1. Lecture 20. The d-Block Elements. VII-VIII B groups
PhD. Halina Falfushynska

2. Manganese
Manganese is obtained mainly from the mineral pyrolusite, MnO2.
Ferromanganese alloys are wear resistant and shock resistant and are used for railroad tracks, bulldozers, and road scrapers.
Manganese(IV) oxide is the starting point for making most other manganese compounds.
Potassium permanganate, KMnO4, is an important oxidizing agent that is used in both analytical and organic chemistry laboratories, and in water treatment.

3. The Iron Triad: Fe, Co, and Ni
Iron is the fourth most abundant element in Earth’s crust. Cobalt and nickel are not nearly as common.
All three elements form 2+ and 3+ ions.
The most common ions of Co and of Ni are the 2+. The most common ion of Fe is the 3+ due to the half-filled d-subshell:

4. Ferromagnetism
The iron triad exhibits ferromagnetism which is a much stronger magnetic effect than paramagnetism.
A ferromagnetic solid consists of regions called domains in which atoms have their magnetic moments aligned.
When placed in a magnetic field, all the domains are aligned and the solid becomes magnetized.

7. Manganese Mn (Manganum)
Manganese Mn (Manganum)
trace element
cofactor of enzymes: superoxide dismutase
pyruvate carboxylase
KMnO Potassium permanganate (INN: Kalii permanganas)
- in water dissolves to give deep purple solutions
- strong oxidizing agent
- dilute solutions can act as desinfectant

8. Biological role of Manganese
Manganese is required for the metabolism of proteins and fats.  A partial list of manganese-dependent enzyme families includes oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. 
Manganese is involved in the function of numerous organ systems and is needed for normal immune function, regulation of blood sugars, production of cellular energy, reproduction, digestion, and bone growth.  Manganese works with vitamin K to support clotting of the blood.
  The National Research Council has recommended an Estimated Safe and Adequate Daily Dietary Intake (ESADDI) for Mn of 2 to 5 mg per day for adults.

9. Manganese in pharmacy
Manganese has been examined as a treatment for a variety of conditions, including osteoarthritis and wound healing. However, manganese is often used in combination with other vitamins and/or minerals. Therefore, the effects of manganese alone are difficult to determine.
Manganese in combination with calcium and zinc may be beneficial in patients with chronic wounds.
A combination of calcium and manganese may alleviate symptoms associated with premenstrual syndrome.

15. Source of manganese
Excellent food sources of manganese include mustard greens, kale, chard, raspberries, pineapple, strawberries, romaine lettuce, collard greens, spinach, garlic, summer squash, grapes, turnip greens, eggplant, brown rice, blackstrap molasses, maple syrup, cloves, cinnamon, thyme, black pepper, and turmeric.

16. Fe in food 10-30 mg/day absorption: only 7-10%  ~ 1 mg/day
Iron Fe (Ferrum)
important microelement
human body: 4–5 g Fe
a) functional form - heme iron proteins hemoglobin 70 % myoglobin %
some enzymes
- non-heme iron proteins
b) tranport form (transferrin)
c) storage of iron (ferritin, hemosiderin)-20 %
Fe in food mg/day absorption: only 7-10%  ~ 1 mg/day

21. HEME iron proteins Hemoglobin - O2 transport in blood
HEME iron proteins
Hemoglobin - O2 transport in blood
- in red blood cells
- tetramer = 4 subunits
(each subunit: one heme + one globin)
HbA ("adult") a2b2
HbF ("fetal") a2g2
Myoglobin - "O2 storage" in muscle cell
Cytochromes - electron transport
- their function is based on: Fe2+ (reduced) Fe3+ (oxidized)
heme

22. iron–sulphur proteins (FeS proteins)
Non-heme iron proteins FeII or FeIII bound to protein SH
iron–sulphur proteins (FeS proteins)
Transferrin - blood plasma protein ( b1 globulin )
- transport of Fe
- 1 molecule of transferrin can carry 2 iron ions in form of Fe3+
Ferritin - intracellular iron storage protein (liver, bone marrow)
- 1 ferritin complex can store about 4500 Fe3+
- ferritin without iron = apoferritin
Hemosiderin - "damaged (Fe-overloaded) ferritin" - Fe from it is less available

23. OVERVIEW OF IRON METABOLISM
OVERVIEW OF IRON METABOLISM
liver
FERRITIN
HEMOSIDERIN
blood plasma
TRANSFERRIN
bone marrow
red blood cells
HEMOGLOBIN
spleen
tissues
CYTOCHROMES
Fe-S proteins
muscles
MYOGLOBIN
BLEEDING (Fe losses)
FOOD

24. Iron metabolism = unique - reutilization ! (closed system)
Iron metabolism = unique
- reutilization ! (closed system)
NO regulated excretion system for Fe !
Fe absorption must be "regulated"
Loss of Fe  through loss of blood (females mestrual bleeding)
Iron deficiency - microcytic anemia "iron deficiency anemia"
Iron overload - hemochromatosis = accumulation of iron in the body
(depositions as hemosiderin)
organ dysfunction (liver, heart, ...)

25. IRON ABSORPTION FOOD Fe3+ STOMACH Fe2+ Fe3+ BLOOD transferrin (Fe3+)
IRON ABSORPTION
FOOD Fe3+
STOMACH
HCl pH 1-2
ascorbic acid
gastroferrin - iron binding protein
reduction
Fe2+
Fe3+
BLOOD
transferrin (Fe3+)
ferritin (Fe3+)
apoferritin
Fe2+
INTESTINAL MUCOSA CELL

27. Measurement of Iron (Phenanthroline Method)
Interferences : Phosphate
Heavy metals
1,10 phenonthroline combines with Fe2+ to form complex ion orange in red color
Color produced confirms Beer’s Law
Visual
Photometric comparison

28. Phenanthroline Method
Sample exposed to atmospfere contains Fe2+ , Fe3+ , ppt of ferric hydroxide.
All iron  must be in soluble form
HCl is used
Fe(OH)3 + 3 H+  Fe H2O
1,10 phenonthroline  specific for measuring Fe(II)
Fe3+ is reduced to Fe2+
Hydroxylamine is used as reducing agent
4Fe(III) + 2 NH2OH  4Fe(II) + N2O + H2O + 4 H+
3 molecules of 1,10 phenantrhroline complex with each Fe2+

29. Manganese measurement
Colorimetric method  depend upon oxidation of Mn to  VII
forms highly colored permanganete ion
Obeys Beer’s Law
Visual or photometric comparison
AAS
ICP

30. Manganese measurement (Persulphate Method)
Ammonium persulphate  oxidizing agent
Cl- interference: Because of reducing action in acid medium.
use Hg2+ for interference. HgCl2 complex is formed
Ag2+ is used as catalyst
Oxidation of Mn in lower valence to permanganete by persulfate.
Ag+
2Mn2++5S2O82- +8H2O  2MnO4- +10SO H+
(permanganete colored)