ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Photochemistry  (16)
  • Wiley-Blackwell  (16)
  • 2015-2019
  • 1995-1999  (16)
  • 1999  (16)
Collection
Keywords
Publisher
  • Wiley-Blackwell  (16)
Years
  • 2015-2019
  • 1995-1999  (16)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Comparison of Electrochemically and Photochemically Induced Electron-Transfer Processes of a Series of Copper(II) Schiff Base Complexes with Thiolate Coordination (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 303-312 
    Details
    ISSN: 1434-1948
    Keywords: Spectroelectrochemistry ; Cyclic voltammetry ; Photochemistry ; Copper(II) complexes ; Thiolate complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical and photoredox properties of copper(II) thiopyrazolone Schiff base complexes 1-9 with imine and thiolate coordination, showing variable degrees of tetrahedral distortion, were investigated by means of combined electrochemical and spectroscopic techniques in the temperature range of 193-293 K. The cyclic voltammograms of 1-9 in butyronitrile revealed that the reduction and oxidation paths are strongly dependent on the geometry of the CuN2S2 moiety. Due to the strong delocalization of the singly occupied redox orbital (SOMO) the oxidations and reductions occur in a narrow potential range. The one-electron-reduced 1(r)-9(r) and oxidized 1(o)-9(o) products were electrogenerated and stabilized inside optically transparent thin-layer electrochemical (OTTLE) cells at variable temperatures and could be characterized for the first time by UV/Vis spectroscopy. The reduced formal d10 copper(I) species absorb only weakly in the visible region. The oxidized products 1(o)-9(o) show several strong absorptions in the visible region due to the presence of formal d8 copper(III) species. The spectral information allowed assignment of the initial photoproducts. Irradiations in donor media such as THF or EtOH initially produces 1(r)-9(r). No photoreduction was observed in tBuOH which cannot liberate reducing Hα. The primary oxidized species 1(o)-9(o) were formed in chlorinated acceptor solvents (CHCl3) on UV irradation. Fast relaxation to the ground state prevents the photoredox reactions from CT or LF excited states.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Efficient and Selective Photochemical Labilization of a Given Bidentate Ligand in Mixed Ruthenium(II) Complexes of the Ru(phen)2L2+ and Ru(bipy)2L2+ Family (L = Sterically Hindering Chelate) (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 383-386 
    Details
    ISSN: 1434-1948
    Keywords: Ruthenium ; Photochemistry ; Photosubstitution ; Diimine chelates ; Sterically hindered ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixed ruthenium(II) complexes containing 1,10-phenanthroline (or 2,2′-bipyridine) and a sterically congested bidentate ligand such as 2,9-diphenyl-1,10-phenanthroline, 6,6′-dimethyl- or 6,6′-diphenyl-2,2′-bipyridine, or 1-(2′-pyridyl)-3,5-dimethylpyrazole undergo clean and selective ligand substitution under irradiation with visible light. For instance, Ru(phen)2(dmbp)2+ in CH3CN is quantitatively converted to Ru(phen)2(CH3CN)22+ in a photochemical reaction accompanied by expulsion of the sterically hindering chelate dmbp (phen = 1,10-phenanthroline; dmbp = 6,6′-dimethyl-2,2′-bipyridine). Interestingly, 2,2′-bipyridine was found to be photochemically ejected in one case, probably as a consequence of its greater flexibility.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Facile Hapticity Changes in (1-Hydronaphthalene)manganese Complexes, Ligand Addition and Photochemical Ligand Cleavage (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 651-654 
    Details
    ISSN: 1434-1948
    Keywords: Manganese ; Coordination modes ; 1-Hydronaphthalene complexes ; Trimethylphosphite addition ; Photochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tricarbonyl(2-4,4a,8a-η-1-hydronaphthalene)manganese (1) reacts readily with trimethyl phosphite to afford tricarbonyl(2-4-η-1-hydronaphthalene)(trimethyl phosphite)manganese (2), by a simultaneous η5-η3-hapticity change. Upon UV irradiation, one carbonyl ligand is preferentially cleaved from 2 to yield dicarbonyl(2-4,4a,8a-η-1-hydronaphthalene)(trimethyl phosphite)manganese (3), with a η5-coordinated 1-hydronaphthalene ligand. In a similar fashion 3 also reacts with trimethyl phosphite and forms dicarbonyl(2-4-η-1-hydronaphthalene)bis(trimethyl phosphite)manganese (4), which loses carbon monoxide upon UV irradiation to afford carbonyl(2-4,4a,8a-η-1-hydronaphthalene)bis(trimethyl phosphite)manganese (5). All compounds were characterized by IR and NMR spectroscopy. The η5-1-hydronaphthalene complexes 1, 3 and 5 show hindered 1,4-H shifts of 1-Hendo. Considerable energy barriers were also found for the rotation of the 1-hydronaphthalene ligand in 2-5.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Benzyl Radicals from Toluene by Photosensitization with Naphthalene-1,4-dicarbonitrile - Benzylation and Hydroxymethylation of Unsaturated Compounds (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2137-2142 
    Details
    ISSN: 1434-193X
    Keywords: Photochemistry ; Alkylation ; Radicals ; Radical ions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In aprotic media, photoinduced electron transfer from toluene to 1,4-naphthalenedicarbonitrile (DCN) is followed by in-cage proton transfer and radical coupling. However, in the presence of a protic co-solvent, the radical ions diffuse out of the cage and deprotonation of the toluene radical cation takes place from the free solvated species. With tBuOH, this results in reductive benzylation of DCN through coupling of benzyl radicals with DCN-·. With MeOH, secondary hydrogen abstraction by PhCH2· yields hydroxymethyl radicals, which couple with DCN-·. Both benzyl and hydroxymethyl radicals are efficiently trapped by electrophilic alkenes. Thus, in the presence of dimethyl maleate, DCN-photosensitized benzylation - or hydroxymethylation - of the substrate occurs through direct activation of the C-H bond. The same reaction has been accomplished with acrylonitrile, albeit with a lower yield.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Photochemistry of 9,10-Dicarbonyl-9,10-dihydroanthracene - A Source of 9,10-Dehydroanthracene? (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 57-60 
    Details
    ISSN: 1434-193X
    Keywords: Benzyne ; Dehydroanthracene ; Matrix isolation ; Photochemistry ; Bergman reaction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -9,10-Didehydroanthracene (1) is an interesting derivative of p-benzyne that has been subject of several studies. In contrast to an earlier report, the photochemical decarbonylation of 9,10-dicarbonyl-9,10-dihydroanthracene (2) does not lead to 1 but rather to the ring-opened ene-diyne 4. The key intermediate for this reaction is keto carbene 7 which is formed by monodecarbonylation of 2. Carbene 7 is labile towards visible-light irradiation and easily looses the second CO molecule to give 4. Carbene 7 and diyne 4 are characterized by IR and UV/Vis spectra, the IR spectra are compared to calculations at the B3LYP/6-31G(d,p) level of theory.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    The Photooxygenation of Benzyl, Heteroarylmethyl, and Allyl Sulfides (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1723-1728 
    Details
    ISSN: 1434-193X
    Keywords: Oxygenations ; Singlet Oxygen ; Sulfides ; Photochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photosensitised oxidation of benzyl ethyl sulfides in aprotic solvents (benzene or acetonitrile) gives the corresponding aldehydes under mild conditions. This is a general reaction which applies to benzyl derivatives containing either electron-donating or electron-withdrawing substituents and furthermore to hetero analogues such as 2-pyridinylmethyl sulfide (not to the 3-indolylmethyl sulfide, since reaction at the heterocycle moiety competes) as well as to allyl sulfides. In a protic solvent (methanol) these sulfides give the sulfoxides instead (except for the nitrobenzyl derivatives, where the aldehyde remains the major product). Among the α-substituted sulfides tested, the α-phenylbenzyl and the 3-cyclohexenyl sulfide give the corresponding ketone (the latter in a low yield), but the α-methylbenzyl sulfide gives the sulfoxide as the main product. The rate for singlet oxygen quenching and for chemical reaction have been measured for representative benzyl sulfides. The reaction is discussed in the frame of the currently accepted mechanism for sulfide photooxygenation. The key step for oxidative C-S bond cleavage appears to be hydrogen transfer from the activated α position in the first formed intermediate, the persulfoxide. This reaction is inhibited in methanol where the persulfoxide is hydrogen-bonded.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Photocycloadditions of Chloranil to Homobenzvalene, Norbornadiene, and Quadricyclane (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2093-2101 
    Details
    ISSN: 1434-193X
    Keywords: Photochemistry ; Cycloadditions ; Small ring systems ; Rearrangements ; Electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solutions of chloranil (CA) in toluene or benzene have been irradiated in the presence of the C7H8 valence isomers homobenzvalene (HB), norbornadiene (N), and quadricyclane (Q). In the case of HB, the adducts 3-6 were obtained, all of them having a rearranged structure. By a separate irradiation it was shown that 4 is a consecutive product of 3. The structure of 4 was established by X-ray diffraction analysis. These reactions are most probably initiated by an electron transfer (ET) from HB to 3CA, continue by bond formation between the radical ions to give the zwitterion 14, which undergoes Wagner-Meerwein rearrangements, and are completed by ring-closure between the charged centres of the resulting zwitterions. The oxidation potential of N is not larger than that of HB and the products 8-10 may well be formed through an ET to 3CA. However, the pathway leading to product 3 most probably involves diradical intermediates. This should also be the case for the adducts 11 and 12, which were produced upon irradiation of methyl phenylglyoxylate (PG) in the presence of N. In the case of Q, an ET to 3CA is again highly likely, followed by a combination of the radical ions to generate the zwitterion 29, which eventually collapses to produce the oxetane 8 as the sole identifiable product. The photoreactions of CA with N and Q proceeded much less efficiently in acetonitrile solution.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    Isolation of Cross-Coupling Products in Model Studies on the Photochemical Modification of Proteins by Tiaprofenic Acid (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 497-502 
    Details
    ISSN: 1434-193X
    Keywords: Proteins ; Cross coupling ; Drug research ; Photochemistry ; Toxicology ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -To gain insight into the chemical nature of drug-induced photoallergy, model studies have been carried out on the photochemical modification of proteins by tiaprofenic acid. Irradiation of decarboxylated tiaprofenic acid (DTPA) in the presence of p-cresol leads to C-C- and C-O-connected p-cresol “dimers”, together with DTPA hydrodimers. The p-cresol-DTPA cross-coupling product was not detected in this reaction. However, a product of this type is formed using a more hindered phenol, such as 2,6-di-tert-butylphenol. Similar results are obtained when tiaprofenic acid (TPA) or its methyl ester are used as photosensitizers. The observed formation of “dimers” can be related to protein photo-crosslinking, through the coupling of two tyrosine units. On the other hand, phenol-(D)TPA cross-coupling may be relevant to the understanding of drug-protein photobinding.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    Diastereoselective Intramolecular meta Photocycloaddition of Side-Chain-Substituted 5-(2-Methoxyphenyl)pent-1-enes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 463-470 
    Details
    ISSN: 1434-193X
    Keywords: meta Photocycloaddition ; Photochemistry ; Steric hindrance ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Irradiation of a series of 5-(2-methoxyphenyl)pent-1-enes substituted with a hydroxy or trimethylsilyloxy group at the α-, β-, or γ-position of the side-chain yields in all cases meta photocycloadducts, in which the configuration at the substituted carbon atom is mainly endo. This indicates that the diastereoselectivity originates from minimization of steric interactions between the side-chain substituent and the ortho-methoxy group at the arene unit. Hydrogen bonding does not seem to be involved. The introduction of the side-chain substituents also influences the regioselectivity of the addition: The linear to angular adduct ratios are significantly increased compared to the case of the parent compound.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 10
    Electronic Resource
    Electronic Resource
    Synthesis, X-ray Structure Analysis and Topochemical Photopolymerization of Substituted 1,6-Bis(2,5-dimethoxyphenyl)hexa-2,4-diynes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 917-922 
    Details
    ISSN: 1434-193X
    Keywords: Crystal engineering ; Diynes ; Photochemistry ; Solid-state chemistry ; Polymers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The 1,6-bis(2,5-dimethoxyphenyl)hexa-2,4-diynes 4a-c were obtained from the corresponding 2,5-dimethoxybenzenes 1 by bromination followed by a copper-catalyzed Grignard reaction with 3-bromoprop-1-yne. Catalyzed coupling of the resulting 3-(2,5-dimethoxyphenyl)prop-1-ynes 3 under Hay conditions gave the hexa-2,4-diynes 4a-c in good yields. The molecular structures of the diynes 4a and 4b were determined by X-ray diffraction analysis. In each crystal structure, an unusual 1,6-synperiplanar conformation of the hexa-2,4-diyne unit is observed, with the 1,6-diphenyl substituents arranged in a coplanar orientation. According to the crystal structure data obtained, irradiation of diynes 4a and 4b afforded the deeply-colored, highly-ordered polymers 5a and 5b under topochemical control. Oxidation of 4a and 4b with cerium(IV) ammonium nitrate gave the corresponding 1,6-bis(2,5-dimethoxyphenyl)hexa-2,4-diyne-1,6-diones 6a and 6b.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 11
    Electronic Resource
    Electronic Resource
    Photochemical Hydrogen Migration in Methylanthronylidenes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1005-1009 
    Details
    ISSN: 1434-193X
    Keywords: Hydrogen migration ; Anthronylidene ; Quinone methide ; Matrix isolation ; Photochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The photochemistry of 4-methyl-9,10-diazoanthrone (7a) and 1,4-dimethyl-9,10-diazoanthrone (7b) was investigated in argon matrices at 10 K. Visible-light irradiation results in the formation of the anthronylidenes 5a and b, respectively, which were identified by oxygen trapping, by comparison of the IR and UV/Vis spectra with that of the parent anthronylidene 6, and by comparison of the IR spectrum with that calculated by DFT methods. The carbenes 5 are thermally stable under the conditions of matrix isolation; however, irradiation with visible or UV light results in the rearrangement to the quinone methides 10a and b.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 12
    Electronic Resource
    Electronic Resource
    Photoisomerization of Bicyclopropylidene and 1,2-Dimethylenecyclobutane in Rare-Gas Matrices: Towards the IR-Spectroscopic Identification of Tetramethyleneethane (2,3-Dimethylenebutane-1,4-diyl) (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1291-1294 
    Details
    ISSN: 1434-193X
    Keywords: Matrix isolation ; IR spectroscopy ; Photochemistry ; Diradicals ; Isomerizations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Bicyclopropylidene (3) and 1,2-dimethylenecyclobutane (7) have been irradiated in rare-gas matrices. If 1,2-dimethylenecyclobutane (7) is exposed to the light of a KrF excimer laser (λ = 248 nm), an isomeric species is produced, showing an absorption at 793.1 cm-1 (argon matrix) or 791.2 cm-1 (xenon matrix) in the IR spectrum. The back reaction can be induced with light of λ = 254 nm. This photochemical interconversion, together with the comparison between the experimental and calculated band positions, supports the assignment of the IR absorption near 790 cm-1 to tetramethyleneethane (5).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 13
    Electronic Resource
    Electronic Resource
    Synthesis, Fluorescence Properties, and Head-to-Tail Regioselectivity in the Photodimerization of a Donor-Acceptor-Substituted Anthracene (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1595-1600 
    Details
    ISSN: 1434-193X
    Keywords: Photochemistry ; Anthracenes ; Fluorescence spectroscopy ; Cycloaddition reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The novel 2,6-donor-acceptor-substituted anthracene, namely 6-methoxy-2-anthracene carboxylic acid (7), was synthesized. The emission of this compound exhibits significant solvatochromism. The fluorescence band position and intensity are also remarkably sensitive to H+. Irradiation of the anthracene 7 in solution yields the syn and anti head-to-tail dimers exclusively. A synergistic electronic effect between the donor and acceptor substituents is proposed to operate on the photophysical and photochemical properties of anthracene 7.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 14
    Electronic Resource
    Electronic Resource
    Photolysis of Tricarbonyl(η5-cyclohexadienyl)manganese in Tetrahydrofuran, Reactions with Cumulated Dienes (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 655-661 
    Details
    ISSN: 1434-1948
    Keywords: Manganese complexes ; Organyl complexes ; C-C coupling ; [5+2] Cycloaddition ; Cumulenes ; Photochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [Mn(η5-C6H7)(CO)3] (1) forms highly reactive [Mn(η5-C6H7)(CO)2(THF)] (2) upon UV irradiation in THF at 208 K. Solvent complex 2 reacts between 208 and 293 K with 1,1-disubstituted allenes C3H2RR′ [R, R′ = CH3, CH3 (A); CH3, C6H5 (B); C2H5, C6H5 (C); C6H5, C6H5 (D); OCH3, Si(CH3)3 (E)] to four different types of complexes: The [5+2] cycloadduct [Mn(η3:2-C9H9RR′)(CO)3] (3E), rearranged [5+2] cycloadducts [Mn(η3:2-C9H9RR′)(CO)3] (4B, 4C, 4D), 1:2 adducts [Mn(η3:2-C12H11R2R′2)(CO)3] (5A-5E), and the 1:3 adduct [Mn{η3:2:2-C15H13(CH3)6}(CO)2] (6A). The constitutions of the products were established by IR and NMR spectroscopy, as well as by C,H elemental analysis and mass spectrometry. The crystal and molecular structure of 6A was determined by X-ray structure analysis. A formation mechanism for the complexes is proposed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 15
    Electronic Resource
    Electronic Resource
    New Rare-Gas-Containing Neutral Molecules (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 729-737 
    Details
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Matrix isolation ; Rare-gas compounds ; Solid-state chemistry ; Photochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of novel neutral rare-gas-containing molecules of type HXY, where × = Xe or Kr and Y is an electronegative atom or fragment, is discussed. The molecules are characterised experimentally by their vibrational spectra and computationally by extensive ab initio calculations. They are formed in low-temperature rare-gas solids from neutral reagents and their bonding consists of both covalent and ionic contributions. Our recent studies add to the previously known class of rare-gas chemical bonds in neutral ground-state molecules the new bonds Xe-H, Xe-I, Xe-Br, Xe-S, Kr-H, Kr-C, and Kr-Cl.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 16
    Electronic Resource
    Electronic Resource
    Macrocyclic Polyamines Containing Phenanthroline Moieties - Fluorescent Chemosensors for H+ and Zn2+ Ions (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1911-1918 
    Details
    ISSN: 1434-1948
    Keywords: Macrocycles ; Photochemistry ; Fluorescence spectroscopy ; Coordination chemistry ; Zinc ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The macrocyclic ligands L2 and L3, containing a triethylenetetraamine and a tetraethylenepentaamine moiety linked to the methyl groups of 2,9-dimethyl-1,10-phenanthroline, bind H+ and Zn2+ ions giving rise to modulation of the fluorescence emission intensity. The equilibrium constants and the enthalpy changes for ligand protonation were determined by means of pH-metric and microcalorimetric methods in 0.1 M Me4NCl solutions at 298.1±0.1 K. Also the stability constants of the Zn2+ complexes were determined under the same experimental conditions. L2 forms only mononuclear complexes, while L3 also forms dizinc(II) species. The phenanthroline group has fluorescence emission properties, but interaction with the lone pairs of benzylic nitrogen atoms produces an efficient quenching of the emission. Such a quenching effect can be avoided by deactivation of the benzylic nitrogen atoms by means of protonation or Zn2+ complexation. Hence, L2 and L3 behave as chemosensor for H+ and Zn2+, the photochemical properties of the ligands being modulated by the formation of different protonated and complexed species. In the case of L3, the fluorescence emission is also controlled by the metal to ligand molar ratio, because of the formation of an emissive binuclear complex.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...