Synthesis of Pd complexes combined with photosensitizing of a ruthenium(II) polypyridyl moiety through a series of substituted bipyrimidine bridges. Substituent effect of the bridging ligand on the photocatalytic dimerization of alpha-methylstyrene

Mononuclear ruthenium complexes and dinuclear Ru...Pd complexes having a series of 2,2'-bipyrimidine ligands, [(bpy)2Ru(Ln)]2+ [Ln = 2,2'-bipyrimidine (L1), 5,5'-dimethyl-2,2'-bipyrimidine (L2), 5,5'-dibromo-2,2'-bipyrimidine (L3), 4,4'-dimethyl-2,2'-bipyrimidine (L4), and 4,4',6,6'-tetramethyl- 2,2'-bipyrimidine (L5)] and [(bpy)2Ru(Ln)PdL]m+ [Ln = L1-L3; PdL = PdMeCl (m = 2) and PdMe(solvent) (m = 3)], are prepared, and the obtained complexes are characterized by means of spectroscopic and crystallographic methods. Introduction of the substituents on the bipyrimidine ligands led to the substantial differences in their electrochemical and photophysical properties. Density functional theory calculations have been performed to understand the substituent effect on the ground-state molecular orbital energy level. Reactivity studies on the catalytic dimerization of alpha-methylstyrene revealed that the Pd complex having a Br-substituted bipyrimidine ligand were much more active than those of the corresponding Pd complexes having methyl-substituted or nonsubstituted bipyrimidine ligands.     

Improved synthesis of 2,2'-bipyrimidine

A high-yield synthesis was developed for the preparation of 2,2'-bipyrimidine (1) using the Ullmann coupling of 2-iodopyrimidine. The new procedure was also used for the preparation of 4,4',6,6'-tetramethyl-2,2'-bipyrimidine (2) and 5,5'-dibromo-2,2'-bipyrimidine (3).     

消旋的有机二磺酸三邻菲咯啉锌配合物(英)

Compound [Zn(phen)₃][BDA] (1) (BDA=6,6′-dibromo-2,2′-dimethoxy-1,1′-binaphthylene-4,4′-disulfonate, phen= 1,10-phenanthroline) composes of the anion part (racemic-(R,S)-6,6′-dibromo-2,2′-dimethoxy-1,1′-binaphthylene-4,4′-disulfonate ) and the cation part which consists of a racemic octahedrally coordinated zinc center defined six nitrogen atoms from three phen rings to form an inorganic chirality that can be resolution by chiral organic ligand, the 3D framework was formed through the strong H-bonding interaction between sulfonate and water. CCDC: 277924.     

Monometallic and dimetallic ruthenium(II)-terpyridine complexes employing the tetradentate ligands dipyridylpyrazolyl,dipyridyloxadiazole, and their dimethyl derivatives

The tetradentate ligands, 2,2'-(1H-pyrazole-3,5-diyl)bis(4- methylpyridine) (4,4'-Me2dppzH), 2,2'-(1H-pyrazole-3,5-diyl)bis(6-methylpyridine) (6,6'-Me2dppzH), 3,5-di(pyrid-2-yl)pyrazole (dppzH), and dipyridyloxadiazole (dpo) react with either Ru(trpy)Cl3 or trans-Ru(trpy)Cl2(NCCH3), where trpy is 2,2',2'-terpyridine, to form a variety of Ru(II) complexes. Among these are the symmetrical chloro-bridged Ru(II) dimer and the "in" and "out" geometric isomers of the monometallic Ru(II) containing species where "in" and "out" refer to the orientation of the Ru-Cl vector relative to the centroid of the ligand backbone. Thirteen complexes were prepared and painstakingly purified by careful recrystallization and/or exhaustive column chromatography. These complexes were characterized by 1H and 13C NMR, electronic absorption, and infrared spectroscopy. Additionally, [Ru2(tryp)2(6,6'-Me2dppz)mu-Cl](BF4)2 (3b(BF4)2), [Ru2(trpy)2(4,4'-Me2dppz)mu-Cl](PF6)2.0.5MeOH (3c), [Ru2(trpy)2(6,6'-Me2dppz)(CH2C(O)CH3)](PF6)2.0.5(CH3)2CO (9b), "in"-[Ru(trpy)(4,4'-Me2dppz)Cl](PF6).(CH3)2CO (1c), and "out"-[Ru(trpy)(dpo)Cl](PF6).(CH3)2CO (2d) were characterized by X-ray crystallography. Several ligand substitution reactions were attempted. For example, [Ru2(trpy)2(6,6'-Me2dppz)mu-Cl](BF4)2 (3b) was reacted with hydroxide ion to produce [Ru2(trpy)2(6,6'-Me2dppz)mu-OH](PF6)2 (6b). Complex 6b reacts with benzyl bromide to produce [Ru2(trpy)2(6,6'-Me2dppz)mu-Br](PF6)2 (7b) or with (CH3)3Sil to produce [Ru2(trpy)2(6,6'-Me2dppz)mu-I](PF6)2 (8b). of 6b with acetone forms the methyl enolate complex [Ru2(trpy)2(6,6'-Me2dppz)(CH2COCH3)](PF6)2 (9b) while, analogously to a Cannizarro reaction, the reaction with benzaldehyde forms the bridging benzoate complex [Ru2(trpy)2(6,6'-Me2dppz)(C6H4CO2)](PF6)2 (11b). The bridging azide complex [Ru2(trpy)2(6,6'-Me2dppz)mu-N3](PF6)2 (10b) is formed by reaction of 6b with (CH3)3-SiN3. Additionally, the chloride ligands of the monometallic complexes of "in"-[Ru(trpy)(dpo)Cl](PF6) (1d), "in"-[Ru(trpy)(4,4'-Me2dpo)Cl](PF6)] (1e), and "out"-[Ru(trpy)(dpo)Cl](PF6) (2d) were substituted with water to form their respective aqua complexes, 4d, 4e, and 5d. All of the complexes exhibit broad unsymmetrial absorption bands in the visible portion of the electromagnetic spectrum. The dimetallic complexes 3b and 3c exhibit two, 1e- reversible oxidation waves at +0.72 and +1.15 V, and at +0.64 and +1.13 V, respectively. These complexes were not emissive.     

Relative binding energies of gas-phase pyridyl ligand/metal complexes by energy-variable collisionally activated dissociation in a quadrupole ion trap

The relative binding energies of a series of pyridyl ligand/metal complexes of the type [M(I)L(2)](+) and [M(II)L(3)](2+) are investigated by using energy-variable collisionally activated dissociation in a quadrupole ion trap mass spectrometer. The pyridyl ligands include 1,10-phenanthroline and various alkylated analogues, 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, and 2,2':6',2' '-terpyridine, and the metal ions include cobalt, nickel, copper, zinc, cadmium, calcium, magnesium, lithium, sodium, potassium, rubidium, and cesium. The effect of the ionic size and electronic nature of the metal ion and the polarizability and degree of preorganization of the pyridyl ligands on the threshold activation voltages, and thus the relative binding energies of the complexes, are evaluated. Correlations are found between the binding constants of [M(II)L(3)](2+) complexes in aqueous solution and the threshold activation voltages of the analogous gas-phase complexes determined by collisionally activated dissociation.     

Molecular wiring of nanocrystals: NCS-enhanced cross-surface charge transfer in self-assembled Ru-complex monolayer on mesoscopic oxide films

We report on rapid ambipolar cross-surface charge transfer within self-assembled monolayers (SAM) of the heteroleptic Ru-complexes cis-RuLL'(NCS)(2) (L = 2,2'-bipyridyl-4,4'-dicarboxylic acid, L' = 4,4'-dinonyl-2,2'-bipyridyl) (1) and cis-RuLL' '(NCS)(2) (L = 2,2'-bipyridyl-4,4'-dicarboxylic acid, L' = 4,4'-dimethyl-2,2'-bipyridyl) (2) on the surface of mesoscopic insulating oxide films. The bipyridyl ligands of the Ru-complex transport electrons, while the NCS groups plays a pivotal role in mediating surface confined hole percolation. Molecular dynamics calculations show the NCS ligands of 1 and 2 to orient in a fashion that enhances the overlap of the HOMOs of neighboring ruthenium complexes. Using ab initio Hartree-Fock calculations the electronic coupling matrix element for intermolecular hole exchange at the surface is estimated to be 0.13 eV. Cyclic voltammetry as well as spectroelectrochemical and impedance measurements performed with a series of other Ru-complexes confirmed the control of the cross surface charge transfer by the molecular structure. Complex 2 shows the highest percolation rate, the surface hole diffusion coefficient being 1.1 x 10(-8) cm(2)/s. The effects of the ligand properties, such as denticity, geometry, and size, on the intermolecular charge transport are discussed in detail.     

Chemistry of Ruthenium Polypyridine Complexes: VIII. Electronic Structure and Reactivity of cis-[Ru(2,2'-Bpy)2(L)Cl]+ Complexes in Excited States

Ab initio and semiempirical CINDO/CI calculations of free ligands L and complexes cis-[Ru(bpy)₂(L)Cl]⁺ [bpy = 2,2'-bipyridyl, L = pyridine, 3-cyanopyridine, 4-picoline, nicotinamide, isonicotinamide, 4-picoline, 4-aminopyridine, 4,4'-bipyridyl (bipy), trans-1,2-bis(4-pyridyl)ethene, 4,4'-azopyridine, pyrazine (pyz), and imidazole] were used to study the interrelation between the electronic structures of the ligands and the complexes in the ground and electronically excited states and to interpret the electronic absorption spectra of the complexes. The quantum yields for photosubstitution of a solvent molecule for a ligand L were measured; for L = pyz and bipy, photolysis quantum yields as a function of irradiation wave-length were studied. The possibility of population of ligand-field photoactive states from overlying charge-transfer states and the associative mechanism of ligand photosubstitution were discussed.     

Electrochemical and phosphorescent properties of new mixed-ligand Ir(II) complexes coordinated with both terpyridine and various bipyridine derivatives.

Seven useful mixed-ligand complexes in the form of [Ir(terpy)(L)Cl]2+ were prepared and their spectroscopic and electrochemical properties were investigated. The ligands used were terpy = 2,2':6',2'-terpyridine, L = 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, 4,4'-diphenyl-2,2'-bipyridine, 1,10-phenanthroline, 5-phenyl-1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, 2,3-bis(2-pyridyl)pyrazine. Synthetic methods were developed by a sequential ligand-replacement which occurred in the reaction vessel using a microwave oven. All complexes showed that LUMOs are based on the pi-system contribution of the terpyridine ligand for [Ir(terpy)(bpy)Cl]2+, [Ir(terpy)(dmbpy)Cl]2+, [Ir(terpy)(dpbpy)Cl]2+, [Ir(terpy)(phen)Cl]2+, [Ir(terpy)(dpphen)Cl]2+ and [Ir(terpy)(phphen)Cl]2+. On the other hand, the LUMO in the [Ir(terpy)(bppz)Cl]2+ complex is localized on the pi-system of the bppz ligand, whereas the HOMOs in the iridium complexes are localized on the terpyridine ligand. It was found that Ir(terpy)(L)Cl emits in a fluid solution at room temperature. The ancillary ligands, such as terpy and bpy, have been explored to extend the lifetime of the triplet 3(pi-pi') excited states of Ir(III) terpyridine complexes. Ir(III) terpyridine units with an electron donor (dmbpy) or electron acceptor substituents (terpy, dpbpy, phphen, dpphen and bppz) are found to decrease the energy of the 3LC states for use as photosensitizer molecular components in supramolecular devices. The spectroscopic and electrochemical details are also reported herein.     

The Crystal Structure of Biphenyltetracarboxylic Dianhydride Isomers

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Tailoring the Exchange Interaction in Covalently Linked Basic Carboxylate Clusters through Bridging Ligand Selection

We are reporting new dimeric units of basic carboxylates bearing the {Fe(III)(2)M(II)O} motif for M = Co and Ni, covalently bound through the tetradentate bridging (LL) 2,2'-azopyiridine (azpy) and 2,3-di(2-pyridyl)quinoxaline ligands (dpq). We structurally characterized the hexanuclear clusters, and their magnetic properties have been fully analyzed. DFT calculations have been performed as a supplementary tool. All results evidence a weak antiferromagnetic interaction through the bridging ligands between isolated spin ground states arising from intra-Fe(2)MO core exchange couplings. Together with the pioneer 2,2'-bipyrimidine bridged systems, the new complexes reported constitute a family of complexes where the exchange interaction can be tuned by the selection of the bridging LL type ligand.     

Towards catenanes using π-stacking interactions and their influence on the spin-state of a bis(2,2':6',2"terpyridine)iron(II) domain

The ligand 6,6"bis(4-methoxyphenyl)-4'-phenyl-2,2':6',2"terpyridine (2) has been prepared and characterized; deprotection using pyridinium chloride leads to the formation of 6,6"bis(4-hydroxyphenyl)-4'-phenyl-2,2':6',2"terpyridinium chloride ([H3]Cl). Treatment of the latter with 3-(2-(2-bromoethoxy)ethoxy)prop-1-ene under basic conditions yields ligand 4 containing pendant, alkene-terminated chains. Whereas direct complexation of 4 with ruthenium(II) proved problematical, the homoleptic complexes [Fe(2)(2)][PF(6)](2) and [Ru(2)(2)][PF(6)](2) were prepared in good to moderate yields. In the solid state, both complexes exhibit multiple face-to-face π-stacking of arene and pyridine rings which influences the coordination geometry about the metal ion. Consequential weakening of the ligand field results in [Fe(2)(2)][PF(6)](2) being high-spin. Variable temperature solution (1)H NMR spectroscopic studies confirm the iron(ii) centre remains high-spin between 200 and 295 K. The paramagnetically shifted (1)H NMR spectrum exhibits signals in the range δ 109.7 to -66.5 ppm and has been fully assigned. Paramagnetic relaxation enhancement (PRE) has been used to correlate the observed proton line-widths to the distances of the protons from the metal centre and these are in good agreement with the Fe···H separations observed in the solid state. The [Fe(2)(2)](2+) ion undergoes two dynamic processes (i) rotation of the pendant phenyl rings which is fast on the NMR timescale at 200 K, and (ii) twisting and sliding of the aromatic rings of the tpy and anisyl units which interconverts the two enantiomers of [Fe(2)(2)](2+) at 295 K.     

Mono- and dinuclear ruthenium(II) 1,6,7,12-tetraazaperylene complexes

We report the synthesis of free 1,6,7,12-tetraazaperylene (tape). Tape was obtained from 1,1'-bis-2,7-naphthyridine by potassium promoted cyclization followed by oxidation with air. Mono- and dinuclear ruthenium(II) 1,6,7,12-tetraazaperylene complexes of the general formulas [Ru(L-L)(2)(tape)](PF(6))(2), [1](PF(6))(2)-[5](PF(6))(2), and [{Ru(L-L)(2)}(2)(μ-tape)](PF(6))(4), [6](PF(6))(4)-[10](PF(6))(4), with{L-L = phen, bpy, dmbpy (4,4'-dimethyl-2,2'-bipyridine), dtbbpy (4,4'-ditertbutyl-2,2'-bipyridine) and tmbpy (4,4'5,5'-tetramethyl-2,2'-bipyridine)}, respectively, were synthesized. The X-ray structures of tape·2CHCl(3) and the mononuclear complexes [Ru(bpy)(2)(tape)](PF(6))(2)·0.5CH(3)CN·0.5toluene, [Ru(dmbpy)(2)(tape)](PF(6))(2)·2toluene and [Ru(dtbbpy)(2)(tape)](PF(6))(2)·3acetone·0.5H(2)O were solved. The UV-vis absorption spectra and the electrochemical behavior of the ruthenium(ii) tape complexes were explored and compared with the data of the analogous dibenzoeilatin (dbneil), 2,2'-bipyrimidine (bpym) and tetrapyrido[3,2-a:2',3'-c:3',2'-h:2',3'-j]phenazin (tpphz) species.     

Synthesis, structure, redox properties, and catalytic activity of new ruthenium complexes containing neutral or anionic and facial or meridional ligands: an evaluation of electronic and geometrical effects

The synthesis of a family of new Ru complexes containing meridional or facial tridentate ligands with the general formula [Ru(II)(T)(D)(X)](n+) [T = 2,2':6',2' '-terpyridine or tripyrazolylmethane; D = 4,4'-dibenzyl-4,4',5,5'-tetrahydro-2,2'-bioxazole (S,S-box-C) or 2-[((1'S)-1'-(hydroxymethyl)-2'-phenyl)ethylcarboxamide]-(4S)-4-benzyl-4,5-dihydrooxazole (S,S-box-O); X = Cl, H(2)O, MeCN or pyridine] has been described. All complexes have been spectroscopically characterized in solution through (1)H NMR and UV-vis techniques. Furthermore, all of the chloro complexes presented here have also been characterized in the solid state through monocrystal X-ray diffraction analysis. The oxazolinic S,S-box-C ligands undergo a Ru-assisted hydrolysis reaction generating the corresponding amidate anionic oxazolinic ligands S,S-box-O, which are also strongly attached to the metal center and produce a strong sigma-donation effect over the Ru metal center. The redox properties of all complexes have also been studied by means of cyclic voltammetry, strongly reflecting the nature of the ligands; both effects, geometrical (facial vs meridional) and electronic (neutral vs anionic), can be unveiled and rationalized. Finally, the reactivity of the Ru-OH(2) complexes has been tested with regard to the epoxidation of trans-stilbene, and it has been shown that, in this particular case, the reactivity is practically not dependent on the redox potentials of the catalyst but, in sharp contrast, it is strongly dependent on the geometry of the tridentate ligands.     

Emissive Osmium(II) Complexes Supported by N-Heterocyclic Carbene-based C(∧)C(∧)C-Pincer Ligands and Aromatic Diimines

Osmium(II) complexes containing N-heterocyclic carbene (NHC)-based pincer ligand 1,3-bis(1-methylimidazolin-2-ylidene)phenyl anion (C(1)(∧)C(∧)C(1)) or 1,3-bis(3-methylbenzimidazolin-2-ylidene)phenyl anion (C(2)(∧)C(∧)C(2)) and aromatic diimine (2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), or 4,4'-diphenyl-2,2'-bipyridine (Ph(2)bpy)) in the form of [Os(C(∧)C(∧)C)(N(∧)N)(CO)](+) have been prepared. Crystal structures for these complexes show that the Os-C(NHC) bonds are essentially single (Os-C(NHC) distances = 2.079(5)-2.103(7) ?). Spectroscopic comparisons and time-dependent density functional theory (TD-DFT) calculations suggest that the lowest-energy electronic transition associated with these complexes (λ(max) = 493-536 nm, ε(max) = (5-10) × 10(3) dm(3) mol(-1) cm(-1), solvent = CH(3)CN) originate from a d(π)(Os(II)) → π*(N(∧)N) metal-to-ligand charge transfer transition, where the d(π)(Os(II)) and π*(N(∧)N) levels contain significant contribution from the C(∧)C(∧)C ligands. All these complexes are emissive in the red-spectral region (674-731 nm) with quantum yields of 10(-4)-10(-2) and emission lifetimes of around 1-6 μs. Transient absorption spectroscopy and spectroelectrochemical measurements have also been used to probe the nature of the emissive excited-states. Overall, this joint experimental and theoretical investigation reveals that the C(∧)C(∧)C ligands can be used to modulate the photophysical properties of a [Os(N(∧)N)] core via the formation of the hybrid [Os + C(∧)C(∧)C] frontier orbitals.     

New Class of Chiral Diphosphine Ligands for Highly Efficient Transition Metal-Catalyzed Stereoselective Reactions: The Bis(diphenylphosphino) Five-membered Biheteroaryls

The synthesis and application of three examples of a new class of chiral (C(2)) atropisomeric diphosphines characterized by two interconnected five-membered heteroaromatic rings, with hindered rotation around the interanular bond, are described. Optically pure (+)- and (-)-2,2'-bis(diphenylphosphino)-4,4',6,6'-tetramethyl-3,3'-bibenzo[b]thiophene (tetraMe-bitianp) (1a) and the parent unsubstituted system (+)- and (-)-bitianp (1b) were synthesized. They were found to be optically stable at 100 degrees C and were successfully employed as ligands in the Ru(II)-catalyzed hydrogenation of alpha- and beta-oxo esters to the corresponding alpha- and beta-hydroxy esters and in the hydrogenation of olefinic substrates. The optical and chemical yields were comparable with those reported for the same Ru(II)-binap-catalyzed reactions carried out under the same experimental conditions. The 2,2'-bis(diphenylphosphino)-3,3'-bibenzo[b]furan (1c), the oxygenated analogue of bitianp, was found to be configurationally unstable at room temperature. Complete structural X-ray elucidation of the Pd complexes of 1a-c is reported. The advantages of these biheteroaromatic ligands over the classical biaryl systems are discussed.     

Remarkable steric effects and influence of monodentate axial ligands l on the spin-crossover properties of trans-[FeII(N4 ligand)L] complexes

Iron(II) complexes obtained from tetradentate, rigid, linear N4 ligands have been investigated to appraise the influence of steric effects and the impact of trans-coordinated anions on the spin-transition behavior. As expected, the well-designed ligands embrace the metal center, resulting in octahedral iron(II) complexes where the basal plane is fully occupied by the pyridine/pyrazole N4 ligand, while anions or solvent molecules are exclusively axially coordinated. Precursor complexes, namely, [Fe(bpzbpy)(MeOH)2](BF4)2 (where bpzbpy symbolizes the ligand 6,6'-bis(N-pyrazolylmethyl)-2,2'-bipyridine) and [Fe(mbpzbpy)(MeOH)2](BF4)2 (where mbpzbpy symbolizes the ligand 6,6'-bis(3,5-dimethyl-N-pyrazolmethyl)-2,2'-bipyridine), have been used for the in situ preparation of a series of structural analogues via the exchange of the weakly coordinated trans methanol molecules by various anions, such as thiocyanate, selenocyanate, or dicyanamide. The magnetic properties of all seven iron(II) compounds thus obtained have been investigated. Two iron(II) complexes, i.e., [Fe(bpzbpy)(NCS)2] and [Fe(bpzbpy)(NCSe)2], exhibit gradual spin-crossover (SCO) properties typical of isolated mononuclear species with weak cooperative interaction. These two SCO materials have been studied by M?ssbauer spectroscopy, and the light-induced excited spin state trapping effect has been investigated, revealing the possibility to induce the spin-transition both by temperature variation and by light irradiation. A correlation between steric/anion effect and SCO behavior is suggested.     

Synthesis, structure, and properties of [Pt(II)(diimine)(dithiolate)] dyes with 3,3'-, 4,4'-, and 5,5'-disubstituted bipyridyl: applications in dye-sensitized solar cells

A family of [Pt(II)(diimine)(dithiolate)] complexes of general formula [Pt{X,X'(CO(2)R)(2)-2,2'-bipyridyl}(maleonitriledithiolate)] (where X = 3, 4, or 5 and R = H or Et) have been synthesized, spectroscopically and electrochemically characterized, and attached to a TiO(2) substrate to be tested as solar cell sensitizers. A single-crystal X-ray structure showing a large torsion angle between the bipyridyl rings was determined for [Pt{3,3'(CO(2)Et)(2)-2,2'-bipyridyl}(maleonitriledithiolate)].MeCN. The effect of changing the position of the bipyridyl substituents from 3,3' to 4,4' and 5,5' is discussed with reference to structural and electronic changes seen within the different members of the family of molecules. The first UV/vis/NIR spectroelectrochemical study of complexes of this general formula is discussed. All three complexes (where R = H) were tested as solar cell sensitizers, with the 3,3'-disubstituted bipyridyl complex giving an intermediate dye loading value but superior photovoltaic performance to those of the other two. The performance of this sensitizer is then compared with that of a well-known Ru polypyridyl sensitizer, the ditetrabutylammonium salt of [RuL(2)(NCS)(2)] (L = 2,2'-bipyridyl-4,4'-dicarboxylato), commonly called N719.     

Syntheses, structures, and luminescence of novel lanthanide complexes of tripyridylamine, N,N,N',N'-tetra(2-pyridyl)-1,4-phenylenediamine and N,N,N',N'-tetra(2-pyridyl)biphenyl-4,4'-diamine

Two novel blue luminescent bridging ligands N,N,N',N'-tetra(2-pyridyl)-1,4-phenylenediamine (tppd) and N,N,N',N'-tetra(2-pyridyl)-1,1-biphenyl-4,4'-diamine (tpbpd) have been synthesized. Several novel lanthanide complexes containing 2,2',2"-tripyridylamine (2,2',2"-tpa), 2,2',3"-tpa, tppd, or tpbpd ligands have been synthesized and characterized structurally, which include Pr(hfa)3(2,2',2"-tpa), I, Ln(tmhd)3(2,2',3"-tpa), 2 (Ln = Dy, 2a; Eu, 2b; Tb, 2c; Sm, 2d), [Eu(tmhd)3][Pr(hfa)3](2,2',3"-tpa), 3, [Pr(hfa)3]2(tppd), 4, and [Ln(hfa)3]2(tpbpd), 5, where Ln = Pr (5a), Eu (5b), tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionato, and hfa = hexafluoroacetylacetonate. The Dy(III), Eu(III), and Tb(III) complexes display a bright photoluminescence, which can be achieved by either a direct excitation process or an indirect excitation process. Compounds 2a-2d can be sublimed readily.     

Synthesis and photophysical properties of novel amphiphilic ruthenium (II) complexes containing 4,4′‐dialkylaminomethyl‐2,2′‐bipyridyl ligands

The synthesis of a number of new 2,2′‐bipyridine ligands functionalized with bulky amino side groups is reported. Three homoleptic polypyridyl ruthenium (II) complexes, [Ru(L)₃]²⁺ 2(PF₆^?), where L is 4,4′‐dioctylaminomethyl‐2,2′‐bipyridine (Ru4a), 4,4′‐didodecylaminomethyl‐2,2′‐bipyridine (Ru4b) and 4,4′‐dioctadodecylaminomethyl‐2,2′‐bipyridine (Ru4c), have been synthesized. These compounds were characterized and their photophysical properties examined. The electronic spectra of three complexes show pyridyl π → π* transitions in the UV region and metal‐to‐ligand charge transfer bands in the visible region. Copyright © 2005 John Wiley & Sons, Ltd.     

Electrochemical and luminescent properties of new mononuclear ruthenium(II) and binuclear iridium(III)-ruthenium(II) terpyridine complexes.

Hexafluorophosphate salts of mononuclear complexes [Ru(II)Cl(L)(terpy)]+ (L = dmbpy (1); dpbpy (2), sambpy (3), and dpp (7), and binuclear complexes [Ru(II)2Cl2(dpp)(terpy)2]2+ (8) and [Ir(III)Ru(II)Cl2(dpp)(terpy)2]3+ (9) were prepared and characterized. Abbreviations of the ligands are bpy = 2,2'-bipyridine, dmbpy = 4,4'-dimethyl-2,2'-bipyridine, dpbpy = 4,4'-diphenyl-2,2'-bipyridine, dpp = 2,3-bis(2-pyridyl)pyrazine, sambpy = 4,4'-bis((S)-(+)-alpha-1-phenylethylamido)-2,2'-bipyridine, and terpy = 2,2':6',2'-terpyridine. The absorption spectra of 8 and 9 are dominated by ligand-centered bands in the UV region and by metal-to-ligand charge-transfer bands in the visible region. The details of their spectroscopic and electrochemical properties were investigated. In both binuclear complexes, it has been found that the HOMO is based on the Ru metal, and LUMO is dpp-based. [Ir(III)Ru(II)Cl2(dpp)(terpy)2]3+, indicating intense emission at room temperature, and a lifetime of 154 ns. The long lifetime of this bimetallic chromophore makes it a useful component in the design of supramolecular complexes.