Terpyridine Groups Research Articles

Synthesis, crystal Structure, and luminescence of zinc coordination polymers with a new Fuctionalized terpyridyl Sulfonate ligand

Four Zinc(II) coordination polymers based on a new ligand with terpyridyl and benzenesulfonyl groups, namely, [Zn1.5(STP)2Cl]n·1.5nH2O (1), [Zn(STP)(1,4- bdc)0.5]n·0.5nH2O(2), [Zn(STP-O)]n·0.5nH2O (3), [Zn(STP-OH)(1,4-bdc)0.5]n·0.5nH2O (4), (HSTP = 2-(4,2':6',4″-terpyridine-4'-yl)benzenesulfonic acid) have been synthesized under hydrothermal and characterized by elemental analysis, IR, PXRD and single crystal X-ray diffraction. Compound 1 exhibits an interpenetrating 3D network. Compound 2 displays a (3,4)-connected Ins topological network. Compound 3 shows a (3,6)-connected 3D rtl network. Compound 4 reveals a (3,4)-connected Ins topological network. The structural diversities well confirm the rich coordination chemistry of HSTP. The photoluminescence for 1–2 and thermal stabilities of 1–4 were also studies. Additionally, a brief analysis for hydroxylation of terpyridine group during hydrothermal reaction was carried out.

Electrochromic/Electrofluorochromic Devices based on Terpyridine‐Attached Viologen Derivatives

AbstractElectrochromic/electrofluorochromic (EC/EFC) dual‐functional materials with electrochemically switchable colors and fluorescence offer the possibility of developing reflection/emission dual‐mode integrated displays in one device. However, unlike the easily adjustable multi‐color EC properties, the EFC properties with tunable fluorescence intensity are relatively broad, while those with tunable color emission are rare. Herein, two terpyridine‐attached viologen derivatives Tpy‐Vio‐1 and Tpy‐Vio‐2 are designed and synthesized for exploring the relationship between molecular structure and their EC/EFC properties. Due to the introduction of 4′‐phenyl‐2,2′:6′,2″‐terpyridine groups, Tpy‐Vio‐1 and Tpy‐Vio‐2 devices exhibited EFC characteristics in addition to EC properties. Tpy‐Vio‐1 and Tpy‐Vio‐2 devices displayed similar color and fluorescence changes after applying electric potentials. Nevertheless, compared to the Tpy‐Vio‐2 devices, the Tpy‐Vio‐1 devices possessed lower applied voltage (1.8 V), shorter response times (9.5 s for coloring and 8.5 s for bleaching), higher cyclic stability (480 cycles), and better coloration efficiency (95 cm2 C−1). This study believes that this work will provide effective guidance for the design and preparation of EC/EFC dual‐functional materials.

A Calix[4]resorcinarene-Copper(II) Based Supramolecular Nanocapsule with Encapsulated Polyoxometalates for Enhanced Photocatalytic Activity

The research on improving the photocatalytic activity of polyoxometalates (POMs) has attracted considerable attention. In this work, a functionalized calix[4]resorcinarene ligand with four terpyridine groups (TPYR4A) was rationally designed, and then a POM-calix[4]resorcinarene based inorganic–organic complex [Cu4Cl4(TPYR4A)]2[PWVI10WV2O40][PWVI12O40]·6DMA·8H2O (DMA= N,N′-dimethylacetamide) (1) was achieved by a self-assembly process. Strikingly, POM clusters were successfully encapsulated in noncovalent dimeric calix[4]resorcinarene-copper(II) based nanocapsules with a size of 3 nm. Markedly, 1 features a visible light absorption response with an optical band gap of 2.3 eV. More importantly, 1 exhibits obviously enhanced photocatalytic activity for oxidation of benzaldehyde upon simulated solar light excitation. Particularly, the photocatalytic performance of 1 is better than that of pure H3PW12O40 or a mixture of TPYR4A and H3PW12O40. This work offers a feasible strategy for designing POM-based hybrid materials with enhanced photocatalytic activity.

Fluorometric Detection of Methanol by Using Triphenylamine Fluorophore Tethered Terpyridine Probe

AbstractTriphenylamine appended terpyridine donor‐acceptor fluorescent probe (TPA‐TP) exhibited specific detection of methanol in presence of other volatile organic compounds, such as benzene, ethanol and biodiesel were described. The role of the terpyridine group in the TPA‐TP toward methanol detection has been demonstrated. The detection mechanism origins from s‐trans to s‐cis and vice‐versa conformational change facilitated by hydrogen bonding interactions between TPA‐TP and methanol. Besides, TPA‐TP coated Whatman filter paper based strip was evaluated for detection of methanol from benzene prepared my means of practical and versatile applications of methanol detection. Thus, TPA‐TP was demonstrated as a sensitive, selective, and inexpensive probe for methanol detection over benzene, ethanol and biodiesel by naked‐eye and fluorescence spectroscopy methods.

Electrocatalytic CO2 Reduction with a Binuclear Bis-Terpyridine Pyrazole-Bridged Cobalt Complex.

A pyrazole-based ligand substituted with terpyridine groups at the 3 and 5 positions has been synthesized to form the dinuclear cobalt complex 1, that electrocatalytically reduces carbon dioxide (CO2 ) to carbon monoxide (CO) in the presence of Brønsted acids in DMF. Chemical, electrochemical and UV-vis spectro-electrochemical studies under inert atmosphere indicate pairwise reduction processes of complex 1. Infrared spectro-electrochemical studies under CO2 and CO atmosphere are consistent with a reduced CO-containing dicobalt complex which results from the electroreduction of CO2 . In the presence of trifluoroethanol (TFE), electrocatalytic studies revealed single-site mechanism with up to 94 % selectivity towards CO formation when 1.47 M TFE were present, at -1.35 V vs. Saturated Calomel Electrode in DMF (0.39 V overpotential). The low faradaic efficiencies obtained (<50 %) are attributed to the generation of CO-containing species formed during the electrocatalytic process, which inhibit the reduction of CO2 .

Nano-Theranostics Constructed from Terpyridine-Modified Pillar [5]arene-Based Supramolecular Amphiphile and Its Application in Both Cell Imaging and Cancer Therapy.

Theranostics play an important role in cancer treatment due to its realized real-time tracking of therapeutic efficacy in situ. In this work, we have designed and synthesized a terpyridine-modified pillar [5]arenes (TP5). By the coordination of terpyridine and Zn2+, the complex TP5/Zn was obtained. Then, supramolecular amphiphile can be constructed by using host–guest complexation between a polyethylene glycol contained guest (PM) and TP5/Zn. Combining the fluorescence properties from the terpyridine group and the amphiphilicity from the system, the obtained TP5/Zn/PM can further be self-assembled into fluorescent particles with diameters of about 150 nm in water. The obtained particles can effectively load anti-cancer drugs and realize living cell imaging and a precise release of the drugs.

Synthesis and Properties of a New Type of Terpyridine Cholesterol Derivative Gelator with Applications to Medical Treatments

Low molecular mass gelators (LMMGs), as a new type of intelligent soft material, possess good response properties to light, electricity, heat, and ultrasound and have many potential applications in fields such as intelligent sensing, biological materials, and drug release. Additionally, steroid derivatives have been a focus in the study of LMMGs for their desirable properties as well, such as their rigid framework, multichiral center, and strong van der Waals accumulation. Furthermore, the coordination ability of terpyridine has been an emphasis in the study of supramolecular chemistry and coordination chemistry as well. Attempts have been made with terpyridine groups that have special responses, such as terpyridine with steroid derivatives, to build more specialized and functional gelators. In this study, we used 2-acetylpyridine, 2-formaldehyde, and cholesterol to synthesize 6-(2,2:6 ′ ,2 ″ -terpyridine-4 ′ -carboxamide group) hexanoic acid (with a yield of 64.39%, P1), glycine cholesterol ester (with a yield of 70.36%, P2), and DMTCP (with a yield of 88.92%). Infrared spectroscopy, nuclear magnetic resonance spectroscopy, mass spectrometry, elemental analysis, and gelator performance tests were then conducted to measure the gelation effect of the materials and to explore their gelation mechanisms. Compared to P1 and P2, the DMTCP synthesized by P1 and P2 was able to form gel in more kinds of solvents. In addition, when it contains both terpyridine and cholesterol functional groups, the gelation properties of DMTCP were also significantly improved, and all the gels prepared in the four solvents in which DMTCP can form gels were stimulus responsive.

Ultrafast-response, highly-sensitive and recyclable colorimetric/fluorometric dual-channel chemical warfare agent probes

In this paper, two donor (D)-acceptor (A) type of small organic fluorescent molecules (T1 and T2) based on terpyridine group are synthesized, characterized and used as colorimetric/fluorometric dual-channel probes towards diethylchlorophosphate (DCP, the mimic of chemical warfare agent sarin) not only in solution but also in gas phase featuring instantaneous responses, excellent recyclability, high selectivity and sensitivity. Interestingly though the discriminated units of both chemosensors are terpyridine, their fluorescent responded signals are different, which is due to the different electron-donating substituents of T1 and T2 caused the different responded mechanism to DCP. And the possible sensing mechanism was proved by using nuclear magnetic resonance (1H NMR, 31P NMR) spectra and natural transition orbitals calculations. Furthermore, facile testing filter paper-constructed strips with the visualization of colorimetric/fluorometric dual-channel responses based on T1 and T2 have been fabricated for real-time, on-site high selective and sensitive, recyclable monitor of DCP vapor.

New derivatives of 4'-phenyl-2,2':6',2″-terpyridine as promising anticancer agents.

Terpyridine derivatives are known from their broad application including anticancer properties. In this work we present the newly synthesized 4'-phenyl-2,2':6',2″-terpyridine group with high antiproliferative activity. We suggest that these compounds influence cellular redox homeostasis. Cancer cells are particularly susceptible to any changes in the redox balance because of their handicapped and inefficient antioxidant cellular systems. The antiproliferative activity of the studied compounds was tested on five different cell lines that represent several types of tumours; glioblastoma, leukemia, breast, pancreatic and colon. Additionally, we also tested their selectivity towards normal cells. We performed molecular biology studies in order to detect the response of a cell to its treatment with the compounds that were tested. We looked at the in-depth changes in the proteins and cellular pathways that lead to cell cycle inhibition (G0/G1 and S), and consequently, death on the apoptosis and autophagy pathways. We proved that the studied compounds targeted DNA as well. Special attention was paid to the targets connected with ROS generation.

Polyterthiophenes Cross‐Linked with Terpyridyl Metal Complexes for Molecular Architecture of Optically and Electrochemically Tunable Materials

AbstractNovel conductive polymer‐based metal complexes were electrochemically synthesized and characterized in relation to (spectro)electrochemical stimuli. Particularly, we focused our attention on terthiophenes functionalized with terpyridine groups, along with Fe2+ cations present during electrochemical synthesis. The resultant electroactive films are coherent, robust, and exhibit mixed absorption profiles upon electrochemical doping, characteristic for both polyterthiophenes and metal‐ligand transitions. At certain oxidation potentials, the formation of radical cation and also dication states were observed. The latter, influence the optical transitions related to metal centers, and can reversibly be everted by switching to lower potentials. Furthermore, the polymer “cross‐linking metal” can be removed from the structure, which we obtained by partial exchange of Fe2+ with Cu2+ and Zn2+ cations. The conducted cation exchange studies however elucidate the complexity and difficulty of such an approach. With future electropolymerization “strategies” we are expecting to extend film stability during application of relatively high potentials, as well as in the interim of cation exchange.

Preparation of terpyridine-functionalized paramagnetic nickel-zinc ferrite microspheres for adsorbing Pb(ii), Hg(ii), and Cd(ii) from water.

A paramagnetic microsphere combining special functional groups may be one kind of the most promising methods for heavy metal adsorption, due to their specific separation capacity, selectivity and reusability. In this study, a novel terpyridine-based magnetic solid-phase adsorbent (TPY-M) is successfully constructed. The paramagnetic Ni0.25Zn0.75Fe2O4 microsphere (M) is synthesized and applied as a magnetic core, and is functionalized by terpyridine (TPY) groups. The naked magnetic core and TPY-M are characterized by vibration sample magnetism (VSM), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FT-IR) techniques. Some parameters of the TPY-M samples are evaluated as potential adsorbents for heavy metal ions in various aqueous solutions. The adsorption capacities of TPY-M for Pb(ii), Hg(ii) and Cd(ii) were 64.75 mg g−1, 33.94 mg g−1 and 24.64 mg g−1 under given conditions, respectively. In the case of Pb(ii), some influencing factors on the TPY-M adsorbent are investigated, including the pH, adsorption time, and ion concentrations. The adsorbent can be easily regenerated by HCl solution after use. The adsorbent revealed good adsorption performance in some real water samples.

Multiplex recognition and logic devices for molecular robot prototype based on an europium(iii)–cyclen system

Molecular robot provides a promising way to receive response signals and make decisions with intelligent information processing at the molecule level. In this work, a molecular robot prototype based on a europium(III)-cyclen complex (EuL) was designed and assembled, consisting of multiplex sensing and information processing in a single system. By utilizing the Eu3+ ion as a central processing unit (CPU) and terpyridine (Terpy) group as an arm of the molecular robot, multiplex detection function of this molecular robot can be accomplished in three test channels: the detection of Fe2+ with UV–vis, Zn2+ using photoluminescence, and Mn2+ using magnetic resonance imaging. The optimized structures revealed that the transition metal ions bound by the arms of two EuL molecules formed a hexacoordination octahedral rigidity structure in the adducts. For the structure of L and EuL, three pyridine rings of Terpy unit were not in a plane, and they were fixed to form a plane when captured the transition metal ions during the formation of the adducts. In addition, three different modes of molecular logic devices (OR, INHIBIT, and YES) were established based on relevant signals in the multiplex detection channels. The sensing of metal ions in human urine using EuL was also carried out, and the result demonstrated the presence of good recoveries and high analytical precision. Such a molecular robot prototype is expected to be used in intelligent medical diagnostics and, in particular, information processing at molecular level.

Helical Inversion of Peptide‐based Supramolecular Co2+ Complexes

Herein, we report the helical inversion of supramolecular polymeric complexes of Co2+ containing a peptide‐based ligand comprising one alanine and three glycine moieties and an achiral terpyridine group. The helicity of the peptide‐based supramolecular polymer is controlled via strain‐induced chirality at different stoichiometric ligand/Co2+ ratios. The supramolecular polymer S‐1 adopts octahedral geometry with right‐handed helicity (P‐type) in the presence of &lt;0.7 equiv of Co2+. In contrast, it adopts coexisting octahedral and square‐pyramidal geometries in the presence of 1.0 equiv of Co2+ and presents left‐handed helicity (M‐type). The helicities of the supramolecular polymer R‐1 with Co2+, prepared using the chirally opposite ligand, were completely opposite to those of S‐1. Furthermore, the circular dichroism intensities of supramolecular polymers S‐1 and R‐1 in the presence of Co2+ were 900–1500 times higher than those of free S‐1 and R‐1. In addition, the helical inversion was completely reversible and controllable by the addition of more Co2+ or ligand.

Redox‐Triggered Folding of Self‐Assembled Coordination Polymers incorporating Viologen Units

We report the study of stimuli-responsive ZnII and FeII coordination polymers (MC34+ or MC24+ with M=Fe2+ or Zn2+ ). These soluble metallopolymers were formed spontaneously by reaction of an organic ligand (C34+ or C24+ ) with one molar equivalent of metal ions. The C34+ and C24+ ligands incorporate two chelating terpyridine groups bridged by a redox responsive hinge featuring two viologen units (viologen=N,N'-dialkyl-4,4'-bipyridinium) linked either with propyl (C34+ ) or ethyl (C24+ ) chains. The viologen units in the polymer chains were reduced (1 e- per viologen group) either by bulk electrolysis or by visible-light irradiation carried out in the presence of a photosensitizer. The 1 e- reduction of the viologen units in the MC24+ polymers induced a slight decrease in the viscosity of the solutions due to a modification of the overall charge carried by the metallopolymers. In strong contrast, reduction of coordination polymers involving propyl linkers (MC34+ ) led to a remarkable increase (≈+400 %) in observed viscosity. This reversible effect was attributed to a folding of the polymer chains triggered by π-dimerization of the photo-generated viologen cation radicals.

Solid-Phase Synthesis of Azole-Comprising Peptidomimetics and Coordination of a Designed Analog to Zn2.

Peptidomimetics that can coordinate transition metals have a variety of potential applications as catalysts, sensors, or materials. A new modular peptidomimetic scaffold, the “azole peptoid”, is introduced here. We report methods for the solid-phase synthesis of eleven examples of trimeric N-substituted oligoamides that include oxazole- or thiazole-functionalized backbones. The products prepared comprise a diversity of functionality, including a metal-coordinating terpyridine group. The modular synthetic approach enables ready preparation of analogs for specific applications. To highlight a potential use of this new synthetic scaffold, a trimeric azole peptoid functionalized with a terpyridine residue was prepared and studied. The characteristic 2:1 ligand:metal binding of this terpyridine-functionalized azole peptoid to Zn2+ in aqueous solution was observed. These studies introduce azole peptoids as a useful class of biomimetic molecules for further study and application.

Photoactive Molecular Dyads [Ru(bpy)3-M(ttpy)2] n+ on Gold (M = Co(III), Zn(II)): Characterization, Intrawire Electron Transfer, and Photoelectric Conversion.

We propose in this work a stepwise approach to construct photoelectrodes. This takes advantage of the self-assembly interactions between thiol with a gold surface and terpyridine ligands with first-row transition metals. Here, a [Ru(bpy)3]2+ photosensitive center bearing a free terpyridine group has been used to construct two linear dyads on gold (Au/[ZnII-RuII]4+ and Au/[CoIII-RuII]5+). The stepwise construction was characterized by electrochemistry, quartz crystal microbalance, and atomic force microscopy imaging. The results show that the dyads behave as rigid layers and are inhomogeneously distributed on the surface. The surface coverages are estimated to be in the order of 10-11 mol cm-2. The kinetics of the heterogeneous electron transfer is determined on modified gold ball microelectrodes using Laviron's formula. The oxidation rates of the terminal Ru(II) subunits are estimated to be 700 and 2300 s-1 for Au/[ZnII-RuII]4+ and Au/[CoIII-RuII]5+, respectively. In the latter case, the rate is limited by the kinetics of electron transfer between an intermediate Co(II) center and the gold surface. For Au/[ZnII-RuII]4+, the Zn-bis-terpyridine center is not involved in the electron-transfer process and the oxidation of the Ru(II) subunit occurs through a superexchange process. In the presence of a tertiary amine in solution, the electrodes at a bias of 0.12 V behave as photoanodes when subjected to visible light irradiation. The magnitude of the photocurrent is around 10 μA cm-2 for Au/[CoIII-RuII]5+ and 5 μA cm-2 for Au/[ZnII-RuII]4+, proving the importance of an electron relay on the photon-to-current conversion. The results suggest an efficient conversion for Au/[CoIII-RuII]5+, since each bound dyad, once excited, injects an electron around 10 times per second.

Synthesis, Chemosensory Properties, and Self-Assembly of Terpyridine-Containing Conjugated Polycarbazole through RAFT Polymerization and Heck Coupling Reaction.

We report the responsive fluorescence chemosensory phenomena of a carbazole-functionalized crosslinked polymer (PCaT) with pendent terpyridine (tpy) groups as receptors of metal ions. The polymer was synthesized using Heck polymerization between 3,6-dibromide groups in a carbazole-based polymer (PC2Br) and divinyl tpy monomer. The effects of the polymeric structure on the optical and chemosensory properties of the PCaT were compared with those of a carbazole-tpy alternating conjugated polymer (PCT). Photoluminescence titrations demonstrated that the PCaT and PCT had the high sensing ability toward Fe3+ ions, with Stern–Volmer constants of 8.10 × 104 and 6.68 × 104 M−1, respectively. The limit of detection (LOD) toward Fe3+ of the PCaT and PCT was estimated to be 1.31 × 10−6 and 1.81 × 10−6 M, respectively, and the superior LOD of the PCaT was ascribed to its lowly crosslinked structure. The fluorescence of the solutions of these polymers that were quenched by Fe3+ ions recovered when trace CN− anions were added because of the high stability constant of the CN−–Fe3+ complex. Micellar aggregates with a mean diameter of approximately 239.5 nm were formed by dissolving the PCaT in tetrahydrofuran (THF) solution. Our results suggest that the PCaT is a promising material for chemosensory applications.

Attachment of a RuII Complex to a Self-Folding Hexaamide Deep Cavitand.

We report the design, synthesis and characterization of a new RuII metallocavitand that is catalytically active in alkene epoxidation reactions. The elaboration of the resorcin[4]arene's aromatic cavity produced a self-folding, deep hexaamide cavitand featuring a single diverging terpyridine (tpy) group installed at its upper rim. The construction of the metallocavitand involved the initial chelation of a RuIII chloride complex by the tpy ligand followed by the incorporation of 2-(phenylazo)pyridine (azpy) as an ancillary ligand. The resulting RuII chloro complex was converted into the catalytically active aqua counterpart by a ligand exchange process.

PH-Stable Eu- and Tb-organic-frameworks mediated by an ionic liquid for the aqueous-phase detection of 2,4,6-trinitrophenol (TNP).

Two pH-stable luminescent metal-organic frameworks (LMOFs), {[Ln2(L)2(OH)(HCOO)]·[H2O]}n (Ln = Eu 1, Tb 2), based on a new π-conjugated organic building block involving both carboxylate and terpyridine groups were rationally synthesized under a combination of hydro/solvothermal and ionothermal conditions (H2L = 4'-(4-(3,5-dicarboxylphenoxy)phenyl)-4,2':6',4''-terpyridine). 1 and 2 are isostructural and feature noninterpenetrated open 3D condensed frameworks constructed by rod-shaped lanthanide-carboxylate building units. Their excellent water-stability and pH-stability allow them to be used in aquatic systems. 1 and 2 both exhibit selective and sensitive aqueous phase detection of the well-known nitroaromatic explosive environmental pollutant 2,4,6-trinitrophenol (TNP), which is highly desirable for practical applications. The presence of a free pyridine group on the LMOF particle surface was strategically utilized for the purpose of exclusive TNP-sensing.

Evaluation of Hexadate Ligand 1, 3-bis(2,2’:6’,2’’-Terpyridyl-5-Ylmethylsulfany l)Propane in the Determination of Iron(II) in Solution by Spectrophotometric and Fluoremetric Methods of Analysis

Uv-visible and fluorescence spectra of the ligand 1,3-bis(2,2’:6’,2’’-ter- pyridyl-5-ymethylsulfanyl)propane L and it’s iron(II) complex have been investigated for analytical purposes. The two spectra of L and terpy are very similar which confirmed the ability of L to co-ordinate through the six N atoms of L with minimum distortion of the metal ion’s octahedral geometry. The ligand-based absorption band of L is shifted to the longer wavelength. It was found that L is able to displace the two terpyridine groups in the complex to give [FeL]2 . The high stability of the complex makes it good in spectrophotometry analysis of metals ions in solution. The fluorescence of L was progressively quenched with an increasing concentration of iron(II). This makes L a possible reagent for the quantitative analysis of metal by measuring fluorescence quenching.