Rigid Bidentate Ligands Research Articles

The synthesis and near-infrared photothermal conversion of organometallic interdigitated complex and “U” type macrocycles

Herein, one interdigitated molecular and two metallarectangles were realized successfully using two rigid bidentate ligands (L1, L2) and two building blocks (E1, E2) via coordination-driven self-assembly strategy. Interestingly, a novel interdigitated structure has been successfully formed through triple π-π stacking interactions, different from the previously reported interlocked [2]catenanes. Based on the π-π stacking interaction, nonradiative transitions were promoted and obvious photothermal transitions effect was triggered in solution and solid states. In addition, it is found that the interdigitated structure has a decent photothermal conversion efficiency of about 12% in solution state. This study provides open up new ideas for our future development of near-infrared photothermal conversion materials.

Construction and in-cage modification of metal-organic polyhedra based on Anderson-like polyoxovanadate clusters

Two tetrahedral metal-organic polyhedra (MOPs) constructed from Anderson-like alkoxo-polyoxovanadate clusters, [NH2Me2]8{[V6O6(OCH3)9(SO4)]4(2,6-NDC)6}(MeOH)15(DMA)9 (1) and [NH2Me2]8{[V6O6(OCH3)9(C6H5PO3)]4(2,6-NDC)6}(MeOH)9(DMA)10 (2), were synthesized under solvothermal conditions. They are isomorphic tetrahedra composed of 3-connected [V6O6(OCH3)9(X)] SBUs and rigid bidentate ligand 2,6-naphthalenedicarboxylic acid (NDC). The difference between the two structures is modification of the inner cage in 2 by introduction of phenylphosphonic acid. The space inside the molecular cage was reduced from 1100 Å3 to 700 Å3 after introduction of phenylphosphonic acid, as calculated by the VIODOO program. Interestingly, the iodine adsorption performance of 2 was improved by more than three times compared to 1 after the introduction of phenylphosphonic acid. These findings may provide new insights into the modification and functionalization within the cage of MOPs.

Novel Lanthanide (III) Complexes Derived from an Imidazole–Biphenyl–Carboxylate Ligand: Synthesis, Structure and Luminescence Properties

A series of neutral mononuclear lanthanide complexes [Ln(HL)2(NO3)3] (Ln = La, Ce, Nd, Eu, Gd, Dy, Ho) with rigid bidentate ligand, HL (4′-(1H-imidazol-1-yl)biphenyl-4-carboxylic acid) were synthesized under solvothermal conditions. The coordination compounds have been characterized by infrared spectroscopy, thermogravimetry, powder X-ray diffraction and elemental analysis. According to X-ray diffraction, all the complexes are a series of isostructural compounds crystallized in the P2/n monoclinic space group. Additionally, solid-state luminescence measurements of all complexes show that [Eu(HL)2(NO3)3] complex displays the characteristic emission peaks of Eu(III) ion at 593, 597, 615, and 651 nm.

Rational Design and Synthesis of Interlocked [2]Catenanes Featuring Half‐Sandwich Cp*Rh/Ir Units and Pyrene‐Based Ligands†

Main observation and conclusionThe construction of interlocked topologies by metal‐cation‐template methods has been extensively explored. However, construction of these species using template‐free chemical self‐assembly methods is hard to rationally achieve due to the inherent unpredictability of self‐assembly processes. In this work, a strategy to construct interlocked [2]catenanes by coordination‐driven template‐free self‐assembly is demonstrated, whereby combining rigid bidentate ligands with large conjugated‐π area units and building blocks with appropriate lengths facilitated construction of interlocked [2]catenane compounds. Two rigid bidentate ligands, L1 and L2, were chosen to self‐assemble with three dinuclear building blocks B1, B2 and B3. Ultimately, the successful construction of three [2]catenanes demonstrated the validity of the strategy. Although [2]catenanes are the simplest of all interlocked topologies, this motif is the basis for constructing more intricate topologies. This successful strategy may therefore lead to construction of other, more intricate topologies in the future.

Synthesis, X‐ray Structures, and Photoluminescence of the Octahedral Cu4I4 Cluster with Bulky Bidentate Bis(phosphanyl)amine Ligand

The reaction of C10H7‐1‐N(PPh2)2 (1) with two equivalents of CuI in acetonitrile resulted in the formation of octahedron Cu4I4[1]2 complex (2). The crystal structure of 2 showed it adopted a rare octahedral arrangement. The rectangular Cu4 plane is μ4‐capped by two of the iodides and is placed in axial positions above and below the Cu4‐plane form an octahedron, whereas the other two iodides are bonded to two copper atoms in a μ2‐fashion. The luminescence of complex 2 arises from a triplet halide‐to‐ligand charge transfer (3XLCT) excited state and 3CC (Cu4I4 cluster‐centered) excited state are not involved in the luminescence by the rigid bidentate ligand 1 in spite of the short CuI–CuI bond length. Complex 2 was identified and characterized by multinuclear NMR (1H, 13C, 31P NMR) and IR spectroscopy. Crystal structure determinations of 1 and 2 were carried out.

Heteroleptic Chini-Type Platinum Clusters: Synthesis and Characterization of Bis-Phospine Derivatives of [Pt3n(CO)6n]2- (n = 2-4).

The reactions of [Pt3n(CO)6n]2- (n = 2-4) homoleptic Chini-type clusters with stoichiometric amounts of Ph2PCH2CH2PPh2 (dppe) result in the heteroleptic Chini-type clusters [Pt6(CO)10(dppe)]2-, [Pt9(CO)16(dppe)]2-, and [Pt12(CO)20(dppe)2]2-. Their formation is accompanied by slight amounts of neutral species such as Pt4(CO)4(dppe)2, Pt6(CO)6(dppe)3, and Pt(dppe)2. A similar behavior was observed with the chiral ligand R-Ph2PCH(Me)CH2PPh2 (R-dppp), and two isomers of [Pt9(CO)16(R-dppp)]2- were identified. All the new species were spectroscopically characterized by means of IR and 31P NMR, and their structures were determined by single-crystal X-ray diffraction. The results obtained are compared to those previously reported for monodentate phosphines, that is, PPh3, as well as more rigid bidentate ligands, that is, CH2═C(PPh2)2 (P^P), CH2(PPh2)2 (dppm), and o-C6H4(PPh2)2 (dppb). From a structural point of view, functionalization of anionic platinum Chini clusters preserves their triangular Pt3 units, whereas the overall trigonal prismatic structures present in the homoleptic clusters are readily deformed and transformed upon functionalization. Such transformations may be just local deformations, as found in [Pt9(CO)16(dppe)]2-, [Pt9(CO)16(R-dppp)]2-, [Pt12(CO)22(PPh3)2]2-, and [Pt9(CO)16(PPh3)2]2-; an inversion of the cage from trigonal prismatic to octahedral, as observed in [Pt6(CO)10(dppe)]2- and [Pt6(CO)10(PPh3)2]2-; the reciprocal rotation of two trigonal prismatic units with the loss of a Pt-Pt contact as found in [Pt12(CO)20(dppe)2]2-.

Self-assembly of Thiolato-Bridged Manganese(I)-Based Metallarectangles: One-pot Synthesis and Structural Characterization.

A new series of thiolato-bridged manganese(I)-based supramolecular rectangles have been achieved by three-precursor self-assembly of Mn2(CO)10, diaryl disulfides (RSSR), and linear ditopic azine ligands (L) [L = pyrazine (pz), 4,4'-bipyridine (bpy), and trans-1,2-bis(4-pyridyl)ethylene (bpe)] using a one-pot synthetic strategy. Oxidative addition of RSSR (diphenyl disulfide and p-tolyl disulfide) to manganese decacarbonyl in the presence of rigid bidentate ligands (L) afforded metallarectangles of the general formula [{(CO)3Mn(μ-SR)2Mn(CO)3}2(μ-L)2] (1-6). Compounds 1-6 were characterized using elemental analyses and NMR, IR, and UV-vis absorption spectroscopic techniques. The molecular structures of metallarectangles 1, 3, and 5 were elucidated by single-crystal X-ray diffraction methods. The guest binding ability of 3 and 5 has been investigated with two aromatic guests using electronic absorption and fluorescence emission spectroscopy, and the results revealed a strong binding interaction between host-guest species.

Rigid bidentate ligands focus the size of gold nanoparticles

Multidentate organic ligand molecules have potentials not only to passivate the inorganic nanoparticles (NPs) but also to tune their structures and functions. Here, we designed novel rigid bidentate ligands to demonstrate their size focusing effect on the gold NPs (AuNPs).

Unusual structural features in tetrabromocatechol-chelated dinuclear manganese(III) complex: Synthesis, electrochemistry and thermally induced valence tautomerism

A novel dinuclear manganese(III) complex derived from tetrabromocatechol is reported. X-ray crystal structure reveals a bipyrimidine-bridged dinuclear manganese(III) complex in which both the metal ions are situated on the crystallographic inversion center. The most important feature of the crystal structure is that the geometrically rigid bidentate tetrabromocatechol ligand stretches one arm to coordinate axially elongated position. Moreover, the complex was found to exhibit thermally induced valence tautomerism accompanied by optical absorption spectral changes. As far as I am aware this is the first structural characterization of a dinuclear manganese(III) complex that consists exclusively of rigid bidentate ligands.

Microwave‐Promoted Palladium(II)‐Catalyzed CP Bond Formation by Using Arylboronic Acids or Aryltrifluoroborates

The first Pd(II)-catalyzed P arylation has been performed by using palladium acetate, the rigid bidentate ligand dmphen (dmphen=2,9-dimethyl-1,10-phenanthroline), and without the addition of base or acid. Couplings of arylboronic acids or aryl trifluoroborates with H-phosphonate dialkyl esters were conducted in 30 min with controlled microwave (MW) heating under non-inert conditions. Aryl phosphites were also synthesized at room temperature with atmospheric air as the sole reoxidant. The arylated phosphonates were isolated in 44-90 % yields. The excellent chemoselectivity of the method was illustrated in the synthesis of a Mycobacterium tuberculosis glutamine synthetase (MTB-GS) inhibitor. Online ESIMS was used to detect cationic palladium species in ongoing reactions directly, and a catalytic cycle has been proposed based on these results.

Synthesis and structural characterization of copper(II), cadmium(II) and zinc(II) complexes with 4,5-diazaspirobifluorene and bis-9-biphenyl-4,5-diazafluorenyl peroxide

The synthesis and structural chemistry of four new divalent transition metal complexes of the fluorene ligands 4,5-diazaspirobifluorene (L1) and bis-9-biphenyl-4,5-diazafluorenyl peroxide (L2), [Cu 3(L1) 4(NO 3) 6(H 2O) 2] · 2CH 3CN ( 1), [Cu(L1)(CH 3CO 2) 2(H 2O)] · 2H 2O ( 2), [Cd(L1) 2(NO 3) 2] · DMF ( 3) (DMF = N,N-dimethylformamide) and [Zn 2(L2)(μ-Cl) 2Cl 2] ∞ ( 4) are described. Single-crystal X-ray diffraction analysis reveal that the four complexes exhibit various frameworks due to diverse coordination modes and different conformations of ligands L1 or L2, as well as nitrate, acetate or chloro counterions. L1 in complexes 1, 2 and 3 present an asymmetric rigid bidentate ligand with two nitrogen atoms as the donor sites. Novel complex 4 was formed through complexation between conformationally bent shaped peroxide ligands and zinc(II) dichlorides that adopt a linear coordination geometry, which can also give rise to extended polymeric chains with a zigzag secondary structure.

A New Bis(1-naphthylimino)acenaphthene Compound and Its Pd(II) and Zn(II) Complexes: Synthesis, Characterization, Solid-State Structures and Density Functional Theory Studies on the syn and anti Isomers

A new rigid bidentate ligand, bis(1-naphthylimino)acenaphthene, L1, and its Zn(II) and Pd(II) complexes [ZnCl 2( L1)], 1, and [PdCl 2( L1)], 2, were synthesized. L1 was prepared by the "template method", reacting 1-naphthyl amine and acenaphthenequinone in the presence of ZnCl 2, giving 1, which was further demetallated. Reaction of 1-naphthyl amine with acenaphthenequinone and PdCl 2 afforded dichloride bis(1-naphthyl)acenaphthenequinonediimine palladium, 2. L1, 1, and 2 were obtained as a mixture of syn and anti isomers. Compound 2 was also obtained by the reaction of PdCl 2 activated by refluxing it in acetonitrile followed by the addition of L1; by this route also a mixture of syn and anti isomers was obtained, but at a different rate. The solid-state structures of L1 and the anti isomer of compound 2 have been determined by single-crystal X-ray diffraction. All compounds have been characterized by elemental analyses; matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry; IR; UV-vis; (1)H, (13)C, and (1)H- (1)H correlation spectroscopy; (1)H- (13)C heteronuclear single quantum coherence; (1)H- (13)C heteronuclear single quantum coherence-total correlation spectroscopy; and (1)H- (1)H nuclear Overhauser effect spectrometry NMR spectroscopies when applied. Density functional theory studies showed that both conformers for [PdCl 2(BIAN)] are isoenergetic, and they can both be obtained experimentally. However, we can predict that the isomerization process is not available in a square-planar complex, but it is possible for the free ligand. The molecular geometry is very similar in both isomers, and only different orientations for naphthyl groups can be expected.

Cooperative Effect of 3,3′,4,4′-Benzophenonetetracarboxylic Acid and 1,10-Phenanthroline under Solvothermal Conditions to Afford Two Novel Zinc(II) and Cadmium(II) Complexes

Rational self-assembly of a flexible ligand 3,3′,4,4′-benzophenonetetracarboxylic acid and d10 transition metal salts in the presence of rigid bidentate ligand 1,10-phenanthroline yields two novel helical coordination polymers with different structural motifs; i.e., [Zn(H2bbtc)(phen)2 · 2H2O] n (1) and [Cd2(bbtc)(phen)4 · 2.25H2O] n (2) (H4bbtc = 3,3′,4,4′-benzophenonetetracarboxylic acid, phen = 1,10-phenanthroline), under solvothermal condition. One is hydrogen bonded and π–π stacked together into a network, and the other is a covalently coordinated 3D framework. The coordination polymers were characterized by FT-IR, UV/VIS and fluorescent spectroscopy, single crystal X-ray diffraction, elemental analysis and differential thermal analysis/thermogravimetry (DTA/TG). The most intriguing structural feature is that each complex exhibits novel helical-spaced chains by reason of two different ligands coordinating to the metal centers. Additionally, compounds 1 and 2 showed good fluorescence properties compared to the free ligands.

Probing the dimensions of semi-rigid inner functionalised U-shaped bis-porphyrin cavities

The synthesis of a series of open U-shaped bis-porphyrin cavity molecules is described, with bridged bicyclic backbones to confer rigidity, and a pendant substituted aromatic probe unit suspended on the inside of the cavity. The dimensions and flexibility of the bis-zincporphyrin cavity were probed using several different techniques. Initially the molecular ruler concept was employed, using flexible bidentate ligands as guests with a range of possible linear dimensions. Secondly, NMR methods were employed with rigid bidentate ligand guests of fixed lengths, and thirdly diffusion based NMR methods were utilised. The range of inter-porphyrin distances estimated by these methods suggests that these types of open-cavity systems have a surprising degree of flexibility.

Synthesis and characterization of new coordination polymers generated from oxadiazole-containing ligands and IIB metal ions

The coordination chemistry of the oxadiazole-containing rigid bidentate ligands 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L1) and 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L2) with inorganic IIB metal salts have been investigated. Five new coordination polymers ( 1–5) were prepared by solution reactions and fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Cd(L1) 2(CH 3CN) 2](ClO 4) 2 · (CH 3CN) 2 ( 1) crystallized in the monoclinic space group P2 1/ c, a = 8.4028(5) Å, b = 21.3726(13) Å, c = 10.5617(7) Å, β = 95.1200(10)°, and Z = 2. In the solid state, it adopts an infinite two-dimensional polymeric structural motif with effective cross section of ca. 14.31 × 14.31 Å. Cd(L2)(H 2O)(NO 3) 2 ( 2) crystallized in the monoclinic space group Ia, a = 7.1203(5) Å, b = 22.2475(15) Å, c = 20.2652(16) Å, β = 90.6080(10)°, and Z = 8. In the solid state, the two Cd(II) centers are connected to each other by L2 ligands and bridging nitrates into a two-dimensional network. [ZnCl 2(L1)] ( 3) and [HgI 2(L1)] · CH 3CN ( 4) crystallized in the monoclinic crystal system ( 3: P2 1/ c, a = 5.3702(3) Å, b = 20.4800(11) Å, c = 12.4093(7) Å, β = 94.7930(10)°, and Z = 4; 4: P2/ n, a = 17.2733(11) Å, b = 5.2173(3) Å, c = 20.4069(13) Å, β = 102.8690(10)°, and Z = 4). In the solid state, Zn(II) and Hg(II) metal centers are connected to each other by L1 ligands into a zigzag chain motif. Compound 5 (HgBr 2(L2) is different from 3 and 4, monoclinic, P2(1)/ n, a = 5.470(4) Å, b = 16.271(13) Å, c = 16.486(12) Å, β = 93.197(15)°, and Z = 4) adopts a novel one-dimensional helical chain motif which resulted from the relative different coordinated orientation of the two N-donors on L2 ligand.

Unsymmetrical Diaryl Sulfones and Aryl Vinyl Sulfones Through Palladium‐Catalyzed Coupling of Aryl and Vinyl Halides or Triflates with Sulfinic Acid Salts.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Unsymmetrical diaryl sulfones and aryl vinyl sulfones through palladium-catalyzed coupling of aryl and vinyl halides or triflates with sulfinic acid salts.

The palladium-catalyzed reaction of sulfinic acid salts with a wide variety of aryl and vinyl halides or triflates provides unsymmetrical diaryl sulfones and aryl vinyl sulfones in good to excellent yields. The reaction is strongly influenced by the presence of nBu4NCl, and the use of Xantphos, a rigid bidentate ligand with a wide natural bite angle, was found to be crucial for the success of the reaction. With neutral, electron-rich, and electron-poor aryl iodides best results were obtained by using Pd2(dba)3, Xantphos, Cs2CO3, and nBu4NCl, in toluene at 80 degrees C. Two general procedures were employed with aryl bromides and triflates: sodium p-toluenesulfinate, Pd2(dba)3, Xantphos, Cs2CO3, 120 degrees C, in toluene with nBu4NCl (procedure A: neutral, electron-rich, and slightly electron-poor aryl bromides or triflates) and without nBu4NCl (procedure B: electron-poor aryl bromides or triflates). With vinyl triflates best results were obtained at 60 degrees C omitting nBu4NCl.

Oxidative addition of phenylacetylene through C-H bond cleavage to form the MgII-dpp-bian complex: molecular structure of [Mg[dpp-bian(H)](C[triplebond]CPh)(thf)2] and its diphenylketone insertion product [Mg(dpp-bian)*-[OC(Ph2)C[triplebond]CPh](thf)

The use of a rigid bidentate ligand allows oxidative addition of an acetylene derivative to a non-transition-metal complex, not through oxidation of the metal atom, but through σ-bond metathesis from ML: and HC to form HL⋅⋅⋅MC (see scheme; Ar=2,6-iPr2C6H3).

Self-assembly of coordination polymers from AgX (X = SbF(6)(-), PF(6)(-), and CF(3)SO(3)(-)) and oxadiazole-containing ligands.

The coordination chemistry of the oxadiazole-containing rigid bidentate ligands 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L1), 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L2), and 2,5-bis(3-aminophenyl)-1,3,4-oxadiazole (L3) with inorganic Ag(I) salts has been investigated. Four new coordination polymers (1, 2, 3, and 5) and one new bimetallic macrocyclic supramolecular complex (4) were synthesized from solution reactions of L1-L3 with inorganic Ag(I) salts, respectively. Compounds [[Ag(L1)]SbF(6)](n) (1) (1, monoclinic, P2(1)/c, a = 6.6846(4) A, b = 27.1113(15) A, c = 8.6802(5) A, beta = 94.1080(10) degrees, Z = 4) and [[Ag(L1)]PF(6)](n) (2) (2, monoclinic, P2(1)/c, a = 6.6753(3) A, b = 27.2824(14) A, c = 8.2932(4) A, beta = 94.6030(10) degrees, Z = 4) were obtained from the reactions of L1 with AgSbF(6) and AgPF(6) in a CH(2)Cl(2)/CH(3)OH mixed solvent system, respectively. Compounds 1 and 2 are isostructural and feature a novel two-dimensional zeolite-like net with two different individual rings. [[Ag(L2)]SbF(6)](n) (3) (3, monoclinic, P2(1)/c, a = 5.5677(3) A, b = 17.3378(9) A, c = 15.6640(8) A, beta = 94.4100(10) degrees, Z = 2) and [Ag(2)(L2)(2)](SbF(6))(2) (4) (4, triclinic, P1, a = 8.7221(5) A, b = 9.2008(6) A, c = 10.7686(7) A, alpha = 70.6270(10) degrees, beta = 75.7670(10) degrees, gamma = 73.7560(10) degrees, Z = 1) were obtained from one-pot reaction of L2 with AgSbF(6) in a CH(2)Cl(2)/CH(3)OH mixed solvent system. Compound 3 features a one-dimensional chain pattern, while compound 4 adopts a novel bimetallic macrocyclic structural motif which consists of Ag(2)(L2)(2) ringlike units (crystallographic dimensions, 8.06 x 7.42 A(2)). [[Ag(L3)]SO(3)CF(3)](n) (5) is generated from L3 and AgSO(3)CF(3) in a CH(2)Cl(2)/CH(3)OH mixed solvent system and crystallizes in the unusual space group Pbcn, with a = 9.8861(5) A, b = 20.2580(10) A, c = 17.5517(8) A, Z = 8. It adopts novel two-dimensional sheets that are cross-linked to each other by strong interlayer N-H...O hydrogen bonding interactions into a novel H-bonded three-dimensional network.

New Coordination Polymers and Supramolecular Complexes Generated from Oxadiazole-Containing Organic Ligands and Inorganic M(II) (M = Zn and Cu) Salts

The coordination chemistry of the oxadiazole-containing rigid bidentate ligands 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L1) and 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L2) with inorganic M(II) (M = Zn and Cu) salts has been investigated. Two new coordination polymers (1 and 2) and two new bimetallic macrocyclic supramolecular complexes (3 and 4) were synthesized from solution reactions of L1 and L2 with inorganic M(II) (M = Zn and Cu) salts, respectively. {[Zn(L1)(H2O)2(CH3CN)2](ClO4)2·(L1)(CH3CN)1.5(CH2Cl2)0.5}n (1; monoclinic, P21/m, a = 7.5755(4) A, b = 8.3120(16) A, c = 9.6449(6) A, β = 99.9920(10)°, Z = 2) was obtained by combination of L1 with Zn(ClO4)·6H2O in a CH2Cl2/CH3CN mixed-solvent system. The structure features one-dimensional chains that are cross-linked to each other by weak noncovalent π−π interactions (alternating face-to-face stacking of coordinated and uncoordinated L1 molecules) to generate a novel two-dimensional network. {[Zn(L1)(H2O)2(NO3)2]·2(CH3CN)2}n (2; monoclinic, C2/c, a = 27.2789(...