; Cheng, X.; Su, H.; Zhang, J.-L. Fine-Tuning of β-Substitution to Modulate the Lowest Triplet Excited States: A Bioinspired Approach to Design Phosphorescent Metalloporphyrinoids. J. Am. Chem. Soc. 2015, 137, 10745− 10752. (b) Ke, X. S.; Ning, Y.; Tang, J.; Hu, J. Y.; Yin, H. Y.; Wang, G. X.; Yang, Z. S.; Jie, J.; Liu, K.; Meng, Z. S. Gadolinium (III) Porpholactones as Efficient and Robust Singlet Oxygen Photosensitizers. Chem. - Eur. J. 2016, 22, 9676−9686.

Wang, C.; Li, T.; Zheng, Y.; Sapelkin, A.; Adamopoulos, G.; Hernández, I.; Wyatt, P. Organo-Erbium Systems for Optical Amplification at Telecommunications Wavelengths. Nat. Mater. 2014, 13, 382−386. (4) Mech, A.; Monguzzi, A.; Meinardi, F.; Mezyk, J.; Macchi, G.; Tubino, R. Sensitized NIR Erbium (III) Emission in Confined Geometries: A New Strategy for Light Emitters in Telecom Applications. J. Am. Chem. Soc. 2010, 132, 4574−4576. (5) (a) Chow, C. Y.; Eliseeva, S. V.; Trivedi, E. R.; Nguyen, T. N.; Kampf, J. W.; Petoud, S.; Pecoraro, V. L. Ga3+/Ln3+ Metallacrowns: A Promising Family of Highly Luminescent Lanthanide Complexes That Covers Visible and Near-Infrared Domains. J. Am. Chem. Soc. 2016, 138, 5100−5109. (b) Kovacs, D.; Lu, X.; Mészáros, L. S.; Ott, M.; Andres, J.; Borbas, K. E. Photophysics of Coumarin and CarbostyrilSensitized Luminescent Lanthanide Complexes: Implications for Complex Design in Multiplex Detection. J. Am. Chem. Soc. 2017, 139, 5756−5767. (6) Armelao, L.; Quici, S.; Barigelletti, F.; Accorsi, G.; Bottaro, G.; Cavazzini, M.; Tondello, E. Design of Luminescent Lanthanide Complexes: From Molecules to Highly Efficient Photo-Emitting Materials. Coord. Chem. Rev. 2010, 254, 487−505. (7) (a) Werner, A. Ber Die Raumisomeren Kobaltverbindungen. Ann. Chem. 1912, 386, 1−272. (b) Werner, A. Zur Kenntnis Des Asymmetrischen Kobaltatoms. Ber. Dtsch. Chem. Ges. 1912, 45, 121−130. (8) (a) Liu, T.; Nonat, A.; Beyler, M.; Regueiro-Figueroa, M.; Nchimi, N. K.; Jeannin, O.; Camerel, F.; Debaene, F.; CianféraniSanglier, S.; Tripier, R. Supramolecular Luminescent Lanthanide Dimers for Fluoride Sequestering and Sensing. Angew. Chem., Int. Ed. 2014, 53, 7259−7263. (b) Doffek, C.; Seitz, M. The Radiative Lifetime in Near-IR-Luminescent Ytterbium Cryptates: The Key to Extremely High Quantum Yields. Angew. Chem., Int. Ed. 2015, 54, 9719−9721. (c) Nonat, A.; Chan, C. F.; Liu, T.; Platas-Iglesias, C.; Liu, Z.; Wong, W. T.; Wong, W. K.; Wong, K. L.; Charbonnière, L. J. Room Temperature Molecular up Conversion in Solution. Nat. Commun. 2016, 7, 11978−11983. (9) (a) Latva, M.; Takalo, H.; Mukkala, V.-M.; Matachescu, C.; Rodríguez-Ubis, J. C.; Kankare, J. Correlation between the Lowest Triplet State Energy Level of the Ligand and Lanthanide (III) Luminescence Quantum Yield. J. Lumin. 1997, 75, 149−169. (b) Yu, J.-a. An Observation of Back Energy Transfer in Complex Tb(III) with 2-Naphthoate in Methanol. J. Lumin. 1998, 78, 265−270. (10) (a) Wang, X.; Chang, H.; Xie, J.; Zhao, B.; Liu, B.; Xu, S.; Pei, W.; Ren, N.; Huang, L.; Huang, W. Recent Developments in Lanthanide-Based Luminescent Probes. Coord. Chem. Rev. 2014, 273−274, 201−212. (b) Heffern, M. C.; Matosziuk, L. M.; Meade, T. J. Lanthanide Probes for Bioresponsive Imaging. Chem. Rev. 2014, 114, 4496−4539. (c) Zhang, T.; Chan, C. F.; Lan, R.; Wong, W. K.; Wong, K. L. Highly Selective and Responsive Visible to Near-IR Ytterbium Emissive Probe for Monitoring Mercury(II). Chem. - Eur. J. 2014, 20, 970−973. (11) (a) Hebbink, G. A.; Reinhoudt, D. N.; van Veggel, F. C. Increased Luminescent Lifetimes of Ln3+ Complexes Emitting in the Near-Infrared as a Result of Deuteration. Eur. J. Org. Chem. 2001, 2001, 4101−4106. (b) Bischof, C.; Wahsner, J.; Scholten, J.; Trosien, S.; Seitz, M. Quantification of C−H Quenching in Near-IR Luminescent Ytterbium and Neodymium Cryptates. J. Am. Chem. Soc. 2010, 132, 14334−14335. (12) (a) Hasegawa, Y.; Ohkubo, T.; Sogabe, K.; Kawamura, Y.; Wada, Y.; Nakashima, N.; Yanagida, S. Luminescence of Novel Neodymium Sulfonylaminate Complexes in Organic Media. Angew. Chem. 2000, 112, 365−368. (b) Mancino, G.; Ferguson, A. J.; Beeby, A.; Long, N. J.; Jones, T. S. Dramatic Increases in the Lifetime of the Er3+ Ion in a Molecular Complex Using a Perfluorinated Imidodiphosphinate Sensitizing Ligand. J. Am. Chem. Soc. 2005, 127, 524−525. (c) Glover, P. B.; Bassett, A. P.; Nockemann, P.; Kariuki, B. M.; Van Deun, R.; Pikramenou, Z. Fully Fluorinated Imidodiphosphinate Shells for Visible- and NIR-Emitting Lanthanides: Hitherto Unexpected Effects of Sensitizer Fluorination on Lanthanide Emission Properties. Chem. I


Article

Inorganic Chemistry (21) (a) Ke, X. S.; Yang, B. Y.; Cheng, X.; Chan, S. L. F.; Zhang, J. L. Ytterbium (III) Porpholactones: β-Lactonization of Porphyrin Ligands Enhances Sensitization Efficiency of Lanthanide Near-Infrared Luminescence. Chem. - Eur. J. 2014, 20, 4324−4333. (b) Ning, Y.; Ke, X.-S.; Hu, J.-Y.; Liu, Y.-W.; Ma, F.; Sun, H.-L.; Zhang, J.-L. Bioinspired Orientation of β-Substituents on Porphyrin Antenna Ligands Switches Ytterbium (III) NIR Emission with Thermosensitivity. Inorg. Chem. 2017, 56, 1897−1905. (22) Desiraju, G. R.; Steiner, T. The Weak Hydrogen Bond: In Structural Chemistry and Biology; Oxford University Press: Oxford, 1999; Vol. 9. (23) Ishida, H.; Bünzli, J.-C. G.; Beeby, A. Guidelines for Measurement of Luminescence Spectra and Quantum Yields of Inorganic Compounds, Metal Complexes, and Materials. Pure Appl. Chem. 2016, 88, 701−711. (24) Foley, T. J.; Harrison, B. S.; Knefely, A. S.; Abboud, K. A.; Reynolds, J. R.; Schanze, K. S.; Boncella, J. M. Facile Preparation and Photophysics of Near-Infrared Luminescent Lanthanide(III) Monoporphyrinate Complexes. Inorg. Chem. 2003, 42, 5023−5032. (25) Beeby, A.; Clarkson, I.; Dickins, R.; Faulkner, S.; Parker, D.; Royle, L. As D. Sousa, Jag Williams and M. Woods. J. Chem. Soc., Perkin Trans. 2 1999, 2, 493−503. (26) Sveshnikova, E. B.; Ermolaev, V. L. Inductive-Resonant Theory of Nonradiative Transitions in Lanthanide and Transition Metal Ions. Opt. Spectrosc. 2011, 111, 34−50. (27) (a) Brites, C. D.; Lima, P. P.; Silva, N. J.; Millan, A.; Amaral, V. S.; Palacio, F.; Carlos, L. D. Lanthanide-Based Luminescent Molecular Thermometers. New J. Chem. 2011, 35, 1177−1183. (b) Wang, X.-d.; Wolfbeis, O. S.; Meier, R. J. Luminescent Probes and Sensors for Temperature. Chem. Soc. Rev. 2013, 42, 7834−7869. (c) Qiao, J.; Mu, X.; Qi, L. Construction of Fluorescent Polymeric Nano-Thermometers for Intracellular Temperature Imaging: A Review. Biosens. Bioelectron. 2016, 85, 403−413. (28) (a) Miyata, K.; Konno, Y.; Nakanishi, T.; Kobayashi, A.; Kato, M.; Fushimi, K.; Hasegawa, Y. Chameleon Luminophore for Sensing Temperatures: Control of Metal-to-Metal and Energy Back Transfer in Lanthanide Coordination Polymers. Angew. Chem., Int. Ed. 2013, 52, 6413−6416. (b) Tang, M.; Huang, Y.; Wang, Y.; Fu, L. An Ytterbium Complex with Unique Luminescence Properties: Detecting the Temperature Based on a Luminescence Spectrum without the Interference of Oxygen. Dalton Trans. 2015, 44, 7449−7457. (c) Gao, Y.; Huang, F.; Lin, H.; Zhou, J.; Xu, J.; Wang, Y. A Novel Optical Thermometry Strategy Based on Diverse Thermal Response from Two Intervalence Charge Ttransfer States. Adv. Funct. Mater. 2016, 26, 3139−3145. (29) (a) Cui, Y.; Xu, H.; Yue, Y.; Guo, Z.; Yu, J.; Chen, Z.; Gao, J.; Yang, Y.; Qian, G.; Chen, B. A Luminescent Mixed-Lanthanide Metal−Organic Framework Thermometer. J. Am. Chem. Soc. 2012, 134, 3979−3982. (b) Rao, X.; Song, T.; Gao, J.; Cui, Y.; Yang, Y.; Wu, C.; Chen, B.; Qian, G. A Highly Sensitive Mixed Lanthanide Metal− Organic Framework Self-Calibrated Luminescent Thermometer. J. Am. Chem. Soc. 2013, 135, 15559−15564. (c) Hatanaka, M.; Hirai, Y.; Kitagawa, Y.; Nakanishi, T.; Hasegawa, Y.; Morokuma, K. Organic Linkers Control the Thermosensitivity of the Emission Intensities from Tb (III) and Eu (III) in a Chameleon Polymer. Chem. Sci. 2017, 8, 423−429. (30) (a) Fischer, L. H.; Harms, G. S.; Wolfbeis, O. S. Upconverting Nanoparticles for Nanoscale Thermometry. Angew. Chem., Int. Ed. 2011, 50, 4546−4551. (b) Brites, C. D.; Lima, P. P.; Silva, N. J.; Millán, A.; Amaral, V. S.; Palacio, F.; Carlos, L. D. Thermometry at the Nanoscale. Nanoscale 2012, 4, 4799−4829. (31) Andrade, E. d. C. XLI. A Theory of the Viscosity of Liquids. Part I. Philos. Mag. 1934, 17, 497−511. (32) (a) Kuimova, M. K. Mapping Viscosity in Cells Using Molecular Rotors. Phys. Chem. Chem. Phys. 2012, 14, 12671−12686. (b) Sloop, G.; Holsworth, R. E., Jr; Weidman, J. J.; St Cyr, J. A. The Role of Chronic Hyperviscosity in Vascular Disease. Ther. Adv. Cardiovasc. Dis. 2015, 9, 19−25.

(33) Bui, A. T.; Grichine, A.; Duperray, A.; Lidon, P.; Riobé, F.; Andraud, C.; Maury, O. Terbium (III) Luminescent Complexes as Millisecond-Scale Viscosity Probes for Lifetime Imaging. J. Am. Chem. Soc. 2017, 139, 7693−7696. (34) APEX2; Bruker AXIS: Madison, WI, 2009. (35) Sheldrick, G. M. SADABS; 2008. (36) Sheldrick, G. M. Phase Annealing in Shelx-90: Direct Methods for Larger Structures. Acta Crystallogr., Sect. A: Found. Crystallogr. 1990, A46, 467−473. (37) Sheldrick, G. M. Acta Crystallogr., Sect. A: Found. Crystallogr. 2008, A64, 112−122. (38) Wu, Z.-Y.; Wang, T.; Meng, Y.-S.; Rao, Y.; Wang, B.-W.; Zheng, J.; Gao, S.; Zhang, J.-L. Enhancing the Reactivity of Nickel (II) in Hydrogen Evolution Reactions (HERs) by β-Hydrogenation of Porphyrinoid Ligands. Chem. Sci. 2017, 8, 5953−5961. (39) Yvon, H. J. A Guide to Recording Fluorescence Quantum Yields. HORIBA, Jobin Yvon Ltd.: Stanmore, Middlesex, UK, 2012.

J


Design of Near-Infrared Luminescent Lanthanide Complexes

Recommend Documents