bluuebunny/crossref_metadata_2025_split huggingface dataset:
Consecutive Vibrational Redistribution and Predissociation Processes in s‐Tetrazine–Argon Van Der Waals Complexes
Authors: Ramaekers J. J. F. , Krijnen L. B. , Lips H. J. , Langelaar J. , Rettschnick R. P. H. 
Published: March 2007

s‐Tetrazine argon complexes T − Arn (n = 1, 2) are formed in a supersonic expansion
of argon seeded with s‐tetrazine. The expansion was conducted through a nozzle of
50 or 100 μm with an argon stagnation pressure between 1 and 1.5 bar. From spectrally
resolved measurements it is clear that vibrational redistribution processes as well as
vibrational predissociation processes take place after SVL excitation within the
complex.From rise and decay time experiments it can be concluded, that after excitation of
the 6a1 complex level, the above mentioned processes are consecutive and not parallel.
It appears that the out of plane mode 16a couples with the Van der Waals stretching
mode. The predissociation rate of the 16a2 complex is observed to be 2.3 × 109 s−1.
Molecular Beam Studies of Primary Photochemical Processes
Authors: Lee Yuan T. 
Published: March 2007

Application of the method of molecular beam photofragmentation translational spectroscopy
to the investigation of primary photochemical processes of polyatomic
molecules is described.Examples will be given to illustrate how information concerning the energetics,
dynamics and mechanism of dissociation processes can be obtained from the precise
measurements of angular and velocity distributions of products in an experiment in
which a well defined beam of molecules is crossed with a laser.
Determination of Vibrational Energy Distributions of CN (A  2Πi) and (X  2Σ+) from the C+N2O Reaction by Chemiluminescence and Laser Induced Fluorescence
Authors: Dorthe G. , Joussot–Dubien J. , Nouchi G. , Kottis Ph. 
Published: March 2007

The CN (A  2Πi) and (X  2Σ+) vibrational distributions from the C + N2O → CN + NO reaction at 300 K were determined in a low pressure flow reactor. From the chemiluminescence
A  2Πi→X  2Σ+ the vibrational distribution of A  2Πi was found to peak at υ′ = 1. From the laser induced fluorescence
B  2Σ+→X  2Σ+, the vibrational distribution of X  2Σ+ was found to peak at υ″ = 4.A C2H2—N2O combustion flame, stabilized at 2.8 torr with a temperature of 2500 K,
gave a CN (A  2Πi) vibrational distribution peaking at υ′ = 2 which can be attributed to the C+N2O
reaction at 2500 K. However the CN ground state vibrational distribution was found to be relaxed.
The Spectrum of the Molecular Eigenstates of Pyrazine and the Reconstruction of Decays of Rotational States of the  1B3u (0–0) Transition of Pyrazine
Authors: van der Meer Barend J. , Jonkman Harry Th. , Kommandeur Jan 
Published: March 2007

The spectrum of the molecular eigenstates (ME) belonging to the various rotational
members of the  1B3u (0–0) transition of pyrazine was measured with a very narrow
band laser in a molecular beam with a Doppler width of 30 MHz.It is shown that, when the ME′s belonging to a single rotational state are Fourier‐transformed,
the beating decays of these states are obtained. A problem is constituted
by the lack of a fast component in these reconstructions, while it is observed in
experiments on higher J‐states.
Picosecond Spectroscopy of Solutions, Proteins and Photosynthetic Membranes
Authors: Fleming Graham R. , Lotshaw William T. , Gulotty Robert J. , Chang Mary C. , Petrich Jacob W. 
Published: March 2007

The photophysics of tryptophan is discussed and a model capable of rationalizing the
photophysics of almost twenty derivatives of tryptophan is proposed. The model is
based on conformers about the Cα—Cβ bond and the relative rates of charge transfer
from indole to various electrophiles. Three new tryptophan derivatives were synthesized
to test the model. Accurate predictions concerning the relative fluorescence lifetimes
and the form of the fluorescence decay law are made for tryptophan and seventeen
of its derivatives, including the three new derivatives.The fluorescence decay kinetics from chloroplasts from green plants are described.
New data are presented on the fluorescence decays obtained from genetic mutants of
chlamydomonas which lack specific components of the photosynthetic apparatus. The
interpretation of the green plant chloroplast data in terms of the two photosystems
and the light harvesting array is discussed in terms of the data from the mutant algae.
Our data indicate that the major short component (∼100 ps) obtained in the fluorescence
decay of chloroplasts results from photochemical trapping by both photosystem
I and photosystem II.A synchronously pumped dye laser which produces two, independently tunable,
synchronized picosecond pulse trains will be described. An application of the laser to
time and frequency resolved polarization spectroscopy will be given. The results are
used to estimate the homogeneous linewidth of the S0 → S1 transition of a large
molecule in solution. The optical heterodyne technique is applied to separate the real
and imagninary contributions of the third order nonlinear susceptibility.
The Tunable, Narrow‐Bandwidth Excimer Laser, the New Workhorse for Photochemistry in the UV and VUV
Authors: Hohla K. , Mückenheim W. , Basting D. 
Published: March 2007

Excimer lasers are powerful sources of radiation in the UV, providing several laser
lines between 157 and 353 nm. The excimer laser transition is bound‐free, and thus
the emitted wavelengths are broad‐band (up to 200 cm−1). In addition the high gain
(0.15 cm−1) of the laser gas causes a rather large divergence (>1 mrad) in conventional
excimer lasers.A new excimer laser concept is described which improves the spectral brightness in
terms of watt/(rad × bandwidth) by three orders of magnitude. This allows, through
non‐linear processes such as Raman shifting the fundamental output and four‐wave‐mixing
in gases, the generation of new laser lines in the UV and VUV.
A Laser Photolysis Study of Triplet Lifetimes and of Triplet–Triplet Annihilation Reactions of Phthalocyanins in DMSO Solutions(Etude des Durées de Vie du Triplet et des Réactions d′Annihilation Triplet–Triplet de Phthalocyanines dans le DMSO par Photolyse Laser)
Authors: Debacker M. G. , Deleplanque O. , Van Vlierberge B. , Sauvage F. X. 
Published: March 2007

Triplet decay of Mg and Zn phthalocyanins have been studied by laser flash photolysis as a function of concentration. The triplet decay mechanism changes from a near first order in dilute solution to an almost second order in concentrated solutions. This is interpreted in terms of triplet–triplet recombinaison. With the help of a reducing agent, it is shown that the triplet–triplet reaction can lead to charge separation.La décroissance des états excités triplet des phthalocyanines de Mg et de Zn a été étudiée
par photolyse éclair laser en fonction de la concentration. Le mécanisme de décroissance du triplet passe d′un premier ordre presque idéal en solution diluée à un quasi second ordre en solution concentrée. Ceci s′explique par une recombinaison triplet–triplet. A l′aide d′un réducteur, la réaction triplet–triplet peut conduire à une séparation de charges.
Picosecond Absorption Spectroscopy of Polymethine Cis‐Trans Isomerization
Authors: Feller K.-H. , Gadonas R. , Krasauskas V. 
Published: March 2007

Results are presented of time resolved fluorescence and absorption investigations of
DDEOCI (3,3′‐diethyl‐6,6′‐diphenyl‐9‐ethyl‐oxacarbocyanine iodide) in solvents
which differ in polarity and viscosity. The measured picosecond absorption and fluorescence
kinetics probed at various wavelengths of the polymethine dye studied can be
fitted to a double exponential decay with a minor fast component of lifetime τ1
and a major slower component of lifetime τ2. Furthermore, probing in the S1 ← S0
absorption region and in the fluorescence region results in a residual with a lifetime of some ns and
belonging to the detected red‐shifted photoisomer with a low quantum yield (φ < 10%). The lifetime and the preexponential factors of the two components are in methanolic
solution uneffected by changes of the anion.The detected two picosecond lifetime components are supposed to belong to two isomeric species (all‐trans and mono‐cis isomer) with strongly overlapping absorption spectra.
Condensed Phase Laser InducedHarpoon Reactions
Authors: Fajardo Mario E. , Withnall R. , Feld J. , Okada F. , Lawrence W. , Wiedeman L. , Apkarian V. A. 
Published: March 2007

Laser induced charge transfer reactions of halogens in rare gas solids and liquids provide
a powerful means for the study of condensed phase dynamics. Many‐body effects with
respect to both electronic and nuclear coordinates, and cooperative interactions with
radiation fields, are some of the studied phenomena that are highlighted in this article.The pertinence of these ionic reactions to chemistry in solids is demonstrated in
photodissociation studies of molecular halogens in rare gas matrices. The coexistence of
both delocalized and localized charge transfer states in solid xenon doped with atomic
halogens is presented and dynamical consequences—charge separation, self‐trapping
and energy storage—are discussed. Static and dynamic solvent effects in liquid phase
harpoon reactions are considered. The characterization of cooperative excitations—
two‐photon, two‐electron transitions—in liquid solutions is presented.
Laser Stimulation andObservation of Simple GasPhase Radical Reactions
Authors: Wolfrum J. 
Published: March 2007

Experiments on the effect of Selective vibrational, translational and orientations excitation
of reactants in bimolecular reactions can give important insights into the microscopic
dynamics of elementary chemical reactions. The information obtained in such
experiments can be compared with the results of theoretical calculations of the reaction
dynamics based on ab initio potential energy surfaces and is also of basic interest to
improve the kinetic data used in detailed chemical kinetic modelling.Rotational and vibrational energy transfer between H2 and H0 has been studied
directly using Raman excitation combined with time resolved CARS spectroscopy. The
competition between reactive and inelastic channels was investigated for reactions of
atoms with vibrationally excited H2 and HCl molecules. Selective vibrational excitation
was achieved by using infrared laser or Raman‐pumping. The reaction products were
detected by time resolved atomic line resonance absorption mass‐spectrometry and
CARS‐spectroscopy. In some cases information on the contributions of adiabatic and
non‐adiabatic reactive pathways could be obtained. The reaction H + O2→ OH + O has
been studied using translationally hot H atoms at various energies. Absolute total
reactive cross‐sections, nascent rotational state distributions and information on the
distribution of orientations of the OH angular momentum vector using polarized
dissociation and analysis laser sources have been obtained.
Laser Induced Fluorescence of4‐N,N‐Dimethylaminobenzonitrile(DMABN) and RelatedCompounds
Authors: Jones Anita C. , Phillips David 
Published: March 2007

The role of polar solvent in determining the photophysics of normal (b*) and anomalous
(a*) fluorescence from 4‐N,N‐dimethylaminobenzonitrile (DMABN) and related compounds
has been investigated by means of picosecond time‐resolved fluorescence studies
in non‐polar/polar solvent mixtures, and by electronic spectroscopic studies on complexes
of 1:1 stoichiometry prepared by nozzle expansion. The solution phase results
indicate clearly that a DMABN‐polar solvent complex is formed initially in either
ground or excited state, and that this rearranges to a geometry from which the b* to a*
state transition can occur. Specific solvent‐solute interactions are clearly indicated by
this work, and these lead to the necessity of modelling b* state decay kinetics in solution
by a distribution of decay times.Laser induced fluorescence studies of jet‐cooled solvated complexes of DMABN and
the related molecule 4‐aminobenzonitrile (4‐ABN) provide evidence for the existence of
1:1 complexes involving interaction of a protic solvent molecule with either the cyano
group or the amino group. In the case of 4‐ABN both types of complex are fluorescent
whereas in the case of DMABN, those complexes involving interaction with the
dimethylamino group appear to be non‐emissive. This behaviour may be due to
formation of DMABN‐solvent exciplex which constitutes a dark state under jet‐cooled
conditions. Neither the DMABN bare molecule nor the observed 1:1 solvated complexes
exhibit a* emission in the jet.
Myochrysine Solution Structure and Reactivity
Authors: Elder R. C. , Jones William B. , Zhao Zheng , Dorsey John G. , Tepperman Katherine 
Published: March 2007

We have determined the framework structure of Myochrysine (disodium gold(I)thiomalate) in the
solid state and extremely concentrated aqueous solution, previously. It consists of an open chain polymer
with linear gold coordination to two thiolates from the thiomalic acid moieties which bridge between pairs
of gold atoms providing an Au‐S‐Au angle of 95°. The question remained: was this structure relevant to
the dilute solutions of drugs administered and the still lower concentrations of gold found in the bodies of
patients (typically 1 ppm Au in blood and urine or 5 μM in Au). We have provided an answer to that
question using extended X‐ray absorption spectroscopy (EXAFS) and capillary zone electrophoresis
(CZE). EXAFS studies confirm that the polymeric structure with two sulfur atoms per gold atom persists
from molar concentrations down to millimolar concentrations. CZE is able to separate and detect
Myochrysine at millimolar levels. More importantly, at micromolar levels Myochrysine solutions exhibit
identical CZE behavior to that measured at millimolar levels. Thus, aqueous solutions of the drug remain
oligomeric at concentrations commensurate with those found in patient blood and urine.The reactivity of Myochrysine with cyanide, a species especially prevalent in smoking patients,
was explored using CZE. Cyanide freely replaces thiomalic acid to form and thiomalic acid via
a mixed ligand intermediate. The overall apparent equilibrium constant (Kapp) for the reaction is 6×10-4M-1.
Further reaction of with a large excess of L, where L is cysteine, N‐acetylcysteine, or
glutathione, shows that these amino acids readily replace cyanide to form . These species are thus
potential metabolites and could possibly be active forms of gold in vivo. That all of these species are readily
separated and quantified using CZE demonstrates that capillary electrophoresis is an accessible and
powerful tool to add to those used for the study of gold‐based antiarthritis drugs.
Stimulation of Phospholipase A2 by Toxic Main Group HeavyMetals: Partly Dependent on G‐proteins?
Authors: Krug H. F. 
Published: March 2007

Organometals induce platelet aggregation and inorganic metal ions such as Cd2+
or Pb2+ sensitise
human blood platelets to aggregating agents and this action is associated with the liberation of arachidonic
acid and eicosanoid formation. The same mechanism is observed using human leukaemia cells (HL‐60)
when treated with MeHgCl or Et3PbCl
. The fatty acid liberation within human platelets and HL‐60 cells
could only be inhibited with phospholipase A2 inhibitors of different specificity.Preincubation of the cells with pertussis toxin reduces the activation induced by Et3PbCl to a great
extent. The non‐catalytic B subunit, that only mediates the binding of the toxin to the cell membranes, has
no effect at all. When summarised, these results suggest that one possible mechanism for the stimulation of
phospholipase A2 by Et3PbCl functions via a G‐protein dependent pathway.
Workshop on: Chemistry of Metals in Medicine ‐ The Industrial Perspective
Authors: Sadler Peter J. 
Published: March 2007

The Workshop was attended by 61 participants from 20 countries. Most of the speakers were
industrialists and the Chairpersons and Discussion Leaders were academics.The area “Chemistry of Metals in Medicine” has the potential for producing innovative, high quality, and original research.This is a new and emerging area of biomedical chemistry. Small firms are already being established which are devoted to the new elemental medicine. Major pharmaceutical and healthcare industries too are becoming aware of the major impact which metal chemistry is likely to have on traditional organic pharmacology and of the new opportunities which it presents for advances including the development of metalloenzyme‐specific inhibitors, targeted radionuclide complexes for diagnosis and therapy, contrast agents for magnetic resonance imaging, safer mineral and vitamin supplements, new agents for the treatment of neurological, gastrointestinal and cardiovascular disease, skin conditions, cancer, and microbial and viral infections.The European scientific and technological research base in this area is potentially attractive for business. Industrial collaboration and cooperation can be accommodated within the COST framework.
Properties of Paramagnetic Metals in MRI
Authors: Schaefer Michel 
Published: March 2007

The use of different metals in Magnetic Resonance Imaging will be briefly described.This overview will be more a qualitative description than a full paper on this topic, in other words, this paper contributes to explaining how and why some metal ions have been chosen for MRI.Paramagnetic compounds are currently used in clinical practice. The main differencesin the four gadolinium complexes come from their different chemical structures. The macrocyclic compounds display a high symmetry and rigidity and therefore a high level of stability.All these four complexes display the same efficacyon the signal in MRI. In addition, they are very well tolerated.The second main class of compounds consists of the iron oxide superparamagnetic particles. They are used in the detection of focal liver lesions. Through their action in dephasing the spin, they are used as negative enhancers.
Ternary Complexes of cis‐ (cis‐DDP) With Guanosine (guo), Cytidine (cyd) and the Aminoacids Glycine (gly), L‐Alanine (ala), L‐2‐Aminobutyric Acid (2‐aba), L‐Norvaline (nval) and L‐Norleucine (nleu)
Authors: Katsarou Erasmia , Charalambopoulos Costas , Hadjiliadis Nick 
Published: March 2007

The ternary complexes of formulae cis‐[Pt(nucl)(amac)]NO3, where nucl = guo and cyd (guanosine and cytidine) and amac = the deprotonated aminoacids glycine (gly), L‐alanine (ala), L‐2‐aminobutyric acid (2‐aba), L‐norvaline (nval) and L‐norleucine (nleu), were prepared from the reactions of the binary chelated ones cis‐[Pt(amac)]NO3 with the nucleosides.They were characterized by  1H,  13C and  195Pt NMR and IR spectra, together with elemental analysis and conductivity measurements. The aminoacids coordinate with Pt(II) in the ternary complexes with their terminal ‐NH2 groups, guo through N7 and cyd through N3. Ligand‐ligand hydrophobic interactions were also observed in the ternary complexes and were stronger with longer aliphatic chains of the aminoacids. The  3E sugar conformation increased by 5‐7% in the ternary systems, as compared to the free nucleosides, while the percentage of the gg conformation remained almost constant and the one of the anti conformation of the sugar increased also slightly.
Finally, the h conformer around the Cα‐Cβ bonds of the aminoacids reached a maximum in the binary systems and decreased again considerably in the ternary ones.
Down‐Regulation of Porcine Heart Diaphorase Reactivity byTrimanganese Hexakis(3,5‐Diisopropylsalicylate),Mn3(3,5‐DIPS) 6 , andDown‐Regulation of Nitric Oxide Synthase Reactivity by Mn3(3,5‐DIPS) 6 and Cu(II) 2(3,5‐DIPS) 4
Authors: Booth Billynda L. , Pitters Eva , Mayer Bernd , Sorenson John R. J. 
Published: March 2007

Purposes of this work were to examine the plausible down‐regulation of porcine heart diaphorase (PHD) enzyme reactivity and nitric oxide synthase (NOS) enzyme reactivity by trimanganese hexakis(3,5‐diisopropylsalicylate), [Mn3(3,5‐DIPS) 6]
as well as dicopper tetrakis(3,5‐ diisopropylsalicylate, [Cu(II)2(3,5‐DIPS)4]
as a mechanistic accounting for their pharmacological activities.Porcine heart disease was found to oxidize 114 μM
reduced nicotinamide‐adenine‐ dinucleotide‐3′‐phosphate (NADPH) with a corresponding reduction of an equivalent concentration of 2,6‐dichlorophenolindophenol (DCPIP). As reported for Cu(II)2(3,5‐DIPS)4, addition of Mn3(3,5‐DIPS) 6
to this reaction mixture decreased the reduction of DCPIP without significantly affecting the oxidation of NADPH. The concentration of Mn3(3,5‐DIPS) 6
that produced a 50% decrease in DCPIP reduction (IC50)
was found to be 5 μM
. Mechanistically, this inhibition of DCPIP reduction with ongoing NADPH oxidation by PHD was found to be due to the ability of Mn3(3,5‐DIPS) 6
to serve as a catalytic electron acceptor for reduced PHD as had been reported for Cu(II)2(3,5‐DIPS)4. This catalytic decrease in reduction of DCPIP by Mn3(3,5‐DIPS) 6
was enhanced by the presence of a large concentration of DCPIP and decreased by the presence of a large concentration of NADPH, consistent with what had been observed for the activity of Cu(II)2(3,5‐DIPS)4Oxidation of NADPH by PHD in the presence of Mn3(3,5‐DIPS) 6
and the absence of DCPIP was linearly related to the concentration of added Mn3(3,5‐DIPS) 6
through the concentration range of 2.4 μM
to 38 μM
with a 50% recovery of NADPH oxidation by PHD at a concentration of 6 μM Mn3(3,5‐DIPS)6Conversion of [3H] L‐Arginine to [3H] L‐Citrulline by purified rat brain nitric oxide synthase (NOS) was decreased in a concentrated related fashion with the addition of Mn3(3,5‐DIPS) 6
as well as Cu(II)2(3,5‐DIPS)4
which is an extention of results reported earlier for Cu(II)2(3,5‐DIPS)4. The concentration of these two compounds required to produce a 50% decrease in L‐Citrulline synthesis by NOS, which may be due to down‐regulation of NOS, were 0.1 mM and 8μM
respectively, consistent with the relative potencies of these two complexes in preventing the reduction of Cytochrome c by NOS.It is concluded that Mn3(3,5‐DIPS) 6, as has been reported for Cu(II)2 (3,5‐DIPS)4
, serves as an electron acceptor in down‐regulating PHD and both of these complexes down‐regulate rat brain NOS reactivity. A decrease in NO synthesis in animal models of seizure and radiation injury may account for the anticonvulsant, radioprotectant, and radiorecovery activities of Mn3(3,5‐DIPS) 6
and Cu(II)2(3,5‐DIPS)4
.
Different Coordination Modes of a Tripod Phosphine in Gold(I) andSilver(I) Complexes
Authors: Sevillano P. , García M. E. , Habtemariam A. , Parsons S. , Sadler P. J. 
Published: March 2007

The following gold(I) and silver(I) complexes of the tritertiary phosphine 1,1,1‐
tris(diphenylphosphinomethyl)ethane, tripod , have been synthesised: Au3(tripod)X3
[X = Cl(1), Br(2), I(3)];
[Au3  (tripod)2Cl2  ]Cl
(4); Au(tripod)X [X = Br(5), I(6)];
(7), Ag(tripod)NO3
(8). They were
characterized by X‐ray diffraction (complexes 2, 3 and 4),  31P
NMR spectroscopy, electrospray and FAB mass
spectrometry and infrared spectroscopy. Complexes 2 and 3 show a linear coordination geometry for Au(I),
with relatively short Au‐P bond distances. Complex 3 has a Au•••Au
intramolecular distance of 3.326
,
while complex 2 had a short Au•••Au intermolecular interaction of 3.048
. Complexes 4-6 were found by
31P
NMR spectroscopy studies to contain a mixture of species in solution, one of which crystallised as
[Au3(tripod|)2Cl2]Cl which was shown by X‐ray diffraction to contain both tetrahedral and linear Au(I), the
first example of a Au(I) complex containing such a mixture of geometries. The reaction of [Au3(tripod)Cl3] (1)
with tripod led successfully to the formation of and
. The silver(I)
complexes, 7 and 8 appear to contain linear and tetrahedral Ag(I), respectively.