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Powinowactwo O2 i CO do hem kompleksów
Modelowy hem kompleks
Mioglobina, hemoglobina
Wymuszona geometria
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Definicja wiazania wodorowego
Latimer and Rodebush (1920) Water shows
tendencies both to add and give up hydrogen,
which are nearly balanced. Then a free pair
of electrons on another water molecule might be
able to exert sufficient force on a hydrogen held
by a pair of electrons on another water molecule
to bind the two molecules together. Such an
explanation amounts to saying that the hydrogen
nucleus held between two octets constitutes a
weak bond. Pauling (1940) It has been
recognized in recent years that under certain
conditions an atom of hydrogen is attracted by
rather strong forces to two atoms, instead of
only one, so that it may be considered to be
acting as a bond between them. This is called the
hydrogen bond. It is now recognized that the
hydrogen bond is largely ionic in character, and
is formed only between the most electronegative
atoms. Although the hydrogen bond is not a strong
bond (its bond energy being only about 5
kcal/mol), it has great significance in
determining the properties of substances. Pimentel
and McClellan (1960) A hydrogen bond exists
between a functional group AH and an atom or a
group of atoms B in the same or a different
molecule when there is evidence of bond
formation (association or chelation) there is
evidence that this new bond linking AH and B
specifically involves the hydrogen atom already
bonded to A. Zeegers-Huyskens and Huyskens
(1991) Specific interactions are short-range
site bounded cohesion forces that considerably
weaken a given chemical bond involves Popelier
(1998) The criteria for the existence of
H-bonding are as follows I . VII
. Hobza (2000) It is not easy to define H-bonds
to include all the featyres ascribed to it by the
different branches of science. Hydrogen bond
always describe an attractive interaction between
two species where the hydrogen atom is placed in
between of these species.
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Natura wiazania wodorowego
It is well recognized that hydrogen bonds are
substantially electrostatic in nature. J. Org.
Chem. 65, 2000, 1448. The hydrogen bond is a
covalent, not an ionic, bond. Angew. Chem. Int.
Ed. 39, 2000, 717.
The hydrogen bond is, at variance with
widespread belief, not a pure or essentially
electrostatic phenomenon. Chem. Eur. J. 5, 1999,
3581. These results are consistent with recent
NMR and X-ray observations, which show that
hydrogen bonding interactions have a significant
covalent character as opposed to the traditional
purely electrostatic view. J. Am. Chem. Soc.,
121, 1999, 9182.
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Covalency of the hydrogen bond in ice A direct
X-ray measurement. Phys. Rev. Lett. 65, 2000,
1448.
Hydrogen bonds are the chemical bonds that exist
between H2O molecules and keep them together.
Recent experiments have obtained new insights on
the hydrogen bond, by shining x-rays of one color
(blue arrow) on an ice crystal and analyzing the
color and direction of the x-rays (red arrow)
that emerge from the ice.
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Wiazanie wodorowe
donor
akceptor
HOHOH2 11,6 kJ/mol
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Definicja parametrów geometrycznych oraz
konfiguracja wiazan wodorowych
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Mocne wiazanie wodorowe
donory wiazania wodorowego
akceptory wiazania wodorowego
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Normalne wiazania wodorowe miekkie oddzialywania
donory wiazania wodorowego
akceptory wiazania wodorowego
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Slabe wiazania wodorowe
- donory wiazania wodorowego
- kierunkowosc wiazania wodorowego
wiazanie wodorowe
wiazanie wodorowe???
brak wiazania wodorowego
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Typy wiazan wodorowych
A - weak or double-well H-bonds (z
podwójna studnia potencjalu) B - low-barrier
H-bonds (LBHBs) C - very strong or single-well
H-bonds (z pojedyncza studnia potencjalu)
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Schematyczna reprezentacja potencjalu wiazania
wodorowego w funkcji odleglosci
E.P
destabilizacja
d
d0
0
stabilizacja

• kcal/mol
• preferowany obszar wystepowania

odpychanie przyciaganie
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AH--D
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Energia niekowalencyjnych oddzialywan
miedzyczasteczkowych

• Oddzialywanie jon dipol 50 200 kJmol-1
• Oddzialywanie dipol dipol 5 50 kJmol-1
• Wiazanie wodorowe 4 120 kJmol-1
• Oddzialywanie kation ? 5 80 kJmol-1
• Oddzialywanie ? ? 0 50 kJmol-1
• Oddzialywanie van der Waalsa lt 5 kJmol-1

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Oddzialywanie ? ? p - stacking
Struktura krystaliczna AIMe(C6F5)m-Me)2
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Struktura krystaliczna GaMe(C6F5)2
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Dimer i pentamer wody w oparciu o teoretyczne
obliczenia, NBO (Natural Bond Orbital)
Wizualizacja nakladania sie wolnej pary tlenu i
orbitalu antywiazacego sOH
HOHOH2 11,6 kJ/mol
HOHOH2 20 kJ/mol
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Tworzenie sie wiazania wodorowego.
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Kierunkowosc i komplementarnosc oddzialywan
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Komplementarnosc oddzialywan w prostych
klasterach wody i metanolu
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• Uklady tworzace sie w wyniku wiazan wodorowych
• lancuchy
• izolowane pierscienie
• uklady sieciowe

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Klastery wody
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Klastery wody
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2,4-Dimetylo-5-aminobenzo-1,8-naftylhydrina (DAN)
Gospodarz -
Samoorganizacja czasteczek wody
Upakowanie w krysztale DAN2.5H2O
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Struktura 1h lodu
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Hydraty metanu
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Gas hydrate is an ice-like crystalline compound
that concentrates molecules of combustible gases
within its structure. This image shows burning
gas hydrate, which can sustain a flame as the gas
is released from the structure during heating.
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Obszary wystpowania hydratów metanu
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Przyklad klasteru
CH4(H2O)6
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Water cluster architecture, based on gas
clathrates