cryptate is one of type of macrocyclic ligand. please note there are typing mistakes in the introduction discovering year is 1968.

1. INORGANIC CHEMISTRY
CRYPTATSE
By ,
T.DEEPA M.sc chemistry 1st yr

2. INTRODUCTION
• CRYPTATSE also known as CRYPTAND.
• Cryptand were discovered by French Chemists Jean-Marie lehn in 1987.
• This French chemists got Noble prize for Chemistry [Discovering &Determining uses] of cryptatse in
1987.
• Cryptand is poly ,di & macrocyclic ligand giving rise to different shape of complexes based on ethereal
oxygen donor atom.

3. STRUCTURE OF CRYPTATSE
• Cryptand word refer to crypt –internal cavity ,intramolecular cavity & hidden. and represent ligand.
• Cryptand bi or tricyclic or multicyclic can provide the cage structure to accommodate the metal ion
&other guest species.
• The cavity size to wrap around or hide alkali cation of different sizes ,with difference strength of
complexation .
• Cryptates are more potent ,selective & even stronger complexing agent for alkali metal .
• And also show high & low complexing ability metal ion of alkaline earth metal ,a few transition &
lanthanides ions.
• Here cryptand are nitrogenous macrocyclic compound with 3- dimensional intramolecular cavities.

4. • The molecules are appropriately cross linked with donor atom [ethereal oxygen] correctly positioned in the bridging group
[N-N] to encapsulate metal ion like a cage structure.
• Basic structure of cryptand is crypt [222].
• which is also known has football ligand.
• Chemical formula for cryptand [222] is N[CH2 CH2 O CH2 CH2 CH2 O CH2 CH2]3N
• 222 is a denotes ethereal oxygen atom.
• Bridged form structure

5. • This image represent synthesis of cryptand in the presence of sutiable alkali metal ion like k+.
• This ligand is a very high formation of complexes constants.
• OCTOPUS LIGANDS
• Marocycles polydentate ligands are not only for production stable alkali complexes.
• Additional conformational flexibility without loss of coordinating power can be achieved with 2-6 pendant mercapto-
polyether group C6H6-nRn where R is –SC2H4OC2H4Me,-S[C2H4O]3Bu etc.
• This ligand are called octopus ligands are more effective as crypt sequestering [form chelate or other compound & used
to prevent chemical effect of an ion without removing it from the solution ] alkali metal cation.

6. • PROPERTIES
1. COMPLEXES WITH ALKALI METALS
• The stability of complexes with common ligands were low & generally found to decrease
In the sequence.
• Li > Na > K > Rb > Cs
• The ligands shows selectively among alkalies in forming complexes.
• It form stable complexes with alkali cation and other metal cation.
• It survive definitely in aqueous solution as well.
• For crypt [222] K+ is appropriate to fit in the cavity.
• But Li+, Na+ are too small Rb+, Cs+ are too big to form stable complexes.
• In crypt 211,221 & another type of ligands [octopus ligands] however, form their most stable complexes with Li+ & Na+.

7. • The stability depends upon :
I. Size of the metal ion.
II. Number ethereal oxygen.
III. Geometric diposition of ethereal oxygen atom.
IV. Size & shape of the macrocycle.

8. 2] ANIONIC CRYPT
• cationic crypt has dominated in its complexes with alkali & a few
other metal cation for a long time.
• Likewise ,anionic crypt have also come into existence.
• Polyamine – based cryptands can be converted to polyammonium
cages.
• Which exhibit high affinities for anions .

9. 3] SEPULCHRATES
• A group of multicyclic encapsulating ligands called sepulchrates are
closely related to football ligands .
• This are synthesized around a metal ion which cannot be released.
• Sepulchrates are stable over PH ranges which makes easier the
investigation of solution chemistry of elements Mo ,W .
• Which are tendency to hydrolysis & polymerization by changes in PH.

10. 4] SIZE
• The cavity diameter of cryptands increase with increasing no: of oxygen donor sites.
• It is evident that for Li+, Na+, K+, the most stable cryptands [211], [221] ,[222].
5] OTHER PROPERTIES
• This complexes resulting lipophilic.
• Some cryptands are lumiscent.

11. • APPLICATIONS
• Cryptand are used to
• preparative organic chemistry
• Solvent extraction
• Phase transfer catalysis
• Reactive oxidation states
• Solubility of alkali metals salts in organic media can be promoted crypts due to presence of hydrophobic organic
ring in the ligand .
• Eg:KOH & KMno4 can be used an alkali an oxidizing agent .
• ZINTL SALTS :
• A number of zintl salts [containing alkali metal cation & zintl anions ]
Been prepared with the help crypt in anhydrous solvent .
• Crypt, the study is not yet complrte . It’s also used for biochemical process involving metal ions.
• Cryptand is used to study a new concept supramolecular chemistry entirely.
• Cryptand enabled the synthesis of the alkalides & electrides
• Many cryptand are commercially available under the trade name kryptofix.