- Type of paper
: Paper in journal
Title: Tunnelling, Reaction Branching and Extreme Kinetic Isotope
Effects
- Authors:
- Ašperger, Smiljko (994)
Journal: Kemija u industriji
Number: 7
ISSN: 0022-9830
Volume: 40
Year: 1991
Pages: from 269 to 273
Number of references: 37
Language: hrvatski
Summary: The primary and secondary kinetic isotope effects of
hydrogenoffen exceed the maximum calculated values. Reaction branchingmay,
under certain conditions, give rise to unusually largekinetic isotope
effects. Extreme isotope effects of this originare sometimes accompanied by
anomalous temperature effects. Theseeffects can mimic those coused by
tunneling. The change ofmechanism may give rise to activation parameters
which also mimicthose of reactions with a large tunneling contribution,
assuggested by our results of solvolyses offerrocenyl-1,1-dideuteriomethyl
esters.
Keywords: kinetic isotope effects, tunnelling
- Type of paper
: Paper in journal
Title: Vitamin B12, the Secrets of its Mechanistic Actions
Involving Free Radicals
- Authors:
- Ašperger, Smiljko (994)
Journal: Kemija u industriji
Number: 5
ISSN: 0022-9830
Volume: 41
Year: 1993
Pages: from 177 to 181
Number of references: 23
Language: hrvatski
Summary: The article reviews what is known on vitamin B12
biologicalactivity. The first important step appears to be the
dissociationof the 5-deoxyadenosyl radical (homolytic disociation of
thecobalt-carbon bond), followed by abstraction of a hydrogen atomfrom the
substrate by 5'-deoxyadenosyl radical. The resultingsubstrate radical can
rearrange, the step that involvesdissociation of the beta-acyl group and
migration of this groupat what was initially the alfa-carabon to yield a
differentalkylated cobalamin.
Keywords: vitamin B12, free radicals, mechanism of action of vitamin B12
- Type of paper
: Paper in journal
Title: Steric Effects and Reactivity of Strictly Oriented
Molecules
- Authors:
- Ašperger, Smiljko (994)
Journal: Kemija u industriji
Number: 2
ISSN: 0022-9830
Volume: 42
Year: 1993
Pages: from 39 to 42
Number of references: 15
Language: hrvatski
Summary: Recent studies with molecular beams of symmetric top
molecules,and with molecular beams in the pendular states, formed
bysupersonic expansions of linear or asymmetric top molecules ataccessible
field strength, enable direct investigations of stericeffects and promise
basic contributions to the theory of chemicalkinetics.
Keywords: steric effects, reactivity of oriented molecules, oriented molecules
- Type of paper
: Paper in journal
Title: Sir Christopher Ingold-Pioneer of the Organic Reaction
Mechanisms
- Authors:
- Ašperger, Smiljko (994)
Journal: Kemija u industriji
Number: 12
ISSN: 0022-9830
Volume: 42
Year: 1993
Pages: from 461 to 462
Number of references: 1
Language: hrvatski
Summary: The scientific achievements of one of the great resarchers
of 20th century in chemistry, Sir Christopher Ingold, the pioneer ofthe
organic reaction mechanisms is described on the occasion ofits 100th bird
anniversary. Also his contributions to the theoryof the so called
octahedral substitutions on cobalt(III)complexes are mentioned.
Keywords: Sir Christopher Ingold, Ingold
- Type of paper
: Paper in journal
Title: Computer-aided Pharmaceutical Quality Control III: Purity
Determination by Defferential Scanning Calorimetry
- Authors:
- Grdinić, V.
- Bezjak, A.
- Janeković, A.
- Cetina-Čižmek, Biserka (121030)
- Briški, D.
Journal: Farmaceutski glasnik
Number: 7
ISSN: 0014-8202
Volume: 47
Year: 1991
Pages: from 195 to 204
Number of references: 15
Language: hrvatski
Summary: A computer program of DSC1 was designed for the final
ofprocessing data resulting from DSC method - purity determination.It
replaces and analyst in the process linearization ofexperimental data in
the calculation of total eutecticimpurities. The program is written in
QBASIC, for IBM-PC and IBMcompatibilic computers. Aplication of designed
algorithm is shownon specimen purity determination of sulfamethoxazole, as
ananlytical model.
Keywords: DSC method, a computer program of DSC1
- Type of paper
: Paper in journal
Title: Nomenclature, sympols and standards in thermal analysis
- Authors:
- Grdinić, V.
- Cetina-Čižmek, Biserka (121030)
- Janeković, A.
Journal: Farmaceutski glasnik
Number: 6
ISSN: 0014-8202
Volume: 48
Year: 1992
Pages: from 167 to 182
Number of references: 47
Language: hrvatski
Summary: A brief review article on nomenclature, symbols and
standards inthermal analysis, is presented. A review is composed
withparticular attention to applications in analysis ofpharmaceutical
materials. Nomenclature, definitions, symbols,acronyms, units, chemical
substances and other information aretabulated and recommended. Problems
connected with the similarityand dissimilarity of terms are discussed.
Moreover, an attempt tocompile a listing of the various Standard Reference
Materials(SRM), which were reported and recommended to be used for
thermalmeasurements, is made.
Keywords: thermal analysis, standards in thermal analysis
- Type of paper
: Paper in journal
Title: Long-Range Electron Transfer in Biological Systems
- Authors:
- Ašperger, Smiljko (994)
Journal: Kemija u industriji
Number: 7
ISSN: 0022-9830
Volume: 43
Year: 1994
Pages: from 305 to 308
Number of references: 19
Language: hrvatski
Summary: The electron transfer in biological systems involves
considerable distances, up to 3.5 nm). One group of investigators claim
that electron transfer rates are largely determined by the distance,
driving force and nuclear reorganization energy, as predicted by Marcus
theory. Other have shown that certain proteins expedite electron transfer
reactions or impede it. Electron transfer through cytochrome c is an
extremely efficient pathway for electron transfer.
Keywords: electron transfer, Marcus theory, biological systems
- Type of paper
: Paper in journal
Title: New Findings about the Shape of the SN2 Potential Surface
in Gas-Phase
- Authors:
- Ašperger, Smiljko (994)
Journal: Kemija u industriji
Number: 2
ISSN: 0022-9830
Volume: 43
Year: 1994
Pages: from 37 to 40
Number of references: 19
Language: hrvatski
Summary: In the SN2 reactions two flat plateaus for the energies of
reactants and products are separated by a transition state energy hill, the
energy of reactants and products being lower than that of the transition
state. Recently, it has been demonstrated that, under certain conditions in
the gas phase, the SN2 reactions can proceed over a double minimum
potential energy surface, with the energy of reactants higher than that of
the transition state.
Keywords: SN2 reactions, bimolecular nucleophylic substitution, transition state
- Type of paper
: Paper in journal
Title: Investigation of eutectic system with acetanilide and
phenacetine
- Authors:
- Cetina-Čižmek, Biserka (121030)
- Grdinić, V.
- Tudja, Marijan
Journal: Farmaceutski glasnik
Number: 1
ISSN: 0014-8202
Volume: 51
Year: 1995
Pages: from 1 to 6
Number of references: 9
Language: hrvatski
Summary: he determination of purity and the phase diagram of
eutectic system with acetanilide and phenacetine have been tested by the
classic methods and by DSC-method. The eutectic composition at Teu is 65
mole% acetanilide and 35 mole% phenacetine.
Keywords: acetanilide, phenacetine, eutectic system, DSC method
- Type of paper
: Paper in proceedings
Title: Secondary Kinetic Isotope Effectas and Tunnelling in the
Reactions of Ferrocenes
- Authors:
- Ašperger, Smiljko (994)
Proceedings title: Proceeding 13th Conference on Coordination Chemistry, Smolenice-Bratislava
Language: engleski
Place: Bratislava, Republika Slovačka
Year: 1991
Pages: from 3 to 6
Meeting: 13th Conference on Coordination Chemistry-Smolenice Bratislava
Held: from 06/11/91 to 06/14/91
Summary: Secondary alfa-deuterium kinetic isotope effect in
formolysis offerrocenyl-1,1-dideuteriomethyl benzoate amounts to
kH/kD(298K)=1.49+/-0.06, while in presence of 0.07 M LiClO4 the ratiois
1.50+/-0.04. The high values of the isotope effects stronglysuggest that
the reaction is a limiting dissociative process withthe carbonium ion
transition state.
Keywords: deuterium kinetic isotope effect, secondary alfa-deuterium kinetic isotope effect , ferrocenylmethyl benzoate-formolysis
- Type of paper
: Paper in proceedings
Title: Hrvoje Iveković-in memoriam
- Authors:
- Ašperger, Smiljko (994)
Proceedings title: Spomenica preminulim akademicima, svezak 69
Language: hrvatski
Place: Zagreb
Year: 1993
ISBN/ISSN: 1330-0865
Pages: from 9 to 21
Meeting: ....
Summary: The life accomplishment of academician Hrvoje Iveković
includingthe description of his main scientific achievements is given.
Thelist of publications contains about 150 references, also 3 books,2
patents, collection of poems, and translatations.
Keywords: Hrvoje Iveković
- Type of paper
: Paper in proceedings
Title: Ferrocens, Strong Electron Donors. A Mechanistic Approach
- Authors:
- Ašperger, Smiljko (994)
- Editors
- G. Ondrejovič, A. Sirota
Proceedings title: Current trends in coordination chemistry
Language: engleski
Place: Bratislava, Slovačka
Year: 1995
Pages: from 203 to 206
Meeting: 15th Conference on Coordination Chemistry
Held: from 06/05/95 to 06/09/95
Summary: We have previously observed that ethanolyses of
ferrocenyl-1,1-dideuteriomethyl acetate and benzoate exhibit a secondary
alfa-deuterium isotope effect (KIE) of about 12 % per D which is roughly
one half at the maximum KIE expected for the C-O bond cleavage. The
strongly reduced KIE indicates solvent participation in the reaction
transition statae, posibly also some Fe-Cexo bond formation. On the other
hand the KIEs in acetolysis and formolysis of
ferrocenyl-1,1-dideuterio-methyl benzoate are the largest ever observed for
a C-O bond cleavage suggesting that carbonium ion-like transition state is
stabilized mainly by conjugation with the pi-system of the pentadienyl
ring. Both acids have equal nucleophylicity, but the ionizing power of
formic acid is much larger than that of acetic acid. Nevertheless, the
solvolyses rates are almost equal, suggesting that the great ionization
power of formic acid is here of little importance. It is a happy
coincidence that both formic and acidic acids have exactly the same
nucleophylicity and that their reactions with ferrocenylmethyl benzoate
follow the same D-type machanism. The possible reason for the independence
of the rates of these solvolyses on solvent's ionizing power is discussed
in terms of the special electron-donating ability of the ferrocenyl system
and the dispersion of the positive charge of the ferrocenylmethyl cation
over the whole molecule.
Keywords: ferrocens, strong electron donors, KIE
- Type of paper
: Summary in proceedings
Title: Solvolysis of Ferrocenylmethyl Esters. Secondary
alfa-Deuterium Kinetic Isotope Effects, Tunneling, and Reaction Branching
- Authors:
- Ašperger, Smiljko (994)
- Kukrić, Z.
- Šutić, D.
Proceedings title: XII Sastanak kemičara Hrvatske, Sinopsisi/Abstract
Language: hrvatski
Place: Zagreb
Year: 1991
Pages: from 215 to 0
Meeting: XII Sastanak kemičara Hrvatske
Held: from 02/11/91 to 02/13/91
Summary: Secondary alfa-deuterium kinetic isotope effect, kH/kD,
(KIE) inacetolysis of ferrocenyl 1,1-dideuteriomethyl benzoate, inpresence
of 0.1 M LiClO4 amounts to 1.53 (23.7% per D). Almoustequal value is found
in formalysis. The rates of these reactionsexibit very abnormal temperature
dependence, which cannot beexplained by tunneling contribution only. More
likely it is theconsequence of reaction coplexity.
Keywords: secondary deuterium kinetic isotope effect, ferrocenylmethyl esters-solvolyses
- Type of paper
: Summary in proceedings
Title: Porphyrin Complexes of Cobalt(III): the Differences of
sigma and pi Bonding between Pyridine and Imidazole Type Entering Ligands
in Methanol
- Authors:
- Ašperger, Smiljko (994)
- Cetina-Čižmek, Biserka (121030)
- Orhanović, Mato
Proceedings title: XII Saastanak kemičara Hrvatske, Sinopsisi/Abstract
Language: hrvatski
Place: Zagreb
Year: 1991
Pages: from 216 to 0
Meeting: XII Sastanak kemičara Hrvatske
Held: from 02/11/91 to 02/13/91
Summary: The rates of replacements of MeOH by pyridine and imidazole
in/CoIIIP(MeO)(MeOH)/ (P=protoporphyrin IX dimethyl ester) weremeasured.
The energy of activation is appreciably lower forpyridine that for
imidazole. Also, the entropy of activation forpyridine entering ligand is
much more negative than that forimidazole. It can be infered that the
transition state withpyridine involves sigma and pi bonding while imidazole
is bondedin the transition state with sigma bond only.
Keywords: cobalt-protoporphyrins, kinetic and mechanism
- Type of paper
: Summary in proceedings
Title: Solvent Efects on the Rate of Dissociation of Complex
Cyanides of Iron(II). Reaction Mechanism
- Authors:
- Murati, I.
- Ašperger, Smiljko (994)
Proceedings title: XII Sastanak kemičara Hrvatske, Sinopsisi/Abstract
Language: hrvatski
Place: Zagreb
Year: 1991
Pages: from 217 to 0
Meeting: XII Sastanak kemičara Hrvatske
Held: from 02/11/91 to 02/13/91
Summary: Dimethylformamide, acetonitrile, methanol, ethanol,
glycerol andethylene glycol added to aqueous solutions of
/Fe(CN)6/4-,/Fe(CN)5NH3/3- and /Fe(CN)5C6H5NO/3- strongly accelerate
thedissociation of CN-. The largest acceleratio (60 times) wasobserved with
/Fe(CN)5NH3/3- in presence of dimethylformamide andacetonitrile. The
influence of solvent's electron-donorproperties and ionization power on
reaction kinetics indiscussed.
Keywords: complex cyanides of iron(II), solvent effects, kinetic of CN- disociation
- Type of paper
: Summary in proceedings
Title: Usual Change of Mechanism of Acetolysis and Formolysis of
Ferrocenylmethyl Benzoate in Temperature Span of 25 K
- Authors:
- Ašperger, Smiljko (994)
- Kukrić, Z.
- Saunders, W. H.
- Šutić, D.
Proceedings title: 29th International Conference on Coordination Chamistry
Language: engleski
Place: Lausanne, Švicarska
Year: 1992
Pages: from 153 to 0
Meeting: 29th International Conference on Coordination Chemistry
Held: from 07/19/92 to 07/24/92
Summary: Acetolysis and formalysis of
dideuterioferrocenylmethylbenzoate, in presence of 0.1 M LiClO4, exibits a
secondaryalfa-deuterium kinetic isotope effect (KIE) of 23.8 and 21.7% perD
(geometric mean), respectively. This is one of the largest KIEsobserved for
C-O cleavage. In the presence of LiClO4 the ratiosof Arrhenius
pre-exponential factors are 0.49 (acetolysis) and0.38 (formalysis). In the
absence of LiClO4 the ratios are 0.02only. This surprisingly low value
results from a charge inmechanism over the 25 K temperature range. The
mechanism isdiscussed.
Keywords: secondary deuterium kinetic isotope effect, ferrocenylmethyl benzoate, acetolysis, formolysis
- Type of paper
: Summary in proceedings
Title: Sigma and pi Bonds of Amine Ligands in Transition States
of Reactions with Cobalt Porphyrin Complexes
- Authors:
- Ašperger, Smiljko (994)
- Cetina-Čižmek, Biserka (121030)
Proceedings title: XIII Skup hrvatskih kemičara, Sinopsisi/Abstract
Language: hrvatski
Place: Zagreb
Year: 1993
Pages: from 257 to 0
Meeting: XIII Skup hrvatskih kemičara
Held: from 02/08/93 to 02/10/93
Summary: In the reaction of /CoIII(protoporphyrin IX
dimethylester)(MeO)(MeOH)/ with a series of amine ligands of
variousbasisicity and pi bonding ability it was found that thecombination
of sigma plus pi bonding better stabilize thereaction transition state than
the lone sigma bond, regardless ofits strength.
Keywords: cobalt-protoporphyrins, substitution reactions, kinetic and mechanism
- Type of paper
: Summary in proceedings
Title: Reactions of Aqua-, Hydroxo-, and Cyano-Cobalamines with
Cyanide
- Authors:
- Ašperger, Smiljko (994)
- Cetina-Čižmek, Biserka (121030)
Proceedings title: XIII Skup hrvatskih kemičara, Sinopsisi/Abstract
Language: hrvatski
Place: Zagreb
Year: 1993
Pages: from 256 to 0
Meeting: XIII Skup hrvatskih kemičara
Held: from 02/08/93 to 02/10/93
Summary: In the reaction of aqua-cobalamine (H2O-Cbl) with CN- in
aqueoussolution the bonded water is first replaced by OH- (formed
byhydrolysis of CN-), which can be noticed spectrophotometrically.The
nucleotide base is still connected to cobalt. By increasingCN-
concentration HO-Cbl is transformed to CN-Cbl and thenucleotide base is
detached.
Keywords: cobalamines, cyanocobalamines
- Type of paper
: Summary in proceedings
Title: Amine ligands bonding modes in Co-porphyrins
- Authors:
- Cetina-Čižmek, Biserka (121030)
- Ašperger, Smiljko (994)
- Editors
- Kemija u industriji,
Proceedings title: XIV Skup Hrvatskih kemičara, Sinopsisi/Abstract
Language: hrvatski
Place: Zagreb
Year: 1995
Pages: from C215 to C215
Meeting: XIV Skup hrvatskih kemičara
Held: from 02/06/95 to 02/08/95
Summary: See sažetak
Keywords: Co(III)-porphyrins, amine ligands
- Type of paper
: Summary in proceedings
Title: Rate Dependence of Solvolysis of Ferrocenylmethyl Benzoate
on Solvent's Ionizing Power
- Authors:
- Ašperger, Smiljko (994)
- Editors
- Kemija u industriji,
Proceedings title: XIV Skup hrvatskih kemičara, Sinopsisi/Abstract
Language: hrvatski
Place: Zagreb
Year: 1995
Pages: from C216 to C216
Meeting: XIV Skup hrvatskih kemičara
Held: from 02/06/95 to 02/08/95
Summary: See sažetak.
- Type of paper
: Summary in proceedings
Title: Metrological limits for tinidazole impurity in
metronidazole
- Authors:
- Grdinić, V.
- Cetina-Čižmek, Biserka (121030)
- Radaić, Alida
- Tudja, Marijan
- Editors
- Europ.Jour.Pharm.Sci,
Proceedings title: Second European Congress of Pharmaceutical Sciences, Abstracts
Language: engleski
Place: Berlin, Njemačka
Year: 1994
Pages: from 157 to 157
Meeting: Second European Congress of Pharmaceutical Sciences
Held: from 09/29/94 to 10/01/94
Summary: A comperative study, including investigation of accuracy
limits, was provided ba two methods, phase solubility (PSA) and
differential scanning calorimetry (DSC), designed on different degree of
tinidazole impurity in range of 1-8 mass%. Using obtained analytical
functions it was possible to realize the relationship between the added
tinidazole impurity and detected one, and metrological limits of PSA and
DSC, respectively.Accuracy for both methods were convenient, but PSA has
been a little bit more sensitive.
Keywords: metronidazole, tinidazole, PSA, DSC
- Type of paper
: Ph.D.
Title: Cobalt(III) porphyrins. Sigma and pi bonding of entering
ligands and dynamic of reactions
Faculty: Farmaceutsko-biokemijski fakultet Sveučilište u Zagrebu
Author: CETINA-ČIŽMEK BISERKA
Date of defense: 04/20/95
Language: hrvatski
Number of pages: 102
Summary: The rate of replacement of MeOH by pyridine and imidazole
and their adducts L in Co(III)P(MeOH)(MeOH) (P=protoporphyrin IX dimethyl
ester) in methanol, were measured by stopped-flow technique.The energies
and entropies of activation increase in a smoot manner by increasing pKa of
LH+. The plot of ln kobs vs. pKa of pyridine and its adducts exhibits a
minimum rate. The obtained "V" diagram is explaned as beeing due to a
change in the electronic transition state from predominantly pi bonding to
predominently sigma bonding, as the pKa of LH+ is increased. Imidazols show
a similar trend but their rates levell off at high pKa. It is inferred that
the transition state between Co(III)P(MeO) intermediate and L is more
sensitive to the change in the strength of pi bonding than in that of sigma
bonding.
Keywords: porphyrin, Co(III) porphyrins, kinetics of substitution
- Type of paper
: Mentorship
Title: Cobalt(III) porphyrins. Sigma and pi bonding of entering
ligands and dynamic of reactions
Faculty: Farmaceutsko-biokemijski fakultet Sveučilište u Zagrebu
Mentor: AŠPERGER SMILJKO
Date of defense: 04/28/95
Number of pages: 102
Author: Cetina-Čižmek Biserka
Degree level: Ph.D.
- Type of paper
: Invited lecture
Title:
Institution: Institut "Ruđer Bošković
Year: 1994
