联三吡啶配体及其衍生物合成进展

金属-配体间的配位作用是超分子化学中最重要的相互作用之一, 寡聚吡啶配体可以与许多过渡金属离子配位, 形成具有独特磁、光物理和电化学性质的过渡金属络合物, 因此联三吡啶配体的合成及其过渡金属络合物性能研究引起化学家的广泛关注. 综述了联三吡啶配体及其衍生物的合成方法, 主要包括成环缩合反应、过渡金属催化的偶联反应以及其它方法, 并选取具有代表性的实例对联三吡啶配体的结构和合成方法进行详细地阐述.     

Connecting BINOL and terpyridine: the electronic effects of the linkage

1,1′-Bi-2-naphthol and terpyridine are covalently connected either directly or through different linkers. It is found that in contrast to the directly connected one, when the saturated methyleneoxy linker is used, there is inefficient electronic communication between the BINOL and terpyridine units and the fluorescence of the BINOL unit cannot be completely quenched by the coordination of terpyridine unit with a Cu²⁺ ion. However, a phenylene linker allows an efficient electronic communication between the BINOL and terpyridine units and the fluorescence of the BINOL is almost completely quenched upon Cu²⁺ coordination. The interaction of these compounds with valinol is studied and large fluorescence enhancements are observed for those with efficient electronic communication between the BINOL and terpyridine units.     

Coordination chemistry of a terpyridine-tris(pyrazolyl) ditopic ligand

A new ditopic ligand, 4'-(4-(2,2,2-tris(1H-pyrazol-1-ido)ethoxymethyl)phenyl)-2,2':6',2'-terpyridine (pzt), has been prepared and its coordination chemistry studied. Metal ions with a preference for octahedral geometry form ML(2) complexes that are readily isolated and characterised, with the metal ion being bound to the terpyridine sites of both ligands. Other metal ions bind to the terpyridine site of just one ligand. In the case of silver(i), a dinuclear M(2)L(2) complex has been isolated in which each silver ion is coordinated to the terpyridine site of one ligand and to a single pyrazolyl donor group from the second ligand. Evidence for binding of metal ions to the tris(pyrazolyl) binding site was obtained by electrospray mass spectrometry and NMR techniques. The free ligand and three metal complexes, including the disilver complex, have been characterised by X-ray crystallographic techniques.     

Iron in a Cage: Fixation of a Fe(II)tpy2 Complex by Fourfold Interlinking

The coordination sphere of the Fe(II) terpyridine complex 1 is rigidified by fourfold interlinking of both terpyridine ligands. Profiting from an octa‐aldehyde precursor complex, the ideal dimensions of the interlinking structures are determined by reversible Schiff‐base formation, before irreversible Wittig olefination provided the rigidified complex. Reversed‐phase HPLC enables the isolation of the all‐trans isomer of the Fe(II) terpyridine complex 1 , which is fully characterized. While temperature independent low‐spin states were recorded with superconducting quantum interference device (SQUID) measurements for both, the open precursor 8 and the interlinked complex 1 , evidence of the increased rigidity of the ligand sphere in 1 was provided by proton T₂ relaxation NMR experiments. The ligand sphere fixation in the macrocyclized complex 1 even reaches a level resisting substantial deformation upon deposition on an Au(111) surface, as demonstrated by its pristine form in a low temperature ultra‐high vacuum scanning tunneling microscope experiment.     

Terpyridine–Porphyrin Hetero‐Pacman Compounds

The two different coordination spheres afforded by Pacman architectures offer cooperativity derived from two different metal centers. A modular strategy is developed to produce a hetero‐Pacman scaffold featuring a porphyrin and terpyridine for metal‐ion binding. A double Suzuki reaction was employed to first attach a terpyridine moiety to a xanthene backbone and then attach a porphyrin. The new hetero‐Pacman scaffold has been characterized and all building blocks have been isolated and structurally characterized. The principle objective to incorporate different metal centers was confirmed by isolating a trinuclear complex comprising two porphyrinic units and a bis(terpyridine)–iron unit. The compounds described herein expand the Pacman scaffold concept by allowing for the incorporation of a terpyridine–metal complex proximate to a porphyrin‐cofactor active site for small‐molecule activation.     

Metallo‐Supramolecular Diethylene Glycol: Water‐Soluble Reversible Polymers

Bis(2,2′:6′,2″‐terpyrid‐4′‐yl) diethylene glycol was synthesized as a monomer unit and further utilized for polymerization with FeCl₂ in order to form water‐soluble coordination polymers. Viscosity measurements and film‐forming properties indicate the formation of linear coordination polymers or larger ring structures. The terpyridine/iron(II) complexes are stable up to temperatures of 210 °C, but can be uncomplexed by the addition of an excess of a strong competitive ligand (HEDTA) under mild conditions.

     

Thermosensitive and Switchable Terpyridine‐Functionalized Metallo‐Supramolecular Poly(N‐isopropylacrylamide)

Metallo‐supramolecular polymers offer attractive possibilities to combine the properties of polymers with the characteristics offered by the metal–ligand coordination. Here we present for the first time the combination of metal‐bis(terpyridine) complexes and lower critical solution temperature (LCST) polymers that can be switched by addressing either the thermosensitive polymer or the metal complex. We describe a new strategy for the synthesis of poly(N‐isopropylacrylamide) (PNIPAM) end functionalized with a terpyridine moiety, which is further used for the preparation of Fe^II and Zn^II‐bis(terpyridine PNIPAM). The comparison of the LCST behavior of the uncomplexed ligands and their metal complexes that bear different counter ions is included. Furthermore, the switchability of the synthesized Fe^II system is demonstrated by a decomplexation reaction followed by the characterization of the uncomplexed ligand.

     

Investigations of Co(II), Ni(II) and Cu(II) (2,2´:6´,2"2"-Terpyridine) Complexes With Sulfur Donor Ligands

The ‘complexes as metal’ strategy has been used to prepare new mixed ligand complexes containing Co(II), Ni(II) and Cu(II) terpyridine (terpy) with dithiooxamide (dto) and thiosemicarbazide (tsc). Characterization of the complexes has been accomplished by elemental analysis, molar conductance, thermal analysis, as well as electronic and IR spectral measurements. It is deduced that the coordination mode of the terpyridine is changed from tridentate in the binary complex to bidentate in the ternary one where the uncoordinated pyridine exists in the protonated form. The dto and tsc act as neutral bidentate ligands coordinating through either sulfur or sulfur and nitrogen atoms respectively, forming chelate ring systems. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ruthenium(II)-<Emphasis Type="Italic">bis</Emphasis>(4′-(4-ethynylphenyl)-2,2′:6′, 2″-terpyridine) — A versatile synthon in supramolecular chemistry. Synthesis and characterization

A homoleptic ethynyl-substituted ruthenium(II)-bisterpyridine complex representing a versatile synthon in supramolecular chemistry was synthesized and analyzed by NMR spectroscopy, mass spectrometry and X-ray diffractometry. Furthermore, its photophysical properties were detailed by UV/Vis absorption, emission and resonance Raman spectroscopy. In order to place the results obtained in the context of the vast family of ruthenium coordination compounds, two structurally related complexes were investigated accordingly. These reference compounds bear either no or an increased chromophore in the 4′-position. The spectroscopic investigations reveal a systematic bathochromic shift of the absorption and emission maximum upon increasing chromophore size. This bathochromic shift of the steady state spectra occurs hand in hand with increasing resonance Raman intensities upon excitation of the metal-to-ligand charge-transfer transition. The latter feature is accompanied by an increased excitation delocalization over the chromophore in the 4′-position of the terpyridine. Thus, the results presented allow for a detailed investigation of the electronic effects of the ethynyl substituent on the metal-to-ligand charge-transfer states in the synthon for click reactions leading to coordination polymers.      

TiO2纳米颗粒对钌(II)三联吡啶配合物光损伤小牛胸腺DNA能力的影响

由于极短的激发态寿命, 钌(II)三联吡啶配合物对脱氧核糖核酸(DNA)的光损伤能力低下. 设计合成了三个钌(II)三联吡啶配合物[Ru(ttp)(tpy)]^2＋ (1), [Ru(ttp-COOH)(tpy)]^2＋ (2)和[Ru(ttp-COOH)(tpy-pyr)]^2＋ (3), 其中tpy为2,2':6',2"-三联吡啶, ttp为4′-(4-甲苯基)-2,2':6',2"-三联吡啶, ttp-COOH为4′-(4-羧基苯基)-2,2':6',2"-三联吡啶, tpy-pyr为4'-(1-芘基)-2,2':6',2"-三联吡啶. 比较了TiO₂纳米颗粒对它们光损伤小牛胸腺DNA的影响. 发现TiO₂纳米颗粒在空气和氩气条件下均可显著提高配合物3光损伤DNA的能力. TiO₂纳米颗粒和配合物3间的光诱导电子转移作用及其该作用生成的钌(III)物种可能是促进配合物3对DNA光损伤的主要原因.     

Silica nanoparticles functionalised with cation coordination sites and fluorophores for the differential sensing of anions in a quencher displacement assay (QDA)

In conjunction with quenching metal ions, silica nanoparticles carrying terpyridine coordination sites and sulforhodamine B signalling units were employed for the differential fluorometric recognition of anions.     

The molecular mechanism of dual emission in terpyridine transition metal complexes--ultrafast investigations of photoinduced dynamics

Temperature dependent luminescence experiments are combined with femtosecond time-resolved transient absorption spectroscopy to decipher the photoinduced excited-state relaxation pathway in mononuclear Fe, Ru and Os terpyridine complexes bearing a conjugated chromophore within the ligand framework. The herein presented complexes constitute a class of coordination compounds, which overcome the poor emission properties commonly observed for most terpyridine transition metal complexes. As reported earlier, the complexes reveal dual emission at room temperature stemming from ligand centered and metal-to-ligand charge-transfer states. The molecular mechanism of the room temperature dual luminescence is addressed experimentally in this contribution. The experimental results indicate an ultrafast branching reaction within the excited-state manifold upon photoexcitation of the ligand-centered S(1) state. This branching occurs from a "hot" excited state geometry close to the Franck-Condon point of absorption and within ～100 fs, i.e. the temporal resolution of our experimental setup. The combination of ultrafast differential absorption experiments and temperature-dependent luminescence data allows not only to draw conclusions about the molecular mechanism underlying the observed dual emission but also to construct quantitative Jablonski diagrams and, thereby, to detail the excited-state topology determining the remarkable luminescence properties of the systems at hand.     

Isomers of Terpyridine as Ligands in Coordination Polymers and Networks Containing Zinc(II) and Cadmium(II)

The use of divergent 4,2′:6′,4″- and 3,2′:6′,3″-terpyridine ligands as linkers and/or nodes in extended coordination assemblies has gained in popularity over the last decade. However, there is also a range of coordination polymers which feature 2,2′:6′,2″-terpyridine metal-binding domains. Of the remaining 45 isomers of terpyridine, few have been utilized in extended coordination arrays. Here, we provide an overview of coordination polymers and networks containing isomers of terpyridine and either zinc(II) and cadmium(II). Although the motivation for investigations of many of these systems is their luminescent behavior, we have chosen to focus mainly on structural details, and we assess to what extent assemblies are reproducible. We also consider cases where there is structural evidence for competitive product formation. A point that emerges is the lack of systematic investigations.     

Messages in molecules: ligand/cation coding and self-recognition in a constitutionally dynamic system of heterometallic double helicates

Double helicates are known to exhibit self-recognition characteristics determined by the coordination geometry of the metal involved as well as by the topicity of the ligands. Combining tridentate (terpyridine, T) or bidentate (bipyridine, B) subunits in a tritopic strand affords a set of ligands able to assemble by pairs to form double helicates, homo- or heterostranded, homo- or heterotopic, depending on the coordination properties of the metals involved. The four ligand strands, BBB, TTT, BBT, and TBT form constitutionally dynamic sets of double helicates with the metal ions Cu(I), Cu(II), and Zn(II); these helicates correspond to the correct coding of the BB, BT, and TT pairs for tetra-, penta-, and hexacoordinate Cu(I), Cu(II), and Zn(II) cations, respectively.     

三联吡啶化合物的溶剂致荧光变色及丁醇异构体鉴别

在三联吡啶分子中引入N,N-二甲基官能团, 实现了三联吡啶分子的局部激发态发光. 研究发现, 溶剂的极性诱导三联吡啶的偶极矩发生变化, 实现了从深蓝光(λ_max=384 nm)到黄光(λ_max=558 nm)的溶剂致荧光变色. 由于三联吡啶的荧光易受醇溶剂中—OH基团振荡猝灭, 不同空间位阻的正丁醇、 异丁醇、 仲丁醇及叔丁醇溶剂使得三联吡啶发光光色相近, 但发光强度的差异较大. 三联吡啶进一步与ZnCl₂配位得到了三联吡啶-Zn(Ⅱ)配合物, 金属离子Zn(Ⅱ)的配位作用促进了三联吡啶分子内电荷转移. 由于电子给体N,N-二甲基官能团可发生平面扭曲, 丁醇异构体可调节三联吡啶-Zn(Ⅱ)的局部激发态和扭曲分子内电荷转移发光, 进而实现其在丁醇异构体溶剂中发光光色的调节. 因此, 三联吡啶和三联吡啶-Zn(Ⅱ)具有良好的溶剂致荧光变色性能, 可应用于4种丁醇异构体的鉴别.     

Self‐Assembly of Conjugated Units Using Metal‐Terpyridine Coordination

Due to their inherently dynamic natures and fascinating photoluminescent/photoelectronic properties, coordination compounds of metal ions and conjugated terpyridine ligands have attracted considerable attention as functional materials for a variety of potential applications. In this feature article, a summary of recent work toward the development of one‐ (1D), two‐ (2D), and three‐dimensional (3D) supramolecular polymers, networks, and metallomacrocycles based on zinc metal ion coordination of conjugated units bearing terpyridine ligands is presented, and it is shown how it fits within the overall framework of work in this field. Here, a sequential study from terpyridines as basic building blocks to their zinc‐coordinated supramolecular 1D polymers, 2D macrocycles, and 2D and 3D networks is developed. These networks are compared with respect to their thermal stabilities, molecular organization, and linear and nonlinear optical properties. This work opens new prospects for the development of supramolecular chemistry of terpyridines and other transition metal ions, and also their application in future optoelectronic devices.

     

Photochemical and thermal ligand exchange in a ruthenium(II) complex based on a scorpionate terpyridine ligand

A ruthenium(II) complex containing a 1,10-phenanthroline unit and a terpyridine fragment covalently linked to a benzonitrile group has been synthesised; coordination and decoordination of the benzonitrile group can be induced thermally and photochemically respectively, in an acetone-water mixture.     

Light-driven electron transfer in a modular assembly of a ruthenium(II) polypyridine sensitiser and a manganese(II) terpyridine unit separated by a redox active linkage. DFT analysis

A series of ruthenium polypyridine-based complexes covalently bound to a terpyridine coordinating site for Mn^II ion coordination has been developed. A redox active unit separates the photoactive unit and the manganese complex. Introducing ester groups on the bipyridine skeleton allows modulation of redox properties of the chromophore. Intramolecular electron transfer from the Mn^II to the photogenerated Ru^III was studied by time-resolved transient absorption and EPR. Photophysical studies support the participation of the imidazole unit in the electron transfer process from the Mn(II) complex and Ru(III) in the case of ester containing chromophores. DFT calculations were performed and used to rationalize the photophysical behavior of the complexes, in particular the effect of coordination of the Mn^II ion to the terpyridine cavity as well as the influence of the electron withdrawing groups on the Ru chromophore.     

Side‐chain terpyridine polymers through atom transfer radical polymerization and their ruthenium complexes

Polymers containing side‐chain terpyridine ligands of well‐defined architectures and controllable molecular weights and molecular weight distributions are reported. These polymers were synthesized by the atom transfer radical polymerization (ATRP) of a newly synthesized terpyridine monomer with three functional initiators. The obtained polymers were characterized with ¹H NMR and gel permeation chromatography techniques. The efficiency of the ATRP technique and the overall control of the molecular characteristics of the polymers were demonstrated by a kinetic study of the polymerization reaction. Subsequently, the ruthenium(III)/ruthenium(II) complexation chemistry was employed for the attachment of bis(dodecyloxy)‐functionalized terpyridine moieties onto each side 2,2′:6′,2″‐terpyridine unit of the main polymeric backbone. Thus, the grafting approach was successfully combined with the metal–ligand coordination chemistry for the preparation of highly soluble polymeric complexes. The resulting complexes were fully characterized by means of ¹H NMR, gel permeation chromatography, and ultraviolet–visible spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4838–4848, 2005     

From encapsulation to polypseudorotaxane: unusual anion networks driven by predesigned metal bis(terpyridine) complex cations

Solvothermal reactions of CuSCN, metal (Mn2+, Fe2+, Co2+, Ni2+, Cu2+) sulfate, and terpyridine (2,2':6',2' '-terpyridine or 4'-p-tolyl-2,2':6',2' '-terpyridine) in the presence of triphenylphosphine yielded a series of hybrid coordination compounds, in which in situ formed metal bis(terpyridine) complex cations are encapsulated by a 3D anionic network or entangled by 2D heartlike networks, forming encapsulation or polypseudorotaxane supramolecules. The complex cations play a role as template to direct the fabrication of the structures.