Terpyridyl Complexes Research Articles

Luminescent Platinum(II) Terpyridyl Complexes: Effect of Counter Ions on Solvent‐Induced Aggregation and Color Changes

A series of platinum(II) terpyridyl complexes [Pt(tpy)(C triple bond C-C triple bond CH)]X, 1-X (X=OTf-; PF6-; ClO4-; BF4-; BPh4-); [Pt(tpy)(C triple bond CC6H5)]X, 2-X (X=OTf-; PF6-; ClO4-; BF4-); [Pt(tpy)(C triple bond CC6H4OCH3-4)]OTf, 3-OTf, and [Pt(4'-CH3O-tpy)(C triple bond CC6H5)]OTf, 4-OTf (tpy=2,2':6',2''-terpyridine, OTf=trifluoromethanesulfonate) were synthesized and their photophysical properties determined. Electronic absorption and emission studies showed the formation of a new band upon increasing the diethyl ether content in an acetonitrile/diethyl ether mixture. This was ascribed to the formation of complex aggregates, the solution color of which is dependent on the nature of the anions. This indicates that counter ions play an important role in governing the degree of aggregation and the extent of interactions within these aggregates. Addition of various anions to solutions of 1-OTf and 1-PF6 produced anion-induced color changes upon solvent-induced aggregation, indicating that these complexes may serve as potential colorimetric anion probes.

Polymer‐Induced Self‐Assembly of Alkynylplatinum(II) Terpyridyl Complexes by Metal⋅⋅⋅Metal/π⋅⋅⋅π Interactions

Die Deprotonierung von Polycarbonsäuren löst die Selbstorganisation von Terpyridylplatin(II)-Komplexen aus (siehe Bild), die mit bemerkenswerten Änderungen in den UV/Vis-Spektren und Emissionsintensitäten einhergeht. Ursache für die Änderungen in den Spektren sind aus der Aggregation der Komplexe folgende Charge-Transfer-Übergänge zwischen Metall-Metall-Bindung und Ligand.

Polymer‐Induced Self‐Assembly of Alkynylplatinum(II) Terpyridyl Complexes by Metal⋅⋅⋅Metal/π⋅⋅⋅π Interactions

Deprotonation of polycarboxylic acids induces the self-assembly of terpyridylplatinum(II) complexes (see picture) and triggers remarkable changes in the UV/Vis spectra and emission intensities. The changes in the electronic spectra arise from metal-metal-to-ligand charge transfer transitions resulting from the aggregation of the complexes.

Synthesis, Photophysical Properties, and Biomolecular Labeling Studies of Luminescent Platinum(II)-Terpyridyl Alkynyl Complexes

Three luminescent alkynylplatinum(II) terpyridyl complexes, [Pt(tBu3tpy)(C⋮C−C6H4−X-4)](OTf) (X = NH2 1, NCS 2, NHCOCH2I 3), have been synthesized and characterized. Their electrochemical and photophysical properties have been studied, and the molecular structure of 2 has also been determined by X-ray crystallography. Complexes 2 and 3 exhibit strong luminescence in various media, the origin of which has been tentatively assigned as a dπ(Pt) → π*(tBu3tpy) 3MLCT excited state, with some mixing of a π(C⋮CR) → π*(tBu3tpy) 3LLCT character. Human serum albumin (HSA) has been labeled by the ready reaction of the isothiocyanate and iodoacetamide functional groups in 2 and 3, to afford the respective bioconjugates, 2-HSA and 3-HSA. Both bioconjugates in 50 mM Tris-Cl buffer (pH 7.4) are highly colored and exhibit luminescence in the visible region upon photoexcitation.

Photocatalytic hydrogen production from hantzsch 1,4-dihydropyridines by platinum(II) terpyridyl complexes in homogeneous solution.

1,4-Dihydropyridines have been photocatalytically oxidized to pyridines by platinum(II) terpyridyl complexes with the generation of hydrogen in homogeneous solution. The hydrogen production proceeds in quantitative yield and with great catalytic turnover.

Photochemical behavior of azobenzene-conjugated CoII, CoIII, and FeII bis(terpyridine) complexes.

Azobenzene-conjugated mononuclear and dinuclear terpyridyl complexes of Co(II), Co(III), and Fe(II) were synthesized, and their photoisomerization behavior was investigated. Co(II) and Co(III) complexes, [tpyCo(tpy-AB)]X(n) and [(Cotpy)(2)(tpy-AB-tpy)]X(n) (tpy-AB = C(15)N(3)H(10)-C(6)H(4)-N=NC(6)H(5), tpy-AB-tpy = C(15)N(3)H(10)-C(6)H(4)-N=NC(6)H(4)-C(15)N(3)H(10), X = PF(6) or BPh(4)), exhibit trans-to-cis photoisomerization by irradiation at 366 nm, and this behavior is dependent on solvents and counterions. For the Co(II) complexes, BPh(4) salts undergo cis-to-trans isomerization in propylene carbonate by both photoirradiation with visible light (435 nm) and heat, indicating that reversible trans-cis isomerization has occurred. [Co(tpy-AB)(2)](BPh(4))(2) shows a two-step trans-to-cis isomerization process. The trans-cis isomerization behavior of Co(III) complexes was observed only in the solvents with a low donor number such as 1,2-dichloroethane. Fe(II) complexes, [tpyFe(tpy-AB)]X(n) (X = PF(6) or BPh(4)), exhibit slight trans-to-cis photoisomerization due to the energy transfer from the azobenzene moiety to Fe(tpy)(2) moieties.

Luminescent platinum(II) terpyridyl-capped carbon-rich molecular rods--an extension from molecular- to nanometer-scale dimensions.

A change in shift! In contrast to the red shift commonly found in organic polyynes and other metal–alkynyl systems, a blue shift in the transition energy was observed in electronic absorption and emission studies on a novel series of structurally characterized dinuclear platinum(II)–terpyridyl complexes [{Pt(tBu3-tpy)}2(CC)n](X)2 (1–3; tBu3-tpy=4,4′,4′′-tri-tert-butyl-2,2′:6′,2′′-terpyridine) upon increasing the extent of π conjugation of the alkynyl bridge.

Extended terpyridyl and triazine complexes of d6-metal centres

The reaction of a series of readily available extended terpyridyl and extended triazine ligands with several d6-metal centres has been investigated. This has led to the isolation and characterisation of nine new complexes, one of which is the first reported transition metal complex to contain the 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (tpymt) ligand. Two of the new complexes have had their molecular structures confirmed via X-ray crystallography studies. It has been shown that changes in the electronic properties of the coordinated ligand results in modulation of the electrochemical and photophysical properties of the complex to which it is coordinated. Furthermore, the emission properties of extended terpyridyl complexes incorporating the [Re(CO)3(MeCN)]+ centre suggest that luminescence in these complexes is from an extended terpyridyl based intraligand state.

Syntheses, electronic absorption, emission, and ion-binding studies of platinum(III) C empty set N empty set C and terpyridyl complexes containing crown ether pendants.

A series of platinum (II) C empty set N empty set C complexes, [Pt(C empty set N empty set C) (L)] (HC empty set N empty set CH=2,6-diphenylpyridine (dppy); L=Ph(2)PB15C5 (1, B15C5=benzo[15]crown-5), Ph(2)PDMP (2, DMP=3,4-dimethoxyphenyl), pyCOA15C5 (3, A15C5=aza[15]crown-5), pyCON(CH(2)CH(2)OCH(3))(2) (4), pyC[triple bond]CB15C5 (5), pyC[triple bond]CDMP (6)) and terpyridyl complexes, [Pt(trpy)(L)](X)(2) (trpy=2,2':6',2''-terpyridine; L=Ph(2)PB15C5, X=OTf (7 a), PF(6) (7 b); X=PF(6), L=Ph(2)PDMP (8), pyC[triple bond]CB15C5 (9), and pyC[triple bond]CDMP (10)) have been successfully synthesized and characterized. The structures of 1, 3, and 7 a have been determined by X-ray crystallography. Excitation of complexes 1-6 in EtOH/MeOH (4:1 v/v) glass gave high-energy structured emission bands, assigned as derived from states of metal-perturbed intraligand (IL) origin. At higher concentrations, complexes 3-6 each displayed an additional, structureless emission band at 600-615 nm, with complexes 5 and 6 showing an obvious increase in the intensity of this emission band when the concentration was increased further. In dichloromethane at room temperature, complexes 3-6 showed, in addition to the high-energy emission at 490-505 nm, an extra, broad emission band at 620-625 nm when the concentration was increased. The emission origins of the low-energy band in glass and in fluid solutions are suggested to be derived from the ground-state oligomerization or aggregation process of the complexes. In the solid state at room temperature, complexes 1-6 each showed a broad, unstructured emission band at 560-600 nm, which was shifted to lower energy upon cooling to 77 K. On the other hand, the terpyridyl analogues 7-10 displayed intense vibronic-structured intraligand (IL) emissions at 460-472 nm in butyronitrile glass at 77 K. Solid-state samples of 9 and 10 displayed strong phosphorescence upon photoexcitation at 298 K and 77 K, tentatively assigned as derived from states of Pt(d pi)-->pi*(trpy) (3)MLCT origin(MLCT=metal-to-ligand charge transfer). The ion-binding properties of complexes 5 and 9 for Na(+), Ba(2+), and K(+) ions have been studied by UV/Vis spectrophotometric methods, and confirmed by ESI mass spectrometric studies. The ion-binding properties for Na(+) ions have also been probed by (1)H NMR experiments. For the same crown ether-containing ligand and the same metal ions, the neutral cyclometalated complexes gave larger binding constants than the positively charged terpyridyl analogues.

Solvent-induced aggregation through metal...metal/pi...pi interactions: large solvatochromism of luminescent organoplatinum(II) terpyridyl complexes.

A dramatic color change and tremendous emission enhancement have been "switched on" upon increasing diethyl ether ratio in acetonitrile or acetone solution of [Pt(tpy)(CC-CCH)]OTf, attributed to the formation of Pt...Pt and pi-pi interactions. Two crystal forms (dark-green and red) of [Pt(tpy)(CC-CCH)]OTf, together with [Pt(tBu3-tpy)(CC-CCH)]OTf, show different crystal-packing modes as revealed by X-ray crystallography.

Separation of linkage isomers of trithiocyanato (4,4′,4″-tricarboxy-2,2′,6,2″-terpyridine)ruthenium(II) by pH-titration method and their application in nanocrystalline TiO2-based solar cells

A new series of panchromatic ruthenium(II) sensitizers derived from carboxylated terpyridyl complexes of tris-thiocyanato Ru(II) have been developed. The linkage isomers {(C4H9)4N}3[Ru(Htcterpy)(–NCS)3] 1, {(C4H9)4N}3[Ru(Htcterpy)(–NCS)2(–SCN)] 2 and {(C4H9)4N}3[[Ru(Htcterpy)(–SCN)3] 3 have been separated by pH titration method and fully characterized by UV–Vis, emission, IR and NMR studies. The absorption and emission maxima of the isomer 1 show a bathochromic shift with decreasing pH, and exhibit pH-dependent excited state lifetimes. The red-shift of the emission maxima is due to better π-acceptor properties of the acid form that lowers the energy of the CT excited state. The isomer 1, when anchored to nanocrystalline TiO2 films achieves very efficient sensitization over the whole visible range extending into the near IR region up to 920 nm, yielding over 80% incident photon-to-current conversion efficiencies (IPCEs). Solar cells containing the isomer 1 were subjected to analysis by a photovoltaic calibration laboratory (NREL, USA) to determine their solar to electric conversion efficiency under standard AM 1.5 sunlight. A short circuit photocurrent density obtained was 20.5 mA/cm2 and the open circuit voltage was 0.72 V corresponding to an overall conversion efficiency of 10.4%.

Engineering of Efficient Panchromatic Sensitizers for Nanocrystalline TiO2-Based Solar Cells

A new series of panchromatic ruthenium(II) sensitizers derived from carboxylated terpyridyl complexes of tris-thiocyanato Ru(II) have been developed. Black dye containing different degrees of protonation [(C(2)H(5))(3)NH][Ru(H(3)tcterpy)(NCS)(3)] 1, [(C(4)H(9))(4)N](2)[Ru(H(2)tcterpy)(NCS)(3)] 2, [(C(4)H(9))(4)N](3)[Ru(Htcterpy)(NCS)(3)] 3, and [(C(4)H(9))(4)N](4)[Ru(tcterpy)(NCS)(3)] 4 (tcterpy = 4,4',4' '-tricarboxy-2,2':6',2' '-terpyridine) have been synthesized and fully characterized by UV-vis, emission, IR, Raman, NMR, cyclic voltammetry, and X-ray diffraction studies. The crystal structure of complex 2 confirms the presence of a Ru(II)N6 central core derived from the terpyridine ligand and three N-bonded thiocyanates. Intermolecular H-bonding between carboxylates on neighboring terpyridines gives rise to 2-D H-bonded arrays. The absorption and emission maxima of the black dye show a bathochromic shift with decreasing pH and exhibit pH-dependent excited-state lifetimes. The red-shift of the emission maxima is due to better pi-acceptor properties of the acid form that lowers the energy of the CT excited state. The low-energy metal-to-ligand charge-transfer absorption band showed marked solvatochromism due to the presence of thiocyanate ligands. The Ru(II)/(III) oxidation potential of the black dye and the ligand-based reduction potential shifted cathodically with decreasing number of protons and showed more reversible character. The adsorption of complex 3 from methoxyacetonitrile solution onto transparent TiO(2) films was interpreted by a Langmuir isotherm yielding an adsorption equilibrium constant, K(ads), of (1.0 +/- 0.3) x 10(5) M(-1). The amount of dye adsorbed at monolayer saturation was (n(alpha) = 6.9 +/- 0.3) x 10(-)(8) mol/mg of TiO(2), which is around 30% less than that of the cis-di(thiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) complex. The black dye, when anchored to nanocrystalline TiO(2) films achieves very efficient sensitization over the whole visible range extending into the near-IR region up to 920 nm, yielding over 80% incident photon-to-current efficiencies (IPCE). Solar cells containing the black dye were subjected to analysis by a photovoltaic calibration laboratory (NREL, U.S.A.) to determine their solar-to-electric conversion efficiency under standard AM 1.5 sunlight. A short circuit photocurrent density obtained was 20.5 mA/cm(2), and the open circuit voltage was 0.72 V corresponding to an overall conversion efficiency of 10.4%.

Palladium-catalysed cross-coupling reactions of ruthenium bis-terpyridyl complexes: strategies for the incorporation and exploitation of boronic acid functionality

The palladium catalysed Miyaura cross-coupling reactions of 4′-(4-bromophenyl)-2,2′:6′,2″-terpyridine (tpy-ϕ-Br) and 4′-bromo-2,2′:6′,2″-terpyridine (tpy-Br) with bis(neopentyl glycolato)diboron (B2neo2) lead to the first reported examples of boronate ester-substituted terpyridine ligands, L1 and L2. Ligand L1, which incorporates a benzene ring between the terpyridine group and the boron, reacts with transition metals such as iron and ruthenium to generate complexes containing the analogous boronic acid-substituted terpyridine L3. The heteroleptic complex [Ru(ttpy)L3]2+ has also been prepared by an analogous cross-coupling reaction of the bromo complex [Ru(ttpy)(tpy-ϕ-Br)]2+ with B2neo2 (ttpy = 4′-tolyl-2,2′:6′,2″-terpyridine). The structurally related complex [Ru(ttpy)L4]2+ (L4 = terpyridine-4′-boronic acid) could not be prepared, either directly from L2 or from [Ru(ttpy)(tpy-Br)]2+, apparently due to competitive hydrodeboration and solvolysis. The complex [Ru(ttpy)L3]2+ reacts with aryl halides under standard palladium-catalysed Suzuki–Miyaura cross-coupling conditions to generate more elaborate 4′-aryl-substituted terpyridyl complexes. Cross-coupling has also been achieved by reaction of [Ru(ttpy)(tpy-Br)]2+ with an arylboronic acid. The photophysical properties of [Ru(ttpy)L3]2+ are shown to be largely typical of ruthenium bis-terpyridyl complexes.

Catalytic Activity of Ni(II)−Terpyridine Complex in Phosphodiester Transesterification Remarkably Enhanced by Self-Assembly of Terpyridines on Poly(ethylenimine)

To enhance the catalytic activity of metal−terpyridyl complexes toward transesterification of an RNA model [(2-hydroxypropyl)-p-nitrophenyl phosphate, HPNPP], the conformation of terpyridyl moieties assembled on poly(ethylenimine) (PEI) is optimized by attaching the Ni(II) complex of a terpyridyl derivative (NiIITP) and lauryl (Lau) group to PEI in random combinations. The catalytic activity per Ni(II) center for transesterification of HPNPP varies by up to several thousand times depending on pH as the content of NiIITP or Lau is changed. The best catalyst obtained is [NiIITP]5Lau12PEI, in which the contents of NiIITP and Lau are 5 and 12 residue mol %, respectively. The catalytic activity of [NiIITP]5Lau12PEI expressed in terms of kcat is much higher than those of previously reported binuclear metal complexes whose structures were designed through deliberate planning. In the PEI derivatives containing NiIITP and Lau, several NiIITP groups can be positioned in proximity in the hydrophobic clusters formed on the polymer. When the NiIITP groups take productive positions, the two phosphoryl−oxygen bonds and the hydroxyl group of HPNPP can be effectively activated. Thus, artificial active sites comprising multiple catalytic groups are obtained by self-assembly of the catalytic groups. Moreover, cooperative action among the catalytic groups is optimized through combinatorial approach.

Electron donating substituent effects on redox and spin state properties of iron(II) bis-terpyridyl complexes

The synthesis of iron(II) terpyridyl (trpy) complexes was achieved with the general formula [Fe(trpy)2−t((R)ttrpy)t](PFb)2, where R represents CH3O and (Et)2N. Both the methoxy and diethylamino substituents are electron donating in nature, where the latter is a new derivative of terpyridine. Cyclic voltammetry was used to assess the substituents' influence on the Fe(III)/II) couple in which an average shift in potential (ΔE1/2) of 0.06 volts per methoxy group, and 0.18 volts for each diethylamino group, was exhibited. Solution magnetic susceptibility measurements were carried out with standard NMR methodology. All of the Fe(II) complexes, except [Fe((Et2N)3trpy)2]2+, exhibited an expected low spin (S = 0) behavior. The [Fe((Et2N)3trpy)2]2+ complex was observed to have a room temperature paramagnetic moment (µelf) of 1.6 BM indicating thermal population of high spin (S = 2) state. Since [Co(trpy)2]2+ is known to be near the spin crossover (µeff = 3.2BM), the [Co((CH3O)3trpy)2]2+ was prepared in order to measure the influence methoxy substituents would have on µeff: a significant shift was observed (µeff = 4.2BM). The results of this study indicate that electron donating para-substituents on terpyridine affect the metal-ligand π-bonding interactions (by increasing the ligand's π-donor properties at the expense of weakening its π-acceptor capabilities) to a greater extent that the σ-interactions. This results in a decrease of the ligand field splitting.

Electronic Energy Transfer Across Ethynyl‐Bridged RuII/OsII Terpyridyl Complexes

Electronic Energy Transfer Across Ethynyl‐Bridged Ru^II/Os^II Terpyridyl Complexes

Rhenium(I) Coordination Chemistry: Synthesis, Reactivity, and Electrochemistry of Terpyridyl Complexes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRhenium(I) Coordination Chemistry: Synthesis, Reactivity, and Electrochemistry of Terpyridyl ComplexesLisa E. Helberg, Joseph Barrera, Michal Sabat, and W. Dean HarmanCite this: Inorg. Chem. 1995, 34, 8, 2033–2041Publication Date (Print):April 1, 1995Publication History Published online1 May 2002Published inissue 1 April 1995https://doi.org/10.1021/ic00112a014RIGHTS & PERMISSIONSArticle Views416Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts

Polarisation ratios in ruthenium(II) complexes containing tridentate ligands: A comment

The changes observed in the lifetimes and polarizations of ruthenium(II) terpyridyl complexes as low temperature are in accord with the general localised excited-state model.

Electro-oxidation and electro-reduction of some iron (II), cobalt(II) and nickel(II) polypyridyl complexes in acetonitrile

Cyclic voltammetry and controlled potential coulometry studies of 2,2′-bipyridyl, 4,4′-dimethyl-2,2′-bipyridyl and 2,2′, 2″-terpyridyl complexes of Fe(II), Co(II) and Ni(II) in acetonitrile are described. E 1/2 values for M(III)/M(II) and M(II)/M)I) couples are compared and crystal field effects discussed. A series of M(I) and M(III) polypyridyl complexes have been prepared by controlled potential electrolysis; these include a number of 3+ and 1+ oxidation state complexes of nickel which have not previously been isolated — [Ni(bipy) 3]-(ClO 4) 3, [Ni(dimbipy) 3](ClO 4) 3, [Ni(terpy) 2](ClO 4) 3 and [Ni(bipy) 2]ClO 4.

Terpyridyl complexes of platinum(II)

Terpyridyl complexes of platinum(II)