New europium coordination polymers with efficient energy transfer from conjugated tetracarboxylate ligands to Eu3+ ion: syntheses, structures, luminescence and magnetic properties.

Two novel lanthanide coordination polymers, [Eu(2)(EBTC)(DMF)(5)(NO(3))(2)]·DMF (1) and [Eu(2)(BBTC)(1.5)(CH(3)OH)(2)(H(2)O)(2)]·7DMF·HNO(3) (2) (EBTC(4-) = 1,1'-ethynebenzene-3,3',5,5'-tetracarboxylate; BBTC(4-) = 1,1'-butadiynebenzene-3,3',5,5'-tetracarboxylate), were successfully synthesized from conjugated ligands of EBTC(4-) and BBTC(4-). Although the two tetracarboxylate ligands have similar structures, their different rigidity/flexibility results in quite different networks upon complexation. Complex 1 has a two-dimensional (2-D) layered structure with two crystallographically independent Eu(3+) ions, one in a distorted monocapped square-antiprism and the other in a distorted square-antiprism coordination geometry. Complex 2 exhibits a three-dimensional (3-D) porous framework, with one type of Eu(3+) in a distorted square-antiprism and the other in a trigondodecahedron environment. Both 1 and 2 emit the intensely red characteristic luminescence of Eu(3+) ion at room temperature, with a long lifetime of up to 1.3 and 0.7 ms, respectively, during which the ligand emission of EBTC(4-)/BBTC(4-) was quenched by the Eu(3+) ion, indicating the existence of efficient energy transfer between the conjugated ligand of EBTC(4-)/BBTC(4-) and the Eu(3+) ion. Thus, both EBTC(4-) and BBTC(4-) are ideal ligands with an "antenna" effect for the Eu(3+) ion. The two complexes show the single-ion magnetic behaviors of Eu(3+) with strong spin-orbit coupling interactions even if there are shorter distances (5.714 Å for 1 versus 4.275 and 5.360 Å for 2) between the neighboring Eu(3+) ions connected by oxygen atoms of the tetracarboxylates.

Hydrogencyanamido bridged multinuclear copper(II) complexes: from strong antiferromagnetic couplings to weak ferromagnetic couplings.

In the presence of ammonia, the reactions of cyanamide and Cu(II) ions with different organic blocking ligands afford three hydrogencyanamido bridged dinuclear complexes: [(dmbpy)(4)Cu(2)(HNCN)](ClO(4))(3)·H(2)O (1, dmbpy = 4,4'-dimethyl-2,2'-bipyridine), [(phen)(4)Cu(2)(HNCN)](ClO(4))(3)·2H(2)O (2, phen = 1,10-phenanthroline) and [(bpy)(2)Cu(2)(HNCN)(2)(ClO(4))(2)] (3, bpy = 2,2'-bipyridine), respectively. However, using the di(2-pyridyl)ketone (dpk) ligand in similar experimental conditions, an interesting reaction between the hydrogencyanamido anion and dpk is observed. Using Cu(ClO(4))·6H(2)O or Co(ClO(4))·6H(2)O as the metal source, it gives the mixed bridged hexanuclear complex [(dpk·OMe)(4)(dpk·NCN)(2)Cu(6)(H(2)O)(2)](ClO(4))(4) (4), or the mononuclear complex [(dpk·OMe)(dpk·HNCN)Co](ClO(4))·2H(2)O (5), respectively. Their structures are characterized by single crystal X-ray diffraction analyses. Magnetic measurements reveal moderate antiferromagnetic interaction between the Cu(II) ions in complex 1, weak ferromagnetic coupling in complex 2, and strong antiferromagnetic interactions for complexes 3 and 4. The magnetostructural correlations of these complexes are discussed.

Structures and physical properties of oligomeric and polymeric metal complexes based on bis(pyridyl)-substituted TTF ligands and an inorganic analogue.

The bis(pyridyl)-substituted TTF derivative, 2,6(7)-bis(4-pyridyl)-1,4,5,8-tetrathiafulvalene (TTF(py)(2)), and an inorganic analogue, [Ni(4-pedt)(2)] (4-pedt = 1-(pyridin-4-yl)ethylene-1,2-dithiolate), were used as bridging ligands to construct two multinuclear complexes {Co(II)(2)(Tp(Ph2))(2)(OAc)(2)[TTF(py)(2)]} (1, Tp(Ph2) = hydridotri(3,5-diphenylpyrazol-1-yl)borate) and {Co(II)(2)(Tp(Ph2))(2)(OAc)(2)[Ni(4-pedt)(2)]} (2), and two 1D zigzag chain complexes, {[M(II)(tta)(2)][TTF(py)(2)]}(n) (M = Cu for 3, and Mn for 4; tta = thenoyltrifluoroacetonate). X-Ray structural studies indicate that complexes 1 and 2 are very similar as a result of the isolobal analogy between TTF(py)(2) and [Ni(4-pedt)(2)], whereas complexes 3 and 4 are isostructural. The absorption spectra, electrochemical and magnetic properties for these new complexes have been studied. The results show that the interactions between the paramagnetic ions are weak owing to the large separation of the bridging ligands of TTFs and the inorganic analogue.

Hexanuclear Fe(III)2Co(III)2M(II)2 (M = Cu, Ni, Mn) clusters based on Kläui's tripodal ligand and tricyanometalates: syntheses, structures and magnetic properties.

With the use of Kläui's tripodal ligand, [(Cp)Co(P(O)(OEt)(2))(3)](-) (L(CoEt), Cp = cyclopentadiene) as the auxiliary ligand to react with different metal salts and tricyanometalate building blocks, five neutral trimetallic hexanuclear complexes: [(Tp)(2)Fe(2)(CN)(6)Cu(2)(L(CoEt))(2)]·6H(2)O (1, Tp = hydridotris(pyrazolyl)borate), [(Tp*)(2)Fe(2)(CN)(6)Cu(2)(L(CoEt))(2)]·2H(2)O (2, Tp* = hydridotris(3,5-dimethyl-pyrazolyl)borate), [(pzTp)(2)Fe(2)(CN)(6)Cu(2)(L(CoEt))(2)]·H(2)O·3MeOH (3, pzTp = tetra(pyrazolyl)borate), [(Tp)(2)Fe(2)(CN)(6)Ni(2)(L(CoEt))(2)(MeCN)(2)]·2MeCN·2H(2)O (4) and [(Tp)(2)Fe(2)(CN)(6)Mn(2)(L(CoEt))(2)(MeCN)(2)]·2MeCN (5), have been obtained and structurally characterized. Magnetic measurements confirm that there are ferromagnetic couplings between the cyano-bridged Fe and Cu/or Ni ions and antiferromagnetic interaction between the cyano-bridged Fe and Mn ions. Slow relaxation of the magnetization is observed in complexes 1 and 4, while complex 3 exhibits metamagnetic behavior with a critical field of 17.5 kOe.

Syntheses, structures, and magnetic properties of two kinds of unique heterometallic chains with mixed-bridging ligands of tricyanometalate and alkoxide.

The reactions of copper(II) salts, 1,3-bis(dimethylamino)-2-propanol (bdmapH) or 1,3-bis(amino)-2-propanol (bapH) and [(Tp)Fe(CN)(3)](-) (Tp = tris(pyrazolyl)hydroborate) gave four mixed-bridged heterometallic one-dimensional (1D) coordination polymers, {[(Tp)(2)Fe(2)(CN)(6)(OAc)(bdmap)Cu(2)(H(2)O)]·2H(2)O}(n) (1, HOAc = acetic acid), {[(Tp)(2)Fe(2)(CN)(6)(Pa)(bdmap)Cu(2)(H(2)O)]·2MeCN}(n) (2, HPa = propionic acid), {[(Tp)(2)Fe(2)(CN)(6)(Tfa)(bdmap)Cu(2)(H(2)O)]·2MeCN}(n) (3, HTfa = trifluoroacetic acid), and {[(Tp)(2)Fe(2)(CN)(6)(OAc)(bap)Cu(2)(MeOH)]·2MeOH·H(2)O}(n) (4). Complexes 1-3 show unique branched zigzag chain structures and complex 4 exhibits as a steplike chain. Ferromagnetic interactions between Fe(III) and Cu(II) ions by bridging cyanides are observed in all complexes. Strong antiferromagnetic interactions are presented between the Cu(II) ions in complexes 1-3, whereas similar antiferromagnetic coupling between Cu(II) ions is obviously weakened in complex 4 because of the distortion of penta-coordinated Cu(II) ions.

Eicosanuclear cluster [Cu(13)W(7)] of copper-octacyanotungstate bimetallic assembly: synthesis, structure, and magnetic properties.

Octacyanotungstate(V) reacts with Cu(NO(3))(2).2H(2)O and 1,4,7-trimethyl-1,4,7-triazacyclononane in methanol, resulting in an eicosanuclear cluster [Cu(13)W(7)], which shows a diamondoid shape with a Tolkowsky cut and bears intracluster ferromagnetic coupling.

Synthesis, structural characterization and photoluminescence properties of rhenium(I) complexes based on bipyridine derivatives with carbazole moieties.

Three N,N-bidentate ligands, 5,5'-dibromo-2,2-bipyridine (L1) and two carbazole containing ligands of 5-bromo-5'-carbazolyl-2,2-bipyridine (L2), 5,5'-dicarbazolyl-2,2'-bipyridine (L3), and their corresponding rhenium Re(CO)3Cl(L) complexes (ReL1-ReL3) have been successfully synthesized and characterized by elemental analysis, 1H NMR and IR spectra. Their photophysical properties and thermal analysis, along with the X-ray crystal structure analysis of L3 and complexes ReL1 and ReL3 are also described. In CH2Cl2 solution at room temperature, all complexes display intense absorption bands at ca. 220-350 nm, which can be assigned to spin-allowed intraligand (pi-->pi*) transitions, and the low energy broad bands in the 360-480 nm region are attributed to the metal to ligand charge-transfer d(Re)-->pi* (diimine) (MLCT). The introduction of carbazole moieties improves the MLCT absorption and molar extinction coefficient of these complexes. Upon excitation at the peak maxima, all complexes show strong emissions around 620 nm, which are assigned to d(Re)-->pi* (diimine) MLCT phosphorescence. The photoluminescence lifetime decay of Re(I) complexes were measured and the quantum efficiencies of the rhenium(I) complexes were calculated by using air-equilibrated [Ru(bpy)3]2+ x 2 Cl- aqueous solution as standard (phi(std) = 0.028). The complexes with appended carbazole moieties exhibit enhanced luminescence performances relative to ReL1.

Synthesis and characterization of neutral iron(II) and ruthenium(II) complexes with the isocyanotriphenylborate ligand.

By reacting metal cyanide complexes with NaBPh(4) in the presence of acid at room temperature, a new class of neutral isocyanotriphenylborate-containing complexes trans-Ru(L)(4)(CNBPh(3))(2) (L = pyridine, 1; 4-methylpyridine, 2; 4-tert-butylpyridine, 3), cis-Ru(bipy)(2)(CNBPh(3))(2) (4, bipy = 2,2'-bipyridine) and cis-M(phen)(2)(CNBPh(3))(2) (M = Ru, 5; M = Fe, 6; phen = 1,10-phenanthroline) have been synthesized. These new complexes are characterized by IR, UV spectroscopy and single-crystal X-ray diffractions. The electron withdrawing triphenylborate group on the isocyanide ligands has a pronounced effect on the photophysical properties of complexes 1-6 in comparison with other ruthenium(II) and iron(II) isocyanide complexes. The excitation energies corresponding to metal-to-ligand charge transfer (MLCT) shift to higher energies while the (3)MLCT emissions are quenched at room temperature.

Heterometallic complexes based on the mixed bridging ligands of tricyanometalate and terephthalate: syntheses, structures, and magnetic properties.

With the use of the tailored tricyanometalate precursors [(L)Fe(CN)(3)](-) (L = Tp, tris(pyrazolyl)hydroborate; L = i-BuTp, 2-methylpropyltris(pyrazolyl)borate) and terephthalate (ta) units as the mixed bridging ligands, a new one-dimensional (1D) chain polymer {[(Tp)(2)Fe(2)(CN)(6)Cu(2)(ta)(dmbpy)(2)] x 7 H(2)O}(n) (1), a pentanuclear heterometallic cluster [(Tp)(2)Fe(2)(CN)(6)Cu(3)(phen)(3)(ta)(2)(MeOH)(H(2)O)(2)] x 8 H(2)O (2), and a tetranuclear heterometallic cluster [(i-BuTp)(2)Fe(2)(CN)(6)Cu(2)(ta)(phen)(2)(EtOH)(2)] x 2 MeOH x H(2)O (3) (dmbpy = 4,4'-dimethyl-2,2'-bipyridyl, phen = 1,10-phenanthroline) have been synthesized and structurally characterized. The Fe(III) and Cu(II) ions are bridged by cyanides, and the Cu(II) ions are further linked by terephthalate to form the 1D chain polymer, the pentanuclear cluster, and the tetranuclear cluster for complexes 1-3, respectively. All complexes show ferromagnetic interactions between the Fe(III) and Cu(II) ions. Complex 1 shows metamagnetic behavior with the critical field of about 1.2 T at 1.8 K.

A family of polynuclear clusters containing cyano-bridged T-shaped Fe(III)3M(II) (M = Cu, Co, Mn) metal cores: syntheses, structures, and magnetic properties.

A new family of polynuclear clusters containing the Fe(III)(3)M(II) cores [(Tp(4Bo))(6)Fe(6)(CN)(18)M(2)Na(2)(H(2)O)(16)] x 4 H(2)O (M = Cu, Co, Mn; 1-3) and [(Tp(4Bo))(6)Fe(6)(CN)(18)M(2)Na(2)(H(2)O)(12)(DMF)(4)] x H(2)O (M = Cu, Co, Mn; 4-6) have been synthesized and structurally characterized. Complexes 1-3 crystallize in the P2(1)/c space group, and 4-6 crystallize in the P2(1)/n space group. All six complexes consist of two symmetry-related T-shaped [(Tp(4Bo))(3)(CN)(9)Fe(3)M](-) subunits linked by two Na(+) cations. Each polynuclear cluster in 1-6 strongly interacts with 12 adjacent such units through pi-pi interactions, leading to the formation of 3D 12-connected frameworks. Magnetic studies show appreciable magnetic anisotropies in compounds 1, 2, 4, and 5. Antiferromagnetic interactions were observed in complexes 3 and 6.