ICP emission spectrometer relative response by the branching-ratio method: branching ratios for Fe, Se, Te, Ge and Pd

The relative spectral response of a commercially available inductively coupled argon plasma (ICP) emission spectrometer has been determined over a wide spectral range (approx. 190 to >900 nm) using overlapping sets of radiative branching ratios of several atomic and ionic species. Response curves were determined in two ways. In the first, calibrations were based on Ar II and Ar I lines emitted by Ar-filled hollow-cathode lamps used as line sources instead of the plasma torch. In the second, the ICP emission of selected lines of Ni and Fe was used. Branching ratios determined from the ICP emission of lines of Fe I, Se I, and Te I, using Ar lines for the intensity calibrations, were compared with previously published branching ratios or f-values for these atoms, and good agreement was found. The calibrations based on Ar II and Ni I were used to measure further branching ratios, and application to the measurement of branching ratios from selected levels of Ge I and Pd I is shown.     

Determination of fluorine, chlorine, bromine and iodine by barrier discharge radiofrequency helium plasma.

A determination method of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I) by a barrier discharge radiofrequency helium plasma-atomic emission spectroscopy was developed. A borosilicate glass was wrapped by two copper film electrodes, one of which was earthed, and the other was supplied with a radiofrequency high voltage (98 kHz, 3.2 kV), resulting in a discharge inside of the tube. An optical emission from the discharge tube was introduced to a charge-coupled device (CCD)-spectrometer through an optical fiber, and was monitored in the wavelength range of 730-960 nm. The emission lines of F (733.2 nm, 739.9 nm), Cl (833.3 nm, 837.6 nm, 858.6 nm, 894.8 nm, 912.1 nm, etc.), Br (827.2 nm, 882.5 nm, 889.8 nm, 926.5 nm, etc.) and I (905.8 nm) were observed. The linearity of the calibration was determined for F and Cl over the range of 1-10 microg, and for Br of 0.1-1 microg. The relative emission intensity was in the order of Br > I > Cl >F.     

Stability indicating methods for determination of Donepezil Hydrochloride according to ICH guidelines

Stability indicating assays for determination of Donepezil Hydrochloride in presence of its oxidative degradate were developed and validated. The first three are spectrophotometric methods depending on using zero order (D(0)), first order (D(1)) and second order (D(2)) spectra. The absorbance was measured at 315 nm for (D(0)) while the amplitude was measured at 332.1nm for (D(1)) and 340 nm for (D(2)) using deionized water as a solvent. Donepezil Hydrochloride (I) can be determined in the presence of up to 70% of its oxidative degradate (II) using (D(0)), 80% using (D(1)) and 90% using (D(2)). The linearity range was found to be 8-56 microg ml(-1) for (D(0)), (D(1)) and (D(2)). These methods were applied for the analysis of I in both powder and tablet form. Also, a spectrofluorimetric method depending on measuring the native fluorescence of I in deionized water using lambda excitation 226 nm and lambda emission 391 nm is suggested. The linearity range was found to be 0.32-3.20 microg ml(-1) using this method, I was determined in the presence of up to 90% of II. The proposed method was applied for the analysis of I in tablet form as well as in human plasma. The last method depends on using TLC separation of I from its oxidative degradate II and I was then determined spectrodensitometrically. The mobile phase was methanol : chloroform : 25% ammonia (16 : 64 : 0.1 by volume). The linearity range was found to be 2-15 microg/spot. This method was applied to the analysis of I in both powder and tablet form using acetonitrile as a solvent.     

Chloroform extraction of ethyl xanthate complexes from sulphuric acid media

The chloroform extraction of 30 elements (Fe, Co, Ni, Zn, Cd, Ge, Sn, V, As, Sb, Bi, Cu, Ag, Au, Mn, Re, Ga, In, Tl, Se, Te, Cr, Mo, U, Pt, Pd, Rh, Ir, Ru and Ce) from 0.1-8M sulphuric acid in the presence of potassium ethyl xanthate has been studied. Pd(II), Bi, As(III), Sb(III), Se(IV) and Te(IV) are completely extracted and Au(III) is largely extracted over the range of acid concentration investigated. Fe(II), Tl(I), Rh(III) and Cr(VI) are only slightly extracted and Se(VI), Te(VI), Ru(III), Cr(III), Mn(II), Zn, Ce(IV), Ir(IV) and Ge(IV) are not extracted at all. Depending on the acid concentration, the remaining elements are all partly extracted. Results are compared with those obtained in an earlier study of the extraction of xanthate complexes from hydrochloric acid media. The processes involved in the formation of some xanthate complexes and potential analytical separations are discussed.     

Reactions of halogens with Pt(II) complexes of N-alkyl- and N,N-dialkyl-N'-benzoylthioureas: oxidative addition and formation of an I2 inclusion compound

The treatment of cis-[Pt(II)(L(1a/b)-S,O)2] complexes of N,N-diethyl- (HL(1a)) and N,N-di(n-butyl)-N'-benzoylthiourea (HL(1b)) with I2 or Br2 in chloroform, leads to rapid oxidative addition to yield several geometric isomers of [Pt(IV)(L-S,O)(2)X(2)](X = I, Br); the reactions can be monitored by (195)Pt NMR and UV-visible spectrophotometry. The products cis-[Pt(IV)(L(1a)-S,O)2I2] and cis-[Pt(IV)(L(1a)-S,O)2Br2], which have been isolated and structurally characterized, are the first-reported crystal structures of complexes of Pt(iv) with this class of ligand. Molecules of 6 pack such that the I-Pt-I axes are essentially aligned, with unusually close nearest-neighbour iodide contacts (3.553(1)A). These short II intermolecular interactions lead to infinite chains of weakly connected molecules in crystals of the compound. No such interactions are evident in the corresponding crystals of . Reaction of the Pt(II) complex of N-propyl-N'-benzoylthiourea (H2L(2a))cis-/trans-[Pt(II)(H2L(2a)-S)2Br2] with Br2 also results in oxidative addition, to yield trans-Pt(IV)(H2L(2a)-S)2Br4. By contrast, treatment of cis-/trans-[Pt(II)(H2L(2a)-S)2I2] with I2 does not lead to an oxidative addition product, yielding instead an interesting iodine inclusion compound of Pt(II), trans-[Pt(II)(H2L(2a)-S)2I2.I2. In 8, short intermolecular II distances of 3.453(1)A between I2 and coordinated iodide ions in trans-[Pt(II)(H(2)L(2a)-S)(2)I(2)] molecules, result in infinite chains of weakly linked trans-[Pt(II)(H2L(2a)-S)2I2]...I2 groups in the lattice. However, the empirically estimated bond order of 0.75 for the included I2 molecules does not support the possible existence of discrete tetraiodide ions (I4(2-)) in the lattice of compound 8.     

Chloroform extraction of metal ethyl xanthates from hydrochloric acid media

The chloroform extraction of 32 elements (Fe, Co, Ni, Zn, Cd, Ge, Sn, Pb, V, As, Sb, Bi, Cu, Ag, Au, Mn, Re, Ga, In, Tl, Ce, Se, Te, Cr, Mo, U, Pt, Pd, Rh, Ir, Ru and Os) from O.1-10M hydrochloric acid media in the presence of potassium ethyl xanthate has been studied. The oxidation states in which some elements react, and potential analytical separations, are discussed. Pd(II), As(III) and Se(IV) are completely extracted as ethyl xanthate complexes, Te(IV) is almost completely extracted, and Au(III) is largely extracted over the range of acid concentration investigated. Mn(II), Zn, Rh(III), Ir(IV), Ru(III), Os(IV), Cr(III), Cr(VI), Ce(III) and Ce(IV) are not extracted. Ge is partly extracted from 6-10M media as the chloro-complex. Depending on the acid concentration, the remaining elements are all partially extracted as xanthate complexes.     

Self-assembly of transition-metal-based macrocycles linked by photoisomerizable ligands: examples of photoinduced conversion of tetranuclear-dinuclear squares

A series of hetero- and homometallic square complexes bridged by a photoactive 4,4'-azopyridine (AZP) or 1,2-bis(4-pyridyl)ethylene (BPE) ligand, cyclobis[[cis-(dppf)M](mu-L)(2)(fac-Re(CO)(3)Br)](OTf)(4) (M = Pd, L = trans-AZP (5); M = Pt, L = trans-AZP (7); M = Pd, L = trans-BPE (8); M = Pt, L = trans-BPE (10)), cyclo[[cis-(dppf)M](mu-L)(2)(fac-Re(CO)(3)Br)](OTf)(2) (M = Pd, L = cis-AZP (6); M = Pd, L = cis-BPE (9)), [cis-(dppf)Pd(mu-trans-AZP)](4)(OTf)(8) (11), and [cis-(dppf)Pd(mu-cis-AZP)](2)(OTf)(4) (12), where dppf is 1,1'-bis(diphenylphosphino)ferrocene and OTf is trifluoromethanesulfonate anion, were prepared by thermodynamically driven self-assembly processes. The photophysical and photochemical properties of these complexes have been investigated, and all of them show a lack of luminescence in room temperature solution. Upon irradiation at 313 or 366 nm, Pd(II)-Re(I)-containing tetranuclear squares 5, 8, and 11 undergo photoisomerization and convert to their corresponding dinuclear complexes 6, 9, and 12, whereas Pt(II)-Re(I)-based squares 7 and 10 show only slow square disassembling processes. The tetranuclear squares can be fully recovered by heating the photoisomerized solution for several hours.     

Quaternary tellurides with different valent Ge centers: Cs2Ge3M6Te14 (M = Ga, In)

New quaternary tellurides, Cs(2)Ge(3)M(6)Te(14) (M = Ga, In), were discovered by solid-state reactions. These compounds crystallize in space group P3ml (No. 164), with a = b = 8.2475(2) ?, c = 14.2734(8) ?, and V = 840.82(6) ?(3) (Z = 1) for Cs(2)Ge(3)Ga(6)Te(14) (1) and a = b = 8.5404(2) ?, c = 14.6766(8) ?, and V = 927.07(6) ?(3) (Z = 1) for Cs(2)Ge(3)In(6)Te(14) (2). The remarkable structural feature is the novel three-dimensional [Ge(3)M(6)Te(14)](2-) anionic framework made by condensed In(6)Te(14) (or Ga(6)Te(14)) layers that are connected alternately by dimeric Ge(3+)(2)Te(6) units and Ge(2+)Te(6) octahedra along the c direction. The presence of Ge centers with different oxidation states is also supported by the results of the electron localization function calculation and X-ray photoelectron spectroscopy measurement.     

First metallamacrocyclic complexes of Pt(iv) with 3,3,3',3'-tetraalkyl-1,1'-phenylenedicarbonylbis(thioureas): synthesis by direct or electrolytic oxidative addition of I(2), Br(2) and Cl(2)

Elemental I(2) and Br(2) cleanly react with the 3:3 Pt(ii) metallamacrocycle of 3,3,3',3'-tetra(n-butyl)-1,1'-terephthaloylbis(thiourea)(cis-[Pt(II)(3)(L(p)(1)-S,O)(3)]3), in chloroform at room temperature, to yield oxidative addition products; (195)Pt NMR studies reveal that a stepwise oxidative addition readily occurs to each of the Pt(ii) centres in the metallamacrocycle to yield the mixed valence species cis-[Pt(II)(2)Pt(IV)I(2)(L(p)(1)-S,O)(3)] and cis-[Pt(II)Pt(IV)(2)I(4)(L(p)(1)-S,O)(3)], and the fully oxidised cis-[Pt(IV)(3)I(6)(L(p)(1)-S,O)(3)] in solution, depending on the mole ratio I(2):3. Similar results are obtained on treatment of solutions of 3 with elemental Br(2). Treatment of the corresponding 2:2 Pt(ii) complex of 3,3,3',3'-tetraethyl-1,1'-isophthaloylbis(thiourea)(cis-[Pt(II)(2)(L(m)(1)-S,O)(2)]4) with iodine, results in facile oxidative addition to yield cis-[Pt(IV)(2)(L(m)(1)-S,O)(2)I(4)], with a trans-Pt(iv)-iodo arrangement. Molecules in the crystal structure of 5 have their trans-Pt(iv)-iodo axes essentially aligned, with very close intermolecular iodide contacts (3.775(1)A), resulting in chains of weakly bound metallamacrocycles in the solid. An alternative electrolytic synthesis method, using a simple two-compartment glass cell containing 4 and a chosen halide salt in dichloromethane, led to the formation of cis-[Pt(IV)(2)(L(m)(1)-S,O)(2)Br(4)] 6 and cis-[Pt(IV)(2)(L(m)(1)-S,O)(2)Cl(4)] 7, completing characterization of a series of first-reported trans-Pt(iv)-X (X=I, Br, Cl) metallamacrocyclic complexes.     

Determination of platinum in plants by emission spectrometry after preconcentration on modified silicagel

Silicagel Separon SGX C18 (particle size 7 microm) was suitable for the preconcentration of 2-20 microg of Pt from 0.1M hydrochloric acid in the presence of cationic surfactants especially dimethyllaurylbenzylammonium bromide, with subsequent elution with 96% ethanol. The recovery was 86-110% for 2 microg of Pt. The sample matrix corresponding to 2.5 g of average plant ash does not interfere. The final emission spectrometry of platinum was carried out in 15 A dc-arc at Pt I 265.942 nm in the presence of Au as internal standard (Au I 267.595 nm). RSD was 6.3% in average.     

Analysis of superconductor oxides YBa2Cu3O8−x by inductively coupled plasma atomic emission spectrometry and complexometric titration

The elemental composition of superconductor oxides YBa₂Cu₃O_8−x were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and complexometric titration. Samples were dissolved in dilute HCl. A sequential PU 7000 Philips inductively coupled plasma atomic emission spectrometer was used for the measurements. A comparison of the different atom and ion emission lines of yttrium, barium and copper was carried out. The effect of changes of forward radio frequency (RF) power coupled into the plasma on emission intensity of various spectral lines was studied. The RF power was changed from 0.8 to 1.2 kW. The changes in the net intensities (%) of the emission lines of Cu(I) at 324.754 nm, Cu(II) at 224.700 nm, Ba(II) at 455.403, Ba(II) at 493.409 nm, Y(II) at 371.030 nm and Y(II) at 360.073 nm were calculated. The indicator 1-(2-Pyridylazo)-2-Naphthol (PAN) and different buffers were used for the complexometric titration of Cu, Y and Ba. No statistically significant differences were found between the results of ICP-AES and chemical methods of analysis.     

Use of (130)Te(2) for frequency referencing and active stabilisation of a violet extended cavity diode laser

This paper reports on the use of (130)Te(2) absorption lines in active laser-locking, and in frequency referencing, of the emission of a violet extended cavity diode laser with a wavelength of around 410 nm. We note the existence of closely spaced tellurium absorption lines, suitable for referencing purposes in gas sensing applications, at wavelengths below the lower limit (417 nm) of the spectral region covered by the tellurium atlas [J. Cariou, P. Luc, Atlas du spectre d'Absorption de la Molecule de Tellure, CNRS, Paris, 1980]. The absolute positions of the lines in the acquired spectra were estimated by comparison to a simultaneously acquired fluorescence spectrum of atomic indium, and were identified using calculations based on fundamental spectroscopic data. The laser frequency was stabilised within a range of 40 MHz, which is negligible compared to typical transition widths at atmospheric pressure.     

Gas-phase ligand loss and ligand substitution reactions of platinum(II) complexes of tridentate nitrogen donor ligands

The source of protons associated with the ligand loss channel of HX((n - 1)+) from [Pt(II)(dien)X](n+) (X = Cl, Br and I for n = 1 and X = NC(5)H(5) for n = 2) in the gas phase was investigated by deuterium-labelling studies. The results of these studies indicate that these protons originate from both the amino groups and the carbon backbone of the dien ligand. In some instances (e.g. X = Br and I), the protons lost from the carbon backbone can be even more abundant than the protons lost from the amino groups. The gas-phase substitution reactions of coordinatively saturated [Pt(II)(L(3))L(a)](2+) complexes (L(3) = tpy or dien) were also examined using ion-molecule reactions. The outcome of the ion-molecule reactions depends on both the ancillary ligand (L(3)) as well as the leaving group (L(a)). [Pt(II)(tpy)L(a)](2+) complexes undergo substitution reactions, with a faster rate when L(a) is a good leaving group, while the [Pt(II)(dien)L(a)](2+) complex undergoes a proton transfer reaction.     

Luminescence of ruthenium halide complexes containing a hemilabile phosphine pyrenyl ether ligand

A series of Ru(II) complexes, tcc-RuX2(POC4Pyr-P,O)2 (X = Cl (3), Br (4), I (5)), containing the hemilabile phosphine pyrenyl ether ligand 4-{2-(diphenylphosphino)phenoxy}butylpyrene (POC4Pyr (1)) are reported. The synthesis and spectroscopic properties of both the ligand, POC4pyr (1), and ligand oxide, P(=O)OC4pyr 2, and the solid-state structure of 1 are reported. Complexes 3-5 react rapidly with CO to give complexes ttt-RuX2(CO)2(POC4pyr-P)2 (X = Cl (6), Br (7), I (8)). No pyrene excimer emission is detected from 3-5; however, different intensities of excimer emission are observed for 6-8. The intensity of excimer emission decreases through the series, with 6 showing the most intense response. The emission is solely due to intramolecular pyrene excimers at low concentrations (< or =10(-4) M). Comparison of the UV-vis and steady-state fluorescence spectra shows overlap between the low energy d-d absorption of 7 and 8 with excimer emission (480 nm), suggesting nonradiative energy transfer may be occurring. Once excess CO is removed, complexes 6-8 isomerize to cis-dicarbonyl complexes cct-RuX2(CO)2(POC4Pyr-P)2 (X = Cl (9), Br (10), I (11)). The intensity of excimer emission from 9-11 increases with respect to the excimer emission observed for 6-8, with 9 showing a significant increase in excimer intensity.     

Organomonophosphines in PtP<Subscript>2</Subscript>XY derivatives: structural aspects

This review covers over two hundred Pt(II) complexes with a PtP₂XY inner coordination sphere, in which the P-donor ligands are organomonophosphines. These complexes can be divided into six groups: PtP₂HX (X = O, N, B, Cl, S, Br, Se, Si, or I); PtP₂OX (X = N, Cl, S, or Se); PtP₂NX (X = CN, Cl, B, S, Br, Se, or Te); PtP₂BX (X = F, Cl, S, Br, or I); PtP₂ClX (X = S, Se, Si, As, or Te); and PtP₂SiX (X = Br or Te). The complexes crystallize in several crystal systems: hexagonal (×1), tetragonal (×1), orthorhombic (×22), triclinic (×78), and monoclinic (×130). There are complexes with cis-configuration and trans-configuration, the latter by far prevails. Besides monodentate ligands, there are also heterobidentate ligands with: O/N, O/S, O/Se, N/S, N/Se, and N/Te, donor sites. These chelating ligands form a wide variety of metallocyclic, four-, five-, and six-membered rings, and the effects of both steric and electronic factors can be seen from the values of the L–Pt–L bite angles. The structural parameters are analyzed and discussed with particular attention to trans-influences.     

Determination of platinum(IV) by UV spectrophotometry

A simple, rapid and sensitive spectrophotometric procedure for the determination of platinum has been elaborated. Pt traces were determined in the form of the PtCl(6)(2-) complex in hydrochloric acid solution whose concentration varies from 0.01 to 2 mol L(-1) by measuring the absorbance at 260 nm. The detection limit is 4.7 x 10(-7) mol L(-1), the linearity range from 2 x 10(-6) mol L(-1) to 7 x 10(-6) mol L(-1), and the correlation coefficient is r=0.9990. No significant interferences were observed from a majority of the investigated ions, such as Zn(II), Pb(II), Mn(II), Cd(II), Co(II) and Ni(II) with the exception of Cu(II), Sb(III), Fe(III), Pd(II), Sn(II) and I(-) ions. The method was successfully applied for the determination of Pt traces in different solid samples and the recovery from inorganic materials was studied.     

Platinum complexes of diazo ligands. Studies of regioselective aromatic ring amination, oxidative halogen addition and reductive halogen elimination reactions

2-(Arylazo)pyridine ligands, L1a-1c react with the salt K2[PtCl4] to give the mononuclear complexes [PtCl2(L1)](1), which readily react with ArNH2 to yield the monochloro complexes of type [PtCl(L2)](HL2= 2-[(2-(arylamino)phenyl)azo]pyridine)(2) via regioselective ortho-amine fusion at the pendent aryl ring of coordinated L1. Oxidative addition of the electrophiles Y2(Y = Cl, Br, I) to the square-planar platinum(II) complex, has led to syntheses of the corresponding octahedral platinum(IV) complexes, [PtY3(L2)](3) in high yields. Ascorbate ion reductions of the platinum(IV) complexes, , resulted in reductive halogen elimination to revert to the platinum(II) complexes almost quantitatively. Isolation of products and X-ray structure determination of the representative complexes followed all these chemical reactions. In crystal packing, the compound [PtCl2(L1c)](1c) forms dimeric units with a Pt...Pt distance of 3.699(1) A. In contrast, the crystal packing of 2b revealed that the molecules are arranged in an antiparallel fashion to form a noncovalent 1D chain to accommodate pi(aryl)-pi(pyridyl) and Pt-pi(aryl) interactions. Notably, the oxidation of [Pt(II)Cl(L2a)](2a) by I2 produced a mixed halide complex [Pt(IV)ClI2(L2a)](5), which, in turn, is reduced by ascorbate ion to produce [Pt(II)I(L2a)] with the elimination of ClI. All the platinum(II) complexes are brown, the platinum(IV) complexes, on the other hand, are green. Low-energy visible range transitions in the complexes of the extended ligand [L2]- are ascribed to ligand basedpi-pi* transitions. Cyclic voltammetric behaviour of the complexes is reported.     

Single-crystal X-ray study of Ba2Cu2Te4O11Br2 and its incommensurately modulated superstructure companion

Compounds containing lone-pair elements such as Te(IV) are very interesting from the structural point of view, as the lone-pair nonbonding regions create low-dimensional geometrical arrangements. We have synthesized two new compounds with these features-Ba(2)Cu(2)Te(4)O(11)Br(2) (I) and Ba(2)Cu(2)Te(4)O(11-delta)(OH)(2delta)Br(2) (II, delta approximately equal to 0.57)-as members of the AE-M-Te-O-X (AE=alkaline-earth metal, M=transition metal, X=halide) family of compounds by solid-state reactions. Preliminary single-crystal X-ray analysis indicated that compound I crystallizes in the orthorhombic system, but attempts at refinement proved unsatisfactory. Closer inspection of the reciprocal lattice revealed systematic, non-crystallographic absences that indicate twinning. The structure is in fact triclinic, space group C_1 (equivalent to P_1), with unit cell parameters (at 120 K) of a=10.9027(9), b=15.0864(7), c=9.379(2) A, beta=106.8947 degrees . It is layered and built from [TeO(3)E] tetrahedra, [TeO(3+1)E] trigonal bipyramids (where E is the lone pair of Te(IV)), [CuO(4)] squares and irregular [BaO(10)Br] polyhedra. The crystal structure of II shows the same basic structure as I but contains additional oxygen, probably in the form of OH groups. The presence of satellites reveals that ordering on this O site creates an incommensurate modulation, primarily affecting Br and Te. The modulated structure of II was solved in the triclinic superspace group X$\bar 1$(alphabetagamma)0 with the vector q approximately equal to1/16 c*.     

Simultaneous Determination of As,Bi, Sb,Se, Te,Hg, Pb and Sn by Small-Sized Electrothermal Vaporization Capacitively Coupled Plasma Microtorch Optical Emission Spectrometry Using Direct Liquid Microsampling

The simultaneous determination of chemical vapor-generating elements involving derivatization is difficult even by inductively coupled plasma optical emission spectrometry or mass spectrometry. This study proposes a new direct liquid microsampling method for the simultaneous determination of As, Bi, Se, Te, Hg, Pb, and Sn, using a fully miniaturized set-up based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry. The method is cost-effective, free from non-spectral interference, and easy to run by avoiding derivatization. The method involves the vaporization of analytes from the 10 µL sample and recording of episodic spectra generated in low-power (15 W) and low-Ar consumption (150 mL min⁻¹) plasma microtorch interfaced with low-resolution microspectrometers. Selective vaporization at 1300 °C ensured the avoidance of non-spectral effects and allowed the use of external calibration. Several spectral lines for each element even in the range 180–210 nm could be selected. Generally, this spectral range is examined with large-scale instrumentation. Even in the absence of derivatization, the obtained detection limits were low (0.02–0.75 mg kg⁻¹) and allowed analysis of environmental samples, such as cave and river sediments. The recovery was in the range of 86–116%, and the accuracy was better than 10%. The method is of general interest and could be implemented on any miniaturized or classical laboratory spectrometric instrumentation.     

Luminescence ranging from red to blue: a series of copper(I)-halide complexes having rhombic {Cu2(mu-X)2} (X = Br and I) units with N-heteroaromatic ligands

A series of Cu(I) complexes formulated as [Cu(2)(mu-X)(2)(PPh(3))(L)(n)] were prepared with various mono- and bidentate N-heteroaromatic ligands (X = Br, I; L = 4,4'-bipyridine, pyrazine, pyrimidine, 1,5-naphthyridine, 1,6-naphthyridine, quinazoline, N,N-dimethyl-4-aminopyridine, 3-benzoylpyridine, 4-benzoylpyridine; n = 1, 2). Single-crystal structure analyses revealed that all the complexes have planar {Cu(2)X(2)} units. Whereas those with monodentate N-heteroaromatic ligands afforded discrete dinuclear complexes, bidentate ligands formed infinite chain complexes with the ligands bridging the dimeric units. The long Cu...Cu distances (2.872-3.303 A) observed in these complexes indicated no substantial interaction between the two Cu(I) ions. The complexes showed strong emission at room temperature as well as at 80 K in the solid state. The emission spectra and lifetimes in the microsecond range were measured at room temperature and at 80 K. The emissions of the complexes varied from red to blue by the systematic selection of the N-heteroaromatic ligands (lambda(em)(max): 450 nm (L = N,N-dimethyl-4-aminopyridine) to 707 nm (L = pyrazine)), and were assigned to metal-to-ligand charge-transfer (MLCT) excited states with some mixing of the halide-to-ligand (XL) CT characters. The emission energies were successfully correlated with the reduction potentials of the coordinated N-heteroaromatic ligands, which were estimated by applying a simple modification based on the calculated stabilization energies of the ligands by protonation.