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Experiment 1






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Experiment 1 . Synthesis of Potassium tris(oxalato)aluminate & Synthesis of Tris(8-hydroxy quinolonine)aluminium(III) . Aluminium. Aluminium is the element in the periodic table that has the symbol Al and atomic number 13.
Experiment 1

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Slide 1

Experiment 1

Synthesis of Potassium tris(oxalato)aluminate

&

Synthesis of Tris(8-hydroxy quinolonine)aluminium(III)

Slide 2

Aluminium

  • Aluminium is the element in the periodic table that has the symbol Al and atomic number 13.

  • It’s the third most abundant element in the Earth's crust and constitutes 7.3% by mass.

  • In nature it only exists in very stable combinations with other materials mainly as substituted aluminium silicates and aluminium oxides.

  • It has nine isotopes, whose mass numbers range from 23 to 30.

Slide 3

  • In 1808, Sir Humphry Davy, from Britain, established the existence of aluminium and named it.

  • In 1827, Friedrich Wöhler, from Germany, described a process for producing aluminium as a powder by reacting potassium with anhydrous aluminium chloride.

  • The basis for all aluminium production today is dissolving aluminium oxide (Al2O3) in a bath of molten cryolite and passing a powerful electric current through it causing molten aluminium to be deposited at the bottom of the bath.

Slide 4

Aluminium Properties

  • Is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when exposed to air.

  • Malleable, ductile, has excellent corrosion resistance and durability due to the protective oxide layer, and is a good heat conductor.

  • Readily forms alloys with many elements such as copper, zinc, magnesium, manganese and silicon.

Slide 5

Applications of Aluminium

  • Aircrafts: Aluminium is the primary aircraft material due to its lightweight, strength, workability, and the ability of wafer thin aluminium panels to keep the cold out and the air in.

  • Road and Sea Transport: It makes a key contribution to fuel-efficient engines in cars and trucks as well as to high speed rail and sea travel. Moreover, it makes cars safer due to its role as a shock absorber.

Slide 6

  • Construction: Attractive in this field due to its resistance to corrosion and its lightweight.

  • Cookware: Around half the cookware sold globally each year is made of aluminium since it loses only about seven per cent of the heat it receives, leaving 93 percent of the heat to cook your food, and because of its corrosion resistance.

  • Packaging: Can be rolled into ultra-thin foils which are recyclable, light, strong and have unique barrier and insulation qualities to preserve food, cosmetics, pharmaceutical products and protect from ultra-violet light, odours and bacteria.

Slide 7

  • Electrical Applications: Due to its high conductivity, most high-voltage overhead transmission and distribution lines are made of aluminium, in addition to light bulbs, antennas, and satellite dishes.

  • Chemical Applications: Mainly it is used as a catalyst (most popular forms are aluminum hydride and aluminum chloride) due to its strong acidic properties.

Slide 8

Potassium tris(oxalato)aluminate Trihydrate

Structure:

K3[Al(C2O4)3].3H2O

  • As shown, the metal Al atom is octahedrally coordinated by 3 bidentate oxalate groups.

  • The oxalate ligands are out of the plane of Al except for the 3rd ligand which is almost planar to Al.

Slide 9

  • The species interact through electrostatic interactions and hydrogen bonding.

  • One of the H2O molecules and K+ ions are cooperatively disordered.

  • The remaining two K+ ions have six bonds to the oxygen atoms of the two H2O molecules and the oxalate anions.

  • The two H2O molecules have hydrogen bonds to other oxygen atoms of water and oxalate in addition to their electrostatic interaction with the K+ ions.

Slide 10

Purpose of Experiment

  • It gives students an experience in preparing and analyzing a compound.

  • Students get excited due to the vigorous reactions that accompany the preparation.

Slide 11

Tris(8-hydroxy quinolonine)aluminium(III)

  • Structure:

  • Alq3 has two isomeric forms, facial and meridianal.

  • The fac isomer has 3 oxygen atoms and three nitrogen atoms on opposite faces of the octahedron.

Slide 12

  • The mer isomer is asymmetric with a C1 point group symmetry, whereas the fac isomer has a C3 point group symmetry.

  • The mer isomer is more stable in energy, but the fac isomer has a larger dipole moment which stabilizes it in the condensed phase.

Slide 13

Applications of Alq3

  • It has a promising use in OLEDs due to its stability, electron transport, emitting properties, and easy wide area deposition and low cost purification.

Slide 14

Principles of the OLEDs

  • The OLED (Organic Light Emitting Diode) works by sandwiching a polymer (in this case Alq3) between a cathode (a reflective metal) and an anode (a transparent substrate with a thin film of Indium Tin Oxide (ITO).

  • The cathode provides the electrons whereas the anode is the source of the holes.

Slide 15

  • Thus by applying a voltage (usually not so high) the electrons are injected into the conduction band of the polymer and the holes are injected into the valence band as shown in the figure below :

-

-

-

-

-

EF

eU

EF

+

+

+

+

+

Cathode

Anode

Slide 16

  • The electrons and holes move by diffusion across the polymer until they recombine in an excited state, which then decay to the ground state, emitting light.


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