Synthesis, characterization, and luminescence properties of the ternary europium complex covalently bonded to mesoporous SBA-15

A novel mesoporous SBA-15 type of hybrid material (phen-SBA-15) covalently bonded with 1,10-phenanthroline (phen) ligand was synthesized by co-condensation of tetraethoxysilane (TEOS) and the chelate ligand 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline (phen-Si) in the presence of Pluronic P123 surfactant as a template. The preservation of the chelate ligand structure during the hydrothermal synthesis and the surfactant extraction process was confirmed by Fourier transform infrared (FTIR) and (29)Si MAS NMR spectroscopies. SBA-15 consisting of the highly luminescent ternary complex Eu(TTA)(3)phen (TTA = 2-thenoyltrifluoroacetone) covalently bonded to a silica-based network, which was designated as Eu(TTA)(3)phen-SBA-15, was obtained by introducing the Eu(TTA)(3).2H(2)O complex into the hybrid materials via a ligand exchange reaction. XRD, TEM, and N(2) adsorption measurements were employed to characterize the mesostructure of Eu(TTA)(3)phen-SBA-15. For comparison, SBA-15 doped with Eu(TTA)(3).2H(2)O and Eu(TTA)(3)phen complexes and SBA-15 covalently bonded with a binary europium complex with phen ligand were also synthesized, and were named SBA-15/Eu(TTA)(3), SBA-15/Eu(TTA)(3)phen, and Eu-phen-SBA-15, respectively. The detailed luminescence studies on all the materials showed that, compared with the doping sample SBA-15/Eu(TTA)(3)phen and binary europium complex functionalized sample Eu-phen-SBA-15, the Eu(TTA)(3)phen-SBA-15 mesoporous hybrid material exhibited higher luminescence intensity and emission quantum efficiency. Thermogravimetric analysis on Eu(TTA)(3)phen-SBA-15 demonstrated that the thermal stability of the lanthanide complex was evidently improved as it was covalently bonded to the mesoporous SBA-15 matrix.     

pH-sensitive fluorescent sensors based on europium(III) complexes

New europium(III) complexes Eu(TTA)(2)-DSQ and Eu(TTA)(3)-DR1 were designed and synthesized as new fluorescent pH probes (where HDSQ = 5-(dimethylamino)-N-(4-(2-((8-hydroxyquinolin-2-yl)methylene)hydrazinecarbonyl)phenyl)naphthalene-1-sulfonamide, DR1 = N(1)-(4-(dimethylamino)benzylidene)-N(2)-(rhodamine-6G) lactamethylene-diamine and TTA = thiophentrifluoroacetone). Eu(TTA)(2)-DSQ exhibited high sensitivity in monitoring pH changes in neutral aqueous solution with negligible background fluorescence. Eu(TTA)(3)-DR1 comprised a green light emitting Rhodamine 6G fluorophore and a Eu(III) moiety as the origin of red light. These pH-sensitive emitter components have pK(a) values of 5.0 and 7.2 respectively, and exhibit isolated protonated steps within one molecule. Luminescence titrations demonstrate that Eu(TTA)(3)-DR1 was able to detect pH values at both near neutral pH and acidic pH ranges, and was also able to detect pH in both cultured cells and in vivo.     

Amidines derived from Pt(IV)-mediated nitrile-amino alcohol coupling and their Zn(II)-catalyzed conversion into oxazolines

The reaction between the platinum(IV) complex trans-[PtCl(4)(EtCN)(2)] and the amino alcohols NH(2)CH(2)CH(2)OH, NH(2)CH(2)CH(Me)OH-(R)-(-), NH(2)CH(Ph)CH(2)OH-(R)-(-), NH(2)CH(Et)CH(2)OH-(R)-(-), NH(2)CH(Et)CH(2)OH-(S)-(+), and NH(2)CH(Pr(n)())CH(2)OH proceeds rapidly at room temperature in CH(2)Cl(2) to furnish the amidine complexes [PtCl(4)(HN=C(Et)NH(arcraise;)OH)(2)] (1-6) in good yield (70-80%). The related reaction between the platinum(II) complex trans-[PtCl(2)(EtCN)(2)] and monoethanolamine in a molar ratio of 1:2 in CH(2)Cl(2) results in the addition of 4 equiv of NH(2)CH(2)CH(2)OH per mole of complex to give [Pt(HN=C(Et)NHCH(2)CH(2)OH)(2)(NH(2)CH(2)CH(2)OH)(2)](2+) (7). Formulation of 1-6 is based upon satisfactory C, H, N elemental analyses, electrospray mass spectrometry, IR spectroscopy, and (1)H, (13)C((1)H), (15)N, and (195)Pt NMR spectroscopies, while the structures of trans-[PtCl(4)((Z)-NH=C(Et)NHCH(2)CH(2)OH)(2)] (1), trans-[PtCl(4)((Z)-NH=C(Et)NHCH(2)CH(Me)OH-(R)-(-))(2)] (2), and trans-[PtCl(4)((Z)-NH=C(Et)NHCH(Et)CH(2)OH-(R)-(-))(2)] (4) were determined by X-ray single-crystal diffraction. The Z-amidine configuration of the ligands is preserved in CDCl(3) solutions as confirmed by gradient-enhanced (15)N,(1)H-HMQC spectroscopy and NOE experiments. The amidines, formed upon Pt(IV)-mediated nitrile-amino alcohol coupling, were liberated from their platinum(IV) complexes 1, 3, and 4 by reaction with Ph(2)PCH(2)CH(2)PPh(2) (dppe) giving free NH=C(Et)NHCHRCH(2)OH (R = H 8, Et 9, Ph 10), with the substituents R of different types, and dppe oxides; the P-containing species were identified by (31)P((1)H) NMR spectroscopy. NOESY spectroscopy indicates that the liberated amidines retained the same configuration relative to the C=N double bond, i.e., syn-(H,Et)-NH=C(Et)NHCHRCH(2)OH. The liberated hydroxo-functionalized amidines 8-10 were converted into oxazolines (11-13) in the presence of a catalytic amount of ZnCl(2). A similar catalytic effect has also been reached using anhydrous MSO(4) (M = Cu, Co, Cd), CdCl(2), and AlCl(3).     

Novel tailoring reaction for two adjacent coordinated nitriles giving platinum 1,3,5-triazapentadiene complexes

The tailoring reaction of the two adjacent nitrile ligands in cis-[PtCl(2)(RCN)(2)] (R = Me, Et, CH(2)Ph, Ph) and [Pt(tmeda)(EtCN)(2)][SO(3)CF(3)](2) (8.(OTf)(2); tmeda = N,N,N',N'-tetramethylethylenediamine) upon their interplay with N,N'-diphenylguanidine (DPG; NH=C(NHPh)(2)), in a 1:2 molar ratio gives the 1,3,5-triazapentadiene complexes [PtCl(2){NHC(R)NHC(R)=NH}] (1-4) and [Pt(tmeda){NHC(Et)NHC(Et)NH}][SO(3)CF(3)](2) (10.(OTf)(2)), respectively. In contrast to the reaction of 8.(OTf)(2) with NH=C(NHPh)(2), interaction of 8.(OTf)(2) with excess gaseous NH(3) leads to formation of the platinum(II) bis(amidine) complex cis-[Pt(tmeda){NH=C(NH(2))Et}(2)][SO(3)CF(3)](2) (9.(OTf)(2)). Treatment of trans-[PtCl(2)(RCN)(2)] (R = Et, CH(2)Ph, Ph) with 2 equiv of NH=C(NHPh)(2) in EtCN (R = Et) and CH(2)Cl(2) (R = CH(2)Ph, Ph) solutions at 20-25 degrees C leads to [PtCl{NH=C(R)NC(NHPh)=NPh}(RCN)] (11-13). When any of the trans-[PtCl(2)(RCN)(2)] (R = Et, CH(2)Ph, Ph) complexes reacts in the corresponding nitrile RCN with 4 equiv of DPG at prolonged reaction time (75 degrees C, 1-2 days), complexes containing two bidentate 1,3,5-triazapentadiene ligands, i.e. [Pt{NH=C(R)NC(NHPh)=NPh}(2)] (14-16), are formed. Complexes 14-16 exhibit strong phosphorescence in the solid state, with quantum yields (peak wavelengths) of 0.39 (530 nm), 0.61 (460 nm), and 0.74 (530 nm), respectively. The formulation of the obtained complexes was supported by satisfactory C, H, and N elemental analyses, in agreement with FAB-MS, ESI-MS, IR, and (1)H and (13)C{(1)H} NMR spectra. The structures of 1, 2, 4, 11, 13, 14, 9.(picrate)(2), and 10.(picrate)(2) were determined by single-crystal X-ray diffraction.     

Regioselective HON-addition of bifunctional hydrazone oximes to Pt(IV)-bound nitriles

Treatment of trans-[PtCl(4)(RCN)(2)](R = Me, Et) with the hydrazone oximes MeC(=NOH)C(R')=NNH(2)(R' = Me, Ph) at 45 degrees C in CH(2)Cl(2) led to the formation of trans-[PtCl(4)(NH=C(R)ON=C(Me)C(R')=NNH(2))(2)](R/R' = Me/Ph 1, Et/Me 2, Et/Ph 3) due to the regioselective OH-addition of the bifunctional MeC(=NOH)C(R')=NNH(2) to the nitrile group. The reaction of 3 and Ph(3)P=CHCO(2)Me allows the formation of the Pt(II) complex trans-[PtCl(2)(NH=C(Et)ON=C(Me)C(Ph)=NNH(2))2](4). In 4, the imine ligand was liberated by substitution with 2 equivalents of bis(1,2-diphenylphosphino)ethane (dppe) in CDCl(3) to give, along with the free ligand, the solid [Pt(dppe)(2)]Cl(2). The free iminoacyl hydrazone, having a restricted life-time, decomposes at 20-25 degrees C in about 20 h to the parent organonitrile and the hydrazone oxime. The Schiff condensation of the free NH(2) groups of 4 with aromatic aldehydes, i.e. 2-OH-5-NO(2)-benzaldehyde and 4-NO(2)-benzaldehyde, brings about the formation of the platinum(II) complexes trans-[PtCl(2)(NH=C(Et)ON=C(Me)C(Ph)=NN=CH(C(6)H(3)-2-OH-5-NO(2))2](5) and trans-[PtCl(2)(NH=C(Et)ON=C(Me)C(Ph)=NN=CH(C(6)H(4)-4-NO(2))2](6), respectively, containing functionalized remote peripherical groups. Metallization of 5, which can be considered as a novel type of metallaligand, was achieved by its reaction with M(OAc)(2).nH(2)O (M = Cu, n= 2; M = Co, n= 4) in a 1:1 molar ratio furnishing solid heteronuclear compounds with composition [Pt]:[M]= 1:1. The complexes were characterized by C, H, N elemental analyses, FAB+ mass-spectrometry, IR, 1H, 13C[1H] and (195)Pt NMR spectroscopies; X-ray structures were determined for 3, 4 and 5.     

Reactivity of a sterically hindered Fe(II) thiolate dimer with amines and hydrazines

The sterically hindered Fe(II) thiolate dimer Fe(2)(mu-STriph)(2)(STriph)(2) (1; [STriph](-) = 2,4,6-triphenylbenzenethiolate) reacts with primary amines ((t)BuNH(2), aniline) and N(2)H(4) to form the structurally characterized addition complexes Fe(STriph)(2)(NH(2)(t)Bu)(2), Fe(2)(mu-STriph)(2)(STriph)(2)(NH(2)Ph)(2), and Fe(2)(mu-eta(1):eta(1)-N(2)H(4))(2)(N(2)H(4))(4)(STriph)(4) in high yield. Chemical and NMR spectroscopic evidence indicate that the binding of these nitrogen donors is labile in solution and multispecies equilibria are likely. With arylhydrazines, 1 catalytically disproportionates 1,2-diphenylhydrazine to aniline and azobenzene, and it rearranges 1-methyl-1,2-diarylhydrazines to give, after treatment with alumina, mononuclear, trigonal bipyramidal Fe(III) complexes of composition Fe(ISQ)(2)(STriph), where [ISQ](-) denotes an appropriately substituted bidentate o-diiminobenzosemiquinonate ligand. Complex 1 shows no reaction with hindered 1,2-dialkylhydrazines (isopropyl or tert-butyl) or tetrasubstituted 1,2-dimethyl-1,2-diphenylhydrazine.     

Lithiation of (tBuNH)3PNSiMe3 and formation of tetraimidophosphate complexes containing M3O3 rings (M = Li, K): X-ray structure of the stable radical [(Me3SiN)P(mu3-N(t)Bu)3[mu3-Li(THF)]3(OtBu))

The reaction of ((t)BuNH)(3)PNSiMe(3) (1) with 1 equiv of (n)BuLi results in the formation of Li[P(NH(t)Bu)(2)(N(t)Bu)(NSiMe(3))] (2); treatment of 2 with a second equivalent of (n)BuLi produces the dilithium salt Li(2)[P(NH(t)Bu)(N(t)Bu)(2)(NSiMe(3))] (3). Similarly, the reaction of 1 and (n)BuLi in a 1:3 stoichiometry produces the trilithiated species Li(3)[P(N(t)Bu)(3)(NSiMe(3))] (4). These three complexes represent imido analogues of dihydrogen phosphate [H(2)PO(4)](-), hydrogen phosphate [HPO(4)](2)(-), and orthophosphate [PO(4)](3)(-), respectively. Reaction of 4 with alkali metal alkoxides MOR (M = Li, R = SiMe(3); M = K, R = (t)Bu) generates the imido-alkoxy complexes [Li(3)[P(N(t)Bu)(3)(NSiMe(3))](MOR)(3)] (8, M = Li; 9, M = K). These compounds were characterized by multinuclear ((1)H, (7)Li, (13)C, and (31)P) NMR spectroscopy and, in the cases of 2, 8, and 9.3THF, by X-ray crystallography. In the solid state, 2 exists as a dimer with Li-N contacts serving to link the two Li[P(NH(t)Bu)(2)(N(t)Bu)(NSiMe(3))] units. The monomeric compounds 8 and 9.3THF consist of a rare M(3)O(3) ring coordinated to the (LiN)(3) unit of 4. The unexpected formation of the stable radical [(Me(3)SiN)P(mu(3)-N(t)Bu)(3)[mu(3)-Li(THF)](3)(O(t)Bu)] (10) is also reported. X-ray crystallography indicated that 10 has a distorted cubic structure consisting of the radical dianion [P(N(t)Bu)(3)(NSiMe(3))](.2)(-), two lithium cations, and a molecule of LiO(t)Bu in the solid state. In dilute THF solution, the cube is disrupted to give the radical monoanion [(Me(3)SiN)((t)BuN)P(mu-N(t)Bu)(2)Li(THF)(2)](.-), which was identified by EPR spectroscopy.     

Synthesis and photophysical properties of colloids fabricated by the layer-by-layer polyelectrolyte assembly onto Eu(III) complex as a core

The luminescent colloids have been synthesized through the layer-by-layer assembly of poly(sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI) onto the luminescent core. The latter has been obtained by the reprecipitation of complex Eu[(TTA)(3)1] (where TTA(-) and 1 are thenoyltrifluoroacetonate and 2-(5-chlorophenyl-2-hydroxy)-2-phenylethenyl-bis-(2-methoxyphenyl)phosphine oxide, respectively) from organic solvent to aqueous solution. The variation of Eu(III) complexes indicates the role of the complex core in the development of such core-shell colloids. Complex Eu[(TTA)(3)1] is most convenient precursor of Eu-doped luminescent nanocomposites. The fluorometric measurements at each step of the layer-by-layer polyelectrolyte assembly onto Eu[(TTA)(3)1] core, at various pHs and additives reveal the quenching of Eu-centered luminescence as a result of the interfacial interaction of the core and the dye. The AFM images and electrochemical behavior of PSS-(PEI-PSS)(n)-Eu[(TTA)(3)1] colloids deposited on the surface indicate the stability of the polyelectrolyte multilayer in the dried state.     

Unusual reaction between (nitrile)Pt complexes and pyrazoles: substitution proceeds via metal-mediated nitrile-pyrazole coupling followed by elimination of the nitrile

The reaction of platinum(IV) complex trans-[PtCl4(EtCN)2] with pyrazoles 3,5-RR'pzH (R/R' = H/H, Me/H, Me/Me) leads to the formation of the trans-[PtCl4{NH=C(Et)(3,5-RR'pz)}2] (1-3) species due to the metal-mediated nitrile-pyrazole coupling. Pyrazolylimino complexes 1-3 (i) completely convert to pyrazole complexes cis-[PtCl4(3,5-RR'pzH)2] by elimination of EtCN upon reflux in a CH2Cl2 solution or upon heating in the solid state; (ii) undergo exchange at the imino C atom with another pyrazole different from that contained in the pyrazolylimino ligand. The reaction of trans-[PtIICl2(EtCN)2] and 3,5-RR'pzH, conducted under conditions similar to those for trans-[PtIVCl4(EtCN)2], is much less selective, and the composition of the products strongly depends on the pyrazole employed: (a) with pzH, the reaction gives a mixture of three products, i.e., [PtCl2NH=C(Et)pz-kappa2N,N}] (4), [PtCl(pzH){NH=C(Et)pz-kappa2N,N}]Cl (5), and [Pt(pzH)2{NH=C(Et)pz-kappa2N,N}]Cl2 (6) (complexes 5 and 6 are rather unstable and gradually transform to trans-[PtCl2(pzH2] and [Pt(pzH)(4)]Cl(2) and free EtCN); (b) with 3,5-Me(2)pzH, the reaction leads to the formation of [PtCl2NH=C(Et)(3,5-Me2pz)-kappa2N,N}] (7) and [PtCl(3,5-Me2pzH)3]Cl (8); (c) in the case of asymmetric pyrazole 3(5)-MepzH, which can be added to EtCN and/or bind metal centers by any of the two nonequivalent nitrogen sites, a broad mixture of currently unidentified products is formed. The reduction of 1-3 with Ph3P=CHCO2Me in CHCl3 allows for the formation of corresponding platinum(II) compounds trans-[PtCl2{NH=C(Et)(3,5-RR'pz)}2] (9-11). Ligands NH=C(Et)(3,5-RR'pz) (12-14) were almost quantitatively liberated from 9-11 with 2 equiv of 1,2-bis-(diphenylphosphino)ethane in CDCl3, giving free imines 12-14 in solution and the precipitate of trans-[Pt(dppe)2](Cl)2. Pyrazolylimines 12-14 undergo splitting in CDCl3 solution at 20-25 degrees C for ca. 20 h to furnish the parent propiononitrile and the pyrazole 3,5-RR'pzH, but they can be synthetically utilized immediately after the liberation.     

Syntheses and structural characterizations of sheet- and column-like lanthanide-transition metal arrays: the effect of hydrogen bonding on the structure when K(+) is replaced by [NH4]+

Sheet- and column-like cyanide bridged lanthanide-transition metal arrays were synthesized through metathesis reactions between anhydrous LnCl(3) (Ln = Eu, Yb) and A(2)[M(CN)(4)] (A = K(+), NH(4)(+); M = Ni, Pt) in a 1:2 molar ratio in DMF (DMF = N,N-dimethylformamide) solution. Single-crystal X-ray analysis revealed that complexes of formula [K(DMF)(7)Ln[M(CN)(4)](2)](infinity) (Ln = Eu, M = Ni, 1; Ln = Yb, M = Pt, 2) consist of infinite layers of neutral, puckered sheets that contain hexagonal rings of composition [(DMF)(10)Ln(2)[M(CN)(4)](3)](6) with interstitial (DMF)(4)K(2)[M(CN)(4)] units located between the layers. The sheet structure is generated through the repeating (DMF)(10)Ln(2)[M(CN)(4)](3) unit with trans cyanide ligands in [M(CN)(4)](2)(-) serving as bridges. The column-like complex [(NH(4))(DMF)(4)Yb[Pt(CN)(4)](2)](infinity), 3, is formed when NH(4)(+) replaces K(+). It consists of infinite, negatively charged, square, parallel columns bundled through N-H...NC hydrogen bonds between NH(4)(+) and terminal CN from the columns. Cis cyanide ligands in [Pt(CN)(4)](2)(-) units serve as bridges. Complex 3 is the first known example where Ln(III) centers are coordinated to four [M(CN)(4)](2)(-) units. Bicapped (square face) trigonal prismatic coordination geometries were observed for Ln(III) centers in 1 and 2. Square antiprismatic geometry for Yb(III) centers are observed in 3. Crystal data for 1: triclinic space group P1, a = 8.797(2) A, b = 15.621(3) A, c = 17.973(6) A, alpha = 105.48(2) degrees, beta = 98.60(2) degrees, gamma = 98.15(2) degrees, Z = 2. Crystal data for 2: triclinic space group P1, a = 8.825(1) A, b = 15.673(1) A, c = 17.946(1) A, alpha = 105.46(2) degrees, beta = 99.10(1) degrees, gamma = 98.59(1) degrees, Z = 2. Crystal data for 3: monoclinic space group P2(1)/c, a = 9.032(1) A, b = 29.062(1) A, c = 15.316(1) A, beta = 94.51(1) degrees, Z = 2.     

双核铕(Ⅲ)配合物的合成及选择性激发

成功地合成一种新的四齿配体2,5-二(4-((2-吡啶-1氢-苯并[d]嘧唑)甲基)苯基)-1,3,4-噁二唑(L),并且将该配体作为第二配体合成出双核Eu3+配合物[Eu(TTA)3]2L(TTA二2-噻吩三氟甲基乙酰丙酮),配合物[Eu(TTA)3]2L的结构用红外光谱,吸外-可见吸收光谱进行了充分表征.为了讨论配...     

Solution and solid-state characterization of Eu(II) chelates: a possible route towards redox responsive MRI contrast agents

We report the first solid state X-ray crystal structure for a Eu(II) chelate, [C(NH2)3]3[Eu(II)(DTPA)(H2O)].8H2O, in comparison with those for the corresponding Sr analogue, [C(NH2)3]3[Sr(DTPA)(H2O).8H2O and for [Sr(ODDA)].8H2O (DTPA5 = diethylenetriamine-N,N,N',N",N"-pentaacetate, ODDA2- =1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diacetate ). The two DTPA complexes are isostructural due to the similar ionic size and charge of Sr(2+) and Eu(2+). The redox stability of [Eu(II)(ODDA)(H2O)] and [Eu(II)(ODDM)]2- complexes has been investigated by cyclovoltammetry and UV/Vis spectrophotometry (ODDM4- =1,4,10,13-tetraoxa-7,16-diaza-cyclooctadecane-7,16-++ +dimalonate). The macrocyclic complexes are much more stable against oxidation than [Eu(II)(DTPA)(H2O)]3- (the redox potentials are E1/2 =-0.82 V, -0.92 V, and -1.35 V versus Ag/AgCl electrode for [Eu(III/II)(ODDA)(H2O)],[Eu(III/II)(ODDM)], and [Eu(III/II)(DTPA)(H2O)], respectively, compared with -0.63 V for Eu(III/II) aqua). The thermodynamic stability constants of [Eu(II)(ODDA)(H2O)], [Eu(II)(ODDM)]2-, [Sr(ODDA)(H2O)], and [Sr(ODDM)]2- were also determined by pH potentiometry. They are slightly higher for the EuII complexes than those for the corresponding Sr analogues (logK(ML)=9.85, 13.07, 8.66, and 11.34 for [Eu(II)(ODDA)(H2O)], [Eu(II)(ODDM)]2-, [Sr(ODDA)(H2O)], and [Sr(ODDM)]2-, respectively, 0.1M (CH3)4NCl). The increased thermodynamic and redox stability of the Eu(II) complex formed with ODDA as compared with the traditional ligand DTPA can be of importance when biomedical application is concerned. A variable-temperature 17O-NMR and 1H-nuclear magnetic relaxation dispersion (NMRD) study has been performed on [Eu(II)(ODDA)(H2O)] and [Eu(II)(ODDM)]2- in aqueous solution. [Eu(II)(ODDM)]2- has no inner-sphere water molecule which allowed us to use it as an outer-sphere model for [Eu(II)(ODDA)(H2O)]. The water exchange rate (k298(ex)= 0.43 x 10(9)s(-1)) is one third of that obtained for [Eu(II)(DTPA)(H2O)]3-. The variable pressure 17O-NMR study yielded a negative activation volume, deltaV (not=) = -3.9cm3mol(-1); this indicates associatively activated water exchange. This water exchange rate is in the optimal range to attain maximum proton relaxivities, which are, however, strongly limited by the fast rotation of the small molecular weight complex.     

Application of chelate phosphine oxide ligand in EuIII complex with mezzo triplet energy level, highly efficient photoluminescent, and electroluminescent performances

The chelate phosphine oxide ligand bis(2-(diphenylphosphino)phenyl) ether oxide (DPEPO) was used as a unit neutral ligand to prepare the complex Eu(TTA)(3)(DPEPO) 1 (TTA = 2-thenoyltrifluoroacetonate). Compound 1 has a photoluminescence (PL) quantum yield of 55.3%, which is more than the twice of the PL quantum yield of Eu(TTA)(3)(TPPO)(2) (TPPO = triphenylphosphine oxide). Investigation indicated that DPEPO in 1 has the mezzo first triplet excited energy level (T(1)) between the first singlet excited energy level (S(1)) and T(1) of TTA, which may support one more additional energy transfer routines from the T(1) energy level of DPEPO to that of TTA, and consequently results in the improvement of energy transfer in the Eu(III) complex. DPEPO forms a complex with a more rigid and compact structure that can improve energy transfer between ligands and the center Eu(III) ion, support the higher saturation level by the coordinating ability of the oxygen atom in the ether moiety, and consequently enhance the PL intensity and efficiency of the corresponding Eu(III) complex. The multilayered electroluminescent (EL) device of 1 used as the red dopant exhibited an impressive brightness of 632 cd m(-2) at 25 V. The device had the excellent voltage-independent spectral stability with an emission peak at 615 nm. To the best of our knowledge, this luminescence is the brightest emission among Eu complexes with phosphine oxide ligands. The maximum external quantum yield (eta(ext)) of 2.89% and the maximum current and power efficiency of 4.58 cd A(-1) and 2.05 lm W(-1) were achieved at a low turn-on voltage of 7 V and current density of 0.021 mA cm(-2). These properties demonstrate that the chelate phosphine oxides ligand DPEPO can not only be favorable to form the rigid and compact complex structure and increase the efficiency of devices, but also reduce the ability of the formation of exciplex. DPEPO shows much better performance compared with the ordinary phosphine oxide ligand triphenylphosphine oxide.     

Tautomerization of methyldiazene to formaldehyde-hydrazone in ruthenium and osmium complexes

Mixed-ligand hydrazine complexes [M(CO)(RNHNH2)P4](BPh4)2 (1, 2) [M = Ru, Os; R = H, CH3, C6H5; P = P(OEt)3] with carbonyl and triethyl phosphite were prepared by allowing hydride [MH(CO)P4]BPh4 species to react first with HBF4.Et2O and then with hydrazines. Depending on the nature of the hydrazine ligand, the oxidation of [M(CO)(RNHNH2)P4](BPh4)2 derivatives with Pb(OAc)4 at -30 C gives acetate [M(kappa1-OCOCH3)(CO)P4]BPh4 (3a), phenyldiazene [M(CO)(C6H5N=NH)P4](BPh4)2 (3c, 4c), and methyldiazene [M(CO)(CH3N=NH)P4](BPh4)2 (3b, 4b) derivatives. Methyldiazene complexes 3b and 4b undergo base-catalyzed tautomerization of the CH3N=NH ligand to formaldehyde-hydrazone NH2N=CH2, giving the [M(CO)(NH2N=CH2)P4](BPh4)2 (5, 6) derivatives. Complexes 5 and 6 were characterized spectroscopically and by the X-ray crystal structure determination of the [Ru(CO)(NH2N=CH2)[P(OEt)3]4](BPh4)2 (5) derivative. Acetone-hydrazone [M(CO)[NH2N=C(CH3)2]P4](BPh4)2 (7, 8) complexes were also prepared by allowing hydrazine [M(CO)(NH2NH2)P4](BPh4)2 derivatives to react with acetone.     

Transfer hydrogenation processes to mu(3)-alkylidyne groups on the organotitanium oxide [Ti(3)Cp*O(3)

The photochemical treatment of mu(3)-alkylidyne complexes [[TiCp*(mu-O)](3)(mu(3)-CR)] (R=H (1), Me (2), Cp*=eta(5)-C(5)Me(5)) with the amines (2,6-Me(2)C(6)H(3))NH(2), Et(2)NH, and Ph(2)NH and the imine Ph(2)C=NH leads to the partial hydrogenation of the alkylidyne moiety that is supported on the organometallic oxide, [Ti(3)Cp*O(3)], and the formation of new oxoderivatives [[TiCp*(3)(mu-CHR)(R'NR")] (R"=2,6-Me(2)C(6)H(3), R'=H, R=H (3), Me (4); R'=R"=Et, R=H (5), Me (6); R'=R"=Ph, R=H (7), Me (8)) and [[TiCp*(mu-O)](3)(mu-CHR)(N=CPh(2))] (R=H (9), R=Me (10)), respectively. A sequential transfer hydrogenation process occurs when complex 1 is treated with tBuNH(2), which initially gives the mu-methylene [[TiCp*(mu-O)](3)(mu-CH(2))(HNtBu)] (11) complex and finally, the alkyl derivative [[TiCp*(mu-O)](3)(mu-NtBu)Me] (12). Furthermore, irradiation of solutions of the mu(3)-alkylidyne complexes 1 or 2 in the presence of diamines o-C(6)H(4)(NH(2))(2) and H(2)NCH(2)CH(2)NH(2) (en) affords [[TiCp*(mu-O)](3)(mu(3)-eta(2)-NC(6)H(4)NH)] (13) and [[TiCp*(mu-O)](3)(mu(3)-eta(2)-NC(2)H(4)NH)] (14) by either methane or ethane elimination, respectively. In the reaction of 1 with en, an intermediate complex [[TiCp*(mu-O)](3)(mu-CH(2))(NHCH(2)CH(2)NH(2))] (15) is detected by (1)H NMR spectroscopy. Thermal treatment of the complexes 4-10 quantitatively regenerates the starting mu(3)-alkylidyne compounds and the amine R'(2)NH or the imine Ph(2)C=NH; however, heating of solutions of 3 or 4 in [D(6)]benzene or a equimolecular mixture of both at 170 degrees C produces methane, ethane, or both, and the complex [[TiCp*(mu-O)](3)[mu(3)-eta(2)-NC(6)H(3)(Me)CH(2)]] (16). The molecular structure of 8 has been established by single-crystal X-ray analysis.     

High performance oxygen sensing nanofibrous membranes of Eu(III) complex/polystyrene prepared by electrospinning

In this paper, we report the synthesis, characterization, crystal structure, and photophysical properties of a Eu(3+) complex of Eu(TTA)(3)Phen, where TTA=2-thenoyltrifluoroacetonate, and Phen=1,10-phenanthroline. Its elementary application for oxygen-sensing application is also investigated by doping it into a polymer matrix of polystyrene (PS). Experimental data suggest that the 3wt% doped Eu(TTA)(3)Phen nanofibrous membrane exhibits a high sensitivity of 3.4 towards oxygen with a good linear relationship of R(2)=0.996. In addition, the 3wt% doped Eu(TTA)(3)Phen nanofibrous membrane owns a quick response of 9s towards molecular oxygen, along with its excellent atmosphere insensitivity and photobleaching resistance. All these results suggest that both Eu(TTA)(3)Phen and Eu(TTA)(3)Phen/PS system are promising candidates for oxygen-sensing optical sensors.     

Electronic structure, spectroscopic properties, and reactivity of molybdenum and tungsten nitrido and imido complexes with diphosphine coligands: influence of the trans ligand

A series of molybdenum and tungsten nitrido, [M(N)(X)(diphos)2], and imido complexes, [M(NH)(X)(diphos)2)]Y, (M = Mo, W) with diphosphine coligands (diphos = dppe/depe), various trans ligands (X = N3-, Cl-, NCCH3) and different counterions (Y-= Cl-, BPh4-) is investigated. These compounds are studied by infrared and Raman spectroscopies; they are also studied with isotope-substitution and optical-absorption, as well as emission, spectroscopies. In the nitrido complexes with trans-azido and -chloro coligands, the metal-N stretch is found at about 980 cm(-1); upon protonation, it is lowered to about 920 cm(-1). The 1A1 --> 1E (n --> pi) electronic transition is observed for [Mo(N)(N3)(depe)2] at 398 nm and shows a progression in the metal-N stretch of 810 cm(-1). The corresponding 3E --> 1A (pi --> n) emission band is observed at 542 nm, exhibiting a progression in the metal-N stretch of 980 cm(-1). In the imido system [Mo(NH)(N3)(depe)2]BPh4, the n --> pi transition is shifted to lower energy (518 nm) and markedly decreases in intensity. In the trans-nitrile complex [Mo(N)(NCCH3)(dppe)2]BPh4, the metal-N(nitrido) stretching frequency increases to 1016 cm(-1). The n --> pi transition now is found at 450 nm, shifting to 525 nm upon protonation. Most importantly, the reduction of this nitrido trans-nitrile complex is drastically facilitated compared to its counterparts with anionic trans-ligands (Epred = -1.5 V vs Fc+/Fc). On the other hand, the basicity of the nitrido group is decreased (pKa{[Mo(NH)(NCCH3)(dppe)2](BPh4)2} = 5). The implications of these findings with respect to the Chatt cycle are discussed.     

一种双核铕配合物的合成、光致发光和电致发光性质研究

合成了一个新的双核铕配合物Eu(TTA)₃(tpphz)Eu(TTA)₃(其中TTA＝去质子化的α-噻吩甲酰三氟丙酮; tpphz＝[3,2-a:2',3'-c:3',2'-h:2'',3''-j]四吡啶基吩嗪). 研究了该配合物的光致发光和电致发光性质. 一个四层电致发光器件ITO/TPD, 10 nm/Eu(TTA)₃(tpphz)Eu(TTA)₃, 20 nm/BCP, 20 nm/AlQ, 40 nm/Mg_0.9Ag_0.1, 200 nm/Ag, 100 nm表现出中心在633 nm处的宽带红光发射, 该宽带发射可能来源于双核Eu(III)配合物和TPD形成的激基复合物. 该器件的启动电压为10 V, 在18 V和135 mA/cm²时的最大亮度达146 cd/m².     

Pop-the-cork strategy in synthetic utilization of imines: stabilization by complexation and activation via liberation of the ligated species

Treatment of trans-[PtCl(4)(RCN)(2)] (R = Me, Et) with ethanol allowed the isolation of trans-[PtCl(4)[E-NH[double bond]C(R)OEt](2)]. The latter were reduced selectively, by the ylide Ph(3)P[double bond]CHCO(2)Me, to trans-[PtCl(2)[E-NH[double bond]C(R)OEt](2)]. The complexed imino esters NH[double bond]C(R)OEt were liberated from the platinum(II) complexes by reaction with 2 equiv of 1,2-bis(diphenylphosphino)ethane (dppe) in chloroform; the cationic complex [Pt(dppe)(2)]Cl(2) precipitates almost quantitatively from the reaction mixture and can be easily separated by filtration to give a solution of NH[double bond]C(R)OEt with a known concentration of the imino ester. The imino esters efficiently couple with the coordinated nitriles in trans-[PtCl(4)(EtCN)(2)] to give, as the dominant product, [PtCl(4)[NH[double bond]C(Et)N[double bond]C(R)OEt](2)] containing a previously unknown linkage, i.e., ligated N-(1-imino-propyl)-alkylimidic acid ethyl esters. In addition to [PtCl(4)[NH[double bond]C(Et)N[double bond]C(Et)OEt](2)], another compound was generated as the minor product, i.e., [PtCl(4)(EtCN)[NH[double bond]C(Et)N[double bond]C(Et)OEt]], which was reduced to [PtCl(2)(EtCN)[NH[double bond]C(Et)N[double bond]C(Et)OEt]], and this complex was characterized by X-ray single-crystal diffraction. The platinum(IV) complexes [PtCl(4)[NH[double bond]C(Et)N[double bond]C(R)OEt](2)] are unstable toward hydrolysis and give EtOH and the acylamidine complexes trans-[PtCl(4)[Z-NH[double bond]C(Et)NHC(R)[double bond]O](2)], where the coordination to the Pt center results in the predominant stabilization of the imino tautomer NH[double bond]C(Et)NHC(R)[double bond]O over the other form, i.e., NH(2)C(Et)[double bond]NC(R)[double bond]O, which is the major one for free acylamidines. The structures of trans-[PtCl(4)[Z-NH[double bond]C(Et)NHC(R)[double bond]O](2)] (R = Me, Et) were determined by X-ray studies. The complexes [PtCl(4)[NH[double bond]C(Et)N[double bond]C(R)OEt](2)] were reduced to the appropriate platinum(II) compounds [PtCl(2)[NH[double bond]C(Et)N[double bond]C(R)OEt](2)], which, similarly to the appropriate Pt(IV) compounds, rapidly hydrolyze to yield the acylamidine complexes [PtCl(2)[NH[double bond]C(Et)NHC(R)[double bond]O](2)] and EtOH. The latter acylamidine compounds were also prepared by an alternative route upon reduction of the corresponding platinum(IV) complexes. Besides the first observation of the platinum(IV)-mediated nitrile-imine ester integration, this work demonstrates that the application of metal complexes gives new opportunities for the generation of a great variety of imines (sometimes unreachable in pure organic chemistry) in metal-mediated conversions of organonitriles, the "storage" of imino species in the complexed form, and their synthetic utilization after liberation.     

Formation of a dinuclear imido complex from the reaction of a ruthenium(VI) nitride with a ruthenium(II) hydride

The treatment of [Ru(L(OEt))(N)Cl(2)] (1; L(OEt)(-) = [Co(η(5)-C(5)H(5)){P(O)(OEt)(2)}(3)](-)) with Et(3)SiH affords [Ru(L(OEt))Cl(2)(NH(3))] (2), whereas that with [Ru(L(OEt))(H)(CO)(PPh(3))] (3) gives the dinuclear imido complex [(L(OEt))Cl(2)Ru(μ-NH)Ru(CO)(PPh(3))(L(OEt))] (4). The imido group in 4 binds to the two ruthenium atoms unsymmetrically with Ru-N distances of 1.818(6) and 1.952(6) ?. The reaction between 1 and 3 at 25 °C in a toluene solution is first order in both complexes with a second-order rate constant determined to be (7.2 ± 0.4) × 10(-5) M(-1) s(-1).