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1.
Six novel Ir(C^N)2(L^X)-type heteroleptic iridium complexes with deep-red and near-infrared region (NIR)-emitting coverage were constructed through the cross matching of various cyclometalating (C^N) and ancillary (LX) ligands. Here, three novel C^N ligands were designed by introducing the electron-withdrawing group CF3 on the ortho (o-), meta (m-), and para (p-) positions of the phenyl ring in the 1-phenylisoquinoline (piq) group, which were combined with two electron-rich LX ligands (dipba and dipg), respectively, leading to subsequent iridium complexes with gradually changing emission colors from deep red (≈660 nm) to NIR (≈700 nm). Moreover, a series of phosphorescent organic light-emitting diodes (PhOLEDs) were fabricated by employing these phosphors as dopant emitters with two doping concentrations, 5% and 10%, respectively. They exhibited efficient electroluminescence (EL) with significantly high EQE values: >15.0% for deep red light0 (λmax = 664 nm) and >4.0% for NIR cases (λmax = 704 nm) at a high luminance level of 100 cd m−2. This work not only provides a promising approach for finely tuning the emission color of red phosphors via the easily accessible molecular design strategy, but also enables the establishment of an effective method for enriching phosphorescent-emitting molecules for practical applications, especially in the deep-red and near-infrared region (NIR).  相似文献   

2.
Yan Chen  Chun Liu  Lei Wang 《Tetrahedron》2019,75(47):130686
Cationic cyclometalated Ir(III) complexes (Ir1-Ir5) with fluorine-substituted 2-phenylpyridine (ppy) derivatives as C^N cyclometalating ligands and 2,2′-bipyridine (bpy) as the ancillary ligand, have been synthesized and fully characterized. The influences of the number and the position of fluorine atoms at the cyclometalating ligands on the photophysical, electrochemical and oxygen sensing properties of the Ir(III) complexes have been investigated systematically. The introduction of fluorine on the C^N cyclometalating ligands of the complexes results in blue-shifts of the maximum emission wavelengths, and increases in the photoluminescence quantum yields (ΦPL), phosphorescence lifetimes and energy gaps, compared to the non-fluorinated [Ir(ppy)2(bpy)]+PF6? (Ir0). Among them, 2-(2,4-difluorophenyl)pyridine-derived Ir4 shows the maximum blue-shift (514 nm vs. 575 nm for Ir0) and the highest ΦPL (50.8% vs. 6.5% for Ir0). The complex Ir3 with 2-(4-fluorophenyl)-5-fluoropyridine as C^N ligand exhibits the highest oxygen sensitivity and excellent operational stability in 10 cycles within 4000 s.  相似文献   

3.
The reaction of the cyclometalated chloro-bridged iridium(III) dimer, [(ppy)2 Ir(μ-Cl)]2 (ppy - 2-phenyl pyridine) with N-aryl picolinamides (LH, LH-NO2, LH-CH3, LH-l, LH-F) resulted in the formation of neutral heteroleptic complexes [Ir(ppy)2L] (1), [Ir(ppy)2L-NO2](2), [Ir(ppy)2L-CH3](3), [Ir(ppy)2L-Cl](4) and [Ir(ppy)2L-F] (5). These complexes contain a six-coordinate iridium with a 2C, 4N coordination environment. The N-aryl picolinamide ligands are deprotonated during complexation and the resulting amidates bind to iridium in a chelating manner (N, N). Optical spectroscopic studies revealed that the complexes 1-5 exhibited intense π→π absorptions in the ultraviolet region. In addition low energy transitions due to 1MLCT, 1LLCT and 3MLCT are also seen. The emission spectra of 1-5, upon excitation at 450 nm, show a single emission with a λmax around 513 nm. The lifetimes of this emission are in between 7.4 and 9.6 μs while the quantum yields are quite high and range from 0.2 to 0.5. Based on density functional theory (DFT) calculations on 1 and 3, the three highest occupied orbitals are composed of ligand π orbitals mixed with Ir-d orbitals while the three lowest unoccupied orbitals are mostly π orbitals of the ligands. From the time dependent DFT calculations it is revealed that the lowest energy electronic singlet and triplet excitations are a mixture of MLCT and LLCT.  相似文献   

4.
The coordination ability of the [(ppy)Au(IPr)]2+ fragment [ppy = 2-phenylpyridine, IPr = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] towards different anionic and neutral X ligands (X = Cl, BF4, OTf, H2O, 2-butyne, 3-hexyne) commonly involved in the crucial pre-equilibrium step of the alkyne hydration reaction is computationally investigated to shed light on unexpected experimental observations on its catalytic activity. Experiment reveals that BF4 and OTf have very similar coordination ability towards [(ppy)Au(IPr)]2+ and slightly less than water, whereas the alkyne complex could not be observed in solution at least at the NMR sensitivity. Due to the steric hindrance/dispersion interaction balance between X and IPr, the [(ppy)Au(IPr)]2+ fragment is computationally found to be much less selective than a model [(ppy)Au(NHC)]2+ (NHC = 1,3-dimethylimidazol-2-ylidene) fragment towards the different ligands, in particular OTf and BF4, in agreement with experiment. Effect of the ancillary ligand substitution demonstrates that the coordination ability of Au(III) is quantitatively strongly affected by the nature of the ligands (even more than the net charge of the complex) and that all the investigated gold fragments coordinate to alkynes more strongly than H2O. Remarkably, a stabilization of the water-coordinating species with respect to the alkyne-coordinating one can only be achieved within a microsolvation model, which reconciles theory with experiment. All the results reported here suggest that both the Au(III) fragment coordination ability and its proper computational modelling in the experimental conditions are fundamental issues for the design of efficient catalysts.  相似文献   

5.
The electronic structures and spectroscopic properties of a series of mixed bis-cyclometalated iridium(III) complexes [Ir(ppy)2X2] (X = CN, 1; X = NCS, 2; X = NCO, 3; ppy = 2-phenylpyridl) were investigated at the B3LYP/LANL2DZ and CIS/LANL2DZ levels. The calculated geometry parameters in the ground state are well consistent with the corresponding experimental values. The HOMO of 1 is dominantly localized on Ir atom and ppy ligand, but the HOMO of 2 and 3 have significant X ligand composition. Under the TD-DFT level with PCM model, the absorption and phosphorescence in CH2Cl2 media were calculated based on the optimized geometries in the ground and excited states, respectively. The lowest-lying absorption of 1 at 403 nm is attributed to {[dx2-y2(Ir)+dxy(Ir)+π(ppy)]→[π(ppy)]} transition with metal-to-ligand and intraligand charge transfer (MLCT/ILCT) transition characters, whereas those of 2 (449 nm) and 3 (475 nm) are related to {[dx2-y2(Ir)+dxy(Ir)+π(ppy)+π(NCS/NCO)]→[π(ppy)]} transition with MLCT/ILCT and ligand-to-ligand charge transfer (LLCT) transition characters. The phosphorescence of 1 at 466 nm can be described as originating from 3{[dx2-y2(Ir)+dxy(Ir)+π(ppy)][π(ppy)]} excited state, while those of 2 (487 nm) and 3 (516 nm) originate from 3{[dx2-y2(Ir)+dxy(Ir)+π(ppy)+π(NCS/NCO)][π(ppy)]} excited states. The calculated results showed that the transition character of the absorption and emission can be changed by adjusting the π electron-accepting abilities of the X ligands and the phosphorescent color can be tuned by altering the X ligands.  相似文献   

6.
Iridium complexes bearing chelating cyclometalates are popular choices as dopant emitters in the fabrication of organic light-emitting diodes (OLEDs). In this contribution, we report a series of blue-emitting, bis-tridentate IrIII complexes bearing chelates with two fused five-six-membered metallacycles, which are in sharp contrast to the traditional designs of tridentate chelates that form the alternative, fused five-five metallacycles. Five IrIII complexes, Px-21 – 23 , Cz-4 , and Cz-5 , have been synthesized that contain a coordinated dicarbene pincer chelate incorporating a methylene spacer and a dianionic chromophoric chelate possessing either a phenoxy or carbazolyl appendage to tune the coordination arrangement. All these tridentate chelates afford peripheral ligand–metal–ligand bite angles of 166–170°, which are larger than the typical bite angle of 153–155° observed for their five-five-coordinated tridentate counterparts, thereby leading to reduced geometrical distortion in the octahedral frameworks. Photophysical measurements and TD-DFT studies verified the inherent transition characteristics that give rise to high emission efficiency, and photodegradation experiments confirmed the improved stability in comparison with the benchmark fac-[Ir(ppy)3] in degassed toluene at room temperature. Phosphorescent OLED devices were also fabricated, among which the carbazolyl-functionalized emitter Cz-5 exhibited the best performance among all the studied bis-tridentate phosphors, showing a maximum external quantum efficiency (EQEmax) of 18.7 % and CIEx,y coordinates of (0.145, 0.218), with a slightly reduced EQE of 13.7 % at 100 cd m−2 due to efficiency roll-off.  相似文献   

7.
The ground and the lowest-lying triplet excited state geometries, electronic structures, and spectroscopic properties of a novel series of neutral iridium(III) complexes with cyclometalated alkenylquinoline ligands [(C^N)2Ir(acac)] (acac = acetoylacetonate; C^N = 2-[(E)-2-phenyl-1-ethenyl]pyridine (pep) 1; 2-[(E)-2-phenyl-1-ethenyl]quinoline (peq) 2; 1-[(E)-2-phenyl-1-ethenyl]isoquinoline (peiq) 3; 2-[(E)-1-propenyl]pyridine (pp) 4; 2-[(E)-1-fluoro-1-ethenyl]pyridine (fpp) 5) were investigated by DFT and CIS methods. The highest occupied molecular orbital is composed of d(Ir) and π(C^N) orbital, while the lowest unoccupied molecular orbital is dominantly localized on C^N ligand. Under the TD-DFT with PCM model level, the absorption and phosphorescence in CH2Cl2 media were calculated based on the optimized ground and triplet excited state geometries, respectively. The calculated lowest-lying absorptions at 437 nm (1), 481 nm (2), 487 nm (3), 422 nm (4), and 389 nm (5) are attributed to a {[dx2-y2(Ir) + dxz(Ir) + π(C^N)] → [π∗(C^N)]} transition with metal-to-ligand/intra-ligand charge transfer (MLCT/ILCT) characters, and the calculated phosphorescence at 582 nm (1), 607 nm (2), 634 nm (3), 515 nm (4), and 491 nm (5) can be described as originating from the 3{[dx2-y2(Ir) + dxz(Ir) + π (C^N)] [π∗(C^N)]} excited state with the 3MLCT/3ILCT characters. The calculated results revealed that the phosphorescent color of these new Ir(III) complexes can be tuned by changing the π-conjugation effect strength of the C^N ligand.  相似文献   

8.
Multi-resonant thermally activated delayed fluorescence (MR-TADF) materials have attracted considerable attention recently. The molecular design frequently incorporates cycloboration. However, to the best of our knowledge MR-TADF compounds containing nitrogen chelated to boron are still unknown. Reported herein is a new class of tetracoordinate boron-containing MR-TADF emitters bearing C^N^C- and N^N^N-chelating ligands. We demonstrate that the replacement of the B–C covalent bond in the C^N^C-chelating ligand by the B–N covalent bond affords an isomer, which dramatically influences the optoelectronic properties of the molecule. The resulting N^N^N-chelating compounds show bathochromically shifted absorption and emission spectra relative to C^N^C-chelating compounds. The incorporation of a tert-butylcarbazole group at the 4-position of the pyridine significantly enhances both the thermal stability and the reverse intersystem crossing rate, yet has a negligible effect on emission properties. Consequently, high-performance hyperfluorescent organic light-emitting diodes (HF-OLEDs) that utilize these molecules as green and yellow-green emitters show a maximum external quantum efficiency (ηext) of 11.5% and 25.1%, and a suppressed efficiency roll-off with an ηext of 10.2% and 18.7% at a luminance of 1000 cd m−2, respectively.

A new class of tetra-coordinate boron-containing MR-TADF emitters and their corresponding high-performance hyperfluorescent organic light-emitting diodes have been successfully achieved.  相似文献   

9.
The occurrence of planar hexacoordination is very rare in main group elements. We report here a class of clusters containing a planar hexacoordinate silicon (phSi) atom with the formula SiSb3M3+ (M = Ca, Sr, Ba), which have D3h (1A1′) symmetry in their global minimum structure. The unique ability of heavier alkaline-earth atoms to use their vacant d atomic orbitals in bonding effectively stabilizes the peripheral ring and is responsible for covalent interaction with the Si center. Although the interaction between Si and Sb is significantly stronger than the Si–M one, sizable stabilization energies (−27.4 to −35.4 kcal mol−1) also originated from the combined electrostatic and covalent attraction between Si and M centers. The lighter homologues, SiE3M3+ (E = N, P, As; M = Ca, Sr, Ba) clusters, also possess similar D3h symmetric structures as the global minima. However, the repulsive electrostatic interaction between Si and M dominates over covalent attraction making the Si–M contacts repulsive in nature. Most interestingly, the planarity of the phSi core and the attractive nature of all the six contacts of phSi are maintained in N-heterocyclic carbene (NHC) and benzene (Bz) bound SiSb3M3(NHC)6+ and SiSb3M3(Bz)6+ (M = Ca, Sr, Ba) complexes. Therefore, bare and ligand-protected SiSb3M3+ clusters are suitable candidates for gas-phase detection and large-scale synthesis, respectively.

The global minimum of SiSb3M3+ (M = Ca, Sr, Ba) is a D3h symmetric structure containing an elusive planar hexacoordinate silicon (phSi) atom. Most importantly, the phSi core remains intact in ligand protected environment as well.

Exploring the bonding capacity of main-group elements (such as carbon or silicon) beyond the traditional tetrahedral concept has been a fascinating subject in chemistry for five decades. The 1970 pioneering work of Hoffmann and coworkers1 initiated the field of planar tetracoordinate carbons (ptCs), or more generally, planar hypercoordinate carbons. The past 50 years have witnessed the design and characterization of an array of ptC and planar pentacoordinate carbon (ppC) species.2–14 However, it turned out to be rather challenging to go beyond ptC and ppC systems. The celebrated CB62− cluster and relevant species15,16 were merely model systems because C avoids planar hypercoordination in such systems.17,18 In 2012, the first genuine global minimum D3h CO3Li3+ cluster was reported to have six interactions with carbon in planar form, although electrostatic repulsion between positively charged phC and Li centers and the absence of any significant orbital interaction between them make this hexacoordinate assignment questionable.19 It was only very recently that a series of planar hexacoordinate carbon (phC) species, CE3M3+ (E = S–Te; M = Li–Cs), were designed computationally by the groups of Tiznado and Merino (Fig. 1; left panel),20 in which there exist pure electrostatic interactions between the negative Cδ− center and positive Mδ+ ligands. These phC clusters were achieved following the so-called “proper polarization of ligand” strategy.Open in a separate windowFig. 1The pictorial depiction of previously reported phC CE3M3+ (E = S–Te; M = Li–Cs) clusters and the present SiE3M3+ (E = S–Te and N–Sb; M = Li–Cs and Ca–Ba) clusters. Herein the solid and dashed lines represent covalent and ionic bonding, respectively. The opposite double arrows illustrate electrostatic repulsion.The concept of planar hypercoordinate carbons has been naturally extended to their next heavier congener, silicon-based systems. Although the steric repulsion between ligands decreases due to the larger size, the strength of π- and σ-bonding between the central atom and peripheral ligands dramatically decreases, which is crucial for stability. Planar tetracoordinate silicon (ptSi) was first experimentally observed in a pentaatomic C2v SiAl4 cluster by Wang and coworkers in 2000.21 Very recently, this topic got a huge boost by the room-temperature, large-scale syntheses of complexes containing a ptSi unit.22 A recent computational study also predicted the global minimum of SiMg4Y (Y = In, Tl) and SiMg3In2 to have unprecendented planar pentacoordinate Si (ppSi) units.23 Planar hexacoordinate Si (phSi) systems seem to be even more difficult to stabilize. Previously, a C2v symmetric Cu6H6Si cluster was predicted as the true minimum,24 albeit its potential energy surface was not fully explored. A kinetically viable phSi SiAl3Mg3H2+ cluster cation was also predicted.25 However, these phSi systems24,25 are only local minima and not likely to be observed experimentally. In 2018, the group of Chen identified the Ca4Si22− building block containing a ppSi center and constructed an infinite CaSi monolayer, which is essentially a two-dimensional lattice of the Ca4Si2 motif.26 Thus, it is still an open question to achieve a phSi atom to date.Herein we have tried to find the correct combination towards a phSi system as the most stable isomer. Gratifyingly, we found a series of clusters, SiE3M3+ (E = N, P, As, Sb; M = Ca, Sr, Ba), having planar D3h symmetry with Si at the center of the six membered ring, as true global minimum forms. Si–E bonds are very strong in all the clusters, and alkaline-earth metals interact with the Si center by employing their d orbitals. However, electrostatic repulsion originated from the positively charged Si and M centers for E = N, P, and As dominates over attractive covalent interaction, making individual Si–M contacts repulsive in nature. This makes the assignment of SiE3M3+ (E = N, P, As; M = Ca, Sr, Ba) as genuine phSi somewhat skeptical. SiSb3M3+ (M = Ca, Sr, Ba) clusters are the sole candidates which possess genuine phSi centers as both electrostatic and covalent interactions in Si–M bonds are attractive. The d orbitals of M ligands play a crucial role in stabilizing the ligand framework and forming covalent bonds with phSi. Such planar hypercoordinate atoms are, in general, susceptible to external perturbations. However, the present title clusters maintain the planarity and the attractive nature of the bonds even after multiple ligand binding at M centers in SiSb3M3(NHC)6+ and SiSb3M3(Bz)6+. This would open the door for large-scale synthesis of phSi as well.Two major computational efforts were made before reaching our title phSi clusters. The first one is to examine SiE3M3+ (E = S–Po; M = Li–Cs) clusters, which adopt D3h or C3v structures as true minima (see Table S1 in ESI), being isoelectronic to the previous phC CE3M3+ (E = S–Po; M = Li–Cs) clusters. In the SiE3M3+ (E = S–Po; M = Li–Cs) clusters, the Si center always carries a positive charge ranging from 0.01 to +1.03|e|, in contrast to the corresponding phC species (see Fig. 1). Thus, electrostatic interactions between the Siδ+ and Mδ+ centers would be repulsive (Fig. 1). Given that the possibility of covalent interaction with an alkali metal is minimal, it would be a matter of debate whether they could be called true coordination. A second effort is to tune the electronegativity difference between Si and M centers so that the covalent contribution in Si–M bonding becomes substantial. Along this line, we consider the combinations of SiE3M3+ (E = N, P, As, Sb; M = Be, Mg, Ca, Sr, Ba). The results in Fig. S1 show that for E = Be and Mg, the phSi geometry has a large out-of-plane imaginary frequency mode, which indicates a size mismatch between the Si center and peripheral E3M3 (E = N–Bi; M = Be, Mg) ring. On the other hand, the use of larger M = Ca, Sr, Ba atoms effectively expands the size of the cavity and eventually leads to perfect planar geometry with Si atoms at the center as minima. In the case of SiBi3M3+, the planar isomer possesses a small imaginary frequency for M = Ca. Although planar SiBi3Sr3+ and SiBi3Ba3+ are true minima, they are 2.2 and 2.5 kcal mol−1 higher in energy than the lowest energy isomer, respectively (Fig. S2). Fig. 2 displays some selected low-lying isomers of SiE3M3+ (E = N, P, As, Sb; M = Ca, Sr, Ba) clusters (see Fig. S3–S6 for additional isomers). The global minimum structure is a D3h symmetric phSi with an 1A1′ electronic state for all the twelve cases. The second lowest energy isomer, a ppSi, is located more than 49 kcal mol−1 above phSi for E = N. This relative energy between the most stable and nearest energy isomer gradually decreases upon moving from N to Sb. In the case of SiSb3M3+ clusters, the second-lowest energy isomer is 4.6–6.1 kcal mol−1 higher in energy than phSi. The nearest triplet state isomer is very high in energy (by 36–53 kcal mol−1, Fig. S3–S6) with respect to the global minimum.Open in a separate windowFig. 2The structures of low-lying isomers of SiE3M3+ (E = N, P, As, Sb; M = Ca, Sr, Ba) clusters. Relative energies (in kcal mol−1) are shown at the single-point CCSD(T)/def2-TZVP//PBE0/def2-TZVP level, followed by a zero-energy correction at PBE0. The values from left to right refer to Ca, Sr, and Ba in sequence. The group symmetries and electronic states are also given.Born–Oppenheimer molecular dynamics (BOMD) simulations at room temperature (298 K), taking SiE3Ca3+ clusters as case studies, were also performed. The results are displayed in Fig. S7. All trajectories show no isomerization or other structural alterations during the simulation time, as indicated by the small root mean square deviation (RMSD) values. The BOMD data suggest that the global minimum also has reasonable kinetic stability against isomerization and decomposition.The bond distances, natural atomic charges, and bond indices for SiE3Ca3+ clusters are given in for M = Sr, Ba). The Si–E bond distances are shorter than the typical Si–E single bond distance computed using the self-consistent covalent radii proposed by Pyykkö.27 In contrast, the Si–M bond distance is almost equal to the single bond distance. This gives the first hint of the presence of covalent bonding therein. However, the Wiberg bond indices (WBIs) for the Si–M links are surprisingly low (0.02–0.04). We then checked the Mayer bond order (MBO), which can be seen as a generalization of WBIs and is more acceptable since the approach of WBI calculations assumes orthonormal conditions of basis functions while the MBO considers an overlap matrix. The MBO values for the Si–M links are now sizable (0.13–0.18). These values are reasonable considering the large difference in electronegativity between Si and M, and, therefore, only a very polar bond is expected between them. In fact, the calculations of WBIs after orthogonalization of basis functions by the Löwdin method gives significantly large bond orders (0.48–0.55), which is known to overestimate the bond orders somewhat. The above results indicate that the presence of covalent bonding cannot be ruled out only by looking at WBI values.Bond distances (r, in Å), different bond orders (WBIs) {MBOs} [WBI in orthogonalized basis], and natural atomic charges (q, in |e|) of SiE3Ca3+ (E = N, P, As, Sb) clusters at the PBE0/def2-TZVP level
r Si–E r Si–Ca r E–Ca q Si q E q Ca
E = N1.6692.5552.2461.57−1.931.74
(1.14) {1.23} [1.84](0.02) {0.13} [0.51](0.22) {0.67} [0.84]
E = P2.1802.9352.6400.25−1.421.67
(1.34) {1.11} [1.52](0.03) {0.14} [0.54](0.27) {0.74} [1.05]
E = As2.3013.0042.7210.07−1.341.65
(1.33) {1.10} [1.45](0.03) {0.15} [0.55](0.29) {0.71} [1.12]
E = Sb2.5383.1552.896−0.39−1.161.62
(1.29) {1.01} [1.33](0.04) {0.18} [0.48](0.30) {0.78} [1.14]
Open in a separate windowOur following argument regarding the presence of covalent Si–M bonding is based on energy decomposition analysis (EDA) in combination with natural orbital for chemical valence (NOCV) theory. We first performed EDA by taking Ca and SiE3Ca2 in different charge and electronic states as interacting fragments to get the optimum fragmentation scheme that suits the best to describe the bonding situation (see Tables S6–S9). The size of orbital interaction (ΔEorb) is used as a probe.28 For all cases, Ca+ (D, 4s1) and SiE3Ca2 (D) in their doublet spin states turn out to be the best schemes, which give the lowest ΔEorb value.
Energy termInteractionCa+ (D, 4s1) + SiN3Ca2 (D)Ca+ (D, 4s1) + SiP3Ca2 (D)Ca+ (D, 4s1) + SiAs3Ca2 (D)Ca+ (D, 4s1) + SiSb3Ca2 (D)
ΔEint−192.9−153.0−144.9−129.9
ΔEPauli139.8115.2115.7110.9
ΔEelstata−162.0 (48.7%)−116.4 (43.4%)−113.0 (43.4%)−100.9 (41.9%)
ΔEorba−170.7 (51.3%)−151.8 (56.6%)−147.6 (56.6%)−140.0 (58.1%)
ΔEorb(1)bSiE3Ca2–Ca+(s) electron-sharing σ-bond−89.2 (52.3%)−79.4 (52.3%)−74.3 (50.3%)−66.9 (47.8%)
ΔEorb(2)bSiE3Ca2 → Ca+(d) π‖-donation−32.9 (19.3%)−32.0 (21.1%)−31.8 (21.5%)−30.8 (22.0%)
ΔEorb(3)bSiE3Ca2 → Ca+(d) σ-donation−13.1 (7.7%)−11.9 (7.8%)−12.0 (8.1%)−11.9 (8.5%)
ΔEorb(4)bSiE3Ca2 → Ca+(d) π-donation−12.3 (7.2%)−12.2 (8.0%)−12.5 (8.5%)−12.5 (8.9%)
ΔEorb(5)bSiE3Ca2 → Ca+(d) δ-donation−8.1 (4.7%)−9.9 (6.5%)−10.9 (7.4%)−11.8 (8.4%)
ΔEorb(rest)b−15.1 (8.8%)−6.4 (4.2%)−6.1 (4.1%)−6.1 (4.4%)
Open in a separate windowaThe values in parentheses are the percentage contributions to total attractive interactions (ΔEelstat + ΔEorb).bThe values in parentheses are the percentage contributions to the total orbital interaction ΔEorb.The decomposition of ΔEorb into pair-wise orbital interaction ΔEorb(n) in Fig. 3) helps us to identify the Si–Ca covalent bond and the orbitals involved in the pairwise interactions. The s orbital of Ca+ takes part in the electron-sharing σ-bond formation with SiE3Ca2, whereas vacant d AOs of Ca+ act as acceptor orbitals in the dative interactions, ΔEorb(2)–(5). Therefore, d AOs of Ca+ are responsible for 39–48% of the total orbital interaction. The present results further strengthen the proposal29–33 that heavier alkaline-earth elements (Ca, Sr, and Ba) should be classified as transition metals rather than main-group elements. Furthermore, a careful look at the Δρ(n) plots shows that in ΔEorb(1) and ΔEorb(2) only peripheral atoms are involved, but in ΔEorb(3)–(5) there is direct covalent interaction between Si and Ca centers. To correlate with the molecular orbitals (MOs) of the SiE3Ca3+ cluster, the related MOs for 24 valence electrons are given in Fig. S8. Δρ(3)–(5) can be correlated with HOMO-4, the HOMO and the HOMO′, respectively. Therefore, although the MO coefficient of Ca centers is small, they should not be neglected as the energy stabilization coming from them is significant. Si and M centers are only connected through delocalized bonds which is the reason for not having any gradient path between them as is indicated in the electron density analysis. Instead, there is a ring critical point at the center of the SiE2M ring (see Fig. S9). The results of adaptive natural density partitioning (AdNDP) analysis also corroborate this, where M centers are connected with the Si center through 7c–2e π-bonds (see Fig. S10).Open in a separate windowFig. 3Plot of the deformation densities, Δρ(1)–(5) corresponding to ΔEorb(1)–(5) and the related interacting orbitals of the fragments in the SiN3Ca3+ cluster at the PBE0/TZ2P-ZORA//PBE0/def2-TZVP level. The orbital energy values are in kcal mol−1. The charge flow of the deformation densities is from red to blue. The isovalue for Δρ(1) is 0.001 au and for the rest is 0.0005 au.Another aspect is to check the nature of electrostatic interaction between Si and M. The natural charges in ). Thus, the SiSb3M3+ cluster presents a case in which covalent bonding is robust and ionic interaction between Si and M centers is attractive in nature. If we look at the inter-atomic interaction energies (VTotal) for Si–M bonds and M–E bonds, it can be understood that the repulsive energy in Si–M bonds is largely overcompensated by two M–E bonds, even for E = N. This is the reason why electrostatic repulsion between Si and M centers does not result in a very large Si–M bond distance. Nevertheless, repulsive Si–M contacts in SiE3M3+ (E = N, P, As) make hexacoordination assignment skeptical. SiSb3M3+ clusters should be considered to possess phSi convincingly. Note that the IUPAC definition of coordination number only demands “the number of other atoms directly linked to that specified atom”,34 but does not say about the overall nature of interaction between them. In SiSb3M3+, phSi is linked to three Sb atoms through strong covalent bonds and is bound to three M atoms through ionic interaction in combination with a weaker covalent interaction. These clusters are only weakly aromatic because of such polar electronic distribution (see Fig. S11).The next challenge is to protect the reactive centers of phSi clusters with bulky ligands, which is required for large scale synthesis. This is not an easy task since slight external perturbation of most of the planar hypercoordinate atom species could result in a loss in planarity. Few years ago, the groups of Ding and Merino35 reported CAl4MX2 (M = Zr, Hf; X = F–I, C5H5) where ppC is sandwiched and protected by a metallocene framework. Therefore, the presence of X groups is mandatory to provide the electronic stabilization in ppC. In the present cases, surprisingly, SiSb3M3+ clusters are found to maintain the planarity around hexagons even after the coordination of M centers with six N-heterocyclic carbene (NHC) and benzene (Bz) ligands forming SiSb3M3(NHC)6+ and SiSb3M3(Bz)6+ (M = Ca, Sr, Ba) complexes, respectively (see Fig. 4). These complexes are highly stable against ligand dissociation as reflected by the high bond dissociation energy (De = 236.1 (Ca), 203.9 (Sr) and 171.3 (Ba) kcal mol−1) for SiSb3M3(NHC)6+ → SiSb3M3+ + 6NHC and De = 153.8 (Ca), 128.0 (Sr) and 114.0 (Ba) kcal mol−1 for SiSb3M3(Bz)6+ → SiSb3M3+ + 6Bz. The Si–M bond distances are slightly elongated because of coordination with the ligands. But the results of IQA given in Table S13 show that Si–M bonds have attractive interaction energies ranging between −20.0 and −32.4 kcal mol−1. Therefore, the planarity of the phSi core and the attractive nature of all the six contacts of phSi are maintained in ligand-bound SiSb3M3(NHC)6+ and SiSb3M3(Bz)6+ (M = Ca, Sr, Ba) complexes.Open in a separate windowFig. 4The minimum energy geometries of SiSb3M3(NHC)6+ and SiSb3M3(Bz)6+ (M = Ca, Sr, Ba) complexes at the PBE0-D3(BJ)/def2-TZVP level.In summary, we have theoretically achieved the first series of planar hexacoordinate silicon (phSi) clusters, SiSb3M3+ (M = Ca, Sr, Ba), by exploring their potential energy surfaces. These phSi systems are both thermodynamically and kinetically stable. The global minimum structures of SiE3M3+ (E = N, P, As, Sb) clusters have a D3h symmetry with the 1A1′ electronic state. The ability of the heavier alkaline-earth metals (Ca–Ba) to utilize their d orbitals in chemical bonding is a key factor that underlies the stability of these systems. The Ca–Ba ligands form weak covalent bonding with Si centers through their d orbitals, mimicking transition metals. The electronic charge distribution and IQA analysis show that electrostatic interaction in the Si–Ca links is essentially repulsive in SiN3M3+, but it sharply reduces with the decrease in electronegativity of E. Eventually, a sizable electrostatic attractive interaction exists between Si and M centers in SiSb3M3+, leading to a truly unprecedented phSi bonding motif that is held together by both covalent bonding and attractive ionic interaction. For SiE3M3+ (E = N, P, As) clusters, the electrostatic repulsion between Si and M dominates over covalent interaction, making Si–M contacts repulsive in nature. Most interestingly, the planarity of the phSi core and the attractive nature of all the six contacts of phSi are maintained in N-heterocyclic carbene (NHC) and benzene (Bz) bound SiSb3M3(NHC)6+ and SiSb3M3(Bz)6+ (M = Ca, Sr, Ba) complexes. Therefore, such clusters protected by bulky ligands would be suitable candidates for large scale synthesis in the presence of bulky counter-ions. Recent experimental reports on ptSi systems have already stimulated much curiosity within the community, and the present results would undoubtedly act as a stimulus to it.  相似文献   

10.
Preparation of Mixed Bis-N-Heterocyclic Carbene Rhodium(I) Complexes     
Ramn Azpíroz  Mert Olgun Karata  Vincenzo Passarelli  Ismail zdemir  Jesús J. Prez-Torrente  Ricardo Castarlenas 《Molecules (Basel, Switzerland)》2022,27(20)
A series of mixed bis-NHC rhodium(I) complexes of type RhCl(η2-olefin)(NHC)(NHC’) have been synthesized by a stepwise reaction of [Rh(μ-Cl)(η2-olefin)2]2 with two different NHCs (NHC = N-heterocyclic carbene), in which the steric hindrance of both NHC ligands and the η2-olefin is critical. Similarly, new mixed coumarin-functionalized bis-NHC rhodium complexes have been prepared by a reaction of mono NHC complexes of type RhCl(NHC-coumarin)(η22-cod) with the corresponding azolium salt in the presence of an external base. Both synthetic procedures proceed selectively and allow the preparation of mixed bis-NHC rhodium complexes in good yields.  相似文献   

11.
Carbazolylgold(iii) complexes with thermally activated delayed fluorescence switched on by ligand manipulation as high efficiency organic light-emitting devices with small efficiency roll-offs     
Chun-Yin Wong  Man-Chung Tang  Lok-Kwan Li  Ming-Yi Leung  Wai-Kit Tang  Shiu-Lun Lai  Wai-Lung Cheung  Maggie Ng  Mei-Yee Chan  Vivian Wing-Wah Yam 《Chemical science》2022,13(34):10129
A series of carbazolyl ligands has been designed and synthesized through the integration of various electron-donating and electron-accepting motifs, including electron-donating 4-(diphenylamino)aryl and electron-accepting cyano and diphenylphosphine oxide moieties, for the development of a new class of gold(iii) complexes, where the energies of their triplet intraligand and ligand-to-ligand charge transfer excited states can be manipulated for the activation of thermally activated delayed fluorescence (TADF). Upon excitation, these complexes show high photoluminescence quantum yields of up to 80% in solid-state thin films, with short excited state lifetimes down to 1 μs. Vacuum-deposited and solution-processed organic light-emitting devices based on these complexes demonstrate promising electroluminescence (EL) performance with maximum external quantum efficiencies of 15.0% and 11.7%, respectively, and notably small efficiency roll-off values of less than 1% at the practical luminance brightness level of 1000 cd m−2. These distinct EL performances are believed to be due to the occurrence of multichannel radiative decay pathways via both phosphorescence and TADF that significantly shorten the emission lifetimes and hence reduce the occurrence of the detrimental triplet–triplet annihilation in the gold(iii) complexes.

Switch on of TADF can be achieved by tuning the excited state energy levels via ligand manipulation of the carbazolylgold(iii) C^C^N complexes. The resulting OLEDs show maximum EQEs of over 11% and efficiency roll-offs of down to less than 1%.  相似文献   

12.
Synthesis, characteristics and photoluminescent properties of novel Ir-Eu heteronuclear complexes containing 2-carboxyl-pyrimidine as a bridging ligand     
Lian P  Wei H  Zheng C  Nie Y  Bian J  Bian Z  Huang C 《Dalton transactions (Cambridge, England : 2003)》2011,40(20):5476-5482
Two novel iridium(III) complexes, [Ir(dfppy)(2)(pmc)] and [Ir(ppy)(2)(pmc)] (dfppy = 2-(4',6'-difluoro-phenyl)pyridine, ppy = 1-phenyl-pyridine), were designed and synthesized using 2-carboxyl-pyrimidine (Hpmc) as an ancillary ligand. Single crystals were obtained and characterized by single crystal X-ray diffraction. The tetrametallic complexes {[(C^N)(2)Ir(μ-pmc)](3)EuCl(3)} (C^N = dfppy, ppy) were synthesized using the iridium(III) complexes as "ligands". Photophysical and theoretical studies indicate that [Ir(dfppy)(2)(pmc)] is more suitable for sensitizing the emission of Eu(III) ions than [Ir(ppy)(2)(pmc)].  相似文献   

13.
Molecular design of efficient yellow- to red-emissive alkynylgold(iii) complexes for the realization of thermally activated delayed fluorescence (TADF) and their applications in solution-processed organic light-emitting devices     
Cathay Chai Au-Yeung  Lok-Kwan Li  Man-Chung Tang  Shiu-Lun Lai  Wai-Lung Cheung  Maggie Ng  Mei-Yee Chan  Vivian Wing-Wah Yam 《Chemical science》2021,12(27):9516
Here, we report the design and synthesis of a new class of fused heterocyclic alkynyl ligand-containing gold(iii) complexes, which show tunable emission colors spanning from the yellow to red region in the solid state and exhibit thermally activated delayed fluorescence (TADF) properties. These complexes display high photoluminescence quantum yields of up to 0.87 and short excited-state lifetimes in sub-microsecond timescales, yielding high radiative decay rate constants on the order of up to 106 s−1. The observation of the drastic enhancement in the emission intensity of the complexes with insignificant change in the excited-state lifetime upon increasing the temperature from 200 to 360 K indicates an increasing radiative decay rate. The experimentally estimated energy splitting between the lowest-lying singlet excited state (S1) and the lowest-lying triplet excited state (T1), ΔES1–T1, is found to be as small as ∼0.03 eV (250 cm−1), comparable to the value of ∼0.05 eV (435 cm−1) obtained from computational studies. The delicate choice of the cyclometalating ligand and the fused heterocyclic ligand is deemed the key to induce TADF through the control of the energy levels of the intraligand and the ligand-to-ligand charge transfer excited states. This work represents the realization of highly emissive yellow- to red-emitting gold(iii) TADF complexes incorporated with fused heterocyclic alkynyl ligands and their applications in organic light-emitting devices.

We report the design of a new class of fused heterocyclic alkynyl ligand-containing gold(iii) complexes, which shows tunable emission colors spanning yellow to red region and exhibits thermally activated delayed fluorescence (TADF) properties.  相似文献   

14.
Discovery of phosphotyrosine-binding oligopeptides with supramolecular target selectivity     
Ana S. Pina  Leonor Morgado  Krystyna L. Duncan  Sara Carvalho  Henrique F. Carvalho  Armnio J. M. Barbosa  Beatriz de P. Mariz  Inês P. Moreira  Daniela Kalafatovic  Bruno M. Morais Faustino  Vishal Narang  Tong Wang  Charalampos G. Pappas  Isabel Ferreira  A. Cecília A. Roque  Rein V. Ulijn 《Chemical science》2021,13(1):210
We demonstrate phage-display screening on self-assembled ligands that enables the identification of oligopeptides that selectively bind dynamic supramolecular targets over their unassembled counterparts. The concept is demonstrated through panning of a phage-display oligopeptide library against supramolecular tyrosine-phosphate ligands using 9-fluorenylmethoxycarbonyl-phenylalanine-tyrosine-phosphate (Fmoc-FpY) micellar aggregates as targets. The 14 selected peptides showed no sequence consensus but were enriched in cationic and proline residues. The lead peptide, KVYFSIPWRVPM-NH2 (P7) was found to bind to the Fmoc-FpY ligand exclusively in its self-assembled state with KD = 74 ± 3 μM. Circular dichroism, NMR and molecular dynamics simulations revealed that the peptide interacts with Fmoc-FpY through the KVYF terminus and this binding event disrupts the assembled structure. In absence of the target micellar aggregate, P7 was further found to dynamically alternate between multiple conformations, with a preferred hairpin-like conformation that was shown to contribute to supramolecular ligand binding. Three identified phages presented appreciable binding, and two showed to catalyze the hydrolysis of a model para-nitro phenol phosphate substrate, with P7 demonstrating conformation-dependent activity with a modest kcat/KM = 4 ± 0.3 × 10−4 M−1 s−1.

Phage-display screening on self-assembled tyrosine-phosphate ligands enables the identification of oligopeptides selective to dynamic supramolecular targets, with the lead peptide showing a preferred hairpin-like conformation and catalytic activity.  相似文献   

15.
Multicolor Emissive Phosphorescent Iridium(III) Complexes Containing L-Alanine Ligands: Photophysical and Electrochemical Properties,DFT Calculations,and Selective Recognition of Cu(II) Ions     
Xi Chu  Yichuan Huang  Wenhao Li  Shisheng Zhao  Hongyan Li  Aidang Lu 《Molecules (Basel, Switzerland)》2022,27(23)
Three novel Ir(III) complexes, (ppy)2Ir(L-alanine) (Ir1) (ppy = 2-phenylpyridine), (F4ppy)2Ir(L-alanine) (Ir2) (F4ppy = 2-(4-fluorophenyl)pyridine), and (F2,4,5ppy)2Ir(L-alanine) (Ir3) (F2,4,5ppy = 2-(2,4,5-trifluorophenyl)pyridine), based on simple L-alanine as ancillary ligands were synthesized and investigated. Due to the introduction of fluorine substituents on the cyclometalated ligands, complexes Ir1–Ir3 exhibited yellow to sky-blue emissions (λem = 464–509 nm) in acetonitrile solution. The photoluminescence quantum yields (PLQYs) of Ir1–Ir3 ranged from 0.48–0.69, of which Ir3 with sky-blue luminescence had the highest PLQY of 0.69. The electrochemical study and density functional theory (DFT) calculations show that the highest occupied molecular orbital (HOMOs) energy of Ir1–Ir3 are stabilized by the introduction of fluorine substituents on the cyclometalated ligands, while L-alanine ancillary ligand has little contribution to HOMOs and lowest unoccupied molecular orbitals (LUMOs). Moreover, Ir1–Ir3 presented an excellent response to Cu2+ with a high selectivity, strong anti-interference ability, and short response time. Such a detection was based on significant phosphorescence quenching of their emissions, showing the potential application in chemosensors for Cu2+.  相似文献   

16.
Near-infrared electroluminescence beyond 940 nm in Pt(N^C^N)X complexes: influencing aggregation with the ancillary ligand X     
Rebecca J. Salthouse  Piotr Pander  Dmitry S. Yufit  Fernando B. Dias  J. A. Gareth Williams 《Chemical science》2022,13(45):13600
We present a study of aggregate excited states formed by complexes of the type Pt(N^C^N)X, where N^C^N represents a tridentate cyclometallating ligand, and X = SCN or I. These materials display near-infrared (NIR) photoluminescence in film and electroluminescence in NIR OLEDs with λmaxEL = 720–944 nm. We demonstrate that the use of X = SCN or I modulates aggregate formation compared to the parent complexes where X = Cl. While the identity of the monodentate ligand affects the energy of Pt–Pt excimers in solution in only a subtle way, it strongly influences aggregation in film. Detailed calculations on aggregates of different sizes support the experimental conclusions from steady-state and time-resolved luminescence studies at variable temperatures. The use of X = I appears to limit aggregation to the formation of dimers, while X = SCN promotes the formation of larger aggregates, such as tetramers and pentamers, leading in turn to NIR photo- and electroluminescence > 850 nm. A possible explanation for the contrasting influence of the monodentate ligands is the lesser steric hindrance associated with the SCN group compared to the bulkier I ligand. By exploiting the propensity of the SCN complexes to form extended aggregates, we have prepared an NIR-emitting OLED that shows very long wavelength electroluminescence, with λmaxEL = 944 nm and a maximum EQE = 0.3 ± 0.1%. Such data appear to be unprecedented for a device relying on a Pt(ii) complex aggregate as the emitter.

The ancillary ligand X strongly influences the aggregates formed by complexes of the type Pt(N^C^N)X. X = I leads to a 4× increase in film PLQY and OLED EQE vs. X = Cl, while X = SCN yields very long wavelength electroluminescence, λmaxEL = 944 nm.  相似文献   

17.
Construction of Two Stable Co(II)-Based Hydrogen-Bonded Organic Frameworks as a Luminescent Probe for Recognition of Fe3+ and Cr2O72− in H2O     
Qi-Ying Weng  Ya-Li Zhao  Jia-Ming Li  Miao Ouyang 《Molecules (Basel, Switzerland)》2021,26(19)
A pair of cobalt(II)-based hydrogen-bonded organic frameworks (HOFs), [Co(pca)2(bmimb)]n (1) and [Co2(pca)4(bimb)2] (2), where Hpca = p-chlorobenzoic acid, bmimb = 1,3-bis((2-methylimidazol-1-yl)methyl)benzene, and bimb = 1,4-bis(imidazol-1-ylmethyl)benzene were hydrothermally synthesized and characterized through infrared spectroscopy (IR), elemental and thermal analysis (EA), power X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD) analyses. X-ray diffraction structural analysis revealed that 1 has a one-dimensional (1D) infinite chain network through the deprotonated pca monodentate chelation and with a μ2-bmimb bridge Co(II) atom, and 2 is a binuclear Co(II) complex construction with a pair of symmetry-related pca and bimb ligands. For both 1 and 2, each cobalt atom has four coordinated twisted tetrahedral configurations with a N2O2 donor set. Then, 1 and 2 are further extended into three-dimensional (3D) or two-dimensional (2D) hydrogen-bonded organic frameworks through C–H···Cl interactions. Topologically, HOFs 1 and 2 can be simplified as a 4-connected qtz topology with a Schläfli symbol {64·82} and a 4-connected sql topology with a Schläfli symbol {44·62}, respectively. The fluorescent sensing application of 1 was investigated; 1 exhibits high sensitivity recognition for Fe3+ (Ksv: 10970 M−1 and detection limit: 19 μM) and Cr2O72− (Ksv: 12960 M−1 and detection limit: 20 μM). This work provides a feasible detection platform of HOFs for highly sensitive discrimination of Fe3+ and Cr2O72− in aqueous media.  相似文献   

18.
Isolation of the elusive bisbenzimidazole Bbim3−˙ radical anion and its employment in a metal complex     
Florian Benner  Selvan Demir 《Chemical science》2022,13(20):5818
The discovery of singular organic radical ligands is a formidable challenge due to high reactivity arising from the unpaired electron. Matching radical ligands with metal ions to engender magnetic coupling is crucial for eliciting preeminent physical properties such as conductivity and magnetism that are crucial for future technologies. The metal-radical approach is especially important for the lanthanide ions exhibiting deeply buried 4f-orbitals. The radicals must possess a high spin density on the donor atoms to promote strong coupling. Combining diamagnetic 89Y (I = 1/2) with organic radicals allows for invaluable insight into the electronic structure and spin-density distribution. This approach is hitherto underutilized, possibly owing to the challenging synthesis and purification of such molecules. Herein, evidence of an unprecedented bisbenzimidazole radical anion (Bbim3−˙) along with its metalation in the form of an yttrium complex, [K(crypt-222)][(Cp*2Y)2(μ-Bbim˙)] is provided. Access of Bbim3−˙ was feasible through double-coordination to the Lewis acidic metal ion and subsequent one-electron reduction, which is remarkable as Bbim2− was explicitly stated to be redox-inactive in closed-shell complexes. Two molecules containing Bbim2− (1) and Bbim3−˙ (2), respectively, were thoroughly investigated by X-ray crystallography, NMR and UV/Vis spectroscopy. Electrochemical studies unfolded a quasi-reversible feature and emphasize the role of the metal centre for the Bbim redox-activity as neither the free ligand nor the Bbim2− complex led to analogous CV results. Excitingly, a strong delocalization of the electron density through the Bbim3−˙ ligand was revealed via temperature-dependent EPR spectroscopy and confirmed through DFT calculations and magnetometry, rendering Bbim3−˙ an ideal candidate for single-molecule magnet design.

The long sought-after bisbenzimidazole radical was isolated through complexation to two rare earth metallocenes followed by reduction, and analysed through crystallography, VT EPR spectroscopy, electrochemistry, magnetometry, and DFT computations.  相似文献   

19.
Synthesis, characterization and antitumor activity study of some cyclometalated organoplatinum(II) complexes containing aromatic N-donor ligands     
Ahmadreza Esmaeilbeig  Hamidreza Samouei  Zahra Amirghofran 《Journal of organometallic chemistry》2011,696(20):3135-3142
A general approach has been designed to synthesize some mononuclear and binuclear cyclometalated platinum(II) complexes, containing aromatic N-donor ligands with the presence of one Cltrans to carbon. In this way, cyclometalated platinum(II) complex [Pt(C^N)Cl(dmso)], 1, C^N = N(1),C(2′)-chelated, deprotonated 2-phenylpyridine and dmso = dimethylsulfoxide, was used as a precursor to react with imidazole derivatives (1-methylimidazole, 2a, imidazole, 2b,), monodentate pyridine derivatives (4-methylpyridine, 2c, pyridine, 2d,) and bidentate pyridine derivative (4,4′-bipyridine, 3 and 4,). Synthesized complexes were fully characterized by using multinuclear NMR spectroscopy (1H, 13C{1H} and 195Pt), correlation NMR spectroscopy (1H-1H COSY, 13C{1H}-1H Heteronuclear Multiple Quantum Correlation, HMQC, Heteronuclear Multiple Bond Correlation, HMBC, 15N-1H HETCOR), elemental analysis, X-ray crystallography and ESI-Mass spectrometry. Antitumor effects of mononuclear cyclometalated platinum(II) complexes 2a, 2c, 2d and 3 were determined on Jurkat, K562, and Raji cell lines and results showed reasonable cytotoxicities.  相似文献   

20.
Uncovering an oxide ion substitution for the OH− + CH3F reaction     
Domonkos A. Tasi  Gbor Czak 《Chemical science》2021,12(43):14369
Theoretical investigations on chemical reactions allow us to understand the dynamics of the possible pathways and identify new unexpected routes. Here, we develop a global analytical potential energy surface (PES) for the OH + CH3F reaction in order to perform high-level dynamics simulations. Besides bimolecular nucleophilic substitution (SN2) and proton abstraction, our quasi-classical trajectory computations reveal a novel oxide ion substitution leading to the HF + CH3O products. This exothermic reaction pathway occurs via the CH3OH⋯F deep potential well of the SN2 product channel as a result of a proton abstraction from the hydroxyl group by the fluoride ion. The present detailed dynamics study of the OH + CH3F reaction focusing on the surprising oxide ion substitution demonstrates how incomplete our knowledge is of fundamental chemical reactions.

Reaction dynamics simulations on a high-level ab initio analytical potential energy surface reveal a novel oxide ion substitution channel for the OH + CH3F reaction.  相似文献   

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