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Anion-π interactions are emerging as exotic features with potential applications in chemistry. In the last years, their relevance in living systems has been outlined, and so far there is no concluding significant evidence recognized about the participation of anion-π interactions in water because anion-π sensors contain large aromatic hydrophobic surfaces with limited solubility. By transforming a neutral heterocycle (for example quinoline) into its corresponding salt (quinolinium), we have been able to overcome these solubility issues, and new cationic water-soluble fluorophores have been prepared. Herein, we used N-alkylated heterocycles as π-acidic surfaces to shed light on the nature of anion-π in water by the direct measurement of the fluorescence and UV/Vis spectra in combination with DFT and X-ray analyses.

Four methylated N-confused free-base tetraarylporphyrins, which are represented as N-CH3(Ar)4NcpH2 (Ar =CH3OPh, CH3Ph, Ph or ClPh), were synthesized and characterized in terms of their spectral and electrochemical properties in nonaqueous media. The first one-electron oxidation of each porphyrin is reversible and located at E1/2=0.51–0.71 V, whereas the first one-electron reduction is quasi-reversible and located between −0.98 and −1.11 V vs. SCE. The electrochemically measured HOMO−LUMO gap ranged from 1.62 to 1.73 V, depending upon the solvent and meso-substituents on the macrocycle, and this range of values is similar to the HOMO−LUMO gaps of both the non-methylated N-confused porphyrins, (Ar)4NcpH2 (1.60–1.68 V), and the nitrated N-confused porphyrins, NO2(Ar)4NcpH2 (1.58–1.68 V). The effect of the N-methyl group on UV/Vis spectra and reduction/oxidation potentials as well as the mechanisms of electron transfer are discussed, and comparisons made with data in the literature for both the non-methylated N-confused porphyrins and related N-confused porphyrins having the same meso-substituents and an inner nitro-substituted carbon atom.

The leather is a durable and flexible protein that can be created by tanning animal rawhide and skins. In this work, a simple method was developed for the functionalization of leather surfaces in terms of excellent coloration and protective properties against micro-organisms and UV radiation. The multifunctional leather surface was obtained through in-situ deposition of silver nanoparticles (Ag NPs) onto the leather surface by employing trisodium citrate (TSC). TSC acts as both a reducing and stabilizing agent. The figuration of Ag NPs in the solutions was evaluated by UV/Vis spectra and the morphology of nanoparticles was determined by TEM. The treated leather samples (Leather/Ag NPs) were evaluated by different tools including SEM, EDX, ATR-FTIR, XRD, TGA, as well as silver content. The impact of the Ag NPs on the coloration, UV-protection, and anti-microbial properties of the leather surface was evaluated. Results disclosed that the nanoparticles are mostly in spherical shapes, regularly distributed, and closely anchored onto the leather surface. The particle size distribution of nanoparticles onto the leather surface was in the range of 55 ± 17 and 130 ± 16 nm for leather/Ag NPs (300 ppm) and leather/Ag NPs (1000 ppm) respectively. The leather/Ag NPs samples were revealed good color properties in terms of color homogeneity, strength as well as excellent fastness properties. The leather/Ag NPs samples were exhibited a yellow/brown color. Moreover, the leather/Ag NPs (1000 ppm) sample was exhibited the highest a* value (6.1 ± 0.8) and b* value (27.8 ± 1.9). The leather/Ag NP sample was showed the highest silver content (1849 ± 3 mg/kg) and much higher UPF value (478 ± 3) than the other samples. Furthermore, the leather/Ag NPs samples were exhibited broad-spectrum antimicrobial activity against different micro-organisms. The leather/Ag NPs (1000 ppm) sample was demonstrated excellent antimicrobial properties with 100% bacterial reduction efficiency against both Gram-positive and Gram-negative bacteria and more than 93% fungal reduction efficiency against Candida albicans

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. The synthesis of new molecular complexes of U2+has been pursued to make comparisons in structure, physical properties, and reactivity with the first U2+complex, [K(2.2.2-cryptand)][Cp′3U], 1 (Cp′=C5H4SiMe3). Reduction of Cp″3U [Cp″=C5H3(SiMe3)2] with KC8in the presence of 2.2.2-cryptand or 18-crown-6 generates [K(2.2.2-cryptand)][Cp″3U], 2-K(crypt), or [K(18-crown-6)(THF)2][Cp″3U], 2-K(18c6), respectively. The UV/Vis spectra of 2-K and 1 are similar, and they are much more intense than those of U3+analogues. Variable temperature magnetic susceptibility data for 1 and 2-K(crypt) reveal lower room temperature χMT values relative to the experimental values for the 5f3U3+precursors. Stability studies monitored by UV/Vis spectroscopy show that 2-K(crypt) and 2-K(18c6) have t1/2values of 20 and 15 h at room temperature, respectively, vs. 1.5 h for 1. Complex 2-K(18c6) reacts with H2or PhSiH3to form the uranium hydride, [K(18-crown-6)(THF)2][Cp″3UH], 3. Complexes 1 and 2-K(18c6) both reduce cyclooctatetraene to form uranocene, (C8H8)2U, as well as the U3+byproducts [K(2.2.2-cryptand)][Cp′4U], 4, and Cp″3U, respectively.

This study concentrates on the isomerization process of the explosive material 5,7-diamino-4,6-dinitrobenzofuroxan (CL-14). It has a benzofuroxan core, which is capable of isomerization via ring opening and closure reactions. To investigate the course of this process, some mechanisms are proposed and certain density functional calculations were carried out at the restricted levels of B3LYP using 6-31G(d) and 6-31G(d,p) basis sets. The stabilities and some other quantum chemical properties of the isomers were obtained. Additionally, the calculated IR and UV/Vis spectra of the structures are presented.

Chromium tricarbonyl η6 complexes of 3cyclacene are considered quantum chemically at the levels of B3LYP/6-31G(d), B3LYP/6-31++G(d, p), B3LYP/LANL2DZ, and RF/6-31G(d, p)//B3LYP/6-31++G(d, p). One of the complexes involves the top ring (A-type) and the other one (B-type) makes use of ring of the acene belt of the cyclacene in the complex formation. Energy calculations reveal that B-type complex is more stable than A-type. Some geometrical and quantum chemical properties were obtained. Additionally, vibrational and UV/Vis spectra of the complexes were produced.

The complexation between lanthanide metal ions like Nd(III), Tb(III), and Er(III) with Glimepiride produces 1: 1 molar ratio (metal: Glimepiride) monodentate complexes of general formula: [M(GMP)(H2O)4]Cl3·xH2O, where: M = Nd, Tb, and Er, x = 1, 10, respectively. The structures of obtained compounds were assigned by IR, 1H NMR and UV/Vis spectra. Themogravimetric analysis and kinetic thermodynamic parameters have proved the thermal stability of Glimepiride complexes. Obtained lanthanide complexes showed significant effect against some bacteria and fungi.

The reaction of Tc(+7) with H2O2 has been studied in HNO3 and the speciation of technetium was performed by UV/Vis spectroscopic analysis. UV/Vis measurements show that for HNO3 concentrations of more than 7 M and H2O2 concentrations of 4.25 M, Tc(+7) reacts immediately and red solutions are obtained, whereas no reaction occurs at H2O2 concentrations of 0.1 M. The UV/Vis spectra of the red solutions exhibit a single band centered at 500 nm that is attributed to a Tc(+7) peroxo species. The nature of the Tc(+7) peroxo species was investigated by computational methods. The structures and electronic spectra of the putative species Tc(O2)4–, TcO(O2)3–, TcO3(O2)–, TcO(O2)2(H2O)(OH), and TcO2(O2)(H2O)2(OH) were studied by first principles methods. Calculations show these species to be stable; their calculated spectra were compared to the experimental spectrum and the results are consistent with the presence of diperoxo pertechnetic acid, i.e., TcO(O2)2(H2O)(OH).

Two new polymeric iodoargentate hybrids induced by rare earth metal complexes and conjugated organic cations, {[Er(DMF)8][Ag6I9]}n (1) and [(MMP)(AgI2)]n (2) (MMP = 1-methyl-4-methylpyridinium) were obtained by the routine synthetic reaction and structurally determined. In compound 1, a (Ag6I9)n3n– chain is defined by edge-sharing Ag6I12 units, and in 2, the (Ag2I4)n2– chains are constructed by edge-sharing AgI4 tetrahedra. C–H···I hydrogen bonds between cations and iodoargentate polyanions contribute to their structural extension from 1D to a 2D layer (for 1) and a 3D network (for 2). The UV/Vis spectra indicate that compared with 2, compound 1 exhibits a narrower adsorption scope with an onset at about 360 nm, and it has a much wider bandgap of about 3.50 eV.

Three metal-organic frameworks based on the connectivity co-effect between rigid aromatic dicarboxylic acids and flexible linear linkers have been synthesized and characterized. [Cd(3-NO2-bdc)(bbi)]n (1) and [Co(3-NO2-bdc)(bbi)]n (2) (3-NO2-bdcH2 = 3-nitro-1,2-benzenedicarboxylic acid, bbi = 1,1′-(1,4-butanediyl)bis(imidazole)) are isostructural, which exhibit two-dimensional (2D) layer frameworks; [Co(3,5-pdc)(bbi)·2H2O]n (3) (3,5-pdcH2 = pyridine-3,5-dicarboxylic acid) has 2D 6-connected network with a Schafli symbol of (344653). In addition, compounds 1 and 2 exhibit good photocatalytic activities under visible irradiation, and their different photocatalytic activities have also been analyzed based on the diffuse-reflectance UV/Vis spectra.

The acidity function ( H 0 ) of solutions of trifluoroacetic acid (TFA) in dichloromethane was measured by the indicator method at 298 K in the whole concentration range. The H 0 value for the most acidic solution studied (12.93 M trifluoroacetic acid) is −3.09. The equation describing the dependence of H 0 on the acid concentration was determined. The obtained quantitative data were used for a spectrophotometric study of the basicity of 2,9,16,23-tetra- tert -butylphthalocyanine. Two forms with different UV/vis spectra were observed and their stability constants determined.

This paper describes a new protocol for producing Ag nanocubes of 30 to 70 nm in edge length with the use of CF3COOAg as a precursor to elemental silver. By adding a trace amount of sodium hydrosulfide (NaHS) and hydrochloric acid (HCl) into the polyol synthesis, Ag nanocubes were obtained with good quality, high reproducibility, and on a scale up to 0.19 g per batch for the 70-nm Ag nanocubes. The Ag nanocubes were found to grow in size at a controllable pace over the course of synthesis. The linear relationship between the edge length of the Ag nanocubes and the position of localized surface plasmon resonance (LSPR) peak provides a simple method for finely tuning and controlling the size of the Ag nanocubes by monitoring the UV-vis spectra of the reaction at different times.

By comparing the FIR, MIR, NIR, and vis spectra (pellets) of PrCp*3 (Cp* = η5-C5Me5) (1) with those of LaCp*3 (2) the energies of a number of crystal field (CF) levels of 1 could be determined. The...

New FC[SiMe2(CH2)nSiMeFC]2 [FC = 1,1′-ferrocenylene; FC = 1,1′-ferrocenophane, (η5-C5H4)2Fe); n = 2 (7), 3 (8), 6 (9)] and O[SiMe2-X-SiMeFC]2 [X = (CH2)2 (11), CH═CH (13)] have been synthesized and characterized. The synthesis involved the reactions of FCLi2·tmeda with FC[SiMe2(CH2)nSiMeCl2]2 [n = 2 (4), 3 (5), 6 (6)] and O[SiMe2-X-SiMeCl2]2 [X = (CH2)2 (10), CH═CH (12)] at −78 °C. Compounds 4−13 were characterized by elemental analysis, NMR spectroscopy, and for 11, single-crystal X-ray crystallography. The cyclopentadienyl rings in the structure of 11 are tilted with a dihedral angle of 19.8°. The observed red-shift of the lowest energy transition associated with the ferrocenophanyl groups in UV/vis spectra of 7−9, 11, and 13 also confirms the ring strain. Cyclic voltammetric studies exhibited either a broad (7−9) or sharp (11, 13) wave for the reversible redox process. The broadness of the band for the FC-bridged complexes is a composite of the two types of (η5-C5H4)Fe(η5-C5H4) unit, but no significant...

A new series of benzoylthiourea derivatives of 1, 3, and 5 were prepared, and their chemodosimetric behaviors toward metal cations were investigated in aqueous media at room temperature. Among various metal cations tested, exclusively Hg2+ ion responses to irreversible color changes of receptors, along with distinctive blue shifts in UV/vis spectra. The receptors can be applicable for the monitoring of Hg2+ ion in aqueous solution with a pH span 4-9.

In order to quantify the contribution of mainly, but not only, diimine ligands to the electronic properties of the corresponding complexes, two novel indices, namely modified electronic parameters (ModEP) and electrophilicity, ω, are introduced and discussed in this report. First, we introduce the concept of ModEP, a novel scale relating to the electronic properties of diimine ligands. Mainly on the basis of wellcharacterized M(diimine)(dithiolato) complexes (M = Pt, Pd, or Ni), we derive the contribution of the diimine ligand to the reduction potentials of the complexes, and incorporating its contribution to the main charge-transfer band of the UV/Vis spectra, we obtain our ModEP values. The applicability of the introduced scale to several other classes of diimine compounds (W, Re, and Ru) is then tested. The performance of our scale in predicting the values of the reduction potentials and the position of the charge-transfer bands is very satisfactory. With this approach, some interesting aspects of ligand

The preparation and structures of 2, 2′-dihydroxyazobenzenato-dibutyl-tin [Bu2SnL] and 2, 2′-dihydroxyazobenzenato-dimethyl-tin [Me2SnL] are described. The complexes were characterized by IR, NMR (1H, 13C, 119Sn) and UV/VIS spectra. The crystal structures were determined by X-ray diffraction on single crystals. [Bu2SnL]: monoclinic, space group P21/c, cell constants at 208 K: a = 860.73(5), b = 973, 51(18), c = 2340.0(3) pm, β = 93.615(11)°; R1 = 0.0546. [Me2SnL]: orthorhombic, space group Pbcn, cell constants at 208 K: a = 1914.6(4), b = 1041.3(3), c = 1323.27(14) pm; R1 = 0.0529. Organozinn Farbstoffe: Darstellung und strukturelle Charakterisierung von Dibutylzinn- und Dimethylzinn-Komplexen mit 2, 2′-Dihydroxyazobenzen Darstellungen und Strukturen von 2, 2′-Dihydroxyazobenzenato-dibutyl-zinn (Bu2SnL) und 2, 2′-Dihydroxyazobenzenato-dimethyl-zinn [Me2SnL] werden beschrieben. Die Komplexe wurden durch IR-, NMR (1H, 13C, 119Sn)- und UV/VIS-Spektren charakterisiert. Die Kristallstrukturen liesen sich durch Rontgenbeugung an Einkristallen bestimmen. [Bu2SnL]: monoklin, Raumgruppe P21/c, Gitterkonstanten bei 208 K: a = 860.73(5), b = 973, 51(18), c = 2340.0(3) pm, β = 93.615(11)°; R1 = 0.0546. [Me2SnL]: orthorhombisch, Raumgruppe Pbcn, Gitterkonstanten bei 208 K: a = 1914.6(4), b = 1041.3(3), c = 1323.27(14) pm; R1 = 0.0529.

Two isomeric cis-2,9-bis(aminomethyl)-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (1 and 2) and two 2-aminomethyl-2-methyl-1,4,8,11-tetraazacyclotetradecane (3 and 4) cobalt(III) complexes have been prepared and characterised. During the synthesis of 2 a minor oxidation product 5 was formed. The structures of 3, 4 and 5 have been determined by X-ray crystallography, and the UV/Vis spectra of 1−5 have been analysed. The average Co−N distances in 1 and 2 have been estimated from the correlation between the average Co−N bond lengths and position of the maximum absorption for hexaamine complexes given in literature. The electrochemical behaviour of 1−5 in neutral and acidic solutions has been studied by cyclic voltammetry. In complexes displaying electronic maxima at higher energy, cobalt(III) was reduced at more negative potentials. Small differences in the conformation of ligand between 3 and 4 explain the different behaviour of these complexes in acidic solutions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Metallophthalocyanines (MPc) exhibit, among many useful properties, the ability to protect sensors against short, intense pulse deleterious to efficient sensor operation. For the successful application of this optical-limiting property, an important issue is the incorporation of MPc molecules in a matrix to fabricate a solid-state system. We report here the study of different concentrations of zinc tetrasulfophthalocyanine (ZnTSPc) encapsulated in silica xerogel matrix obtained by sol–gel technique. The resulted composites were transparent and homogeneous with appropriate optical quality. The trapping effect was checked by the characteristic absorption bands of ZnTSPc in the UV/Vis spectra and the different pore structures of the doped and undoped composites. The optical-limiting properties of the composites were measured at 532 nm with 8-ns pulses.

Reaction of [PdCl2(DMSO)2], [PtCl2(DMSO)2], and [RuCl2(η4-C8H12)(MeCN)2] with S-acetyl Nβ-acetyldithiocarbazate (=2-acetylhydrazinecarbodithioic acid anhydrosulfide with ethanethioic acid; aadt; 1), S-methyl Nβ-[(5-nitrothiophene-2-yl)methylene]dithiocarbazate (=S-methyl 2-[(5-nitrothiophene-2-yl)methylene]hydrazinecarbodithioate; mntdt; 2), and S-benzyl Nβ-[(5-nitrothiophene-2-yl)methylene]dithiocarbazate (=S-benzyl 2-[(5-nitrothiophene-2-yl)methylene]hydrazinecarbodithioate; bntdt; 3) led to new complexes [PdCl2(L)], [PtCl2(L)], and [RuCl2(η4-C8H12)(L)] (L=ligands 1–3). All these compounds were characterized by elemental analysis, IR, 1H- and 13C-NMR and UV/VIS spectra and thermogravimetric analysis. Ligand 1 coordinates through the thioxo S-atom and the carbazate N(β) atom, whereas in ligands 2 and 3 the thioxo S-atom and the azomethine N-atom are coordinated to the metal ion. Screening of antiamoebic activity of these compounds was performed in vitro against the HK-9 strain of E. histolytica. All the complexes were more active than their respective ligands; compound 3a showed the most promising activity.

Three ligands have been formed by the 1:2 molar condensation of o-phenylenediamine with salicyldhyde, 2-hydroxy-1-naphthaldhyde or o-hydroxyacetophenone. The potentially tetradentate ligands are N,N′-bis(salicyldhyde)-o-phenylenediamine(SalophH2), N,N′-bis(2-hydroxy-1-naphthaldhyde)-o-phenylenediamine (NophH2) and N,N′-bis(o-hydroxyacetophenone)-o-phenylenediamine (AophH2), respectively. These ligands form complexes (1:1 molar ratio) with nickel, copper and zinc ions. The complexes have been characterized by IR, 1HNMR, MS, uv/vis spectra in addition to elemental analysis. The spectral data of the ligands and their complexes with nickel, copper and zinc are discussed in connection with the structural changes which occur due to complexation.

The uniformity and ordering of the surface of (Al)MCM-41 channel walls was investigated employing bare Co(II) ions as probes. VIS spectra of Co(II) ions evidenced the presence of two types of uniform cationic sites in dehydrated Co-(Al)MCM-41 in a wide range of Si/Al/Co chemical composition (Si/Al = 11-76, Co/Al = 0.08-0.44). These cationic sites represent centers of two types of uniform domains, containing in minimum 18 surface T atoms, present on the surface of the channel walls of (Al)MCM-41. These domains represent majority of the inner surface of the (Al)MCM-41 molecular sieve.

Three ligands have been formed by the 1:2 molar condensation of ℴ-phenylenediamine with salicylaldehyde, 2-hydroxy-l-naphthaldehyde or ℴ-hydroxyacetophenone. The potentially tetradentate ligands are N,N-bis-(salicylaldehyde)-ℴ-phenylenediamine (SalophH2), N,N-bis(2-hydroxy-1-naphthalde-hyde)-ℴ-phenyIenediamine (NophH2) and N,N-bis(ℴ-hydroxyacetophenone)-ℴ-phenylenediamine (AophH2), respectively. These ligands form 1:1 complexes with nickel, copper and zinc ions. The complexes have been characterized by IR, 1H NMR, MS, UV/Vis spectra in addition to elemental analyses. The spectral data of the ligands and their complexes are discussed in connection with the structural changes which occur due to complexation.

The complexes [Ni(bdt)(Cp ∗ Rubdt)] and [Ni(Cp ∗ Rubdt)2][CF3SO3] (bdt = 1,2-benzenedithiol) have been prepared by reaction of TBA[Ni(bdt)2] with one or two equivalents of [Cp ∗ Ru(CH3CN)3][CF3SO3], respectively. These complexes contain Ru sandwich complexes used as chelating bis-1,2-dithiolene ligands. UV/Vis spectra, EPR and electrochemical studies, in addition to confirming the structure, point towards an extended delocalised electronic framework with communication between the different metal centres for the latter complex but an electronic nature similar to the parent [Ni(bdt)2]− for the former complex.

UV/vis spectra of hydrated and activated Ag+xNa+12-xA, Ag+xCa2+6-0.5xA, and Ag+9.5ZK-4 materials were studied. Any absorption band or color observed in silver zeolite A materials is due to the presence of silver ions. The marked site preference of ions in Ag+xCa2+6-0.5xA was found to offer the unique possibility of investigating different coordination sites of Ag+ ions in zeolite A. Observations we made lead to the result that Ag+ coordinated to 6- and 8-ring oxygens gives rise to electronic transitions in the near-UV region. Only Ag+ coordinated to 4-ring oxygens leads to the 22 000 cm-1 absorption responsible for the typical deep yellow color. The red color which is caused by a strong absorption band at 19 000 cm-1 is observed if a 4-ring coordinated Ag+ has a second Ag+ as a neighbor. We assume that the second Ag+ is at a 6-ring site. Yellow and red colored materials turn colorless again when exposed to humidity. The reversibility is complete for the yellow samples while a broad but weak absorption in ...

Die zwei- bzw. dreizahnigen Farbstoffanionen von 1-Aminoanthrachinon, Oracetblau (1-Amino-4-anilinoanthrachinon), 1,4-Diaminoanthrachinon, Solventgreen 3 [1,4-Bis(4′-methylanilino)anthrachinon], 1,1′-Dianthrimid [Di-(1-anthrachinonyl)-amin], 1-Azo-β-naphtolanthrachinon, 1-Anilido-o-carbonsaure-anthrachinon und Chinizarin (1,4-Dihydroxyanthrachinon) bilden mit den chloroverbruckten Komplexen [(R3P)MCl2]2 (M Pd, Pt; R Ethyl, Phenyl, n-Butyl), [(Ph3P)2PdCl]2(BF4)2, [(η5-C5Me5)MCl2]2 (M Rh, Ir), [(η6-p-Cymol)RuCl2]2, Mono- bzw. Bischelat-Komplexe. 2:1 Metallkomplexe des 1-Aminoanthrachinon-Anions entstehen mit CuII und PdII. Die spektroskopischen Daten der Komplexe werden vergleichend beschrieben. In allen Fallen wird ein bathochromer Shift der langwelligsten Absorptionsbande der Komplexe im Vergleich zu den freien Liganden im UV-VIS Spektrum beobachtet. Die Strukturen von (Ethyl)3P(Cl)Pt(1-Amino-anthrachinon-H+), (η-C5Me5)(Cl)Ir(1-Azo-β- #naphtolanthrachinon-H+) und (η-C5Me5)Rh(1-Anilido-o-carbonsaure-anthrachinon-2 H+) wurden rontgenographisch bestimmt. Metal Complexes of Dyes. X. New Transition Metal Complexes of Anthraquinone Dyes The chloro-bridged compounds [(R3P)MCl2]2 (M Pd, Pt; R ethyl, phenyl, n-butyl), [(Ph3P)2PdCl]2(BF4)2, [(η5-C5Me5)MCl2]2 (M Rh, Ir), [(η6-p-cymene)RuCl2]2, react with mono- and dianions of several 9,10-anthracene-dione dyes [1-amino-9,10-anthracene-dione, Disperse Blue 19 (1-amino-4-anline-9,10-anthracene-dione), 1,4-diamino-9,10-anthracene-dione, Solventgreen 3 [1,4-bis(4′-methylaniline)-9,10-anthracene-dione], dianthrimide [1,1′-dianthraquinonylamin], 1-azo-β-naphtol-9,10-anthracene-dione, 1-anilido-o-carboxy-9,10-anthracene-dione and Quinizarin (1,4-dihydroxy-9,10-anthracene-dione)] to give N,O-, O,O- and O,N,O-chelate complexes. Copper(II)- and palladium(II) acetate and the anion of 1-aminoanthraquinone afford N,O-bischelates. Spectroscopic data are discussed. In comparision to the free anthraquinones the dye complexes show a bathochromic shift in the UV/VIS spectra. The structures of (ethyl)3P(Cl)Pt(1-aminoanthraquinone-H+), (η-C5Me5)(Cl)Ir(1-azo-β- #naphtolanthraquinone-H+) and (η-C5Me5)Rh(1-anilido-o-carboxyanthraquinone-2 H+) were determined by X-ray diffraction.

A new concept for molecular switches, based on thermal or photochemical double-bond shifts (DBS) in [4n]annulenes such as heptalenes or cyclooctatetraenes, is introduced (cf. Scheme 2). Several heptalene-1,2- and -4,5-dicarboxylates (cf. Scheme 4) with (E)-styryl and Ph groups at C(5) and C(1), or C(4) and C(2), respectively, have been investigated. Several X-ray crystal-structure analyses (cf. Figs. 1–5) showed that the (E)-styryl group occupies in the crystals an almost perfect s-trans-conformation with respect to the CC bond of the (E)-styryl moiety and the adjacent CC bond of the heptalene core. Supplementary 1H-NOE measurements showed that the s-trans-conformations are also adopted in solution (cf. Schemes 6 and 9). Therefore, the DBS process in heptalenes (cf. Schemes 5 and 8) is always accompanied by a 180° torsion of the (E)-styryl group with respect to its adjacent CC bond of the heptalene core. The UV/VIS spectra of the heptalene-1,2- and -4,5-dicarboxylates illustrated that it can indeed be differentiated between an ‘off-state’, which possesses no ‘through-conjugation’ of the π-donor substituent and the corresponding MeOCO group and an ‘on-state’ where this ‘through-conjugation’ is realized. The ‘through-conjugation’, i.e., conjugative interaction via the involved s-cis-butadiene substructure of the heptalene skeleton, is indicated by a strong enhancement of the intensities of the heptalene absorption bands I and II (cf. Tables 3–6). The most impressive examples are the heptalene-dicarboxylates 11a, representing the off-state, and 11b which stands for the on-state (cf. Fig.8).

Die Umsetzung einiger sterisch anspruchsvoller Trialkylphosphine L = PR2R′ (R = iPr, R′ = tBu; R = tBu, R′ = iPr, Me) mit NiX2 (X = Cl, Br) in Ethanol liefert infolge Beteiligung des Solvens statt der erwarteten Nichtelektrolyte [NiL2X2] tertiare Phosphoniumnickelate [HL][NiLX3]. Im Falle des weniger raumerfullenden PtBu2Me entstehen beide Komplextypen. [Ni(PtBu2Me)2Cl2] ist tetraedrisch und stellt somit eines der beiden bisher bekannten Beispiele fur paramagnetische Bis(trialkylphosphin)dihalogenonickel(II)-Komplexe dar. In Losungen dieser Verbindung existiert ein Gleichgewicht zwischen tetraedrischem (paramagnetischem) und planarem (diamagnetischem) Konformer. Vis-Spektren sowie Ergebnisse magnetischer Messungen und 1H- bzw. 31P-NMR-Untersuchungen werden mitgeteilt. [NiL2X2] or [HL][NiLX3] – Reaction of Sterically Demanding Trialkylphosphines L with NiX2 (X = Cl, Br) in Ethanol The reaction of some sterically demanding trialkylphosphines L = PR2R′ (R = iPr, R′ = tBu; R = tBu, R′ = iPr, Me) with NiX2 (X = Cl, Br) in ethanol affords instead of the expected non-electrolytes [NiL2X2] tertiary phosphonium nickelates [HL][NiLX3] due to participation of the solvent. In case of the less bulky PtBu2Me both complex types were obtained. [Ni(PtBu2Me)2Cl2] is tetrahedral and therefore one of the two examples of paramagnetic bis(trialkylphosphine)dihalogenonickel(II) complexes known so far. In solution the latter compound undergoes an equilibrium of tetrahedral (paramagnetic) and planar (diamagnetic) conformer. Vis spectra as well as the results of magnetic measurements and 1H and 31P NMR investigations are reported.

The reduction of Fe(III) by caffeic acid (CAF) in the presence of desferrioxamine-B (DFOB) was studied as a function of pH and time. The HPLC analyses, UV/vis spectra and kinetic data provide evidence that the reduction of Fe(III) by caffeic acid is strongly inhibited by DFOB and that it can be induced by the siderophore at low pH values. The stoichiometry and the possible mechanism of the reduction process are reported.

The prepaparation of amorphous, homogeneous blends of zwitterionic polymers with various low molecular weight salts, and in particular with ionic dyes was studied. Homogeneous miscibility was achieved in many cases up to equimolar amounts of salt, even for bulky compounds. Whether miscibility is achieved, or not, depends in a subtle way on the chemical structure of the salt, but no obvious correlation between structure and miscibility could yet be revealed. Spectral shifts of the dye UV/Vis spectra in solution as well as in bulk suggest strong interactions between the polybetaines and the admired salts.

3,3-Dimethyl-1-(4-R-phenyl)- [R = (CH3)2N, C2H5O, CH3O, CH3; 3] and 3-Methyl-1-(4-R1-phenyl)-3-(4-R2-phenyl)triazenes [R1 = (CH3)2N, CH3O, NO2, R2 = CH3O, H, 4] are oxidized electrochemically and chemically to their one-electron oxidation products. Cyclic voltammograms of the triazenes are discussed, and ESR as well as UV/Vis spectra of the radical cations are presented. The stability of the triazene radical cations generated depends on the substituents on the aryl rings. 4-R-Benzenediazonium ions are identified as one of the decay products of the radical cations by means of cyclic voltammetry and UV/Vis spectroelectrochemistry.

Acidity (dehydronation) constants of N,N-dimethylthreonine (DMT) and stability constants of its complexes with Cu+2, Ni+2, and Co+2 were determined in aqueous solution by means of potentiometric titration. UV/Vis spectra were also taken during the titration. It is suggested thatDMT acts as a bidentate ligand toward copper(II) by engaging either (a) amino and carboxyl groups (in [Cu(DMT)] and [Cu(DMT)2]), or, (b) upon dehydronation, amino and hydroxyl groups (in [Cu(DMT)H−1], [Cu(DMT)2H−1], and [Cu(DMT)2H−2]). It is suggested that the coordination in threoninato andallo-threoninato complexes is similar to that described under (a).

Symmetrical Azopyridinone Dyes: Synthesis, Spectrophotometrical and Acidobasic Properties, Metal-Complex Formation and Kinetical Investigation of the Azo-Dye Formation The 13 substituted symmetrical azopyridinone dyes 2a–n were synthesized and their VIS spectra measured. The pK*a values of some dyes and of pyridinone coupling components were determined in MeOH/H2O 64:36. The metal-complex formation of the dyes with Cd2+, Zn2+, Co2+, Ni2+, and Cu2+ was investigated, and complex-formation constants of the 1:1 complexes were determined in H2O for 2k (Table 2) and in dimethylformamide/H2O 1:1 for some other azopyridinone dyes (Table 3). The mechanism of the azo-dye formation was investigated and found to be much more complicated than expected. A mechanism of the coupling reaction was developed (see Scheme 4) and fitted by least-squares calculations.

The first 1-silanaphthalene, 4, was successfully synthesized by taking advantage of an efficient steric protection group, 2,4,6-tris[bis(trimethylsilyl)-methyl]phenyl (Tbt), and the aromaticity of 4 was discussed on the basis of its 1 H, 1 3 C, and 2 9 Si NMR, Raman, and UV/vis spectra together with theoretical calculations. In contrast to the thermal stability of the Tbt-substituted 2-silanaphthalene 2, 1-Tbt-1-silanaphthalene (4) undergoes a ready [2 + 4] dimerization reaction in solution even at room temperature, despite its stability in the solid state.

The nonenzymatic synthesis of aurodrosopterin (5) from 6-acetyl-2-amino-3, 7, 8, 9-tetrahydro-4H-pyrimido-[4,5-b][1,4]diazepin-4-one (3) and 7,8-dihydrolumazine (4) at pH 3 (HCl) was performed. The identity of the synthesized compound with the natural eye pigment isolated from drosophila heads was confirmed by thin-layer chromatography on cellulose and by comparisons of the 1H-NMR and UV/VIS spectra. The nonenzymatic synthesis of a neodrosopterin-like red pigment from 3 and 2,4-diamino-7,8-dihydropteridine was also carried out, but its identity could not be established. This pigment, called aminodrosopterin, has an absorption peak at 489 nm, which is very close to that of neodrosopterin.

Fruhere Befunde, wonach 2-(Dimethylaminomethyl)ferrocenyl-Gruppen (FcN) zur Bildung stabiler, heterobimetallischer Organolanthanoid(III)-Verbindungen befahigt sind, wurden durch die Synthese der Organoseltenerd(III)-Derivate (C5H5)2SE(FcN) [SE = Y (II), Dy (III), Ho (IV)], C5H5Dy(FcN)2 · 2,5 THF (V) und C5H5SE(FcN)Cl [SE = Dy (VI), Ho (VII)] aus den betreffenden Cyclopentadienylseltenerd(III)-chloriden (C5H5)2SECl bzw. C5H5SECl2 und (FcN)Li (I) bestatigt. Die erhaltenen Verbindungen wurden durch Elementaranalysen, IR-, 1H-NMR-, 13C-NMR- und UV-Vis-Spektren sowie durch Bestimmung der effektiven magnetischen Momente und die Aufnahme von Massenspektren charakterisiert. Contributions to Organolanthanide Chemistry. II. On 2-(dimethylaminomethyl)ferrocenyl Compounds of Yttrium, Dysprosium, and Holmium Early reports about the ability of the 2-(dimethylaminomethy1)ferrocenyl group to form stable heterobimetallic organolanthanide(III) compounds have been confirmed by the synthesis of the organolanthanide(III) derivatives (C5H5)2Ln(FcN) [Ln = Y (II), Dy (III), Ho (IV)], C5H5Dy(FcN)2 · 2,5 THF (V) und C5H5Ln(FcN)Cl [Ln = Dy (VI), Ho (VII)] from the corresponding cyclopentadienyllanthanide(III) chlorides (C5H5)2LnCl or C5H5LnCl2 resp. and (FcN)Li (I). The products have been characterized by elemental analyses, IR-, 1H-NMR, 13C-NMR and UV/Vis spectra as well as mass spectra and the determination of their effective magnetic moments.

Five N, N-dialkylamino acids were synthesised [4]: N, N-dimethylisoleucine (DMIL), N, N-dimethyl-alloisoleucine (DMAIL), N, N-dimethylvaline (DMV), N, N-diethyl-alanine (DEA), and N, N-diethylvaline (DEV), as well as their complexes with copper(II): Cu(DMIL)2, Cu(DMAIL)2, Cu(DMV)2, Cu(DMIL)(DMV), Cu(DEA)2, and Cu(DEV)2. UV/VIS spectra of the complexes were recorded in CH2Cl2 solutions and the ESR spectra in CH2Cl2, CD3OD, and D2O solutions. By applying the analysis of variance, ESR spectra were shown to be influenced by the solvent and substituent differences, the former effect being related to the degree of covalency of the copper-ligand bonds. The effect of the ligand's spatial configuration (diastereoisomerism) upon the ESR spectrum of the complex was demonstrated and explained

The conjugated polyenes 10, 11, and 17 respectively, with 9-anthryl- and 2-tetraphenylporphyrinyl (TPP) terminal groups and a bicyclooctane unit incorporated into the polyene chain were synthesized by Wittig olefinations. In all cases it was possible to obtain the all-(E) compounds from the (E)/(Z)-isomeric mixtures by chromatographic purification and several recrystallizations. From the UV/Vis spectra the separation of the TPP group and the polyene chain in 10, 11, and 17 can be deduced whereas in 10 and 11 the two conjugated double bonds are amalgamated into the anthryl group. In 17 the anthryl group is electronically separated from the polyene chain, and a selective excitation therefore is possible.

Heterocumulenes, 6. — C5OS (5-Thioxo-1,2,3,4-pentratetraen-1-one) — Preparation and Spectroscopic Properties C5OS (8) is prepared by flash pyrolysis of the precursor molecules 4, 5, and 7 and by matrix photolysis of 7. The IR- and UV/Vis spectra of matrix-isolated 8 are reported.

Halochromic Molecules. Substituted 6,11-Dihydrospiro[[1]benzopyrano[4,3-b]indol-6,9′-9′H-xanthene]-2′,6′-diamines and Their Aza Analogues: New Chromogenes for Black Images. We have synthesized a series of substituted 6,11-dihydrospiro[[1]benzopyrano[4,3-b]indo1-6,9′-9′H-xanthene]-2′,6′-diamines and their respective aza analogues. These compounds develop a black colour in acidic media. The assumed structures of the analytically pure starting and final products are consistant with the fragmentations in the MS and are also supported by FT 1H-NMR. The UV/VIS spectra in buffered MeOH/H2O solutions were measured. From the ϵpH* curves, we determined the pK* values. The title compounds can be used in so-called pressure-sensitive copying systems.

Synthesis, Structure, and Properties of Novel Chain-Substituted and Chiral Trimethine Cyanine Dyes with Indoline End Groups Synthesis and spectroscopic properties of the trimethine cyanine dyes 3, 8a, b, and 13a, b as well as 14a-c with new substitution patterns are described. Constitutions and configurations of 3, 8a, b and 14c have been determined by X-ray analyses (Figures 1, 2, and 6). Dye 3 exists in the previously unknown di-cis (E, E, Z, Z) configuration along the methine chain. Attempts to prepare 3 in a base-catalysed reaction unexpectedly led to the rearranged trimethine cyanine dyes 8a, b with a centre of chirality in one of the indoline end groups. Using this Wagner-Meerwein rearrangement after resolution, the chiral heterocyclic quaternary salts (S)-12a- c have been prepared, from which the optically active trimethine cyanine dyes (S,S)-14a-c have been obtained for the first time. The UV/VIS spectra of 3, 8a and 13a (Figure 7) as well as the CD spectra of 12a and 14a (Figures 3 and 4) are compared and discussed.

A new compound (NaCuAsO 4 .1.5H 2 O) was synthesized, and its composition was determined by means of the methods of ignition loss-in-weight and chemical analysis. The standard molar enthalpies of dissolution of the mixtures (Na 3 AsO 4 ·12H 2 O(s)+ CuSO 4 ·5H 2 O(s)} and {NaCuAsO 4 ·1.5H 2 O(s) + Na 2 SO 4 (s)} in 1.498 mol·dm - 3 HCl solution at 298.15 K have been determined to be respectively Δ s H 0 m.1 = (64322 ±63) J·mol -1 and Δ s H 0 m.2 = -(20558 ±25) J·mol -1 using an isoperibol solution-reaction calorimetry. From these values and other thermodynamic data, the standard molar enthalpy of formation of NaCuAsO 4 ·1.5H 2 O(s) has been derived: Δ f H 0 m (NaCuAsO 4 ·1.5H 2 O, s, 298.15 K) = -(1469.33 ± 0.65) kJ.mol -1 . In addition, UV/Vis spectra and refractive indexes of solution A and solution A' were measured to examine the reliability of the designed thermodynamic cycle.

Photon correlation spectroscopy and microelectrophoresis are investigated as tools to characterize SERS-active systems. Mutual relations of SERS spectra, UV/vis spectra, hydrodynamic size and zeta-potential are studied for systems based on Ag sol and two different adsorbates (2,2′-bipyridine and pefloxacin).

The preparation and X-ray crystal structures of (CyNC)Au(I)CN, (n-BuNC)Au(I)CN, and (i-PrNC)Au(I)CN.0.5CH(2)Cl(2) are reported and compared with those of (MeNC)Au(I)CN and (t-BuNC)Au(I)CN, which were previously described. These linear molecules are all organized through aurophilic interactions into three structural classes: simple chains ((CyNC)Au(I)CN and (t-BuNC)Au(I)CN), side-by-side chains in which two strands make Au...Au contact with each other ((n-BuNC)Au(I)CN), and nets in which multiple aurophilic interactions produce layers of gold(I) centers ((i-PrNC)Au(I)CN and (MeNC)Au(I)CN). All of these five solids dissolve to produce colorless, nonluminescent solutions with similar UV/vis spectra. However, each of the solids displays a unique luminescence with emission maxima occurring in the range 371-430 nm.

Cyclotrimerization of 4,5-bis(hexylthio)phthalodinitrile (1) in 1-chloronaphthalene in the presence of BCl 3 leads to the subphthalocyanine 4. Unsymmetrical phthalocyanines (5, 6) with six alkylthio substituents on three of the benzenoid units are synthesized by the reaction of 4 with an diiminoisoindoline derivative (R'=H or NO 2 ). These extremely soluble compounds are characterized by IR, 1 H- and 13 C-NMR as well as UV/Vis spectra

The stepwise complexation kinetics of Cu2+ with three tetratopic ligands L1, L2 and L3, tren-centred macrocycles with different bridges connecting the 14-membered macrocycles with the tren unit, have been measured by stopped-flow photodiode array techniques at 25 degrees C, I= 0.5 M (KNO3), and pH = 4.96. The reaction between the first Cu2+ and the ligand consists of several steps. In a rapid reaction Cu2+ first binds to the flexible and more reactive tren-unit. In this intermediate a translocation from the tren unit to the macrocyclic ring, which forms the thermodynamic more stable complex, takes place. This species can react further with a second Cu2+ to give a heterotopic dinuclear species with one Cu2+ bound by the tren-unit and the other coordinated by the macrocycle. A further translocation occurs to give the homoditopic species with two Cu2+ in the macrocycles. Finally a slow rearrangement of the dinuclear complex gives the final species. The rates of the translocation are dependent on the length and rigidity of the bridge, whereas the complexation rates with the tren unit are little affected by it. VIS spectra of the species obtained by fitting the kinetic results, EPR-spectra taken during the reaction, and ES mass spectra of the products confirm the proposed mechanism. The addition of a second, third and fourth equivalent of Cu2+ proceeds in an analogous way, but is complicated by the fact that we start and end with a mixture of species. These steps were evaluated in a qualitative way only.

Elektronenschiebende und -ziehende Substituenten werden in 4-Stellung des 8-Hydroxychinolins (Oxins) (1) ausgehend von 4-Chlor-8-methoxychinolin (2) eingefuhrt. Die UV/Vis-Spektren der Oxine 4, 5 und ihrer Nickel-, Kupfer, und Cobalt-Komplexe werden mit denen des Oxins selbst verglichen, wobei fur 4 Intensitatserhohungen der langwelligen Banden beobachtet werden. Die substituierten Oxine werden auch als donorverstarkte Endgruppen in Podanden 8–12 eingesetzt. Die Ammonium-Komplexe der neuen Podanden werden untersucht. 4-(Dimethylamino)-8-hydroxyquinoline as a new Chelating Ligand and as a Donor-enforced Terminal Group in Podands Electron releasing and -withdrawing substituents are introduced into the 4-position of 8-hydroxyquinoline (oxine) (1), starting with 4-chloro-8-methoxyquinoline (2). The UV/Vis spectra of the oxines 4, 5 and their Ni-, Cu-, and Co-complexes are compared with those of oxine. Intensity increases of the long wave length absorptions are observed with the new ligand 4 compared to oxine itself and with the metal complexes. The substituted oxines are also used as new donor end groups in podands 8–12. The ammonium complexes of the new podands are investigated.

The basicities of 2H- and 4H-1,3-benzothiazines (1,2) were measured spectrophotometrically in buffer solutions. The rates of quaternization with methyl iodide were monitored in sealed ampoules by an oscillometric method. The stabilities were determined by measurement of the rate of acidic hydrolysis via changes in the uv/vis spectra. As a cyclic Schiff base, 4-aryl-2H-1,3-benzothiazine (2) is the stronger base, and reacts about ten times faster with methyl iodide; its stability is greater than that of 2-aryl-4H-1,3-benzothiazine (1). On the basis of these results and by means of the different water-solubilities of the hydrochlorides the isomers formed during the synthesis can be separated and purified.