Reactions of Pinacols with One-Electron Oxidants

Oxidation of the tetraarylpinacols (Ar(2)COH)(2), 1a-e, in which Ar = C(6)H(5) (1a), 4-ClC(6)H(4) (1b), 4-MeC(6)H(4) (1c), 4-MeOC(6)H(4) (1d) and 4-Me(2)NC(6)H(4) (1e), by thianthrene cation radical (Th(*+)) in CH(3)CN and in CH(2)Cl(2) led quantitatively to the corresponding diaryl ketones Ar(2)C=O (2a-e), provided a sufficient amount of base, 2,6-di-tert-butyl-4-methylpyridine (DTBMP), was present to prevent presumed acid-catalyzed rearrangement. In the case of 1e, continued oxidation of 2e was also observed. Oxidation of 1a by (4-BrC(6)H(4))(3)N(*+)SbCl(6)(-) and (4-BrC(6)H(4))(3)N(*+)SbF(6)(-) (Ar(3)N(*+)) occurred analogously. Evidence for the catalytic, cation-radical rearrangement of 1a by Ar(3)N(*+) (reported in earlier literature) and by Th(*+) could not be found. Quantitative oxidation of 1a to 2a and of 1d to 2d was obtained also with NOBF(4), again provided that sufficient DTBMP was present to prevent acid-catalyzed rearrangement. Catalytic, oxidative rearrangement of 1d at room temperature and (as reported in earlier literature) at -5 degrees C was not observed. Oxidation was also observed of 2,3-diphenyl-2,3-butanediol (3) to acetophenone (9) and of 1,1-dimethyl-2,2-diphenylethanediol (4) to 2a and acetone by Th(*+). Oxidation of 2,3-dimethyl-2,3-butanediol (5) by Th(*+) was not observed. Instead, even in the presence of DTBMP, pinacolone (10) and tetramethyloxirane (11) were formed, through, it is proposed, a mechanism involving complexation with Th(*+).     

Luminescent properties of water-soluble conjugated metallopolymers and their application to fluorescent nitric oxide detection

Water-soluble pi-conjugated polymers (CPs) incorporating 5,5'-(2,2'-dipyridyl) (CP1) or 6,6'-(2,2'-dipyridyl) (CP2) units within the pi-conjugated backbone were prepared as scaffolds for macromolecular metal complexation. The response of CP emission to a range of metal ions was investigated in water, 10 mM aqueous sodium dodecyl sulfate, and acetonitrile/water (95:5). Cupric ions are the most efficient quenchers of CP emission, with K(SV) = 1.1 x 10(5) and 5.2 x 10(4) M(-1) in water for CP1a (40% bipyridyl monomer units) and CP1b (20% bipyridyl monomer units), respectively. Quenching is approximately twice as effective in acetonitrile/water (95:5) (K(SV) = 3.1 x 10(5) M(-1) for CP1a and 1.1 x 10(5) M(-1) for CP1b). Partial restoration of emission was observed upon exposure of Cu(II)-CP solutions to excess NO(g) in acetonitrile/water (95:5) or 10 mM SDS(aq).     

Synthesis and characterization of new coordination polymers generated from bent bis(cyanophenyl)oxadiazole ligands and Ag(I) salts

Two new bent bis(cyanophenyl)oxadiazole ligands, 2,5-bis(4-cyanophenyl)-1,3,4-oxadiazole (L7) and 2,5-bis(3-cyanophenyl)-1,3,4-oxadiazole (L8), were synthesized. The coordination chemistry of these ligands with various Ag(I) salts has been investigated. Seven new coordination polymers, namely, {[Ag(L7)(H2O)]ClO4}n) (1) (triclinic, P1, a = 9.342(4) A, b = 9.889(4) A, c = 10.512(4) A, alpha = 68.978(6) degrees, beta = 78.217(6) degrees, gamma = 81.851(7) degrees, Z = 2), {[Ag(L7)]SO3CF3}n (2) (monoclinic, P2(1)/n, a = 7.559(2) A, b = 23.739(6) A, c = 10.426(3) A, beta = 108.071(4) degrees, Z = 4), {[Ag(L8)]BF4 x 0.5(C6H6) x H2O}n (3) (triclinic, P1, a = 7.498(3) A, b = 10.649(4) A, c = 13.673(5) A, alpha = 98.602(5) degrees, beta = 100.004(5) degrees, gamma =110.232(5) degrees, Z = 2), {[Ag(L8)SbF6] x H2O}n (4) (triclinic, P1, a = 8.2621(9) A, b = 10.6127(12) A, c = 13.3685(15) A, alpha = 98.012(2) degrees, beta = 106.259(2) degrees, gamma = 112.362(2) degrees, Z = 2), {[Ag2(L8)2(SO3CF3)] x H2O}n (5) (triclinic, P1, a = 10.713(4) A, b = 13.449(5) A, c = 15.423(5) A, alpha = 65.908(5) degrees, beta = 74.231(5) degrees, gamma = 83.255(5) degrees, Z = 2), {[Ag2(L8)(C6H6)(ClO4)] x ClO4}n (6) (monoclinic, P2(1)/n, a = 6.9681(17) A, b = 20.627(5) A, c = 17.437(4) A, beta = 95.880(4) degrees, Z = 4), and {[Ag2(L8)(H2PO4)2]}n (7) (triclinic, P1, a = 7.956(2) A, b = 9.938(3) A, c = 14.242(4) A, alpha = 106.191(4) degrees, beta = 97.322(4) degrees, gamma = 107.392(4) degrees, Z = 1), were obtained by the combination of L7 and L8 with Ag(I) salts in a benzene/methylene chloride mixed-solvent system and fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. In addition, the luminescence and electrical conductance properties of compounds 1-6 and the host-guest chemistry of compound 3 were investigated.     

Molecular wires comprising pi-extended ethynyl- and butadiynyl-2,5-diphenyl-1,3,4-oxadiazole derivatives: synthesis, redox, structural, and optoelectronic properties

2,5-Diphenyl-1,3,4-oxadiazole (OXD) derivatives with terminal ethynyl- (4a,b) and butadiynyl- (8a,b) substituents have been synthesized in high yields. 2-Methyl-3,5-hexadiyn-2-ol has not been exploited previously in the synthesis of terminal butadiynes. Crystals of 8a and 8b are remarkably stable to long-term storage under ambient conditions. The X-ray crystal structure of 8a reveals that the butadiyne moieties are spatially isolated by the aromatic moieties, which explains the high stability. Two series of derived pi-conjugated molecules, Donor-(C[triple bond]C)(n)-OXD (n = 1, 2) and OXD-(C[triple bond]C)(n)-Donor-(C[triple bond]C)(n)-OXD (n = 1) [Donor = tetrathiafulvalene (TTF), bithiophene, 9-(4,5-dimethyl-1,3-dithiol-2-ylidene)fluorene, and triphenylamine], have been synthesized using Sonogashira reactions and characterized by X-ray crystallography, cyclic voltammetry, and optical absorption/emission spectroscopy. The electron-withdrawing effect of the OXD units is manifested by a positive shift of the donor oxidation waves in these systems: the butadiynylene spacer (n = 2) further shifts the first oxidation waves by 40-80 mV compared to analogues n = 1. The absorption spectra of TTF-OXD hybrids 10d and 11 are blue-shifted by 80 nm compared to the bithienyl-bridged derivative 10f and are similar to the butadiynyl-OXD building-block 8a, demonstrating that conjugation is disrupted by a neutral TTF unit. Solutions of the TTF-OXD and 9-(4,5-dimethyl-1,3-dithiol-2-ylidene)fluorene-OXD hybrids, 10d, 10g, 11, and 13, are only very weakly fluorescent due to quenching from the electron-donor moieties. In contrast, the triphenylamine-OXD hybrids 12a, 12b, 14a, and 14b are fluorescent; the PLQYs of the butadiynylene derivatives 14a and 14b are lower than those of the ethynylene-bridged analogues 12a and 12b.     

Synthesis and structural, electronic, and optical properties of oligo(thienylfuran)s in comparison with oligothiophenes and oligofurans

[structure: see text] Alternate thiophene/furan oligomers having four and six heterocycles, i.e., oligo(thienylfuran) dimer and trimer 2 (n = 4 and 6), were newly synthesized by repetitive Stille coupling reactions. The structural, electronic, and optical properties of these oligomers were investigated by X-ray crystallography (for n = 4), cyclic voltammetry (CV), UV-vis and fluorescence spectroscopy, and DFT calculations, and the results were compared with those of corresponding oligothiophenes (1) and oligofurans (3). The inter-ring torsional energy profiles calculated for bithiophene 1 (n = 2), thienylfuran 2 (n = 2), and bifuran 3 (n = 2) at the B3LYP/6-31G(d) level indicated that the most stable conformers of 2 (n = 2) and 3 (n = 2) are fully coplanar with transoid structure while that of 1 (n = 2) is twisted with a dihedral angle of 158 degrees . In accord with this, X-ray crystallographic analysis of 2 (n = 4) revealed that the pi-conjugated system is nearly planar with the inter-ring C=C-C=C dihedral angles between the thiophene and furan rings of 173.6(7) degrees , -177.0(7) degrees , and 172.6(6) degrees . In the packing structure, these nearly planar molecules are arranged in a herringbone pattern. The CV on a series of oligo(thienylfuran)s 2 showed irreversible oxidation peaks at +0.90, +0.42, and +0.29 V vs Fc/Fc(+) for n = 2, 4, and 6, which were 0.15-0.18 V lower than those for corresponding oligothiophenes 1 and were closer to those for oligofurans 3. On the other hand, the UV-vis spectra of 2 showed the longest wavelength absorption to be almost identical with those of the corresponding 1, and more bathochromically shifted than those of the corresponding 3. The results of CV and UV-vis measurements were supported by DFT calculations (B3LYP/ 6-311+G(2d,p)//B3LYP/6-31G(d)). Thus, oligo(thienylfuran)s 2 have HOMOs which are higher than those of oligothiophenes 1 and close to those of 3, and HOMO-LUMO gaps which are close to those of 1 and smaller than those of 3. In fluorescence spectra, the quantum yield of 2 increased with elongation of the pi-system (n = 2 (3.5%), 4 (19%), 6 (24%)).     

Synthesis and characterization of six new quaternary actinide thiophosphate compounds: Cs(8)U(5)(P(3)S(10))(2)(PS(4))(6)(,) K(10)Th(3)(P(2)S(7))(4)(PS(4))(2), and A(5)An(PS(4))(3), (A = K, Rb, Cs; An = U, Th)

Six new actinide metal thiophosphates have been synthesized by the reactive flux method and characterized by single-crystal X-ray diffraction: Cs(8)U(5)(P(3)S(10))(2)(PS(4))(6) (I), K(10)Th(3)(P(2)S(7))(4)(PS(4))(2) (II), K(5)U(PS(4))(3) (III), K(5)Th(PS(4))(3) (IV), Rb(5)Th(PS(4))(3) (V), and Cs(5)Th(PS(4))(3) (VI). Compound I crystallizes in the monoclinic space group P2(1)/c with a = 33.2897(1) A, b = 14.9295(1) A, c = 17.3528(2) A, beta = 115.478(1) degrees, Z = 8. Compound II crystallizes in the monoclinic space group C2/c with a = 32.8085(6) A, b = 9.0482(2) A, c = 27.2972(3) A, beta = 125.720(1) degrees, Z = 8. Compound III crystallizes in the monoclinic space group P2(1)/c with a = 14.6132(1) A, b = 17.0884(2) A, c = 9.7082(2) A, beta = 108.63(1) degrees, Z = 4. Compound IV crystallizes in the monoclinic space group P2(1)/n with a = 9.7436(1) A, b = 11.3894(2) A, c = 20.0163(3) A, beta = 90.041(1) degrees, Z = 4, as a pseudo-merohedrally twinned cell. Compound V crystallizes in the monoclinic space group P2(1)/c with a = 13.197(4) A, b = 9.997(4) A, c = 18.189(7) A, beta = 100.77(1) degrees, Z = 4. Compound VI crystallizes in the monoclinic space group P2(1)/c with a = 13.5624(1) A, b = 10.3007(1) A, c = 18.6738(1) A, beta = 100.670(1) degrees, Z = 4. Optical band-gap measurements by diffuse reflectance show that compounds I and III contain tetravalent uranium as part of an extended electronic system. Thorium-containing compounds are large-gap materials. Raman spectroscopy on single crystals displays the vibrational characteristics expected for [PS(4)](3)(-), [P(2)S(7)](4-), and the new [P(3)S(10)](5)(-) building blocks. This new thiophosphate building block has not been observed except in the structure of the uranium-containing compound Cs(8)U(5)(P(3)S(10))(2)(PS(4))(6).     

Synthesis and structural characterization of quaternary thorium selenophosphates: A2ThP3Se9 (A = K, Rb) and Cs4Th2P5Se17

Single crystals of A2ThP3Se9 (A = K (I), Rb (II)) and Cs4Th2PsSe17 (III) form from the reaction of Th and P in a molten A2Se3/Se (A = K, Rb, Cs) flux at 750 degrees C for 100 h. Compound I crystallizes in the triclinic space group P1 (No. 2) with unit cell parameters a = 10.4582(5) A, b = 16.5384(8) A, c = 10.2245(5) A, alpha = 107.637(1); beta = 91.652(1); gamma = 90.343(1) degrees, and Z = 2. Compound II crystallizes in the triclinic space group P1 (No. 2) with the unit cell parameters a = 10.5369(5) A, b = 16.6914(8) A, c = 10.2864(5) A, alpha = 107.614(1) degrees, beta = 92.059(1) degrees, gamma = 90.409(1) degrees, and Z = 2. These structures consist of infinite chains of corner-sharing [Th2Se14] units linked by (P2Se6)4- anions in two directions to form a ribbonlike structure along the [100] direction. Compounds I and II are isostructural with the previously reported K2UP3Se9. Compound III crystallizes in the monoclinic space group P2(1)/c (No. 14) with unit cell parameters a = 10.238(1) A, b = 32.182(2) A, c = 10.749(1) A; beta = 95.832(1) degrees, and Z = 4. Cs4Th2P5Se17 consists of infinite chains of corner-sharing, polyhedral [Th2Se13] units that are also linked by (P2Se6)4- anions in the [100] and [010] directions to form a layered structure. The structure of III features an (Se2)2- anion that is bound eta 2 to Th(2) and eta 1 to Th(1). This anion influences the coordination sphere of the 9-coordinate Th(2) atom such that it is best described as bicapped trigonal prismatic where the eta 2-bound anion occupies one coordination site. The composition of III may be formulated as Cs4Th2(P2Se6)5/2(Se2) due to the presence of the (Se2)2- unit. Raman spectra for these compounds and their interpretation are reported.     

Fabrication of electrochemical transistor based on pi-conjugate polymer Langmuir-Blodgett film

We fabricated an efficient organic electrochemical transistor (OECT) composed of polymer Langmuir-Blodgett (LB) film. The pi-conjugated polymer LB film, which was constructed from a poly(N-dodecylacrylamide) (pDDA) and poly(3-hexylthiophene) (PHT) mixture, was used as a conduction channel layer to connect source and drain electrodes. The mixed-polymer LB film was characterized using UV-vis spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), and cyclic voltammetry. Subsequent UV spectra measurements, XRD measurements, and AFM measurements show that PHT forms a crystalline lamellar domain in the layered structure of pDDA. The OECT included 10 layers of the mixed-polymer LB film as the conduction channel layer. The OECT showed an on/off ratio of 1.1x10(4) and mobility of 7.5x10(-2) cm2 V(-1) s(-1) at low gate (VG=-1.2 V) and source-drain voltages (VDS=-0.5 V). Moreover, the necessary charge to operate the OECT was 1.1x10(-9) mol of e(-1) cm(-2), which was 2 orders smaller than the value reported using a similar device structure. The relatively high on/off ratio and low charge consumption suggest that this OECT, which is fabricated from pi-conjugated polymer LB films, is applicable to macroelectronic devices.     

Thiophosphate phase diagrams developed in conjunction with the synthesis of the new compounds KLaP(2)S(6), K(2)La(P(2)S(6))(1/2)(PS(4)), K(3)La(PS(4))(2), K(4)La(0.67)(PS(4))(2), K(9-)(x)La(1+x/3)(Ps(4))(4) (x = 0.5), K(4)Eu(PS(4))(2), and KEuPS(4)

An alkali-metal sulfur reactive flux has been used to synthesize a series of quaternary rare-earth metal compounds. These include KLaP(2)S(6) (I), K(2)La(P(2)S(6))(1/2)(PS(4)) (II), K(3)La(PS(4))(2) (III), K(4)La(0.67)(PS(4))(2) (IV), K(9-x)La(1+x/3)(PS(4))(4) (x = 0.5) (V), K(4)Eu(PS(4))(2) (VI), and KEuPS(4) (VII). Compound I crystallizes in the monoclinic space group P2(1)/c with the cell parameters a = 11.963(12) A, b = 7.525(10) A, c = 11.389(14) A, beta = 109.88(4) degrees, and Z = 4. Compound II crystallizes in the monoclinic space group P2(1)/n with a = 9.066(6) A, b = 6.793(3) A, c = 20.112(7) A, beta = 97.54(3) degrees, and Z = 4. Compound III crystallizes in the monoclinic space group P2(1)/c with a= 9.141(2) A, b = 17.056(4) A, c = 9.470(2) A, beta = 90.29(2) degrees, and Z = 4. Compound IV crystallizes in the orthorhombic space group Ibam with a = 18.202(2) A, b = 8.7596(7) A, c = 9.7699(8) A, and Z = 4. Compound V crystallizes in the orthorhombic space group Ccca with a = 17.529(9) A, b = 36.43(3) A, c = 9.782(4) A, and Z = 8. Compound VI crystallizes in the orthorhombic space group Ibam with a = 18.29(5) A, b = 8.81(2) A, c= 9.741(10) A, and Z = 4. Compound VII crystallizes in the orthorhombic space group Pnma with a = 16.782(2) A, b = 6.6141(6) A, c = 6.5142(6) A, and Z = 4. The sulfur compounds are in most cases isostructural to their selenium counterparts. By controlling experimental conditions, these structures can be placed in quasi-quaternary phase diagrams, which show the reaction conditions necessary to obtain a particular thiophosphate anionic unit in the crystalline product. These structures have been characterized by Raman and IR spectroscopy and UV-vis diffuse reflectance optical band gap analysis.     

Preparation and characterization of [[M(dmb)2]TCNQ.xTCNQo]n polymers (M=Cu,Ag; dmb = 1,8-diisocyano-p-menthane; x = 0, 0.5, 1.0, 1.5; TCNQ = 7,7,8,8-tetracyano-p-quinodimethane) and design of new semi- and photoconducting organometallic materials

New thermoplastic organometallic materials of the type [[M(dmb)2]TCNQ.xTCNQo.y solvent], (M = Cu(I), Ag(I); dmb = 1,8-diisocyano-p-menthane; TCNQ = 7,7,8,8-tetracyano-p-quinodimethane, x = 0, 0.5, 1.0, 1.5; solvent = none, THF or toluene) have been prepared and characterized from X-ray powder diffraction patterns, X-ray crystallography (for some Ag polymers), DSC, and conductivity measurements. While the [[M(dmb)2]TCNQ.xTCNQo]n polymers (M = Cu,Ag; x = 0, 0.5) are insulating, the others (x = 1.0 and 1.5) are semiconducting, and the relative conductivity is found to be a function of the molecular weight and crystallinity. The [[Cu(dmb)2]TCNQ.1.5TCNQ]n material is also photoconducting, while the Ag analogue is not. Photochemical and luminescence quenching experiments in the solid-state established that the Cu+ center and TCNQo act as electron donor and acceptor, respectively, in this photoprocess. Finally photocells of the type glass/SnO2/[Cu(dmb)2]TCNQ.TCNQo]n + 0.5 acceptor/Al (acceptor = TCNQo, C60 and TCNN (13,13,14,14-tetracyano-5,12-naphthacenequinodimethane)) have been designed and characterized. The quantum yields (number of photoproduced electrons/number of photons) are as follows: TCNQ, 1.6 x 10(-4), C60, 5 x 10(-5), TCNN, 3.0 x 10(-4) at lambdaexc = 330 nm. X-ray data for [[Ag(dmb)2]TCNQ.2THF]n: space group P2(1/c), monoclinic, a = 13.5501(10), b = 9.9045(10), c = 32.564(2) A, beta = 91.130(10) degrees, Z = 4. X-ray data for [[Ag(dmb)2]TCNQ.0.5TCNQo.0.5 toluene]n: space group P2(1/c), monoclinic, a = 14.3669(19), b = 9.1659(3), c = 34.012(3) A, beta = 92.140(8) degrees, Z = 4. X-ray data for [[Ag(dmb)2]TCNQ.1.5TCNQo]n: space group C2/c, monoclinic, a = 25.830(11), b = 9.680(2), c = 42.183(19) A, beta = 104.87(4) degrees, Z = 8. X-ray data for [[Ag(dmb)2]DCTC]n: space group P2(1/a), monoclinic, a = 26.273(3), b = 9.730(3), c = 31.526(3) A, beta = 112.12(2)degrees, Z = 4.     

Oxidation of [Ru(NH3)5isn](BF4)2 by hyochlorous acid and chlorine in aqueous acidic media

UV-vis stopped-flow studies of the reaction of [Ru(NH3)5isn](2+) (isn = isonicotinamide) with excess HOCl at 25 degrees C demonstrate that it proceeds in two time-resolved steps. In the first step [Ru(NH3)5isn](3+) is produced with the rate law -d[Ru(II)]/dt = 2(aK(h)[H(+)] + b[H(+)][Cl(-)] + c[Cl(-)])[HOCl](tot)[Ru(II)]/(K(h) + [H(+)][Cl(-)]). Here, K(h) is 1.3 x 10(-3) M(2) and corresponds to the equilibrium hydrolysis of Cl2, a is (8.34 +/- 0.19) x 10(3) M(-2) s(-1) and represents the acid-assisted reduction of HOCl, b is (4.04 +/- 0.13) x 10(4) M(-1) s(-1) and represents the reduction of Cl2, and c is (6.25 +/- 0.59) x 10(2) s(-1) and represents the Cl(-)-assisted reduction of HOCl. In the second step [Ru(NH3)5isn](3+) undergoes further oxidation to a mixture of products with the rate law -d[Ru(III)]/dt = e[Ru(III)][HOCl]/[H(+)] where e is (1.18 +/- 0.01) x 10(-2) s(-1). This step is assigned a mechanism with Cl(+) transfer from HOCl to [Ru(III)(NH3)4(NH2)isn](2+) occurring in the rate-limiting step. These results underline the resistance of HOCl to act as a simple outer-sphere one-electron oxidant.     

Structural variations and spectroscopic properties of luminescent mono- and multinuclear silver(I) and copper(I) complexes bearing phosphine and cyanide ligands

Reaction of equimolar amounts of AgCN and PCy3 gave the polymer [(Cy3P)Ag(NCAgCN)]infinity (1), whereas employment of excess PCy3 yielded the discrete compound [(Cy3P)2Ag(NCAgCN)] (2). Reacting bis(dicyclohexylphosphino)methane (dcpm) with AgCN in 1:1 and 1:2 molar ratios gave two crystalline forms, namely [Ag2(mu-dcpm)2][Ag(CN)2]2 x (CH3OH)2 (3a x (CH3OH)2) and [Ag2(mu-dcpm)2][Ag(CN)2]2 (3b), respectively. The similar reaction of CuCN with PCy3 afforded the polymeric compound [{(Cy3P)Cu(CN)}3]infinity (4), whereas treatment of CuCN with dcpm gave [Cu2(mu-dcpm)2(CN)2] (5). Employment of diphosphine ligands with longer -(CH2)n- spacers, such as 1,2-bis(dicyclohexylphosphino)ethane (dcpe, n = 2) and 1,3-bis(diphenylphosphino)propane (dppp, n = 3), in reactions with [Cu(CH3CN)4]PF6 and KCN afforded the macrocylic compounds [{Cu(dcpe)}2(CN)(mu-dcpe)]PF6 (6(PF6)) and [{Cu(dppp)}3(CN)2(mu-dppp)]PF6 (7(PF6)), respectively. The hexanuclear complex [Cu(CN)(PCy3)]6 (8) was obtained by reacting CuCN with PCy3 in the presence of sodium pyridine-2-thiolate. The UV-vis absorption spectrum of 1 in acetonitrile displays a weak shoulder at 245 nm (epsilon = 350 dm3 mol(-1) cm(-1)). For 3a, 3b, and 5, the intense absorption bands at lambdamax = 257-276 nm with epsilon values of (1.73-1.80) x 10(4) dm3 mol(-1) cm(-1) are assigned to [ndsigma --> (n + 1)psigma] transitions. Complexes 3a and 3b emit at lambdamax = 365 nm in CH3CN (quantum yield approximately 6 x10(-3), lifetime approximately 0.2 micros). The solid-state emission of 5 (lambdamax = 470 and 488 nm at 298 and 77 K) is red-shifted in energy from that of 4 (lambdamax = 401 and 405 nm at 298 and 77 K, respectively). In 77 K MeOH/EtOH (1:4) glassy solution, complexes 4-8 display intense emission with lambdamax at 382-416 nm, which is assigned to the [3d --> (4s, 4p)] triplet excited state.     

Measurement of sulfite at oxide-coated copper electrodes

The amperometric determination of sulfite was performed using copper electrodes in alkaline media. A mechanism for the oxidation of sulfite at these electrodes is suggested, based on the formation of superficial CuO(.OH), which acted as an electron transfer mediator to the analyte. At 0.5 V versus SCE in 1 M NaOH, sulfite could be calibrated at a sensitivity of 0.2 A l mol-1 cm-2, with a response time for the steady state of 30 s. The limit of detection (three times the signal-to-noise ratio) was 2.5 x 10(-6) M and the response was linear up to 5 x 10(-4) M (r2 = 0.9996, n = 15). The standard deviation (n = 10) at 1 x 10(-5) and 1 x 10(-4) M was 3.27 x 10(-7) A cm-2 (mean = 3.62 x 10(-6) A cm-2) and 1.07 x 10(-13) A cm-2 (mean = 2.25 x 10(-5) A cm-2), respectively.     

Synthesis and characterization of diverse coordination polymers. Linear and zigzag chains involving their structural transformation via intermolecular hydrogen-bonded, interpenetrating ladders polycatenane, and noninterpenetrating square grid from long, rigid N,N'-bidentate ligands: 1,4-bis[(x-pyridyl)ethynyl]benzene (x = 3 and 4)

The long, rigid ligands 1,4-bis[(3-pyridyl)ethynyl]benzene (L1) and 1,4-bis[(4-pyridyl)ethynyl]benzene (L2) were used in the synthesis of 10 new organic-inorganic coordination frameworks, each of them adopting different structural motifs. Synthesis, single-crystal X-ray structure determination, and spectroscopic and thermogravimetric analyses are presented. The reactions between M(NO3)2 x xH2O; M = Cd(II), Cu(II), and Co(II); x = 3-6 and Cu(hfac)2 x H2O [hfac = bis(hexafluoroacetylacetonato)] with L1 afforded the following one-dimensional zigzag chain structures: [Cd(C20H12N2)0.5(NO3)(CH3OH)]n (1, monoclinic, C2/c; a = 7.586(1) A, b = 23.222(1) A, c = 13.572(1) A, beta = 92.824(1), Z = 4); [{Cu(C20H12N2)(NO3)2(CH3OH)} x CH3OH]n (2, orthorhombic, P2(1)2(1)2(1); a = 8.589(1) A, b = 15.766(1) A, c = 17.501(1) A, Z = 4); [Co(C20H12N2)2(NO3)2(H2O)2] (5, triclinic, P1; a = 7.493(1) A, b = 8.948(1) A, c = 14.854(1) A, alpha = 100.427(1), beta = 97.324(1), gamma = 110.901(1), Z = 1); [Cu(C20H12N2)(hfac)2]n (4, monoclinic, C2/c, a = 18.828(1) A, b = 14.671(1) A, c = 13.427(1) A, beta = 90.447(1) degrees, Z = 4). Moreover, the minority phase compound formed from Cu(NO3)2 x 3H2O and L1 yielded a metallocyclic chain structure, [Cu(C20H12N2)(NO3)]n (3, triclinic, P; a = 8.728(1) A, b = 10.018(1) A, c = 11.893(1) A, alpha = 109.991(1), beta = 97.109(1), gamma = 115.542(1), Z = 1). In addition to the dinuclear coordination complex 5, all other polymeric structures (1-4) from L1 are composed of interpenetrating 2D and 3D cross-linked zigzag chains via hydrogen-bonding interactions. The reactions between M(NO3)2 x xH2O; M = Cd(II), Cu(II), and Co(II); x = 3-6 and Cu(hfac)2 x H2O [hfac = bis(hexafluoroacetylacetonato)] and L2 were dependent on the nature of the metal center and resulted in the formation of four different interpenetrating and noninterpenetrating compounds (6-10): [Co(C20H12N2)1.5(NO3)2]n (6, triclinic, P; a = 14.172(1) A, b = 15.795(1) A, c = 18.072(1) A, alpha = 115.380(1), beta = 101.319(1), gamma = 93.427(2), Z = 4), which consists of T-shaped building blocks assembled into three-dimensional interpenetrating polycatenated ladders; [Cd(C20H12N2)2(NO3)2]n (7, monoclinic, I2/a; a = 11.371(1) A, b = 20.311(2) A, c = 15.240(2) A, beta = 100.201(2) degrees, Z = 4), which adopts a two-dimensional noninterpenetrating square-grid motif; [Cu(C20H12N2)(hfac)2]n (8, monoclinic, I2/a; a = 11.371(1) A, b = 20.311(2) A, c = 15.240(2) A, beta = 100.201(2) degrees, Z = 4), composed of three sets of distinct one-dimensional linear chains; [Cu(C20H12N2)(EtOH)(NO3)2] [Cu(C20H12N2)1.5(NO3)2] x 2EtOH (9, triclinic, P; a = 12.248(2) A, b = 13.711(3) A, c = 18.257(4) A, alpha = 108.078(4) degrees, beta = 97.890(4) degrees, gamma = 103.139(5) degrees, Z = 2) and [Cu(C20H12N2)(MeOH)(NO3)2] [Cu(C20H12N2)1.5(NO3)2] x 2MeOH (10, triclinic, P; a = 12.136(1) A, b = 13.738(2) A, c = 17.563(3) A, alpha = 107.663(3) degrees, beta = 94.805(4) degrees, gamma = 104.021(4) degrees, Z = 2). Both 9 and 10 stack into infinite interpenetrating ladders through bundles of infinite chains and are described in our preliminary communication.     

Synthesis, spectroscopic, electrochemical and Pb2+-binding studies of tetrathiafulvalene acetylene derivatives

A series of tetrathiafulvalene acetylene derivatives, [TTF-Ctriple bondC-A] [A=C6H4N(CH3)2-4 (1), C6H4OCH3-4 (2), C6H5 (3), C6H4F-4 (4), C6H4NO2-4 (5), C5H4N-2 (6), C5H4N-3 (7), and C5H4N-4 (8)], have been designed and synthesized to provide insight into the nature of the donor-acceptor interaction via a pi-conjugated triple bond. The X-ray crystal structure of [TTF-(Ctriple bondC)-C6H4OCH3-4] (2) reveals that the phenyl ring linked by acetylene is almost coplanar to the plane of TTF with a dihedral angle of 3.6 degrees. The strong intermolecular C-H...O hydrogen bonding was found to direct the molecular helical assemblies with a screw pitch of 5.148 A when viewed along the a-axis. Spectroscopic and electrochemical behaviors of the tetrathiafulvalene acetylene derivatives demonstrate that the TTF unit interacts with the electron-accepting group through the triple bond, thus leading to the intramolecular charge transfer. The pyridine-substituted TTF compounds 6-8 show remarkable sensing and coordinating properties toward Pb2+. Comparison of the spectroscopic and electrochemical properties and the calculation at the B3LYP/6-31G* level available in Gaussian 03 reveals that varying the bridged unit of the TTF-pi-A system from a double bond to a triple bond leads to positive shifts for the first and second oxidation potentials of the TTF moieties, while the extent of intramolecular charge transfer interactions through the pi-conjugated triple bond is smaller than that through the double bond.     

Hydrocarbon-Soluble Mercuracarborands: Syntheses, Halide Complexes, and Supramolecular Chemistry

The syntheses of macrocyclic species composed of carborane derivatives joined via their carbon vertices by electrophilic mercury atoms are described. The reaction of closo-1,2-Li(2)[C(2)B(10)H(10)(-)(x)()R(x)()] with HgI(2) gives Li(2)[(1,2-C(2)B(10)H(10)(-)(x)()R(x)()Hg)(4)I(2)] [R = Et, x = 2 (5.I(2)Li(2)); R = Me, x = 2 (6.I(2)Li(2)); R = Me, x = 4 (7.I(2)Li(2))]. 6.I(2)(K.[18]dibenzocrown-6)(2) crystallizes in the monoclinic space group C2/m [a = 28.99(2) ?, b = 18.19(1) ?, c = 13.61(1) ?, beta = 113.74(2) degrees, V = 6568 ?(3), Z = 4, R = 0.060, R(w) = 0.070]; 7.I(2)(NBu(4))(2) crystallizes in the monoclinic space group P2(1)/c [a = 12.77(1) ?, b = 21.12(2) ?, c = 20.96(2) ?, beta = 97.87(2) degrees, V = 5600 ?(3), Z = 2, R = 0.072, R(w) = 0.082]. The precursor to 7, closo-8,9,10,12-Me(4)-1,2-C(2)B(10)H(8) (4), is made in a single step by reaction of closo-1,2-C(2)B(10)H(12) with MeI in trifluoromethanesulfonic acid. The free hosts 5, 6, and 7 are obtained by reaction of the iodide complexes with stoichiometric quantities of AgOAc. A (199)Hg NMR study indicates that sequential removal of iodide from 5.I(2)Li(2) and 6.I(2)Li(2) with aliquots of AgOAc solution leads to formation of two intermediate host-guest complexes in solution, presumed to be 5(6)ILi and 5(2)(6)(2).ILi. Crystals grown from a solution of 6.I(2)Li(2) to which 1 equiv of AgOAc solution had been added proved to be an unusual stack structure with the formula 6(3).I(4)Li(4) [tetragonal, I4/m, a = 21.589(2) ?, c = 21.666(2) ?, V = 10098 ?(3), Z = 2, R = 0.058, R(w) = 0.084]. Addition of 2 equiv of NBu(4)Br ion to 5 or 6 gives 5.Br(2)(NBu(4))(2) and 6.Br(2)(NBu(4))(2), respectively, while addition of 1 equiv of KBr to 6 forms 6.BrK. 5.Br(2)(NBu(4))(2) crystallizes in the triclinic space group P&onemacr;, [a = 10.433(1) ?, b = 13.013(1) ?, c = 15.867(2) ?, alpha = 91.638(2) degrees, beta = 97.186(3) degrees, gamma = 114.202(2) degrees, V = 1492 ?(3), Z = 1, R = 0.078, R(w) = 0.104]. The hosts 5 and 6 form 1:1 supramolecular adducts with the polyhedral anions B(10)I(10)(2)(-) and B(12)I(12)(2)(-) in solution.     

Structures of dimeric hydrolysis products of thorium

Three unique thorium dimeric compounds have been crystallized from either direct hydrolysis of Th4+(aq)/HCl or titration of Th(OH)4(am) with Th(NO3)4(aq) and their structures determined using single-crystal X-ray diffraction. The compound [Th2(micro2-OH)2(NO3)6(H2O)6]H2O (1) is identical to that identified previously by Johansson. Two additional unreported compounds have been identified, [Th2(micro2-OH)2(NO3)4(H2O)8](NO3)2 (2) and [Th2(micro2-OH)2Cl2(H2O)12]Cl4.2H2O (3). 1 crystallizes in the monoclinic space group P21/c, with a = 6.792(2) A, b = 11.710(4) A, c = 13.778(5) A, and beta = 102.714(5) degrees and 2 crystallizes in the monoclinic space group P21/n, with a = 6.926(5) A, b = 7.207(1) A, c = 21.502(1) A, and beta = 96.380(1) degrees . The chloride-containing dimer, 3, crystallizes in triclinic P, with a = 8.080(2) A, b = 8.880(2) A, c = 9.013(2) A, alpha = 97.41(3) degrees , beta = 91.00(3), and gamma = 116.54(3) degrees . We also present high-energy X-ray scattering data demonstrating the presence of the hydroxo-bridged moiety in solution and discuss our findings in the context of known solid-state structures. The three structures demonstrate 11-, 10-, and 9-coordinate thorium, respectively, and coupled with the scattering experiments provide additional structural and chemical insight into tetravalent actinide hydrolysis.     

Polymorphism of heptalithium nitridovanadate(V) Li7[VN4

The system Li-V-N was studied by means of X-ray and neutron powder diffraction, thermal and chemical analyses, and XAS spectroscopy at the vanadium K-edge. Three polymorphs of Li(7)[VN(4)] have been established from X-ray and neutron powder diffraction (gamma-Li(7)[VN(4)], space group Pfourmacr;3n, No. 218, a = 960.90(4) pm, V = 887.23(6) x 10(6) pm(3), Z = 8; beta-Li(7)[VN(4)], space group Pathremacr;, No. 205, a = 959.48(3) pm, V = 883.31(5) x 10(6) pm(3), Z = 8; alpha-Li(7)[VN(4)], P4(2)/nmc, No. 137, a = 675.90(2) pm, c = 488.34(2) pm, V = 223.09(1) x 10(6) pm(3), Z = 2). Crystallographic and phase relations are discussed. All three modifications are diamagnetic, indicating vanadium in the oxidation state +5. The V-K XAS spectra support the oxidation state assignment, the non-centrosymmetric coordination (tetrahedral), and the nearly identical second coordination sphere of vanadium, made up from Li in all three phases. The 3d-related features of the spectra display strongly localized properties. The phase transitions appear to be reconstructive; no direct group-subgroup symmetry relations of the crystal structures exist. The formation of solid solutions between Li(2)O and beta-Li(7)[VN(4)] with the general formula Li(1.75)((V(0.25(1)(-)(x))Li(0.25)(x))(N(1)(-)(x)O(x)())) with 0 相似文献   

Copper(I)-rhenate hybrids: syntheses, structures, and optical properties

The new copper(I) rhenates, CuReO4(pyz) (I) and Cu3ReO4(q6c)2 (II) (pyz = pyrazine; q6c = quinoline-6-carboxylate), were synthesized by hydrothermal methods at 140-150 degrees C, and their structures determined via single-crystal X-ray diffraction (I, P21/n, No. 14, Z = 4, a = 7.972(1) A, b = 11.928(2) A, c = 8.430(1) A, beta = 102.161(2) degrees ; II, P21, No. 4, Z = 2, a = 8.253(2) A, b = 6.841(2) A, c = 18.256(6) A, beta = 101.37(2) degrees ) and characterized by thermogravimetric analyses and UV-vis diffuse reflectance. The structure of I contains 'CuReO4' layers that are pillared through bridging pyrazine ligands via the Cu sites, while the structure of II is polar and contains chains of 'Cu2ReO4' that are condensed into layers by coordination to linear 'Cu(q6c)2' bridges between the chains. In contrast to air-sensitive CuReO4, both hybrid analogues are stable in air owing to a stabilization of the Cu1+ oxidation state by N-donating ligands, but decompose upon heating with the removal of the organic ligands, which for I yields crystalline CuReO4. UV-vis diffuse reflectance measurements and electronic structure calculations on all three copper perrhenates, I, II, and CuReO4, show that each exhibits an optical band gap of approximately 2.1-2.2 eV, with conduction and valence band levels that are primarily derived from the Re d0 and Cu d10 orbitals, respectively, and mixed with O p-orbital contributions. In contrast to the silver rhenates, which have relatively lower energy Ag d10 orbitals, the inclusion of the organic ligands into the structures has only a very minor effect ( approximately 0.1 eV) on the band gap size. The optical absorptions, in combination with the air-stable open-framework layered structures, illustrate that heterometallic Cu1+/Re7+ oxides can be promising candidates for investigating in visible-light photocatalytic reactions.